JP2000213357A

JP2000213357A - Two-cycle internal combustion engine

Info

Publication number: JP2000213357A
Application number: JP11015693A
Authority: JP
Inventors: Takeshi Oshiro; Yuji Tsushima; Minoru Ueda; Akio Yagasaki; 稔上田; 健史大城; 勇二津島; 昭夫矢ヶ崎
Original assignee: Honda Motor Co Ltd; 本田技研工業株式会社
Priority date: 1999-01-25
Filing date: 1999-01-25
Publication date: 2000-08-02
Also published as: AU1355500A; DE60014978D1; EP1022448A2; DE60014978T2; EP1022448B1; AU752366B2; EP1022448A3

Abstract

[PROBLEMS] To provide a two-stroke internal combustion engine that purifies exhaust gas by realizing scavenging by air, preventing air-fuel mixture from flowing through in a scavenging process, preventing combustion of lubricating oil in a combustion chamber, and purifying exhaust gas. provide. A two-cycle internal combustion engine (1) includes a compressor (20) that performs a compression stroke in accordance with a scavenging stroke in conjunction with a piston (7) reciprocating in a cylinder (8), and pressurizes an air-fuel mixture from a carburetor (17) with the compressor. The air is supplied to the cylinder combustion chamber 12 and the air is pressurized by a compressor and supplied from the side of the cylinder to perform scavenging. And
An oil pump 60 driven by the crankshaft 3 is provided, and the bottom of the crank chamber is used as a lubricating oil reservoir to lubricate the crankshaft with lubricating oil from the oil pump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke internal combustion engine that performs scavenging of air in a combustion chamber by an air flow introduced from outside.

[0002]

2. Description of the Related Art A two-stroke internal combustion engine is required to purify exhaust gas, and various inventions have been proposed to solve this problem. For example, in the invention described in Japanese Patent Publication No. 50-25083, a sub-combustion chamber provided with an ignition plug is attached to a combustion chamber, and a rich air-fuel mixture is supplied to the sub-combustion chamber, while scavenging of a cylinder is performed. A lean air-fuel mixture is supplied from the port by the compression action of the crank chamber, and the lean air-fuel mixture in the combustion chamber is burned by a strong flame generated in the sub-combustion chamber.
Thereby, purification of exhaust gas of the two-cycle internal combustion engine is realized.

[0003] Japanese Patent Application Laid-Open No. 7-310554 discloses a method for purifying exhaust gas of a two-cycle internal combustion engine by supplying air-fuel mixture after scavenging air in a combustion chamber to reduce blow-by of the air-fuel mixture. A plausible invention is described. According to the present invention, a diaphragm-operated poppet valve is provided as a scavenging valve at the top of the cylinder, and air containing no fuel is compressed in the crank chamber and supplied to the scavenging valve through the scavenging passage. Then, a carburetor is provided in the middle of the scavenging passage from the crank chamber to the scavenging valve and the operating diaphragm, and in the scavenging stroke, when the scavenging pressure from the crank chamber acts on the diaphragm to open the scavenging valve,
The air from the crank chamber flows into the combustion chamber through the scavenging passage to scavenge the air, and subsequently, the air flow supplies the air-fuel mixture sucked from the carburetor into the combustion chamber.

[0004]

Various inventions have been conventionally proposed as described above for purifying exhaust gas in a two-cycle internal combustion engine, but from the viewpoint of environmental protection,
Further improvements are desired. That is, although a certain degree of scavenging blow-through cannot be avoided mechanically in a two-cycle internal combustion engine, in the invention described in Japanese Patent Publication No. 50-25083, scavenging is performed with an air-fuel mixture even though it is lean. Gas purification also had certain limitations.

[0005] Here, as an important problem in purifying exhaust gas of a two-cycle internal combustion engine, there is also prevention of combustion of lubricating oil. The conventional two-stroke internal combustion engine employs an air-fuel mixture lubrication system in which an air-fuel mixture containing lubricating oil is supplied into a crank chamber or a cylinder to lubricate movable parts such as a crankshaft and a piston. In this method, since the lubricating oil in the air-fuel mixture is also burned in the combustion chamber, the combustion of the lubricating oil produces white smoke and the like, which has been a major obstacle in purifying the exhaust gas.

Further, in the invention described in Japanese Patent Application Laid-Open No. Hei 7-310554, scavenging in the initial period is performed with air containing no fuel, but the scavenging air and the air-fuel mixture flow from the scavenging valve at the top of the cylinder. Because of the uniflow scavenging type which flows in the same direction to the scavenging port at the lower part of the cylinder, the air-fuel mixture supplied in the latter part of the scavenging has a drawback that a certain amount of the air-fuel mixture is drawn by the air flow and discharged. Furthermore, when the scavenging valve is closed, the air-fuel mixture sucked out of the vaporizer will remain in the upstream portion of the scavenging valve, but this air-fuel mixture flows into the diaphragm by the scavenging pressure from the crank chamber,
As a result, there has been a problem that the diaphragm made of an elastic film such as rubber is wetted with fuel and deteriorates, and the desired diaphragm movable characteristics cannot be obtained, resulting in a shift in the timing of supplying the air-fuel mixture to the combustion chamber.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and realizes scavenging by air, prevents air-fuel mixture from flowing through in a scavenging process, and further prevents combustion of lubricating oil in a combustion chamber. It is another object of the present invention to provide a two-cycle internal combustion engine in which exhaust gas is significantly purified. Further, in the case where a diaphragm-operated poppet valve is used as a valve for controlling air-fuel mixture supply to a combustion chamber in order to realize exhaust gas purification, the poppet valve can be operated with expected performance. It is an object of the present invention to provide a two-stroke internal combustion engine that can guarantee safe combustion. Further objects of the present invention will be apparent in the following description.

[0008]

A two-stroke internal combustion engine according to the present invention includes a first compressor and a second compressor which perform a compression stroke in accordance with a scavenging stroke of a piston in association with a piston reciprocating in a cylinder. A mixture supplied from a fuel supply device such as a carburetor or a fuel injector is pressurized by a first compressor and supplied to the combustion chamber from the top of the cylinder, and scavenging air taken in from the outside is supplied by a second compressor. It is pressurized and supplied from the side of the cylinder, and scavenging is performed by a fuel-free air flow.

That is, a control valve such as an electromagnetic control valve or a diaphragm-operated poppet valve that opens during a scavenging stroke is provided in a main passage communicating the fuel supply device and the top of the combustion chamber, and the control valve and the fuel supply device are provided. Between the check valve and the control valve, and a branch path communicating the main passage between the check valve and the control valve and the first compressor. A scavenging sub-passage communicating the scavenging port opened to the cylinder side wall with the second compressor is provided, and an air check valve for preventing flow to the outside is provided in the sub-passage to introduce scavenging air from outside. It is possible. Therefore, during the scavenging stroke in which the piston moves downward in the cylinder, the air pumped by the second compressor flows across the cylinder to scavenge, and the air-fuel mixture pumped from the first compressor flows into the cylinder at its top. Since the flow directions are different from each other, the scavenging flow and the air-fuel mixture are double-layered, and scavenging by the air flow is performed without mixing the air-fuel mixture.

Further, in the two-cycle internal combustion engine, like the four-cycle internal combustion engine, an oil pump is provided, and lubricating oil pumped by the oil pump is supplied to each part of the engine such as a crankshaft. The bottom of the crank chamber is a so-called direct lubrication system as a lubricating oil reservoir pumped up by an oil pump. When such a direct lubrication system is simply employed in a conventional two-stroke internal combustion engine, mist of the lubricating oil generated in the crankcase mixes with the air-fuel mixture and the scavenging air, causing illegal combustion and exhaust gas pollution. However, in the two-stroke internal combustion engine of the present invention,
Since the crank chamber is separated from the compression chamber for air-fuel mixture and scavenging, a direct lubrication system can be adopted without causing such a problem.

In the two-stroke internal combustion engine, the stepped cylinder is connected to the crank chamber at a distance of 90 degrees from the cylinder forming the combustion chamber, and the stepped piston reciprocating in the stepped cylinder is connected to the piston. First and second compressors coaxially connected to a crankpin for connecting the shaft and a crankshaft, and performing a compression stroke in accordance with a scavenging stroke of the piston by the stepped cylinder and the stepped cylinder in conjunction with the piston. Is configured. Thereby, the cylinders constituting the combustion chamber and the cylinders constituting the first compressor and the second compressor are 9
Primary vibrations caused by pistons reciprocating in the cylinders are arranged in a V-shape that is opened by 0 degrees, and vibrations during operation of the two-cycle internal combustion engine are suppressed.

Also, in the two-stroke internal combustion engine of the present invention,
In the same manner as described above, the scavenging air flow and the air-fuel mixture are two-layered to purify the exhaust gas. However, a diaphragm-operated poppet valve is used as the control valve, and the scavenging auxiliary passage and the diaphragm operation of the poppet valve are used. A control passage communicating with the port is provided, and in the scavenging stroke of the piston, the poppet valve is opened by the air pressure of the sub passage to supply the air-fuel mixture into the combustion chamber. As a result, even when a diaphragm-operated poppet valve is used to control the supply of the air-fuel mixture, the air flow that is structurally separated from the air-fuel mixture acts on the diaphragm, thereby preventing deterioration of the diaphragm due to fuel wetting. Is done.

In the above two-stroke internal combustion engine, the operating pressure of the diaphragm-operated poppet valve is determined by the air pressure from the second compressor driven by the crankshaft, so that the diaphragm is operated in accordance with the rotation speed of the crankshaft. Operating pressure can be changed. That is, since the diaphragm-operated poppet valve is opened corresponding to the operation of the crankshaft, the timing of supplying the air-fuel mixture to the combustion chamber can be reliably set with a simple configuration, and the air-fuel mixture can be appropriately cranked. Good combustion can be realized by injecting at an angle.

Further, in the above two-cycle internal combustion engine, a pressure control valve that opens and closes in conjunction with a throttle operation is provided in a control passage that guides drive air pressure to the diaphragm, and the pressure control valve increases as the throttle opening increases. The degree of opening is increased. This allows a simple configuration,
The air-fuel mixture supply timing from the diaphragm-operated poppet valve can be changed according to the throttle operation, and fine-grained timing control according to the operating state of the two-cycle internal combustion engine can be realized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A two-stroke internal combustion engine according to the present invention will be specifically described based on an embodiment shown in the drawings. In addition,
The embodiment shown below is a single-cylinder two-cycle internal combustion engine, but a plurality of cylinders can be similarly configured. FIG. 1 is a longitudinal sectional view of a two-cycle internal combustion engine according to one embodiment of the present invention. A two-cycle internal combustion engine 1 (hereinafter, simply referred to as an engine 1) includes a crankcase 2 and a crankcase 2. A rotatably supported crankshaft 3, a connecting rod 5 rotatably mounted on a crankpin 4 of the crankshaft 3, a piston 7 rotatably mounted on the tip of the connecting rod 5 via a piston pin 6, and a piston 7 The cylinder block 9 is slidably accommodated, and comprises a cylinder block 9 attached to the crankcase 2 and a cylinder head 10 attached to the top end of the cylinder block 9. In addition, 10a is an ignition plug.

Here, lubricating oil OL is stored at the bottom in the crankcase 2, and this lubricating oil OL is sucked up through a strainer 11 by the operation of an oil pump, which will be described later, as in a four-cycle internal combustion engine. And lubricating the movable parts of these mechanisms.

The engine 1 includes a cylinder head 10
A diaphragm-operated poppet valve 13 as a control valve attached to the combustion chamber 12 for interrupting the supply of air-fuel mixture to the combustion chamber 12;
A joint member 14 having one opening connected to one side upstream of the poppet valve 13, a reed valve 15 as a check valve connected to the other one of the joint members 14, and a mixed gas pipe 16 connected upstream of the reed valve 15. A carburetor 17 as a fuel supply connected to the end of the mixing pipe 16, a branch pipe 18 as a branch connected to the other one of the joint members 14, and a compressor connected to the other end of the branch pipe 18. And a unit 20.

In this embodiment, a main passage 19 for communicating the carburetor 17 and the top of the combustion chamber 12 with the joint member 14 and the mixing pipe 16 is formed. The upstream side of the carburetor 17 is connected to an air cleaner (not shown) to supply outside air, and the reed valve 15 prevents the air-fuel mixture supplied from the carburetor 17 from flowing back to the carburetor side. In addition, since the direct lubrication system is used as described above, the air-fuel mixture supplied from the vaporizer 17 does not include lubricating oil.

The compressor section 20 is of a reciprocating type that performs a compression stroke in a scavenging stroke of the piston in conjunction with the piston 7 and is rotatably mounted on the crankpin 4 of the crankshaft 3 coaxially with the piston 7. A connecting rod 21, a stepped piston 23 rotatably mounted on the connecting rod 21 via a piston pin 22, and a stepped cylinder 24 for slidably receiving the stepped piston 23. Further, the stepped cylinder 24 includes a large diameter portion 24a with which the large diameter portion 23a of the stepped piston 23 slides,
Small-diameter portion 2 with which small-diameter portion 23b of stepped piston 23 slides
4b, a cylinder block 25 in which a stepped cylinder 24 is formed is attached to the crankcase 2, and a cylinder head 26 is attached to an upper portion of the cylinder block 25.

With the above configuration, the compressor section 20 includes a first compressor including a stepped piston small diameter portion 23b and a stepped cylinder small diameter portion 24b, a stepped piston large diameter portion 23a and a stepped cylinder large diameter portion 24a. And the other end of the branch pipe 18 is connected to the pressurizing chamber 27 of the first compressor. Further, between the cylinder block 9 constituting the combustion chamber and the cylinder block 25 constituting the compressor,
An intake pipe 29 having a three-way air passage 30 is attached. One end of the air passage 30 is connected to the pressurizing chamber 28 of the second compressor, and the other end of the air passage 30 (scavenging sub-passage) is connected to a scavenging port 31 formed in a lower portion of the side wall of the cylinder 8. I have. In addition, 36 is an exhaust port, and 37 is an exhaust pipe.

An air cleaner (not shown) is connected to the other end of the intake pipe air passage 30 through an air supply pipe 32. The connection between the air passage 30 and the air supply pipe 32 is reversed. A reed valve 33 as a stop valve is provided. The reed valve 33 prevents external air supplied from the air cleaner from flowing back to the air cleaner. Also, as shown in detail in FIG.
A pipe 34 constituting a control passage 34a is attached between the control passage 34a. One end of the control passage 34a communicates with the air passage 30, and the other end of the control passage 34a is connected to the poppet valve 13a.
Is communicated with the diaphragm operation port 35.

As shown in detail in FIG. 3, the diaphragm-operated poppet valve 13 is provided on the upper portion of the cylinder head 10, and its axial poppet valve body passes through the main passage of the joint member 14 and has a distal end. Combustion chamber 1 from top of cylinder 8
I'm facing 2. That is, the mushroom-shaped tip of the poppet valve body 40 opens and closes the air-fuel mixture supply port provided at the top of the cylinder, and when the air-fuel mixture supply port is open, the air-fuel mixture from the main passage is The fuel is supplied into the combustion chamber 12 through a passage 41 around the shaft. A return spring 42 is wound around the poppet valve element 40, and the poppet valve element 40 is normally urged by the return spring 42 in a closing direction (upward in FIG. 3).

A diaphragm 43 is attached to the rear end of the poppet valve body 40.
A pressure chamber 44 communicating with the diaphragm operation port 35 is formed on the upper surface side of 3. Therefore, when the compressed air is guided from the air passage 30 to the diaphragm operation port 35 via the control passage 34a, the pressure in the pressure chamber 44 increases,
Thereby, the poppet valve element 4 provided with the diaphragm 43
1 will open against the return spring 42.
Reference numeral 45 denotes a rattling suppressing spring provided on the upper surface side of the diaphragm 43, and reference numeral 46 denotes an air vent passage on the lower surface side of the diaphragm 43.

The diaphragm operation port 35 and the pressure chamber 4
A shaft 48 that penetrates the passage 47 is rotatably provided in a portion of the passage 47 that communicates with the shaft 4, and a pressure control valve 49 that opens and closes the passage 47 is provided in an inner portion of the shaft 48. An operation piece 50 connected to a throttle operated by a driver is attached to an end of the shaft 48. Therefore, the pressure control valve 4 is linked with the driver's throttle operation.
The opening degree of the pressure passage from the control passage 34a to the pressure chamber 44 is controlled by the control 6, whereby the opening timing of the poppet valve body 40 is adjusted according to the operating condition, as described later.

FIG. 4 is a cross-sectional view of the engine 1 taken along the axis of the crankshaft and both cylinders. The engine 1 has an AC generator 54 at one end of the crankshaft 3.
A crank angle detection plate 55 attached to the outside of the AC generator 54, and a projection 55 formed on the crank angle detection plate 55.
a, 55b..., 55c... are connected to one end of the crankshaft 3 and crank angle sensors 56 and 57 for detecting a crank angle and the like, respectively. And a water pump 58.

An oil pump 60 communicating with the strainer 11 is mounted in the crankcase 2.
The oil pump 60 is connected to the crankshaft 3 by a known power transmission mechanism 61 such as a chain or a gear mechanism, and is driven by rotation of the crankshaft 3. An oil passage 2a is formed in the crankcase 2 to communicate with the bearing 62 of the crankshaft 3. The crankpin 4 communicates between the bearings 62 at both ends of the crankshaft.
An oil passage 4a communicating with the oil passage 4a is formed in the crankshaft 3, and one end of the oil passage 2a is connected to the oil pump 6a.
0 discharge port. Reference numeral 63 denotes an oil seal.

Therefore, when the engine 1 is operated and the crankshaft 3 rotates, the oil pump 60 is driven, and the lubricating oil OL is pumped from the oil reservoir at the bottom of the crank chamber through the strainer 11. And the oil pump 6
The lubricating oil OL discharged from the oil passages 2a and 2
a, flows through the oil passage 4a, and is supplied to each movable part of the engine 1 including the bearings 62 and 63.

As in the present embodiment, since the crank chamber is not used as a scavenging chamber or a compression chamber for air-fuel mixture, a direct lubrication system can be implemented using the bottom of the crank chamber as an oil reservoir.
Further, when the direct lubrication method is used, it is not necessary to mix the lubricating oil into the air-fuel mixture, so that the exhaust gas can be prevented from being polluted by the combustion of the lubricating oil. Furthermore, since the second compressor is a part that compresses air, it is difficult to achieve sufficient lubrication that can withstand intense driving accompanying engine rotation even if a lubrication system in which lubricating oil is mixed into an air-fuel mixture is used. It is. In this regard, since the second compressor portion can be sufficiently lubricated by the direct lubrication method, the second compressor for compressing the scavenging air can be realized with sufficient lubrication.

Next, the operation of the engine 1 will be described with reference to FIGS. As shown in FIG.
In the state where the air-fuel mixture burns inside the piston 2 and the piston 7 slightly descends from the top dead center to the bottom dead center, the stepped piston 23 of the compressor section 20 continues to descend further, and the pressurizing chamber of the first compressor is pressed. Inside of 27 becomes negative pressure. As a result, the outside air taken in from the air cleaner passes through the carburetor 17 to become an air-fuel mixture, opens the reed valve 14, and reaches the inside of the branch pipe 18 from the main passage 19. At the same time, the pressure in the pressurizing chamber 28 of the second compressor also becomes negative, so that the outside air taken in from the air cleaner passes through the air supply pipe 32, opens the reed valve 33, and reaches the inside of the air passage 30.

Then, as shown in FIG. 6, in a state immediately before the combustion gas expands and the piston 7 further descends to exhaust the gas, the piston 7 still blocks the exhaust port 36 and the scavenging port 31. However, the stepped piston 23 of the compressor section 20 shifts from the bottom dead center position to an ascending position, whereby the pressure inside the first pressurizing chamber 27 and the second pressurizing chamber 28 changes from negative pressure to positive pressure. Therefore, the air-fuel mixture reaching the middle of the branch pipe 18 in the state shown in FIG. 5 changes its direction and moves from the branch pipe 18 to the main passage 19 side in the state shown in FIG. Due to the closing, the pressure of the air-fuel mixture in the main passage 19 increases. Similarly, the air taken into the air passage 30 in the state shown in FIG. 5 is increased in pressure and closes the reed valve 33 in the state shown in FIG.

Then, as shown in FIG. 7, when the piston 7 is further lowered to open the exhaust port 63 and the scavenging port 31, the burned gas is discharged from the exhaust port 63. At the same time, the stepped piston 23 further rises to further increase the pressure of the air-fuel mixture in the main passage 19 and the air in the air passage 30, and is confined in the air passage 30 from the exhaust port 31. The high-pressure air flows into the cylinder 8 and scavenges the burned gas by a lateral air flow from the scavenging port 31 to the exhaust port 36.

Then, as shown in FIG. 8, immediately after the piston 7 has passed through the bottom dead center and started to move upward, and the scavenging port 31 and the exhaust port 36 have been closed, the stepped piston 23 of the compressor section 20 is closed. Is substantially at the top dead center position, the first pressurizing chamber 27 and the second pressurizing chamber 28 are in the most compressed state, and are again confined in the air-fuel mixture and the air confined in the main passage 19. The air has the highest pressure.

In this state, the poppet valve body 40 is pushed down against the return spring 42 by the air pressure in the air passage 30 guided from the control passage 34a to the pressure chamber 44 of the diaphragm 43. Therefore, cylinder 8
An air-fuel mixture supply port provided at the top of the air-fuel mixture is opened, and air-fuel mixture from the main passage 19 is supplied into the combustion chamber 12. When an electromagnetic control valve is used as a control valve for controlling the supply of the air-fuel mixture instead of the diaphragm-operated poppet valve, the electromagnetic control valve is energized in the above state and the electromagnetic control valve is opened for a predetermined time.

Then, as shown in FIG. 9, when the piston 7 further rises to reach the position before the top dead center, the stepped piston 23 passes through the top dead center and turns downward, and the air passage The air pressure in the pressure chamber 30, that is, in the pressure chamber 44 of the diaphragm decreases, the poppet valve body 40 closes, and the air-fuel mixture in the combustion chamber 12 becomes the most compressed state. In this state, the ignition plug 10a is energized, and the mixture is ignited by the ignition plug 10a.

Next, the operation of the pressure control valve 49 which opens and closes in conjunction with the throttle operation will be described with reference to FIGS. FIG. 10 is a graph showing the operating characteristics of the diaphragm-operated poppet valve 13 by the pressure control valve 49. The horizontal axis represents the angle θ (deg.) Of the crankshaft 3, and
The vertical axis represents the pressure Pd (Pa) of the pressure chamber 44 of the diaphragm-operated poppet valve. When the piston 7 is at the top dead center TDC, the crank angle θ is 0 (de)
g. ), And the crank angle θ is 180 (deg.) When the piston 7 is at the bottom dead center BDC.

In this graph, the line A is a pressure line in which the set load of the return spring 42 of the diaphragm-operated poppet valve 13 is replaced by the pressure of the diaphragm pressure chamber 44, and the pressure is Pd1. The compressor 20 is set to start pressurizing when the crank angle is θ1, and the pressure Pd of the diaphragm pressure chamber 44 is represented by a curve such as a line B or C each time the crankshaft 3 makes one rotation. Change. Note that a line B is a pressure curve of the diaphragm pressure chamber 44 when the pressure control valve 49 is fully opened,
Line C is a pressure curve of the diaphragm pressure chamber 44 when the pressure control valve 49 is opened by a predetermined opening in conjunction with the throttle opening.

The pressure Pd of the diaphragm pressure chamber 44 changes according to the opening of the pressure control valve 49. The waveform of the pressure curve of the pressure chamber 44 increases as the opening of the pressure control valve 49 increases. Therefore, as is clear from this graph, the waveform of the line B is larger than the waveform of the line C. Therefore, when the pressure control valve 49 is fully opened, the line B
1, the pressure Pd1 matches the pressure Pd1 corresponding to the set load of the return spring 42, and when the pressure Pd1 is exceeded,
The diaphragm operated poppet valve 13 opens. on the other hand,
When the pressure control valve 49 is set to a predetermined opening, the line C coincides with the pressure Pd1 corresponding to the set load of the return spring 42 at the point C1, and when the pressure exceeds this pressure Pd1, the diaphragm-operated poppet valve 13 becomes Open. As described above, by changing the opening of the pressure control valve 49 so as to increase as the throttle opening increases, the opening timing of the diaphragm-operated poppet valve 13 can be changed with respect to the crank angle θ. Thus, combustion according to the operating condition of the engine 1 can be performed.

FIG. 11 shows a diaphragm-operated poppet valve 1.
3 is a graph showing control characteristics of the opening timing of the crankshaft 3, in which the horizontal axis represents the rotation speed Ne (rpm) of the crankshaft 3 and the vertical axis represents the crank angle θ (deg.) Of the crankshaft 3. In addition, “exhaust start” and “exhaust end” indicate an exhaust start timing and an exhaust end timing from the engine 1, and “scavenging start” and “scavenging end” mean a scavenging start timing and a scavenging And an end timing.

In this graph, a line D is an opening timing characteristic curve of a control valve for controlling the supply of an optimum air-fuel mixture required for the engine 1, and a line E is an opening timing characteristic curve specific to the diaphragm-operated poppet valve 13. It is. As described above, the pressure control valve 49 controls the operation characteristics of the diaphragm-operated poppet valve 13 in conjunction with the throttle opening (that is, substantially in conjunction with the rotation speed Ne of the crankshaft 3). By increasing the opening timing of the poppet valve 13 and increasing the opening time as the opening increases, as shown in FIG. 11, a line E which is the opening timing characteristic of the diaphragm-operated poppet valve 13 is It is possible to approximate the characteristic of the line D.

FIG. 12 is a graph showing the opening angle characteristics of the diaphragm-operated poppet valve 13. The horizontal axis represents the rotation speed Ne (rpm) of the crankshaft 3, and the vertical axis represents the range α (deg) in which the crank angle changes. .). This graph shows, for each rotation speed Ne of the crankshaft 3, the relationship in which the diaphragm-operated poppet valve 13 keeps the opening operation over the time in which the crank angle changes by a certain angle. This is referred to as “open angle characteristic”, and a line indicating the open angle characteristic is referred to as “open angle characteristic curve”. For example, in the opening angle characteristic curve F, the rotational speed Ne of the crankshaft 3 is 7000
rpm, the crank angle is about 210 deg. The diaphragm-operated poppet valve 13 remains open for the time required to change.

A line F is an optimal opening angle characteristic curve of the air-fuel mixture injection valve required for the engine 1, and a line G is an opening angle characteristic curve specific to the diaphragm-operated poppet valve 13. As described above, the operating characteristics of the diaphragm-operated poppet valve 13 can be changed by the pressure control valve 49, so that the open-angle characteristics of the diaphragm-operated poppet valve 13 are linear regardless of the rotational speed Ne of the crankshaft 3. F can be approximated. As described above, by changing the operating characteristics of the diaphragm-operated poppet valve 13 with the pressure control valve 49 according to the throttle opening, the supply of the air-fuel mixture is maintained in an optimum state over almost the entire rotational speed range of the crankshaft 3. can do.

In the above embodiment, since the compressor is of a reciprocating type having a cylinder / piston configuration, and this compressor is arranged in a V-shape separated from the combustion chamber cylinder by 90 degrees, the primary Although the quiet operation is possible by canceling the vibration, the type and arrangement of the compressor are not particularly limited for the purpose of purifying the exhaust gas. Further, by providing the throttle pressure control valve 49, the engine can be operated more satisfactorily in accordance with the throttle operation. However, for the purpose of purifying exhaust gas, the pressure control valve 49 can be omitted.

[0043]

As described above, according to the present invention,
By employing a direct lubrication system using an oil pump in a two-stroke internal combustion engine, it is possible to prevent the blow-by exhaust due to the combustion of the lubricating oil and the air-fuel mixture, to purify the exhaust gas, and to further reduce the combustion chamber cylinder. The reciprocating compressor and the reciprocating compressor are arranged in a V-shape so as to be separated from each other by 90 degrees, so that engine operation can be quiet. Also, even when a diaphragm-operated poppet valve is used as a supply control valve for the air-fuel mixture, the diaphragm is operated by a mechanism separated from the air-fuel mixture. Control can be maintained normally, and furthermore, the opening characteristics of the diaphragm are changed in accordance with the throttle operation, so that an optimal air-fuel mixture supply can be performed according to the operating conditions.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a two-cycle internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a control passage portion in FIG.

FIG. 3 is a sectional view showing a diaphragm-operated poppet valve portion.

FIG. 4 is a cross-sectional view of a two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating the operation of the two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation of the two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 7 is a diagram illustrating the operation of the two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation of the two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 9 is a diagram illustrating the operation of the two-stroke internal combustion engine according to one embodiment of the present invention.

FIG. 10 is a graph showing operating characteristics of a poppet valve based on a relationship between a crank angle and a pressure applied to a diaphragm.

FIG. 11 is a graph showing operating characteristics of a poppet valve based on a relationship between a crankshaft rotation speed and a crank angle.

FIG. 12 is a graph showing operating characteristics of a poppet valve based on a relationship between a crankshaft rotation speed and a crank angle change range.

[Explanation of symbols]

1: two-stroke internal combustion engine, 2: crankcase,
3: Crank shaft, 4: Crank pin, 7: Piston,
8: cylinder, 11: oil strainer, 12: combustion chamber, 13: diaphragm operated poppet valve, 15:
Reed valve, 17: vaporizer, 18: branch pipe, 19: main passage, 20: compressor, 23: stepped piston,
24: stepped cylinder, 30: air passage (sub passage),
31: scavenging port, 33: reed valve, 34a: control passage, 36: exhaust port, 43: diaphragm, 4
4: pressure chamber, 49: throttle pressure control valve, 60: oil pump, 2a, 4a: oil passage OL: lubricating oil,

──────────────────────────────────────────────────続き Continuing on the front page (72) Inventor Takeshi Oshiro 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Yuji Tsushima 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference) 3G013 AA12 BA02 BB04 BB18 BC01 BC02 BD25 BD29 CA17

Claims

[Claims]

A first compressor and a second compressor that perform a compression stroke in accordance with a scavenging stroke of the piston in conjunction with a piston that reciprocates in the cylinder, wherein the first compressor and the second compressor are configured to supply a mixture supplied from a fuel supply device to a first compressor. In a two-cycle internal combustion engine, which is pressurized by a compressor and supplied to a combustion chamber in a cylinder, and scavenging air taken in from the outside is supplied to the cylinder by pressurization by a second compressor, a fuel supply device, a top of the combustion chamber, A control valve that opens during the scavenging stroke is provided in the main passage communicating with the fuel supply device, and a mixture check valve that prevents flow toward the fuel supply device is provided between the control valve and the fuel supply device. A branch path communicating the main passage between the stop valve and the control valve and the first compressor is provided, and a scavenging port opened on the cylinder side wall and the second compressor are connected. A scavenging sub-passage is provided, and an air check valve for preventing flow to the outside is provided in the sub-passage so that scavenging air can be introduced from the outside, and a lubricating oil reservoir is formed at the bottom of the crankcase of the engine. A two-stroke internal combustion engine comprising an oil pump for supplying lubricating oil from the reservoir to each part of the engine.
2. The two-stroke internal combustion engine according to claim 1, wherein the stepped cylinder is connected to the crank chamber at a distance of 90 degrees from the cylinder constituting the combustion chamber, and reciprocates in the stepped cylinder. A stepped piston is coaxially connected to a crankpin connecting the piston and the crankshaft. One of the pump chambers formed in the stepped cylinder is used as a pressurizing chamber of the first compressor, and the other pump chamber is used as a pump chamber. A two-stroke internal combustion engine, wherein the pressurizing chamber of a second compressor is used.
3. A first compressor and a second compressor which perform a compression stroke in accordance with a scavenging stroke of the piston in conjunction with a piston reciprocating in the cylinder, wherein the air-fuel mixture supplied from the fuel supply device is supplied to the first compressor. In a two-cycle internal combustion engine, which is pressurized by a compressor and supplied to a combustion chamber in a cylinder, and scavenging air taken in from the outside is supplied to the cylinder by pressurization by a second compressor, a fuel supply device, a top of the combustion chamber, A diaphragm operated poppet valve is provided in a main passage communicating with the fuel supply device, and a mixture check valve for preventing a flow toward the fuel supply device is provided between the poppet valve and the fuel supply device, and the check valve is provided. A branch passage communicating the main passage between the first compressor and the poppet valve; and a scavenging port opened to the cylinder side wall and a second compressor. A scavenging sub-passage communicating with the air passage is provided, and an air check valve for preventing flow to the outside is provided in the sub-passage so that scavenging air can be introduced from the outside. A two-stroke internal combustion engine, wherein a poppet valve is opened by air pressure in a sub-passage during a scavenging stroke of a piston to supply a mixture to a combustion chamber during a scavenging stroke of a piston.
4. The two-stroke internal combustion engine according to claim 3, wherein a pressure control valve that opens and closes in conjunction with a throttle operation is provided in the control passage.