JP2737086B2 - 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 becomes extremely complicated, so that 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]

According to the first aspect of the present invention, the main combustion chambers (17) are formed at positions opposed to the tops of the pistons (1) of the cylinders adjacent to each other, and the main combustion chambers (17) are provided adjacent to each other. One end of a main exhaust passage (4d) opened and closed by an exhaust valve (7) is opened at a portion on one side of the center plane (C) connecting the axes of the pistons (1). The main intake passage (4), which is opened and closed by an intake valve (6) at a portion on the other side of
In a four-cycle engine in which one end of c) is opened and a spark plug mounting hole (16) is provided at the center of each main combustion chamber (17), these main combustion chambers (17) are located between the main combustion chambers (17). A sub-combustion chamber (18) that constantly communicates with the combustion chamber (17)
And a sub-exhaust passage (4g) is formed at one side of the sub-combustion chamber (18), which is deviated toward the exhaust valve (7) from a center plane (C) connecting the piston axes. One end is opened, and a sub-exhaust valve (10) that opens and closes the sub-combustion chamber (18) is provided in the opening. (6) One end of the sub intake passage (4f) is opened at the other side portion deviated to the side, and a sub intake valve (9) for opening and closing the sub intake chamber (18) is provided at the opening. doing.

In the invention described in claim 2, the auxiliary combustion chamber (1
The auxiliary spark plug mounting hole (20) is arranged on the line connecting the spark plug mounting hole (16) in 8).

[Action]

According to the above configuration, the air-fuel mixture is sucked into the adjacent main combustion chamber (17) communicated by the sub-combustion chamber (18) 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 type engine mounted on a motorcycle.

As shown in FIGS. 2 and 3, this engine
It includes a pair of pistons 1, 1 provided 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 are connected to each other at their circumferential upper ends, and 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 suitable for 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 opposite to the tops of the pistons 1, 1, respectively, and have one end opening of a main intake port (main intake passage) 4c and a main exhaust port (main exhaust port) therein. Each of the passages 4d has two one-end openings, and ignition plug mounting holes 16, 16 for mounting an ignition plug (not shown) at the center of each of the openings.

The main intake ports 4c, 4c, 4c, 4c and the main exhaust ports 4d, 4d, 4d, 4d each have an opening at one end of the recess 4b,
4b, one row is arranged along the longitudinal direction of the cylinder head 4 at a portion on one side and a portion on the other side of the center plane C connecting the axial centers of the adjacent pistons 1 and 1 in the cylinder head 4. The other ends of the cylinder heads 4 are open to opposite side walls of the cylinder head 4. As is clear from the figure, the main intake ports 4c, 4c, 4c, 4c and the main exhaust ports 4d, 4d, 4d, 4d merge at the respective other ends corresponding to the recesses 4b, 4b. ing. The other end of each of the main intake ports 4c, 4c, 4c, 4c has a recess 4b, 4b.
Are connected to the vaporizers 5 having the same diameter.

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 by the intake valve camshaft 11 disposed on the cylinder head 4 at the same time.

The exhaust valves 7, 7, 7, 7 are connected to the main exhaust ports 4d, 4d, 4
The openings d and 4d are arranged to be opened and closed, and are simultaneously opened and closed at the same time by an exhaust valve cam shaft 12 arranged on the cylinder head 4.

Further, the cylinder head 4 has a connecting recess 4e on the cylinder block mounting surface 4a. This connecting recess 4e
Is formed between the adjacent concave portions 4b, 4b, and connects the pair of concave portions 4b, 4b to each other.

One end of each of a sub-intake port (sub-intake passage) 4f and a sub-exhaust port (sub-exhaust passage) 4g is opened in the connection recess 4e, and a pair of sub ignition plug mounting holes is formed in the center thereof. 20 are open.

The sub intake port 4f is formed between the main intake ports 4c, 4c, 4c, 4c communicating with the respective recesses 4b, 4b, and one end opening thereof is open at one end of the main intake ports 4c, 4c, 4c, 4c. While the other end opens between the openings of the main intake ports 4c, 4c, 4c, 4c on the side wall of the cylinder head 4, and further, the main intake port 4c, 4c, 4c, a vaporizer 8 having a smaller diameter than the vaporizer 5, 5 connected to 4c is held.

The sub-exhaust port 4g is formed between the main exhaust ports 4d, 4d, 4d, 4d communicating with the respective recesses 4b, 4b, and one end opening thereof is formed at the main exhaust port 4d, 4d, 4d.
The openings at the same arrangement as the one end openings of d and 4d are opened, while the other end openings are opened between the openings of the main exhaust ports 4d, 4d, 4d and 4d on the side wall of the cylinder head 4.

The auxiliary ignition plug mounting holes 20 are arranged side by side on a line connecting the ignition plug mounting holes 16, 16 of the recesses 4b, 4b described above, and each hold an unillustrated ignition wire.

Further, a sub intake valve 9 and a sub exhaust valve 10 are provided in the connection recess 4e. These auxiliary intake valves 9
As shown in FIG. 4, the sub exhaust valve 10 is disposed at a position to open and close one end of each of the sub intake port 4f and the sub exhaust port 4g. The intake valve camshaft 11 that opens and closes 6, 6, 6, 6 allows these intake valves
Exhaust valves 7 and 7 are opened and closed at the same time by the exhaust valve camshafts 12 that are opened and closed at the same time as 6, 6, 6, and 6. Reference numeral 13 in FIG. 4 denotes a swing arm type hydraulic lash adjuster. In addition to the auxiliary intake valve 9 and the auxiliary exhaust valve 10, the intake valves 6, 6, 6, and
6 and the exhaust valves 7, 7, 7, 7 are provided with the same components. Reference numerals 14 and 15 in FIGS. 3 and 4 denote a valve recess for a sub-intake valve and a valve recess for a sub-exhaust valve, respectively, provided at a connection portion of the sleeves 3 and 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. The main combustion chamber 17,
A sub-combustion chamber 18 is defined between the main combustion chambers 17 and 17 by the connecting portion of the connecting recess 4e and the sleeves 3, 3, and the main combustion chambers 17 and 17 always communicate with each other. Is done.

Now, the intake valves 6, 6, 6, 6 in the main combustion chambers 17, 17 are operated by the intake valve cam shaft 11, and the main intake port
Openings of 4c, 4c, 4c, 4c are opened and pistons 1, 1
Is lowered, the main intake ports 4c, 4c, 4c, 4c, 4c, 4c, into the main combustion chambers 17, 17 and the sleeves 3, 3, which are in a negative pressure state.
The air-fuel mixture is sucked from the vaporizers 5, 5 via 4c.

At this time, in the sub-combustion chamber 18 communicating with the main combustion chambers 17, 17, the sub-intake valve 9 and the intake valves 6, 6, 6, 6 are simultaneously placed.
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 17, 17 and the sleeves 3, 3
The air-fuel mixture is also drawn in from the carburetor 8 via the sub-intake port 4f and the sub-combustion chamber 18, so that the air-fuel mixture suction efficiency is greatly improved and the engine output is improved. .

When the air-fuel mixture is sucked into each of the main combustion chambers 17, 17, the intake valves 6, 6, 6, 6 and the auxiliary intake valve 9 are operated by the operation of the intake valve camshaft 11, so that the main intake ports 4c, 4c, 4 respectively.
The openings of c and 4c and the opening of the sub-intake port 4f are closed, and the pistons 1 and 1 move upward to start the compression of the air-fuel mixture.

The compressed air-fuel mixture is ignited by an ignition plug (not shown) in each of the main combustion chambers 17, 17 and burns to move the piston 1, 1 downward.

At this time, also in the sub-combustion chamber 18, at the same time as the above-mentioned ignition plug (not shown), the ignition plug (not shown) held in the ignition plug mounting holes 20, 20 is ignited, and the combustion is performed by the main combustion chamber 17, It will assist the combustion of 17 and improve the combustion efficiency of the air-fuel mixture.

On the other hand, after the air-fuel mixture in the main combustion chambers 17, 17 and the sub-combustion chamber 18 is burned, the exhaust valves 7, 7, 7, 7 are operated by the exhaust valve cam shaft 12, and the main exhaust ports 4d, 4d ,
The openings of 4d and 4d are opened, the pistons 1 and 1 are moved upward, and the burned gas in the main combustion chambers 17 and 17, the sleeves 3 and 3 and the sub-combustion chamber 18 is released from the exhaust ports 4d, 4d and 4d. , 4d.

At this time, in the auxiliary combustion chamber 18, the exhaust valves 7, 7, 7, 7
At the same time, the sub-exhaust valve 10 is operated, the opening of the sub-exhaust port 4g is opened, and the main combustion chambers 17, 17,
The burned gas in the sleeves 3, 3 and the sub-combustion chamber 18 is also discharged from the sub-exhaust port 4g,
Exhaust efficiency will be greatly improved.

In the above embodiment, the main combustion chambers 17, 17 of the two cylinders are used.
Are illustrated as communicating each other by the auxiliary combustion chamber 18, but in the present invention, the combustion chambers of three or more cylinders may be communicated with each other. Further, although the cylinders communicating the main combustion chambers 17 are illustrated as one set of engines, an engine including 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 and one sub-exhaust port 4g are respectively opened in the sub-combustion chamber 18, and one sub-intake valve 9 and one sub-exhaust valve 10 are provided in the sub-combustion chamber 18, respectively. Although they are provided, in the present invention, a plurality of sub intake ports 4f, sub exhaust ports 4g, sub intake valves 9, and sub exhaust valves 10 may be provided.

〔The invention's effect〕

As described above, according to the four-stroke engine according to the present invention, since the intake efficiency and the exhaust efficiency can be improved by using the cylindrical piston, the output can be improved by a simple machining operation.

In addition, since the sub-combustion chamber is provided with the sub-exhaust passage and the sub-exhaust valve, the engine output can be improved due to the improvement in exhaust efficiency.

Further, when the auxiliary ignition plug mounting hole is provided in the auxiliary combustion chamber, the air-fuel mixture in the main combustion chamber can be ignited even through the auxiliary combustion chamber, so that the combustion efficiency can be improved. Become like

[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 line IV-IV in FIG. 1 ... Piston, 4c ... Main intake passage, 4d ... Main exhaust passage, 4f ... Sub intake port, 4g ... Sub exhaust port, 6 ... Intake valve, 7 ... Exhaust valve, 9 ...
Auxiliary intake valve, 10 Auxiliary exhaust valve, 16 Ignition plug mounting hole, 17 Main combustion chamber, 18 Auxiliary combustion chamber, 20 Auxiliary ignition plug mounting hole, C: Between piston axes A central plane connecting the two.

Claims (2)

(57) [Claims] 1. A main combustion chamber (17) is formed at a position facing the top of each piston (1) of cylinders adjacent to each other,
In each main combustion chamber (17), a main exhaust passage (open / closed by an exhaust valve (7)) is provided at a portion on one side of a center plane (C) connecting the axes of the adjacent pistons (1). 4d), one end of a main intake passage (4c) opened / closed by an intake valve (6) is opened at a position on the other side of the center plane (C), and each main combustion chamber is further opened. In a four-stroke engine provided with a spark plug mounting hole (16) in the center of each of the main combustion chambers (17), the main combustion chambers (17) are located between the main combustion chambers (17).
A sub-combustion chamber (18) that constantly communicates with each other, and is displaced toward the exhaust valve (7) side from a center plane (C) connecting the piston axes of the sub-combustion chamber (18). One end of the sub-exhaust passage (4g) is opened at the side of the sub-exhaust passage (4g), and the sub-exhaust valve (1
0), and one end of the auxiliary intake passage (4f) is opened at a portion on the other side deviated toward the intake valve (6) from a center plane (C) connecting the piston axes, A four-stroke engine, characterized in that a sub-intake valve (9) for opening and closing the sub-combustion chamber (18) is provided at the opening. 2. The four-stroke cycle according to claim 1, wherein a sub-spark plug mounting hole (20) is arranged on a line connecting the spark plug mounting hole (16) in the sub-combustion chamber (18). engine.