JPH10325331A - Mixture supply passage structure for two-stroke internal combustion engine - Google Patents

Abstract

(57) Abstract: A control valve (1) for closing a main passage (19) in a main passage (19) communicating a carburetor (16) and a combustion chamber (11).
2 and the control valve 12 and the carburetor 16
A two-stroke internal combustion engine provided with a check valve 14 between the control valve 12 and the check valve 14;
8, the tip of the branch passage 18 is connected to a reciprocating compressor 20, and the main passage 19 is set shorter than the branch passage 18. [Effect] By arranging the compressor not at the main passage but at the end of the branch passage, fuel does not adhere to the inner wall of the compressor. And a mixture with a stable air-fuel ratio can be supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved mixture supply passage structure for a two-stroke internal combustion engine.

[0002]

2. Description of the Related Art As a structure of a mixture supply passage of a two-cycle engine, for example, Japanese Patent Publication No. 50-25083, "Combustion System for Two-Cycle Engine" is known.

[0003] The above technology improves the ignitability of a two-stroke engine during low-load operation to prevent irregular explosion.
It stabilizes low-load operation and purifies exhaust gas by enabling operation with a lean mixture. As shown in the figure of the publication, the carburetor 13 and the carburetor 13
, A suction pipe 10 connected to the suction pipe 21, a positive displacement air pump P connected to the suction pipe 10, and a downstream side of the suction pump P. And a combustion chamber 4, an intake valve 14, a sub-combustion chamber 5, and a through hole 6 interposed in this order.

[0004]

The air-fuel mixture supply passage according to the above-mentioned technology includes a sub-intake cylinder 24 of the carburetor 13-a sub-intake pipe 21-.
Because the distance is long, even if a gas mixture that is well atomized by the carburetor 13 is generated, the gas mixture passes through the gas mixture supply passage. ,
The fuel adheres to the passages and the walls of the pump P, and the fuel accumulates in the passages and the pump P. Therefore, a stable air-fuel ratio cannot be maintained, and an expected engine performance cannot be obtained. .

Therefore, an object of the present invention is to prevent fuel from adhering to a mixture supply passage or a wall surface inside a compressor,
It is an object of the present invention to provide a mixture supply passage structure for a two-cycle internal combustion engine that can maintain a stable air-fuel ratio.

[0006]

According to a first aspect of the present invention, a control valve for closing a main passage is provided in a main passage communicating between a carburetor and a combustion chamber. In a two-stroke internal combustion engine in which a check valve is provided between a control valve and a carburetor, a branch path that opens between the control valve and the check valve is formed, and the tip of this branch path is used for a reciprocating compressor. In addition to the connection, the main passage was set shorter than the branch passage.

By providing the compressor not at the main passage but at the end of the branch passage, fuel does not adhere to the inner wall of the compressor, and the air-fuel mixture produced by the carburetor passes through the main passage through the control valve to the combustion chamber. Smoothly supplied,
An air-fuel mixture with a stable air-fuel ratio can be supplied.

According to a second aspect of the present invention, the branch path has an upward slope toward the compressor. If fuel adheres to the inner wall of the branch road,
Since the fuel flows to the main passage without flowing to the compressor side,
The fuel can be used effectively.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a cross-sectional view of a two-cycle internal combustion engine according to the present invention. A two-cycle internal combustion engine 1 (hereinafter, referred to as “engine 1”) is rotatably supported by a crankcase 2 and the crankcase 2. A 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 the piston 7 slides The cylinder block 8 is provided with a cylinder 8a, and is attached to the crankcase 2; and a cylinder head 9 attached to the tip of the cylinder block 8. Note that lubricating oil is stored in the crankcase 2 like a four-cycle internal combustion engine, and contributes to lubrication around the crankshaft 3.

The engine 1 has a solenoid valve 12 mounted on the cylinder head 9 for interrupting the supply of air-fuel mixture to be supplied to the combustion chamber 11, and one end connected upstream of the solenoid valve 12. Member 13 that opens to the front, a reed valve 14 as a check valve connected to another side of the coupling member 13, and a bent pipe 1 connected upstream of the reed valve 14.
5 and a carburetor 16 connected to the tip of the bent pipe 15
And a branch pipe 18 which is a branch path connected to the joint member 13 via a connection pipe 17A.
7B, and a compressor section 20 which is a compressor connected through the 7B. The carburetor 16 is connected upstream to an air cleaner (not shown). A main passage 19 is formed by the joint member 13 and the bent pipe 15.

Here, 41 is an air supply pipe connected to an air cleaner (not shown), 42 is a reed valve, 43 is an intake pipe attached to the crankcase 2, 44 is a scavenging port, 45 is a water jacket, 46 is an exhaust port, 47 is an exhaust pipe,
48 is a spark plug, 51 and 52 are piston rings, B
Reference numerals 1, B2,...

The compressor section 20 is of a reciprocating type that sucks and compresses an air-fuel mixture by using the output of the engine 1, and includes a connecting rod 21 rotatably attached to a crankpin 4 of a crankshaft 3. A piston 23 is rotatably attached to the connecting rod 21 via a piston pin 22.

The compressor section 20 includes a piston 2
The first cylinder 24a on which the third large piston portion 23a slides
And a second cylinder 25a having a first cylinder block 24 mounted on the crankcase 2 and a second cylinder 25a mounted on the first cylinder block 24 so that the small piston portion 23b of the piston 23 slides. It comprises a block 25 and a cylinder head 26 mounted on the upper part of the second cylinder block 25.

Here, 27 is a first chamber, 28 is a first air passage, 31 is a second chamber, 32 is a second air passage, 33 is a water jacket, 34, 35 and 36 are piston rings, B
3 and B3 are bolts.

FIG. 2 is a cross-sectional view passing through the center of the crankshaft and each cylinder axis of the two-stroke internal combustion engine according to the present invention.
The engine 1 has an AC generator 54 at one end of the crankshaft 3, a crank angle detection board 55 attached to the outside of the AC generator 54 with bolts B 4, and convex portions 55 a, 55 b formed on the crank angle detection board 55. , 55c,... (Crank angle sensors corresponding to the convex portions 55a are omitted), and elastic members provided on the extension of the axis of the crankshaft 3 and the crankshaft 3. Water pump 6 connected via 58
1 is provided.

Here, reference numerals 4a and 4b denote lubricating oil supply holes opened in the crankpin 4, 62 and 62 denote bearings, 63 and
64 is an oil seal, 65, 65, 66, and 66 are needle bearings, and 67 and 68 are scavenging ports.

The operation of the engine 1 described above will be described with reference to FIGS. FIG. 3 is a cross-sectional view (first operation diagram) for explaining the operation of the engine according to the present invention. FIG. 4 is a sectional view (second operation diagram) for explaining the operation of the engine according to the present invention. FIG. 5 is a sectional view (third operation diagram) illustrating the operation of the engine according to the present invention. FIG. 6 is a sectional view (fourth operation diagram) illustrating the operation of the engine according to the present invention. FIG. 7 is a sectional view (fifth operation diagram) illustrating the operation of the engine according to the present invention.

In FIG. 3, when the air-fuel mixture is burning in the combustion chamber 11 or when the combustion is finished, the piston 7 is slightly lowered from the top dead center to the bottom dead center. At this time, the piston 23 of the compressor section 20 descends from the top dead center, and the inside of the second chamber 31 and the second cylinder 25a becomes a negative pressure.
The air passes through the carburetor 16, becomes an air-fuel mixture, passes through the bent pipe 15, opens the reed valve 14, and reaches from the inside of the joint member 13 to the inside of the branch pipe 18.

Further, since the inside of the first chamber 27 and the inside of the first cylinder 24a also become negative pressure with the introduction of the air from the carburetor 16, air flows from the air cleaner (not shown) through the air supply pipe 41 to the reed valve 42. Open the intake pipe 43
And the first air passage 28.

In FIG. 4, in a state immediately before the burned gas expands and exhausts the gas, the piston 7
And the upper end of the piston 7 is
The upper end is closed. At this time, the piston 23 of the compressor section 20 is almost at the bottom dead center position, and shifts from descending to ascending.

As a result, the pressure in the second chamber 31 and the inside of the second cylinder 25a changes from negative pressure to positive pressure. Therefore, in FIG. 3, the air-fuel mixture reaching the middle of the branch pipe 18 changes its direction in FIG. 4 and moves from the branch pipe 18 to the joint member 13 side. At this time, the reed valve 14 is closed by the pressure in the joint member 13.

In addition, since the direction of the air-fuel mixture in the branch pipe 18 is changed and the pressure in the first chamber 27 and the first cylinder 24a also changes from negative pressure to positive pressure, the air in the first air passage 28 is Return into the tube 43. At this time, the reed valve 42 is closed by the pressure in the intake pipe 43.

In FIG. 5, the burned gas is discharged,
In the scavenging stroke in which fresh air scavenges inside the cylinder 8a, the piston 7 is at a position slightly elevated from the bottom dead center, and both the scavenging port 44 and the exhaust port 46 are open. At this time, the piston 23 of the compressor section 20 has moved largely toward the top dead center with respect to the position shown in FIG.
The inside of 5 a and the inside of the second chamber 31 are compressed, and the air-fuel mixture is returned to the vicinity of the joint member 13 and has a high pressure. The air in the first air passage 28 passes through the intake pipe 43, passes through the scavenging port 44, and enters the cylinder 8a.

In FIG. 6, the piston 7 is connected to the exhaust port 4
At the start of the compression stroke immediately after closing the valve 6, the piston 23 of the compressor section 20 is almost at the top dead center position, the second chamber 31 is in the most compressed state, and the air-fuel mixture is in the vicinity of the joint member 13. And accumulate at the highest pressure. In this state, the solenoid valve 12 is energized to operate the solenoid valve 12 for a predetermined time. Thereby, the high-pressure mixture near the joint member 13 is injected into the cylinder 8a.

In FIG. 7, at the end of the compression stroke, the piston 7 is at a position before the top dead center, and the air-fuel mixture in the combustion chamber 11 is in the most compressed state. In this state, the ignition plug 48 is energized, and the ignition plug 48 is ignited. As a result, the high pressure air-fuel mixture explodes instantaneously.

The piston 23 of the compressor section 20 is slightly lowered from the top dead center. As shown in FIG. 3, air is introduced from the inlet of the carburetor 16 and the air-fuel mixture is bent to form the bent pipe 15 and the lead. It is guided into the joint member 13 via the valve 14. Further, since the inside of the first chamber 27 and the inside of the first cylinder 24a becomes negative pressure, the air passes through the air supply pipe 41, opens the reed valve 42, and reaches the inside of the intake pipe 43 and the first air passage 28. Thereafter, the same is repeated from FIG.

As described above, the carburetor 16 and the combustion chamber 11
A solenoid valve 12 for closing the main passage 19 is provided in a main passage 19 communicating with the solenoid valve, and a reed valve 14 is provided between the solenoid valve 12 and the carburetor 19. A branch pipe 18 opening between the pipes 18 is formed. The distal end of the branch pipe 18 is connected to the compressor section 20, and the main passage 19 is set shorter than the branch pipe 18. However, since it is provided at the end of the branch pipe 18, fuel does not adhere to the inner wall of the compressor section 20, and the air-fuel mixture generated by the carburetor 16 smoothly flows through the main passage 19 to the combustion chamber 11 via the electromagnetic valve 12. And a mixture with a stable air-fuel ratio can be supplied.

The branch pipe 18 is connected to the compressor 20
With the upward slope, when fuel adheres to the inner wall of the branch pipe 18, the fuel flows to the main passage 19 without flowing to the compressor section 20 side, so that the fuel can be used effectively.

The control valve of the present invention may be a pneumatic or hydraulic valve in addition to the electric solenoid valve described in the embodiment.

[0030]

According to the present invention, the following effects are exhibited by the above configuration. In the air-fuel mixture supply passage structure of the two-stroke internal combustion engine according to the first aspect, a branch passage that opens between the control valve and the check valve is formed, and a tip of the branch passage is connected to a reciprocating compressor. Since the main passage is shorter than the branch passage, the compressor is installed at the tip of the branch passage instead of the main passage, so that fuel does not adhere to the inner wall of the compressor, and the air-fuel mixture generated by the carburetor is The inside of the passage is smoothly supplied to the combustion chamber via the control valve, so that a mixture having a stable air-fuel ratio can be supplied.

In the mixture supply passage structure for a two-cycle internal combustion engine according to the second aspect of the present invention, the fuel injection does not flow to the compressor side when the fuel adheres to the inner wall of the branch passage because the branch passage is inclined upward toward the compressor. Since the fuel flows into the main passage, the fuel can be used effectively.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a two-stroke internal combustion engine according to the present invention.

FIG. 2 is a sectional view of the two-stroke internal combustion engine according to the present invention passing through the center of the crankshaft and each cylinder axis.

FIG. 3 is a cross-sectional view (first operation diagram) for explaining the operation of the engine according to the present invention.

FIG. 4 is a sectional view (second operation diagram) for explaining the operation of the engine according to the present invention;

FIG. 5 is a sectional view (third operation diagram) for explaining the operation of the engine according to the present invention;

FIG. 6 is a sectional view (fourth operation diagram) illustrating the operation of the engine according to the present invention.

FIG. 7 is a cross-sectional view (fifth operation diagram) illustrating the operation of the engine according to the present invention.

[Explanation of symbols]

1 ... 2 cycle internal combustion engine (engine), 11 ... combustion chamber,
12: control valve (solenoid valve), 14: check valve (lead valve),
16: Carburetor, 18: Branch passage (branch pipe), 19: Main passage, 20: Compressor (compressor section).

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Yoshihiro Takada 1-4-1 Chuo, Wako-shi, Saitama

Claims (2)

[Claims] A control valve for closing the main passage in a main passage communicating the carburetor with the combustion chamber;
In a two-stroke internal combustion engine provided with a check valve between the control valve and the carburetor, a branch path that opens between the control valve and the check valve is formed. A mixture supply passage structure for a two-stroke internal combustion engine, wherein the main passage is connected to a compressor and the main passage is set shorter than the branch passage. 2. The mixture supply passage structure for a two-stroke internal combustion engine according to claim 1, wherein the branch passage is formed to have an upward slope toward the compressor.