JPS637257B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention belongs to the technical field of a starting assist device for a two-stroke engine using low-quality liquid fuel such as white kerosene or alcohol. The mixture is mixed with clean air from the air cleaner and sucked into the crank chamber, and the air-fuel mixture sucked into the crank chamber is compressed as the piston descends and injected into the combustion chamber from the scavenging port in the scavenging passage. This invention relates to a two-stroke engine that uses scavenged low-quality oil as fuel.

In general, in two-stroke engines that use low-quality oil such as white kerosene or alcohol as fuel, fuel vaporization is poor, and the particle size of the fuel in the mixture formed in the carburetor is large, causing the mixture sucked into the crank chamber to It tends to adhere to the side wall of the crank chamber and dilute the air-fuel mixture, making cold starting particularly difficult.

Therefore, in order to improve the cold start of such an engine, the present applicant has developed an air-fuel mixture that is injected from the crank chamber 17 through the scavenging air passage 16 into the combustion chamber 9, as shown in FIG. Previously, a system was proposed in which heating is performed using a heating device 24 provided in the scavenging air passage 16 to promote vaporization and improve starting performance.

However, these methods had the following problems.

That is, in order to sufficiently heat and vaporize the air-fuel mixture passing through the scavenging passage, the heating device must be large and have a high output, which not only increases the cost but also increases the size of the engine.

Moreover, the warm air-fuel mixture injected into the combustion chamber before the air-fuel mixture is sufficiently heated and vaporized by the heating device is released to the outside in the form of raw gas, which not only increases heat loss but also reduces fuel consumption. It would also be a waste.

The present invention was proposed to solve the above problems, and for example, as shown in FIGS. 1 and 3,
A pressure reducing passage 28 is opened in the combustion chamber 9, the pressure reducing passage 28 is made openable and closable by a pressure reducing valve 29, and the pressure reducing passage 28 is connected to the carburetor 19.
The recirculation passage 27 communicates with the inlet side of the bench lily part 26, thereby allowing the flow from the bench lily part 26 to the mixing passage 1.
8. Form a circulation path R that passes through the crank chamber 17, the scavenging path 16, the combustion chamber 9, the pressure reduction path 28, and the recirculation path 27 in order and returns to the bench lily portion 26, and at least part of the path of this circulation path R is heated with intake air. A device 24 is provided.

The present invention is constructed and operates as described above, and thus has the following effects.

In other words, when the engine is started cold, the pressure reducing valve is opened and the air-fuel mixture is repeatedly heated by the intake air heating device as it flows through the circulation path, so the air-fuel mixture is sufficiently vaporized and the ignition performance is improved, making it easier to start the engine. Can be cold started.

In addition, since the air-fuel mixture is repeatedly heated by the intake air heating means as it flows through the circulation path, the intake air heating means can be small and inexpensive with low output, making it possible to implement the system at low cost and making the engine larger. Not at all.

Moreover, the air-fuel mixture is circulated in the circulation path until it is sufficiently heated and vaporized by the air-intake heating device, and the air-fuel mixture is discharged outside in the form of raw gas until it is heated. It eliminates heat loss and fuel waste, and completely eliminates out-of-cylinder explosions and pollution causes.

In addition, when the piston rises, the mixture injected into the combustion chamber is pushed out from the pressure reducing valve provided in the combustion chamber to the pressure reducing valve and flows through the circulation path, so the piston slides up and down when the air-fuel mixture is heated. The crankshaft can be rotated with a small force without compressive force. As a result, the engine can be easily started by applying sufficient rotational inertia to the engine. Therefore, the engine starting device can be a low-output, inexpensive device, and the engine can be made smaller and cheaper.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a longitudinal sectional side view of a water-cooled two-stroke engine that uses low-quality oil as fuel. A cylinder head 5 is mounted and fixed on the upper surface of the cylinder 4.

The piston 3 is connected via a connecting rod 7 to a crankshaft 6 which is rotatably supported in the crankcase 2, and a combustion chamber 9 with a spark plug 8 facing therein is formed above the piston 3. be.

An exhaust port 11, a scavenging port 12, and an intake port 13 are opened in order from the top on the inner circumferential surface of the cylinder 10 that houses the piston 3. The exhaust port 11 communicates with a muffler 15 through an exhaust passage 14 to The port 12 communicates with a crank chamber 17 of the crankcase 2 through a scavenging passage 16, and the intake port 13 communicates with a carburetor 19 through a mixing passage 18. An intake air purifying device 22 consisting of an air cleaner 20 and a surge tank 21 is attached to the front end of the carburetor 19, and an intake air heating device 24 is provided in an intake passage 23 between the air cleaner 20 and the surge tank 21.

The intake air purified by the intake air purification device 22 is sent to the carburetor 1.
The low-quality oil stored in the float chamber 25 of 9 is mixed with the fuel sucked up into the bench lily part 26 by the suction negative pressure caused by the rise of the piston 3 to form an air-fuel mixture, which is then sucked into the crank chamber 17. There is.

and a cylinder head 5 forming a combustion chamber 9.
A decompression passage 28 communicates the combustion chamber 9 with the intake passage 23 on the windward side of the intake air heating device 24 of the intake air purification device 22.
A circulation path R is formed by the crank chamber 17, the scavenging path 16, the combustion chamber 9, the pressure reduction path 28, and the intake path 23. A pressure reducing valve 29 is provided at a pressure reducing opening 28a of the reflux passage 27 connected to the pressure reducing passage 28, which opens into the combustion chamber 9.

This pressure reducing valve 29 is composed of a solenoid valve, and together with the intake air heating device 24 provided in the intake air purifying device 22,
When the main switch 30 is set to a preheating position 31, power is supplied from a battery 32 to operate and open the valve.

Further, an electromagnetic fuel cutoff valve 33 that is interlocked with the operation of the intake air heating device 24 and the pressure reducing valve 29 is provided in the carburetor 19 .

As shown in FIG. 2, this electromagnetic fuel cutoff valve 33 is provided at the bottom 35 of a cup 30 forming the float chamber 25 of the carburetor 19, and when the solenoid 36 is energized, a needle valve 37 protrudes. The fuel inlet 39 of the main nozzle 38 protruding into the bench lily portion 26 is closed.The operation of the two-stroke engine configured as described above and using low-quality oil as fuel will be described.

When starting the engine 1 in cold weather, when the main switch 30 is moved from the engine stop position 40 to the operating position 41 to the starting position 42, the current from the battery 32 is supplied to the starter S to start the engine 1.
starts to start up, and sucks the low quality oil mixture formed in the carburetor 19 into the crank chamber 17.

When the main switch 30 is further rotated to the intake heating position 31, the current from the battery 32 is supplied to the intake heating device 24, the pressure reducing valve 29, and the electromagnetic 33, causing the intake heating device 24 to generate heat and opening the pressure reducing valve 29. At the same time, the electromagnetic fuel cutoff valve 33 stops the fuel supply to the main nozzle 38 facing the bench lily portion 26 of the carburetor 19.

When the starter S continues to rotate in this state, the air-fuel mixture sucked into the crank chamber 17 is compressed by the downward movement of the piston 3, and is injected into the combustion chamber 9 when the scavenging port 12 opens. When the piston 3 rises, the air-fuel mixture injected into the combustion chamber 9 passes through the pressure reducing valve 29, the source pressure path 28, the recirculation path 27, and the intake air heating device 24.
is heated and vaporized.

The air-fuel mixture heated and vaporized by the intake air heating device 24 is sucked into the crank chamber 17 again through the circulation path R when the piston 3 rises, and thereafter flows through the mixing path 18, the crank chamber 17, the scavenging path 16, the combustion chamber 9, and the reflux path. 27, the air repeatedly flows through the circulation path R formed by the air intake path 23 and is sufficiently vaporized by the air intake heating device 24.

In this way, when the main switch 30 is switched from the intake air heating position 31 to the starting position 42 when the air-fuel mixture is sufficiently vaporized, the power supply to the pressure reducing valve 29, the electromagnetic fuel cutoff valve 33, and the intake air heating device 24 is cut off. At the same time, power is supplied to the ignition circuit 45, so that the air-fuel mixture injected into the combustion chamber 9 and vaporized to a state where it is easy to ignite is compressed, ignited and combusted by the spark plug 8, and starts the engine 1.

When engine 1 starts to start, main switch 3
0 from the starting position 42 to the operating position 41, the starter S is stopped, the engine 1 is warmed up, and then the engine 1 is operated.

Note that FIG. 3 shows another embodiment, in which an intake air heating device 24 is provided near the scavenging air passage 16 in addition to or in place of the intake air heating device 24 of the above embodiment.
It has been established.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, FIG. 1 is a longitudinal sectional side view of a water-cooled two-stroke engine, FIG. 2 is a longitudinal sectional view of a carburetor, and FIG. 3 is another embodiment. A longitudinal sectional side view of the main part is shown, and FIG. 4 is a view corresponding to FIG. 1 showing a conventional example. 4... Cylinder block, 9... Combustion chamber, 14
...exhaust passage, 15...muffler, 16...scavenging passage,
17...Crank chamber, 18...Mixing path, 19...
Carburizer, 20... Air cleaner, 24... Intake heating device, 26... Bench lily section, 27... Reflux path, 28... Pressure reduction path, 29... Pressure reduction valve, R... Circulation path.

Claims (1)

[Claims] 1 The low quality liquid fuel supplied from the fuel tank and the air supplied from the air cleaner 20 are transferred to the vaporizer 1.
The mixture is mixed in the bench lily portion 26 of the cylinder block 4, and the mixture is passed through the mixing passage 18 in the cylinder block 4 and the crank chamber 1.
7. The scavenging air is sequentially supplied to the combustion chamber 9 through the scavenging passage 16 to be burned, and the exhaust gas is passed from the exhaust passage 14 to the muffler 15.
In a two-stroke engine for low-quality liquid fuel configured to discharge water, a pressure reducing passage 28 is opened in the combustion chamber 9, and the pressure reducing passage 28 is made openable and closable with a pressure reducing valve 29,
The pressure reduction path 28 is communicated with the inlet side of the bench lily portion 26 of the carburetor 19 through a reflux path 27, thereby allowing the flow from the bench lily portion 26 to the mixing path 18, the crank chamber 17, the scavenging path 16, the combustion chamber 9, the pressure reduction path 28, and the reflux path. 27 in order and returns to the bench lily part 26, and an intake air heating device 24 is provided at least in a part of the circulation path R. Auxiliary equipment.