JP2000186559A - Stratified scavenging 2-cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the proper air fuel mixture concentration in the whole operation region of an engine by providing a connecting mechanism for interlocking an air control valve with a throttle valve between them, totally closing the air control valve until the throttle valve reaches a designated opening, and making both valves operated in proportion to each other when it reaches the designated opening or more. SOLUTION: This engine is provided with a throttle valve 4 for controlling the flow of an air fuel mixture and an air control valve 20 for controlling the flow of air introduced into a combustion chamber 25 through an air supply path 10 to make scavenging action. Two valves are interlocked with each other through a swivel 125, a projecting part 126 and an air valve operating lever 114. During low-load operation including idling operation until the throttle valve 14 reaches a fixed opening, the air control valve 20 is totally closed, and after that, the opening of the throttle valve 14 and the opening of the air control valve are set to be proportional. Thus, combustion during low load operation is stabilized, and during high load operation, the fuel consumption rate can be reduced and harmful emission in the exhaust gas can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crankcase compression type 2
The present invention relates to a cycle engine, and particularly to a two-cycle gasoline engine that performs stratified scavenging.

[0002]

2. Description of the Related Art In a two-stroke gasoline engine of a crankcase compression type, in a scavenging process, a combustion gas in a combustion chamber is sufficiently discharged to prevent a gas mixture from flowing into an exhaust port, and combustion is performed at a required concentration. Various techniques for filling a large amount in a room have been provided.

One of them is disclosed in Japanese Patent Application Laid-Open No. 7-139.
There is an invention proposed in US Pat. In this method, an air passage opening in a position close to the scavenging port is provided in the scavenging passage, a check valve is provided in the air passage, and the air flow rate in the air passage is linked with the throttle operation of the engine.
In this invention, when the piston rises, the pressure in the crank chamber becomes negative, and the air-fuel mixture is sucked into the crank chamber from the air-fuel mixture supply port. Air enters all or part of

[0004] When the scavenging port is opened at the time of the piston descending in the explosion and exhaust strokes, first, air is blown into the combustion chamber, and then the air-fuel mixture is supplied.

[0005]

In the prior art, air supplied from the scavenging port into the combustion chamber at the beginning of the scavenging process, and the air is supplied to the combustion chamber from the scavenging port via the crank chamber after the air. There is a means for supplying the mixture to the combustion chamber so that the mixture does not blow through to the exhaust port.

However, in such a two-stroke engine, during low load operation including idling operation, the amount of air is suppressed to stabilize combustion as a rich mixture ratio, and during high load operation as described above, a relatively thin mixture ratio is used. Reduction of fuel consumption rate and reduction of harmful emission in exhaust gas are required.

However, in such prior art, the flow rate of air supplied from the air supply passage during the scavenging operation is not accurately controlled in accordance with the operating state of the engine, so that low-load operation including idling operation is performed. In some cases, the amount of air tends to increase, making it difficult to restrict the amount of air and stabilize combustion as a rich mixture ratio, and to maintain a constant mixture concentration at a low mixture ratio during high-load operation to reduce the fuel consumption rate. It is also difficult to operate with reduced emissions and reduced harmful emissions in the exhaust gas.

The present invention has been made in view of the problems of the prior art,
The amount of air supplied to the combustion chamber through the scavenging port,
Controllable in accordance with the amount of air-fuel mixture controlled by the throttle valve, it is possible to maintain an appropriate air-fuel mixture concentration over the entire operating range of the engine, stabilize combustion during low-load operation, and perform high-load operation It is an object of the present invention to provide a stratified scavenging two-cycle engine with reduced fuel consumption and reduced harmful emissions in exhaust gas.

[0009]

According to the present invention, an exhaust port and a scavenging port are provided in a cylinder, and the scavenging port and the crank chamber are communicated with each other. In the stratified scavenging two-cycle engine, the crank chamber is provided with a supply port of a mixture whose flow rate is controlled by a throttle valve, and further provided with an air supply port for supplying air to a scavenging passage to the scavenging port. In the air passage connecting the supply port and the air cleaner, an air control valve for adjusting the passage area of the air passage is provided, and a connection mechanism for interlocking the air control valve and the throttle valve is provided between the air control valve and the throttle valve. The connection mechanism is configured such that the air control valve is fully closed up to a predetermined opening of the throttle valve, and the throttle valve and the air control valve are moved substantially in proportion to the opening equal to or larger than the predetermined opening. hand To propose a stratified scavenging two-cycle engine according to claim Rukoto.

According to a second aspect of the present invention, in the first aspect, the connecting mechanism includes a swivel attached to a control lever for operating the throttle valve, a protrusion protruding from the swivel, and the air control. An air valve actuating lever connected to the valve and having one end fitted with the projection and changing the opening of the air control valve by movement of the projection.

According to this invention, the air control valve is closed during the low load operation including the idling operation in which the opening of the throttle valve is equal to or less than the predetermined opening, and the air-fuel mixture whose flow rate is controlled by the opening of the throttle valve is formed. The gas is sent into the combustion chamber through the scavenging port, and after being scavenged, is charged. Therefore, at the time of the low-load operation, operation with a slightly rich mixture can be performed, and combustion is stabilized.

When the throttle valve is operated at a high load exceeding the predetermined opening, the air control valve is interlocked with the throttle valve via a swivel, a projection, and an air operated lever attached to the control lever, and the throttle valve is operated. The opening is increased substantially in proportion to the opening of the valve. As a result, the amount of air supplied to the scavenging port via the air passage increases, enabling operation at a thin mixture ratio required during high-load operation, and maintaining the entire mixture concentration at a constant level. Operation with low fuel consumption rate and reduced harmful emissions in exhaust gas can be realized.

Therefore, according to the invention, an air control valve for controlling the flow rate of air supplied to the combustion chamber via the scavenging port of the engine is provided, and the air control valve is connected to the control lever for operating the throttle valve. By connecting the air control valve to the throttle valve via the connecting mechanism, the air control valve can be opened and closed in association with the throttle valve. Thereby, when the engine is under low load operation, the air control valve can be operated at a rich mixture ratio with the opening degree of the air control valve fully closed or a small opening degree to stabilize combustion, and at the time of high load operation at or above the load, By opening and closing the air control valve almost in proportion to the throttle valve, it is possible to operate at a low mixture ratio, thereby reducing the fuel consumption rate and reducing harmful emissions in exhaust gas.

According to a third aspect of the present invention, in any one of the first and second aspects, the air supply port and the air-fuel mixture supply port are provided in the crankcase in the same direction.
In the insulator fixed to the side of the crankcase, an air passage communicating with the air supply port, and a mixture supply port communicating with the mixture supply port are provided in parallel in the same direction. It becomes.

According to a fourth aspect of the present invention, in any one of the first and second aspects, the air supply port and the air-fuel mixture supply port are provided in a crankcase in the same direction.
The insulator fixed to the side of the crankcase communicates with the air supply port, the air passage provided with the air control valve, and the mixture supply passage communicated with the mixture supply port have the same direction. Are arranged side by side. According to a fifth aspect of the present invention, in the third or fourth aspect, an opening surface of the air supply port and an opening surface of the air-fuel mixture supply port of the crankcase are formed on the same plane, and an air passage of the insulator is provided. The opening surface and the opening surface of the mixture supply passage are formed on the same surface, and the insulator is fixed to the crankcase by bringing the two surfaces into fluid-tight contact with each other.

According to a sixth aspect of the present invention, in the fourth aspect, the insulator is such that an inlet of an air passage having the air control valve is opened on an upper surface, and an outlet of the air passage is connected to an air supply opening of the crankcase. Opened in the same direction.

According to the third and fifth aspects of the present invention, the air supply port and the air / fuel mixture supply port are provided in the crankcase so as to open in the same direction. Since the openings of the air passage and the mixture supply passage of the insulator are made the same surface, and both surfaces are brought into fluid-tight contact, only one seal surface for the mixture and air is required,
In addition, since the seal is formed on one surface, leakage of air or air-fuel mixture is prevented, and processing of the seal surface is facilitated and processing accuracy is improved.

According to the fourth and sixth aspects of the present invention, since the inlet of the air passage is opened on the upper surface of the insulator, the bent portion in the insulator has one bend.
In this case, the air flow path resistance is reduced, and the thickness of the insulator is reduced. Further, since the air control valve is provided in the insulator, no space is required for providing the air control valve on the air cleaner outlet side, the length from the engine side to the air cleaner is reduced, and a small and compact engine can be obtained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

FIG. 1 is a cross-sectional view of a stratified scavenging two-stroke gasoline engine according to a first embodiment of the present invention, which is perpendicular to a crankshaft center including a cylinder center line. FIG. And FIG. 3 is a diagram showing an opening relationship between a throttle valve and an air control valve.

1 and 2, 2 is a cylinder, 4 is a piston, 6 is a crankshaft, 5 is a crankcase, 3 is a connecting rod connecting the piston 4 and the crankshaft 6, 7 is a cylinder head, 8 Is the spark plug, 1
1 is an air cleaner, 12 is a carburetor, 15 is an air-fuel mixture supply passage, 14 is a throttle valve that controls the flow rate of the air-fuel mixture by changing the opening of the air-fuel mixture supply passage 15, and 51 and 51 are main bearings.

Reference numeral 25 denotes a combustion chamber, 15a denotes a crank chamber formed inside the crankcase 5, and 16 denotes a check valve for opening and closing between the crank chamber 15a and the mixture supply passage 15. The check valve 16 is configured to allow only the flow from the mixture supply passage 15 toward the crank chamber 15a. Reference numeral 13a denotes an exhaust port opened on the side of the cylinder 2 and connected to the exhaust passage 13.

9a is an exhaust port 13a of the cylinder 2.
A scavenging port 9 is provided at a position opposite to the scavenging port 9 and is a scavenging passage connecting the scavenging port 9a and the crank chamber 15a. 109a is the exhaust port 1 of the cylinder 2
Two scavenging ports provided so as to face left and right sides of the exhaust port 13a in a direction substantially perpendicular to the exhaust port 13a, and each pair of the scavenging ports 109a is a scavenging port provided in the cylinder 2 in the vertical direction. It communicates with the crank chamber 15a via a passage 109e, a scavenging passage 109c provided in the crankcase 5 in a horizontal direction, a scavenging passage 109d formed in an arc shape in the wall of the crankcase 5, and a scavenging communication hole 109b.

Reference numeral 10 denotes an air supply passage provided inside the side portion of the cylinder 2, and connects an air passage 10b in the insulator 30 described later and a scavenging passage 109e communicating with the pair of scavenging ports 109a. . An air valve 20 for controlling the amount of air passing through the passage 10 is provided upstream of the air supply passage. As in the prior art, the air supply passage 10 has a check valve 17 that allows only the flow toward the scavenging passages 109e, 109e at the opening to the scavenging passages 109e, 109e to the left and right scavenging ports 109a, 109a. , 17.

11 is an air cleaner, 12 is a vaporizer, 30
Is an insulator for thermally isolating the engine body side from the intake system. The insulator 30 is fixed to the side surfaces of the cylinder 2 and the crankcase 5 by a plurality of bolts (not shown). In the interior of the insulator 30, an air passage 10b communicating with the air supply passage 10 is formed at an upper portion thereof, and a mixture passage 15b communicating with the mixture supply passage 15 is formed at a lower portion thereof. I have. The upstream side of the mixture passage 15b is communicated with a throttle valve 14 for controlling the mixture flow rate in the carburetor 12.

An air cleaner case 110a connects the air cleaner 11, the insulator 30, and the carburetor 12. 110 is the air cleaner case 11
An air passage formed on the upper side inside Oa communicates with the air outlet of the air cleaner 11 and the air passage 10b of the insulator 30. Reference numeral 10e denotes an air passage formed in a lower portion inside the air cleaner case 110a, and is connected to an air inlet of the carburetor 12.

Reference numeral 20 denotes a butterfly valve type air control valve which is provided in the air passage 110 and changes the passage area of the air passage 110. An air valve operating lever 114 is connected to the valve shaft 113 of the air control valve 20 and rotates it. A control lever 124 is connected to the throttle valve 14 to adjust the opening degree of the throttle valve 14, that is, the flow rate of the air-fuel mixture. As shown in FIG.
Is controlled by A swivel 125 is provided at one end of the control lever 124.
The swivel 125 has a projection 126 fixed to the top of the swivel 125.

As shown in FIG. 2, an end of the air valve operating lever 114 is provided with an engaging hole 115 formed of an arc-shaped elongated hole, and the engaging hole 115 is provided on the swivel 125. The protrusion 126 is fitted, and the air control valve 20 is opened and closed in conjunction with the throttle valve 14. A torsion spring 114 urges the air control valve 20 to a normally closed side.

During operation of the stratified scavenging two-cycle gasoline engine having the above configuration, when the piston 4 is lowered by the explosion pressure in the combustion chamber 25 and the exhaust port 13a is opened, the combustion gas (exhaust gas) in the combustion chamber 25 is opened. ) Is discharged to the exhaust passage 13 through the exhaust port 13a. Further, when the piston 4 descends, the left and right scavenging ports 109
The air supplied to the air supply passage 10 flows into the combustion chamber 25 and pushes the combustion gas toward the exhaust port 13a by an operation described later.

Next, the scavenging port 9a facing the exhaust port 13a is opened, and the air-fuel mixture in the crank chamber 15a flows through the scavenging passage 9 from the scavenging port 9a into the combustion chamber 25, while the left and right scavenging air flows. Port 109a,
Also from the crank chamber 15a, the scavenging communication hole 109
b, the air-fuel mixture passing through the scavenging ground 109d, the scavenging passage 109c, and the scavenging passage 109e is caused to flow.

When the piston 4 is lowered and is at the bottom dead center, the exhaust port 13a and the three scavenging ports 109
The openings a, 109a, and 9a are open, and the supply of the fresh air and the air-fuel mixture into the combustion chamber 25 is completed or is about to be completed. When the piston 4 rises from the bottom dead center,
The scavenging port 9a is closed by the piston 4, and then the left and right scavenging ports 109a, 109a are closed, so that the inside of the crank chamber 15a becomes a closed space, and expansion, that is, a decrease in pressure starts.

When the piston 4 further rises, the exhaust port 13a is closed and the compression of the gas in the combustion chamber 25 starts, while the pressure in the crank chamber 15a further decreases.
As a result, the check valve 16 including the reed valve opens,
An air-fuel mixture formed by the carburetor 12 and having a flow rate controlled by a throttle valve 14 flows from the air-fuel mixture supply passage 15 through a crank chamber 15a.
Supplied within. The pressure drop in the crank chamber 15a is caused by the scavenging communication hole 109b and the scavenging passages 109d and 109c.
And 109e are also transmitted to the scavenging port 109a, so that the check valves 17 and 17 formed of a reed valve are also opened, and the air supplied into the air supply passage 10 by an operation described later is supplied to the check valve 17a. Through the crank chamber 15a. Here, the scavenging ports 109a, 109a
Passages 109e, 109 extending from the air to the crank chamber 15a
Since c and 109d are configured as long scavenging passages, the air first fills the long scavenging passage and then flows into the crank chamber 15a.

When the piston 4 is in the vicinity of the compression top dead center, a spark discharge is generated in the air-fuel mixture in the combustion chamber 25 by the spark plug 8, thereby igniting and burning the air-fuel mixture. Due to the pressure from such combustion, the piston 4 is pushed down and does work on the crankshaft 6.

The piston 4 descends and the exhaust port 13
When a is opened, the combustion gas in the combustion chamber 25 is discharged from the exhaust port 13a to the outside through the exhaust passage 13 and the muffler (not shown). On the other hand, due to the lowering of the piston 4, the inside of the crank chamber 15a is compressed on the back side of the piston 4, and when the scavenging ports 109a, 109a on the side open soon, the gas supplied to the crank chamber 15a as described above. Is the scavenging communication hole 109b and the scavenging passage 109
D, 109c, and 109e are blown into the combustion chamber 25 from the scavenging port 109a to perform a scavenging action of pushing out the combustion gas (exhaust gas) in the combustion chamber 25 from the exhaust port 13a.

During the scavenging operation, since the inside of the scavenging passages 109e, 109c, and 109d is initially filled with air, the scavenging ports 109e, 109a, 109a, 109a are not connected within a certain period from the start of the scavenging operation. The scavenging action is performed by air into the combustion chamber 25, and thereafter, the air-fuel mixture in the crank chamber 15 a flows into the scavenging passage 109.
d, 109c, 109e, and scavenging port 109a, 1
09a is blown into the combustion chamber 25. The scavenging port 9a at the opposing position is opened slightly after the opening of the left and right scavenging ports 109a, 109a, and the air-fuel mixture is also blown into the combustion chamber 25 from the scavenging port 9a.

Normally, in a two-cycle gasoline engine, at a partial load, the opening degree of the throttle valve 14 is changed to control the flow rate of the air-fuel mixture supplied into the combustion chamber 25 through the crank chamber 15a. In the operating range, a substantially constant mixture concentration is maintained. However, in the stratified scavenging two-cycle gasoline engine according to the present invention, as described above, in addition to the air-fuel mixture during the scavenging process, air is supplied into the combustion chamber 25 through the air supply passage 10, so that the air-fuel mixture side is If the concentration is constant, it is necessary to maintain the entire mixture concentration constant by supplying air into the combustion chamber 25 in an amount proportional to the amount of the mixture.

Therefore, in this embodiment, a throttle valve 14 for controlling the flow rate of the air-fuel mixture, and an air control valve for controlling the flow rate of the air sent to the combustion chamber 25 through the air supply passage 10 and performing a scavenging action are provided. 20 are interlocked with each other via the swivel 125, the projection 126, and the air valve operating lever 114, so that the concentration of the air-fuel mixture is maintained constant by the following operation and effect. .

That is, in this embodiment, the throttle valve 14
And the opening of the air control valve 20, as shown in FIG.
During low load operation including idling operation until the throttle valve 14 reaches a certain opening Z point, the operation is performed at a slightly rich mixture ratio in order to stabilize combustion. The air control valve 20 is fully closed up to the point Z, and the opening degree of the throttle valve 14 and the air control valve 2
The opening degree is set to be proportional to 0.

That is, at the time of low load operation including idling operation, as shown in FIG. 2, the protrusion 12b fixed to the throttle valve 14 side is inserted into the engagement hole 115 formed by the long hole of the air valve operation lever 114. Since the air control valve 20 is in a so-called play state and is urged in the closing direction by the torsion spring 116, the throttle valve 14 moves in the opening direction, and the projection 126 is engaged with the engagement hole 115 via the swivel 125. The air control valve 20 is fully closed until the air operated lever 114 starts to move, that is, until the point Z in FIG. The air-fuel mixture whose flow rate is controlled by the throttle valve 14 is sent in, and performs a scavenging action and is filled for combustion.

The opening degree of the throttle valve 14 is Z
When the temperature exceeds the point, the protrusion 126 comes into contact with the inner end of the engagement hole 115 and pushes the air valve operation lever 114 to operate the air control valve 20 in the opening direction. As a result, the air from the air cleaner 11 flows into the air passage 110 and the air control valve 2.
The air is supplied from the scavenging port 109a into the combustion chamber 25 via the air passage 10b in the insulator 30, the air supply passage 10 in the cylinder 2, and the scavenging passage 10e.

That is, the engine load increases and the throttle valve 14
At a load equal to or higher than the Z point at which the opening degree of the throttle valve becomes large, the air control valve 20 includes the throttle valve 14, the swivel 125, and the projection 12.
6. Operated with an opening proportional to the opening of the throttle valve 14 in conjunction with the air valve operating lever 114, the air flow rate increases, and the thin mixture ratio required during such high load operation is increased. Driving is performed.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment of the present invention. In this embodiment, a scavenging passage 109e (left and right scavenging ports 109) provided in the cylinder 2 is provided.
a, a scavenging passage communicating with 109a) and an external scavenging passage 10a provided on the side of the crankcase 5 at the outside. As a result, the upper end of the air supply passage 10 is opened downward, and the air passage 10 b in the insulator 30 is opened.
After being bent downward from the inlet portion, is bent horizontally and connected to the outer air passage 10a. Other configurations are the same as those of the first embodiment shown in FIGS. 1 and 2, and the same members are denoted by the same reference numerals.

In this embodiment, the mixture supply passage 15b and the air passage 1 provided in the insulator 30 are provided.
0b is communicated with the mixture supply passage 15 and the external air passage 10a provided on the side of the crankcase 5 by one joint surface between the insulator 30 and the crankcase 5, so that the mixture and the air Since only one sealing surface is required and the sealing is performed on one surface, the sealing performance also increases, and the leakage of air and air-fuel mixture is suppressed. In addition, machining of the sealing surface is facilitated, and machining accuracy is improved.

5 and 6 show a third embodiment of the present invention. FIG. 5 is a partial sectional view showing a side surface near an insulator portion, and FIG. 6 is a view taken along line BB in FIG. It is.

In this embodiment, the air control valve 20
Are provided in the insulator 30. That is, in FIGS. 5 and 6, a mixture supply passage 15 b similar to that of the second embodiment is provided in a lower portion of the insulator 30. 10b is an air passage provided on the upper side inside the insulator 30.
After extending downward from the upper surface of No. 0, it is bent in the horizontal direction and connected to the external air passage 10a shown in FIG.

An air duct 150 connects the air cleaner 11 and the insulator 30.
The air passage connecting the air cleaner 11 and the air passage 10b inside the insulator 30 is formed inside the insulator 30 while being bent horizontally above the insulator 30 and fitted into the fitting portion on the upper surface of the insulator 30. 1
10 are formed.

Reference numeral 20 denotes an air control valve which is provided in the air passage 10b in the insulator 30.
The area b is controlled. Reference numeral 113 denotes a valve shaft of the air control valve 20, which is provided so as to cross the air passage 10b. Similar to the first and second embodiments, the air valve operating lever 114, the projection 126, the swivel 125, and the like are provided. The throttle valve 14 is connected to the throttle valve 14. Therefore, in this embodiment, the throttle valve 14 (see FIGS. 1 and 4) and the valve shaft 113 of the air control valve 20 are arranged at substantially 90 degrees.

In this embodiment, since the inlet of the air passage 10b of the insulator 30 is opened upward, only one bend is required in the insulator 30, so that the air flow path resistance is reduced and the insulator 30 Also becomes thinner. Further, the air control valve 20
Is provided in the insulator 30, so that the air cleaner 1
A space for providing the air control valve 20 on the outlet side of the air cleaner 1 becomes unnecessary, and the length from the engine side surface to the air cleaner 11 is reduced.

[0049]

As described above, according to the present invention, an air control valve for controlling a flow rate of air supplied to a combustion chamber through a scavenging port of an engine is provided, and the air control valve is used for controlling a mixture flow rate. By connecting the air control valve to the throttle valve via the connection mechanism, the air control valve can be opened and closed in association with the throttle valve.

Thus, when the engine is operated at a low load, the opening of the air control valve is set to a fully closed or small opening to operate the engine at a rich mixture ratio, thereby stabilizing the combustion. During high-load operation, the air control valve is opened and closed almost in proportion to the throttle valve, thereby enabling operation at a low mixture ratio, keeping the overall mixture concentration constant, and reducing the fuel consumption rate. Further, it is possible to provide a stratified scavenging two-cycle engine in which harmful emissions in exhaust gas are reduced.

According to the third and fifth aspects of the present invention, the air supply port and the mixture supply port are provided on the same plane in the crankcase, and the air supply port and the mixing port are provided in the insulator. Since the air supply passage is brought into fluid-tight contact with the same opening surface, only one sealing surface for air and air-fuel mixture is required, leakage of air and air-fuel mixture is prevented, and processing of the sealing surface is facilitated. Processing accuracy is also improved.

According to the fourth and sixth aspects of the present invention, since the inlet of the air passage is opened on the upper surface of the insulator, only one bent portion of the air passage in the insulator is required, and the resistance of the air passage is reduced. Is done. Also,
By the above, the thickness of the insulator is reduced, and furthermore, by providing the air control valve in the insulator,
Space for providing an air control valve on the outlet side of the air cleaner is not required. Thus, the length from the engine side to the air cleaner is reduced, and a small and compact engine can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view including a cylinder center of a stratified scavenging two-cycle gasoline engine according to a first embodiment of the present invention and perpendicular to a crankshaft center.

FIG. 2 is a cross-sectional view of a main part showing a manner of connecting a throttle valve and an air control valve in the first embodiment.

FIG. 3 is a diagram showing an opening relationship between a throttle valve and an air control valve in the first embodiment.

FIG. 4 is a view corresponding to FIG. 1, showing a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a side surface near an insulator part according to a third embodiment of the present invention.

6 is a view taken in the direction of arrows BB in FIG. 5;

[Explanation of symbols]

 2 Cylinder 3 Connecting rod 4 Piston 5 Crankcase 6 Crankshaft 7 Cylinder head 8 Spark plug 9 Scavenging passage 9a Scavenging port 10 Air supply passage 10b, 10e Air passage 11 Air cleaner 12 Vaporizer 13 Exhaust passage 13a Exhaust port 14 Throttle valve 15 Mixing Air supply passage 15a Crank chamber 15b Mixture passage 16 Check valve 20 Air control valve 25 Combustion chamber 30 Insulator 109b Scavenging communication passage 109c, 109d, 109e Scavenging passage 110 Air passage 113 Valve shaft 114 Air valve operating lever 115 Engagement hole 116 Torsion spring 124 Control lever 125 Swivel 126 Projection 142 Control cable 150 Air duct

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F02B 33/44 F02B 33/44 C F02D 9/02 F02D 9/02 G 361 361J (72) Inventor Yoshio Kobayashi 1F, Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya F-term in Nagoya Machinery Works, Mitsubishi Heavy Industries, Ltd. 3G005 DA04 EA02 FA00 GA03 GB01 GC10 GD11 HA19 JA06 3G023 AA02 AA03 AA18 AB01 AC01 AD03 AD05 AD07 AF02 AG01 3G065 AA02 AA07 CA12EA HA03 KA13

Claims (6)

[Claims] An exhaust port and a scavenging port are provided in a cylinder, and the scavenging port and a crank chamber are communicated with each other. The crank chamber is provided with a supply port of an air-fuel mixture whose flow rate is controlled by a throttle valve. In a stratified scavenging two-cycle engine including an air supply port for supplying air to a scavenging passage to the scavenging port, air for adjusting a passage area of the air passage is provided in an air passage connecting the air supply port and an air cleaner. A control valve is provided, and a connection mechanism for interlocking the air control valve and the throttle valve is provided between the air control valve and the throttle valve. The connection mechanism does not fully close the air control valve until a predetermined opening degree of the throttle valve. A stratified scavenging two-stroke engine characterized in that the throttle valve and the air control valve are configured to move in proportion to each other when the opening is equal to or greater than a predetermined opening. 2. The connecting mechanism is connected to a swivel attached to a control lever that operates the throttle valve, a protrusion protruding from the swivel, and the air control valve, and the protrusion is provided at one end. 2. The stratified scavenging two-stroke engine according to claim 1, further comprising: an air valve actuating lever fitted to change an opening degree of the air control valve by moving the protrusion. 3. An air supply port and a supply port of the air-fuel mixture are provided in a crankcase in the same direction, and an insulator fixed to a side of the crankcase communicates with the air supply port. The stratified scavenging two-stroke engine according to any one of claims 1 to 2, wherein an air passage that communicates with the air-fuel mixture supply port that communicates with the air-fuel mixture supply port is arranged in the same direction. 4. An air supply port and a supply port for the air-fuel mixture are provided in a crankcase in the same direction, and an insulator fixed to a side portion of the crankcase is connected to the air supply port. The air passage provided with the air control valve and a mixture supply passage connected to a supply port of the mixture are arranged in parallel in the same direction.
The stratified scavenging two-cycle engine according to any one of claims 1 to 2. 5. An opening surface of the air supply port and an opening surface of the air-fuel mixture supply port of the crankcase, and an opening surface of an air passage of the insulator and an opening surface of the air-fuel mixture supply passage. 5. The stratified scavenging two-cycle engine according to claim 3, wherein the two surfaces are fluid-tightly contacted with each other, and the insulator is fixed to a crankcase. 6. 6. The insulator according to claim 4, wherein an inlet of an air passage having the air control valve is opened on an upper surface, and an outlet of the air passage is opened in the same direction as an air supply port of the crankcase. Stratified scavenging two-cycle engine.