JPS63167028A - Two-cycle engine - Google Patents

Abstract

PURPOSE:To improve scavenging efficiency in all rotation regions by providing a combustion chamber and a press-in chamber at the upper part and the lower part in a cylinder and by connecting a piston in the cylinder to a connecting rod through a rod piercing through a partition wall forming the press-in chamber. CONSTITUTION:A combustion chamber 2 and a press-in chamber 3 are formed at the upper part and the lower part ion a cylinder 1. The combustion chamber 2 is provided with an exhaust hole 6 and a scavenging hole 7 formed at places which are opened when a piston 5 descends. On the other hand, a partition wall 8 for blocking up the lower end of the cylinder 1 is provided with a scavenging hole 9 and an intake port 10. The respective scavenging holes 7, 9 of the combustion chamber 2 and the press-in chamber 3 are communicated with each other through a scavenging path 11. A rod 13 is fixed to the lower surface of the piston 5, and the rod 13 is pierced through a through hole opened in the partition wall 8 in such a manner as to freely slide. The lower end of the rod 13 is connected to a connecting rod 15. In this arrangement, a sufficient quantity of fresh air is sucked in the press-in chamber 3, and the sucked fresh air is pressed in the combustion chamber 2 with good efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-stroke engine that forcibly scavenges fresh air into a combustion chamber, and particularly relates to a two-stroke engine that can realize a supercharged state with a simple structure.

[Prior art and its problems] Since a two-stroke engine explodes once every revolution of the crankshaft, it can produce high horsepower per cylinder displacement. Since a two-stroke engine exhausts combustion gas and inhales air-fuel mixture at the same time, it is extremely important to bring the scavenging air as close to the ideal state as possible. The ideal scavenging hole is one that allows combustion gases to be completely exhausted and also allows a sufficient amount of fresh air to be supplied into the cylinder. In the actual engine,
Various methods have been developed with the aim of approaching this state.

The simplest structure uses the resonance phenomenon of exhaust gas flow within the exhaust pipe to increase maximum horsepower. This method allows combustion gas to flow into the exhaust pipe at high speed the moment the exhaust hole opens, and then, before the piston rises and the exhaust hole closes, the reflected waves of the exhaust gas that occur inside the exhaust pipe pass through the exhaust pipe. The fresh air is pushed back into the cylinder to increase horsepower. Although this system has an extremely simple structure, the resonance frequency is determined by the shape of the exhaust pipe, and it is effective only at a specific rotation speed and is not effective over the entire rotation range. Used only in engines.

Other methods include a cylinder head equipped with an exhaust valve so that combustion gas and fresh air can be scavenged without mixing, or a uniflow system equipped with two pistons that reciprocate within the cylinder. A scavenging two-stroke engine has also been developed, but due to its complicated structure, it has not been put into practical use.

As another method, an engine using a supercharger has also been developed. There are several types of superchargers, such as those that use an exhaust gas star pin, those that are driven by the engine, and those that are driven by an electric motor, but this method requires a supercharger separate from the engine, so it reduces the overall power consumption of the engine. The cost is considerably high, and the maintenance of the supercharger itself is time-consuming.

If a two-stroke engine with a simple structure and high scavenging effect at all rotational speeds could be realized without using a supercharger, the ideal engine could be put into practical use.

[Purpose of the Invention] The present invention was developed with the aim of realizing this. A press-fitting chamber is provided at the lower end of the cylinder, and the piston is inserted through a rod that airtightly penetrates the partition wall that forms this press-fitting chamber. With the extremely simple structure of connecting the connecting rod to the connecting rod, it is possible to bring the scavenging air close to the ideal condition in the entire rotation range, thereby significantly increasing the torque, and furthermore, creating a 2-stroke engine that can prevent the crankshaft from seizing. It is on offer.

Another important object of the present invention is that sufficient fresh air is injected into the cylinder without using a supercharger, so maintenance is easy, there is no breakdown, and the system is durable and can be mass-produced at low cost. To provide cycle engines.

[Means for solving conventional problems] In the two-stroke engine of the present invention, both ends of the cylinder are
A combustion chamber and a press-in chamber are formed at both ends of the cylinder, which are airtightly closed by a cylinder head and a partition wall, with the piston as a boundary. An exhaust hole and a scavenging hole are opened in the combustion chamber at positions that open when the piston descends to a predetermined position.
The scavenging hole communicates with the press-in chamber via a scavenging path. Further, an intake hole is opened in the press-in chamber, and the intake hole is connected to the air-fuel mixture supply means via a valve means. Further, the piston is connected to a connecting rod via a rod. The partition wall has a through hole in which the rod can slide in an airtight manner, and the rod is inserted into the through hole. The opening positions of the through holes are such that a rod, one end of which is connected to the piston, extends in the direction of reciprocating movement of the piston. When the piston descends, the air-fuel mixture in the injection chamber is forcibly scavenged into the combustion chamber through the scavenging passage.

[Operations and Effects] The two-stroke engine of the present invention has two excellent functions in principle, and can sufficiently inject fresh air into the combustion chamber of the cylinder. The first effect is that a sufficient amount of fresh air can be sucked into the pressurization chamber. That is, unlike the two-stroke engine of the present invention, a conventional two-stroke engine does not have a press-in chamber equal to the piston stroke volume of the combustion chamber, but is placed in a crankcase with a large volume (approximately three times the piston stroke volume or more). Because fresh air is being sucked in, the suction pressure inside the crankcase is not sufficient, and a large amount of fresh air cannot be sucked in. The smaller the space inside the crankcase, the more fresh air can be sucked into the engine. In order to achieve this, no matter what shape the crank is, it is necessary to rotate the crank to which the reciprocating connecting rod is connected, so the space cannot be made that small. For this reason, even if the empty space in the crank chamber is small, it has a large volume, approximately three times the stroke volume of the cylinder.

However, in the two-stroke engine of the present invention, the volume of the injection chamber can be made almost the same as the stroke volume of the combustion chamber, and can be reduced to one third of that of the conventional system. Therefore, when the piston 5 rises from the position shown in FIG. 1 to the position shown in FIG.
The pressure inside the pressurization chamber 3 is sufficiently lower than atmospheric pressure, so that a large amount of fresh air can be sucked in smoothly.

Furthermore, the second excellent effect of the two-stroke engine of the present invention is that the fresh air sucked into the injection chamber 3 is efficiently forced into the combustion chamber 2. That is, when the piston 5 descends from the position shown in FIG. 2 to the position shown in FIG. into the combustion chamber.

As described above, in the two-stroke engine of the present invention, a combustion chamber and a press-in chamber are formed at both ends of the cylinder, and since the volume of the press-in chamber can be made almost the same as that of the combustion chamber, each time the piston reciprocates, the press-in chamber The same volume of fresh air as the combustion chamber is taken in and forced into the combustion chamber, so the combustion chamber is scavenged in near-ideal conditions. Therefore, sufficient fresh air can be injected into the combustion chamber, and the horsepower per volume can be significantly increased.

Regardless of the engine speed, the injection chamber effectively injects fresh air into the combustion chamber, so torque can be significantly increased in all engine speed ranges, making the engine easier to use.

Furthermore, since it has a very simple structure in which a press-fitting chamber is provided by a partition wall below the cylinder and the piston is connected to the crankshaft via a rod and a connecting rod, it can be produced in large quantities at low cost.

Furthermore, there is no need for high-speed rotating moving parts like a supercharger,
A two-stroke engine that is easy to maintain, has few breakdowns, and is durable can be put into practical use.

Furthermore, immediately after the piston descends and the scavenging hole in the combustion chamber opens, fresh air is blown into the combustion chamber from the scavenging hole at high speed, promoting exhaustion. In the state of descending to the bottom dead center, fresh air is not injected at high speed through the scavenging holes, and by preventing fresh air from passing through in this state, the scavenging efficiency and intake efficiency can be improved.

[Preferred embodiment code] Embodiments of the present invention will be described below based on the drawings.

In the two-stroke engine shown in FIGS. 1 and 2, both upper and lower ends of a cylinder 1 are hermetically closed, and a combustion chamber 2 is formed in the upper part of the cylinder, and a press-in chamber 3 is formed in the lower part. The upper end opening of the cylinder 1 is closed with a cylinder radiator 4 as in a conventional engine, and an ignition plug (not shown) is provided at the center of the cylinder head 4.

A combustion chamber 2 located in the cylinder and above the piston has a combustion chamber 2 at a position that opens when the piston 5 descends.
An exhaust hole 6 and a scavenging hole 7 are opened through the cylinder 1.

The upper opening edge of the exhaust hole 6 is located higher than the scavenging hole 7,
When the piston 5 descends, the exhaust hole 6 first hits to exhaust combustion gas, and then the scavenging hole 7 opens and fresh air is forced in.

The opening positions and opening shapes of the exhaust hole 6 and the scavenging hole 7 can be used in a conventional engine as they are. However, the second aspect of the present invention
Since a cycle engine has a high effect of blowing fresh air immediately after the scavenging hole opens, it is also possible to open the scavenging hole later by shifting the upper edge of the opening of the scavenging hole 7 somewhat downward.

The partition wall 8 airtightly closes the lower end of the cylinder 1, and the partition wall 8 forming the press-fitting chamber 3 has an air scavenging hole 9 and an intake hole 10 opened therein. This scavenging hole 9 is connected to the scavenging hole 7 of the combustion chamber 2 via a scavenging passage 11. Pressure chamber scavenging hole 9
is opened at the bottom of the press-in chamber 3 or at the bottom so that fresh air in the press-in chamber 3 is pressurized into the combustion chamber 2 until the piston 5 descends to the bottom dead center.

The scavenging passage 11 is provided in the cylinder block outside the cylinder liner, similar to conventional engines.

Fresh air is forced into the combustion chamber 2 from the injection chamber 3 through the scavenging passage 11, and is forcibly introduced as the piston 5 descends. At this time, the larger the volume of the scavenging passage 11, the lower the upper limit pressure of the press-in chamber 3 when the piston is lowered, thereby reducing the amount of fresh air flowing from the press-in chamber 3 into the combustion chamber 2. On the other hand, if the scavenging passage 11 is too narrow, the resistance to passage of fresh air increases and the effect of fresh air flowing in decreases. However, in the engine of the present invention, fresh air is forcefully and smoothly injected into the combustion chamber 2 from the injection chamber 3, so even if the scavenging passage 11 is narrowed, it is possible to inject fresh air smoothly. .

The intake hole 10 is provided with a reed valve 12, which is a valve means, to prevent fresh air from flowing backward from the press-in chamber 3 when the piston is lowered. The reed valve 12 is disposed close to the intake hole IO so that the volume of the press-fitting chamber 3 can be made as small as possible.

In the present invention, the opening position of the intake hole 1O is not limited to the position shown in FIG. 1, but for example, although not shown, it is also possible to open the intake hole 1O in the scavenging passage 11 communicating with the press-in chamber 3.

Further, the present invention does not specify the valve means of the intake hole 10 to be the reed valve 12, and for example, although not shown, all valve means used in conventional two-stroke engines, such as piston valves and rotary valves, may be used. can. Although not shown in the drawings, the piston valve has an intake hole formed through the cylinder that forms the press-in chamber 3, similar to a conventional two-stroke engine.

The air supply hole 10 is connected to an air-fuel mixture supply means such as a carburetor, and fresh air mixed with fuel is taken in therein.

In order to minimize the volume of the press-fitting chamber 3 at the bottom dead center, the piston 5 preferably has a closed structure as shown in FIGS. 1 and 2. A rod 13 is fixed to the center of the lower surface of the piston 5 so as to extend directly downward in the reciprocating direction of the piston in FIGS. 1 and 2.

The rod 13 slidably passes through a through hole 14 opened in the partition wall 8 in an airtight manner, and is connected to a connecting rod 15 at its lower end. The overall length of the rod 13 is determined to be such that the lower end of the rod 13 connected to the connecting rod 15 is located within the crank chamber when the piston 5 is raised to the top dead center as shown in FIG. Furthermore, this rod 13 moves up and down along a guide 16 provided within the crankcase.

As shown in FIGS. 1 to 3, the guides 16 are disposed on both sides of the rod 13, and a protrusion is provided on the rod sliding surface of the guide 16, and the rod 13 is attached to the protrusion. A groove is provided along which it slides.

The rod 13 whose both sides are supported by the guides 16 in this manner has increased strength against bending, and a thin and light rod can be used.

The lower end of the rod 13 is rotatably connected to the upper end of the connecting rod 15 via a pin 17. The upper end of the connecting rod 15 is connected to the connecting rod 15 via a pin 17 that is located on both sides of the rod 13 and passes through the rod 13, as shown in FIG. 3, so as not to hit the guide 16. The lower end of the connecting rod 15 is connected to a crank pin 18.

The crank chamber 19 divided by the partition wall 8 can be filled with engine oil for lubrication as in a four-stroke engine.

In the engine shown in FIGS. 1 and 2, a rod 13 is fixed to the piston 5, but the rod 13 does not necessarily need to be fixed to the piston 5. Although not shown, even if the piston and rod are tiltably connected via a piston pin as in a conventional engine, the direction of movement of the rod is determined by the direction of movement of the piston due to the piston and the through hole in the partition wall. Ru.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a two-stroke engine showing an embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a rod, a guide, and a connecting rod. l...Cylinder, 2...Combustion chamber, 3...Pressure chamber, 4...Cylinder head, 5...Piston, 6...Exhaust hole, 7...Scavenging hole, 8...
- Partition wall, 9...Scavenging hole, 10...Intake hole, 1
1... h' is the airway, 12... Riet valve, 1
3... Lot, 14... Through hole, 15... Con [
Kotsuto, 16...Guide, 17...Pin, 18
...Crank pin, 19...Crank chamber. Most applications 1) Yoshikazu

Claims (5)

[Claims] (1) Both ends of the cylinder, in which the piston reciprocates, are hermetically closed by the cylinder head and a partition wall, and a combustion chamber and a press-in chamber are formed at both ends of the cylinder with the piston as a boundary. An exhaust hole and a scavenging hole are opened at the positions that open when the piston descends to a predetermined position, and the scavenging hole is communicated with the press-fitting chamber via a scavenging passage, and the suction hole is opened in communication with the press-fitting chamber. The intake hole is connected to a mixture supply means through a valve means, and the piston is connected to a connecting rod through a rod, and the partition wall is connected to the connecting rod through a rod. A slidable through hole is drilled and a rod is inserted through the through hole, and the opening position of the through hole is such that the rod, one end of which is connected to the piston, extends in the direction of reciprocating movement of the piston. The two-stroke engine is configured so that when the piston descends, the air-fuel mixture in the injection chamber is forcibly scavenged into the combustion chamber through the scavenging passage. (2) Claim 1 in which the valve means is a reed valve
2-stroke engine as described in section. (3) The intake hole is opened to the piston passage of the cylinder,
A two-stroke engine according to claim 1, wherein the piston also serves as the valve means. (4) A two-stroke engine according to claim 1, wherein the rod is fixed to the piston. (5) A two-stroke engine according to claim 1, wherein the rod is tiltably connected to the piston via a pin.