JPH05280344A - Two cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To improve engine output at the time of a large intake air amount while ensuring good ignition combustion at the time of a small intake air amount. CONSTITUTION:An intake valve 5 and an exhaust valve 6 are arranged on the inner wall surface of a cylinder head 3, and also a scavenging hole 12 to be opened/closed by a piston 2 is formed on the inner wall surface of a cylinder bore 11. When there is few intake air amount, air discharged from a mechanical supercharger 15 is supplied from the intake valve 5 into a combustion chamber 4 through a connecting duct 19. On the other hand, when there is much intake air amount, air discharged from the mechanical supercharger 15 is supplied from the scavenging hole 12 into the combustion chamber 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a two-cycle internal combustion engine.

[0002]

2. Description of the Related Art An exhaust valve is arranged on the inner wall surface of a cylinder head, and a scavenging hole that can be opened and closed by a piston is formed on the inner wall surface of a cylinder bore to allow air to flow into the combustion chamber from the scavenging hole and to exhaust burnt gas from the exhaust valve. There is known a two-cycle internal combustion engine which is designed to be discharged from a fuel cell (Japanese Patent Laid-Open No. 6-68242).
2-13915).

[0003]

When the air is introduced into the combustion chamber from the scavenging hole in this way, the entire burnt gas is pushed up toward the exhaust valve by the air flowing in from the scavenging hole, so the burnt gas is scavenged. It is scavenged well by the air flowing in from. Therefore, during high-speed, high-load operation of the engine with a large intake air amount, the entire combustion chamber is filled with air, so good ignition combustion can be obtained and high engine output can be obtained. However, when the air is made to flow into the combustion chamber from the scavenging hole in this way, only the lower region of the combustion chamber is filled with air when the intake air amount is small,
The middle height region and the upper region of the combustion chamber will be filled with burnt gas. As a result, good ignition cannot be obtained when the spark plug is arranged on the inner wall surface of the cylinder head, and when the auxiliary chamber that opens on the inner wall surface of the cylinder head is provided, the auxiliary chamber is sufficiently Since the air is not scavenged, there arises a problem that the fuel injected into the sub chamber cannot be satisfactorily ignited and burned.

[0004]

According to the present invention, in order to solve the above-mentioned problems, an intake valve and an exhaust valve are arranged on the inner wall surface of a cylinder head, and a sweep which can be opened and closed by a piston on the inner wall surface of a cylinder bore. Pores are formed, and when the intake air amount is small, air is supplied from the air supply valve into the combustion chamber, and when the intake air amount is large, air is supplied from the scavenging holes into the combustion chamber.

[0005]

When the intake air amount is small, air is supplied from the air supply valve, so that the upper region of the combustion chamber is filled with air.
On the other hand, when the intake air amount is large, air is supplied from the scavenging holes, so that the entire combustion chamber is filled with air.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, 1 is a cylinder block,
2 is a piston, 3 is a cylinder head, and 4 is a combustion chamber. As shown in FIGS. 1 and 2, a pair of air supply valves 5 and a pair of exhaust valves 6 are arranged on the inner wall surface of the cylinder head 3, and each of the air supply valves 5 formed on the exhaust valve 6 side is The opening is covered by the mask wall 7. Further, the injection port 9 of the sub chamber 8 is opened on the inner wall surface of the cylinder head 3, and the fuel is injected from the fuel injection valve 10 into the sub chamber 8.

On the other hand, a large number of scavenging holes 12 are formed at equal angular intervals on the inner wall surface of the cylinder bore 11, and these scavenging holes 12 are burned in the same circumferential direction as shown in FIG. Open into chamber 4. An annular air supply passage 13 is formed around the scavenging hole 12, and the air supply passage 13 is formed.
Is connected to the discharge port of an engine-driven mechanical supercharger 15 via an air supply duct 14. A first opening / closing valve V1 is arranged in the air supply duct 14, and the air supply duct 14 downstream of the first opening / closing valve V1 is connected to the crank chamber 15 via a second opening / closing valve V2.

On the other hand, as shown in FIG. 1, an air supply port 16 is formed in the cylinder head 3 for the air supply valve 5, and an exhaust port 17 is formed for the exhaust valve 6. A duct 18 is connected to the air supply port 16, and a third opening / closing valve V3 is arranged in the duct 18. Also, air supply port 1
The duct 18 between the No. 6 and the third on-off valve V3 is connected to the air supply duct 14 between the first on-off valve V1 and the mechanical supercharger 15 via the connection duct 19, and the fourth open / close is provided in this connection duct 19. A valve V4 is arranged.

In the embodiment shown in FIG. 1, the exhaust valve 6 opens before the intake valve 5 and closes before the intake valve 5, as shown in FIG. Further, the range indicated by the broken line in FIG. 4 indicates the range in which the scavenging holes 12 open into the combustion chamber 4. As shown in FIG. 1, the first on-off valve V1 is closed and the second on-off valve V1 is closed during low-speed low-load operation of the engine with a small intake air amount.
2 is opened, the third opening / closing valve V3 is closed, and the fourth opening / closing valve V4 is opened. At this time, the air discharged from the mechanical supercharger 15 is supplied into the combustion chamber 4 via the connection duct 19, the duct 18, the air supply port 16 and the air supply valve 5, as indicated by the solid arrow. At this time, since the opening of the air supply valve 5 on the exhaust valve 6 side is covered by the mask wall 7, air flows into the combustion chamber 4 from the opening of the air supply valve 5 on the opposite side of the exhaust valve 6, thus At this time, air is prevented from blowing into the exhaust port 17.

On the other hand, since the amount of intake air is small, the flow velocity of the air flowing into the combustion chamber 4 from the air supply port 16 is slow, and therefore the air does not diffuse to the lower region of the combustion chamber 4 and the combustion chamber 4
Will gather in the upper area of the. As a result, the sub-chamber 8 is scavenged well by the air flowing in from the air supply port 16, and thus the fuel injected from the fuel injection valve 10 into the sub-chamber 8 is satisfactorily ignited and burned. At this time, the lubricating oil scraped off by the piston 2 on the inner wall surface of the cylinder bore 11 flows out from the scavenging hole 12 into the air supply duct 14, and is then returned to the crank chamber 15 via the second opening / closing valve V2.

On the other hand, at the time of high-speed and high-load operation of the engine with a large intake air amount, as shown by the broken line in FIG.
The opening / closing valve V1 is opened, the second opening / closing valve V2 is closed, the third opening / closing valve V3 is opened, and the fourth opening / closing valve V4 is closed. Therefore, at this time, the air discharged from the mechanical supercharger 15 flows into the combustion chamber 4 from the scavenging hole 12 via the air supply duct 14 and the air supply passage 13 as shown by the dashed arrow. At this time, air is ejected from each scavenging hole 12 toward the circumferential direction of the inner wall surface of the cylinder bore 11, and thus the air is swirling while being burned.
Rise inside. As a result, the burnt gas is gradually pushed up by the swirling airflow as indicated by the dashed arrow, then on the one hand into the exhaust port 17 via the exhaust valve 6 and on the other hand into the duct 18 via the intake valve 5. Is discharged to.

As a result, the burnt gas in the combustion chamber 4 is scavenged well by the fresh air flowing in from the scavenging hole 12, and the inside of the combustion chamber 4 is thus filled with air. Therefore, the inside of the sub-chamber 8 is scavenged well, so that the fuel injected into the sub-chamber 8 is satisfactorily ignited and burned, and the unburned air-fuel mixture flowing out from the sub-chamber 8 is satisfactorily burned in the combustion chamber 4. Therefore, high engine output can be obtained. In addition,
Since the burned gas is discharged from both the exhaust valve 6 and the air supply valve 5 during the engine high-speed and high-load operation, the burned gas is immediately discharged as soon as the exhaust valve 6 and the air supply valve 5 are opened. Also in terms of leverage, the scavenging efficiency can be improved.

[0013]

When the intake air amount is small, the air is supplied from the air supply valve, so that the upper region of the combustion chamber is filled with air, and thus good ignition combustion can be obtained. On the other hand, when the intake air amount is large, air is supplied from the scavenging holes, so that the entire combustion chamber is filled with air, and thus good ignition combustion can be obtained and a high engine output can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of a two-cycle internal combustion engine.

FIG. 2 is a bottom view of a cylinder head.

FIG. 3 is a cross-sectional plan view of a cylinder block.

FIG. 4 is a diagram showing an opening period of a supply / exhaust valve and an opening period of a scavenging hole.

[Explanation of symbols]

 4 ... Combustion chamber 5 ... Air supply valve 6 ... Exhaust valve 11 ... Cylinder bore 12 ... Scavenging hole 15 ... Mechanical supercharger V1, V2, V3, V4 ... Open / close valve

Claims (1)

[Claims] 1. A supply valve and an exhaust valve are arranged on an inner wall surface of a cylinder head, and a scavenging hole which is opened and closed by a piston is formed on an inner wall surface of the cylinder bore. When the intake air amount is small, the intake valve is introduced into the combustion chamber. A two-cycle internal combustion engine that supplies air and supplies air from the scavenging holes into the combustion chamber when the intake air amount is large.