JPS6111477Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an active thermal atmosphere combustion type two-stroke internal combustion engine, which prevents raw gas from being released into the atmosphere during depressurization operations for starting and stopping, and also simplifies the decompression device for starting and stopping the engine. The purpose is to create a structure that is

A two-stroke internal combustion engine, called an activated thermal atmosphere combustion two-stroke internal combustion engine, leaves some of the high-temperature combustion gas remaining in the combustion chamber, and this residual high-temperature combustion gas is injected into the combustion chamber by the descent of the piston. The mixture is reformed to a state where it is easy to ignite, and then the mixture is self-ignited by the heat of compression caused by the upward movement of the piston.

Therefore, when stopping such an internal combustion engine,
The internal combustion engine cannot be stopped simply by stopping the discharge of the spark plug.

Therefore, the conventional method for stopping an active thermal atmosphere combustion type two-stroke internal combustion engine has been to install a pressure reducing valve on the upper wall of the combustion chamber, release the pressure in the combustion chamber to the atmosphere, reduce the pressure, and stop the internal combustion engine. It is being

However, with these devices, there is a risk that the mixture, which has been decomposed and reformed to a state where it can easily ignite in the active heat atmosphere of the combustion chamber, will ignite directly and then ignite, and even if it does not burn, it will release Hc and Co. The decomposed mixture is released into the atmosphere, causing air pollution.

The present invention was proposed in order to solve the above-mentioned drawbacks.The combustion chamber and exhaust port are communicated with each other through a starting pressure reduction hole provided separately from the exhaust port, and this communication hole is opened and closed with a single valve to combust the combustion chamber. By reducing the pressure in the combustion chamber, depressurization operations for starting and stopping an activated thermal atmosphere combustion type two-stroke internal combustion engine can be performed with a single valve switching operation. The air-fuel mixture, which is easily ignited, is released into the exhaust port and burned in the exhaust passage to render it harmless, thereby preventing the risk of combustion outside the machine due to the release of raw gas into the atmosphere and the occurrence of pollution. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a longitudinal sectional front view of a forced air-cooled vertical two-stroke internal combustion engine. This internal combustion engine E performs activated thermal atmosphere combustion, and has a cylinder block 2 integrally formed in the upper part of a crankcase 1.
A head block 3 is fixed above the cylinder block 2.

A cylinder liner 5 into which a piston 4 is slidably fitted is cast into the cylinder block 2.

An exhaust port 6, a scavenging port 7, and an intake port 8 are opened in the inner surface 5a of the cylinder liner 5 in this order from the top.
The intake port 8 communicates with a carburetor 10 and an air cleaner 11 via an intake port 9 formed in the cylinder block 2, and the scavenging port 7 communicates with a muffler 14 via an exhaust port 13 provided in the crank 2 through a scavenging passage 12. It's communicating.

Reference numeral 15 in the figure is a crankshaft, and the piston 4 housed in the cylinder liner 5 is communicated with this crankshaft 15 via a connecting rod 14. code 16
is a combustion chamber formed by the headblock 3 and the upper wall 4a of the piston 4.

The combustion chamber 16 and the exhaust port 13 are connected to a start pressure reduction hole 17 and a stop pressure reduction hole 18 provided separately from the exhaust port 9.
will be communicated with. The stop decompression hole 18 is provided toward the exhaust port 13 from a position on the inner circumferential surface 5a of the cylinder liner 5 that is covered by the upper circumferential wall of the piston 4 at a crank angle of 50 degrees before top dead center (JDC). be.

Starting pressure reduction hole 17 is 100° before top dead center (TDC)
At 130°, it opens at a position on the inner circumferential surface 5a of the cylinder liner 5 that is covered by the upper circumferential wall of the piston 4, and a small diameter starting pressure reducing hole 17 is provided from the outside of the cylinder block 2. Bolt 1 through the opening
It is covered with 9.

The start pressure reduction hole 17 and the stop pressure reduction hole 18 are opened and closed by a single valve 20 provided at the portion where both 17 and 18 meet.

As shown in FIGS. 4 and 5, this valve 20 is provided with an operation knob 22 at the tip 21a of a round rod-shaped valve body 21, and the portion of the valve body 21 where the start pressure reduction hole 17 and the stop pressure reduction hole 18 meet is The valve body 23 is formed to have a half-moon cross section.

The operation knob 22 has a driving position 24, a starting position 25,
It can be swung to a stop position 26, and its operating state is held by a ball spring type holder 27.

The operation of the activated thermal atmosphere combustion type two-stroke internal combustion engine constructed as described above will now be described.

First, when the operation knob 22 is set to the starting position 25,
As shown in FIG.
The communication with the exhaust port 13 is cut off, and the starting pressure reduction hole 1
7 and the exhaust port 13 are communicated with each other. When the internal combustion engine E is started and rotated in such a state, a part of the compression pressure applied to the piston 4 escapes from the starting pressure reducing hole 17 to the exhaust port 13, so the compression ratio decreases and the piston 4 moves to top dead center with a light starting rotational force. I started going to

Then, the piston 4 rises with a light starting rotational force until it reaches the starting pressure reducing hole 17, and after passing the starting pressure reducing hole 17, it rises while compressing the air-fuel mixture and combustion gas in the sealed combustion chamber 16. Then,
When the piston 4 rises to near the top dead center, the ignition plug 28 screwed onto the head block 3 ignites the piston 4 at an early stage, and the internal combustion engine E starts. When the internal combustion engine E starts, the operating knob 22 is moved from the starting position 25 to the operating position 2.
Switch to 6. Then, communication between both the stop pressure reduction hole 18 and the start pressure reduction hole 17 to the exhaust port 13 is cut off, the compression ratio returns to normal, and the output of the internal combustion engine E also returns to normal output.

In this way, after the internal combustion engine E is started and an active thermal atmosphere is formed in the combustion chamber 16, even if the discharge of the spark plug 28 is cut off, the air-fuel mixture injected into the combustion chamber 16 is on the verge of ignition due to the remaining active atmosphere. It is broken down into
The heat of compression caused by the rise of the piston 4 causes self-ignition, and the internal combustion engine continues to operate.

To stop this internal combustion engine E, use the operation knob 2.
2 to the stop position 26. Then, the valve body 23 connects the start pressure reduction hole 17, the stop pressure reduction hole 18, and the exhaust port 13.
Since most of the compressed gas in the combustion chamber 16 is released to the exhaust port 13, the internal combustion engine E is stopped quickly.

Incidentally, the unburned gas flowing out from the start pressure reduction hole 17 and the stop pressure reduction hole 18 to the exhaust port 13 is burned in the exhaust port 13 and the exhaust path P of the muffler 14 connected to the tip thereof, and after being rendered harmless, it is released into the atmosphere. released.

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

(b) To reduce the pressure in the combustion chamber during starting and stopping,
The raw gas discharged from the combustion chamber enters the exhaust port through the start pressure reduction hole or the stop pressure reduction hole, is sufficiently combusted in the exhaust passage, becomes harmless, and is then released into the atmosphere, so it is not exposed to the atmosphere like in the past. There is no risk of combustion outside the machine or pollution of the atmosphere due to direct release of raw gas.

(b) Furthermore, the structure for reducing the pressure in the combustion chamber during starting and stopping is simple and requires only a starting pressure reducing hole, a stopping pressure reducing hole, and one valve for opening and closing these holes, making it inexpensive. can be implemented.

(c) Furthermore, at the time of starting, the air-fuel mixture and combustion gas in the combustion chamber are released to the exhaust port through the starting pressure reducing hole opened in the side wall of the combustion chamber, so when the piston is raised toward top dead center at the time of starting. This can be divided into two periods: a period in which the piston is raised with a light starting rotational force, and a period in which the piston is raised with the combustion chamber sealed to strongly compress the air-fuel mixture and combustion gas. Therefore, the piston can be raised with a light force. At the same time, the compression heat in the combustion chamber generated by the rising of the piston is stored inside the combustion chamber without escaping to the outside, making it possible to quickly ignite the air-fuel mixture within the combustion chamber, improving starting performance. You can also do that.

(d) In addition, the stop pressure reduction hole is opened above the starting pressure reduction hole opened in the side wall of the combustion chamber, and the passage cross-sectional area of this stop pressure reduction hole is made larger than the passage cross-sectional area of the start pressure reduction hole, so that the stop When the piston rises, the air-fuel mixture and combustion gas located above the starting pressure reducing valve in the combustion chamber can also escape to the outside. Moreover, the time required for the rising piston to arrive at the stop pressure reduction hole is longer than the time required for the piston to reach the start pressure reduction hole, so the amount of air-fuel mixture in the combustion chamber at the time of stop is larger than that at the time of start. It can be vented to the exhaust port for an extended period of time. Therefore, most of the air-fuel mixture in the combustion chamber can be quickly released to the exhaust port, and the internal combustion engine can be stopped quickly.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional front view of a forced air-cooled vertical two-stroke internal combustion engine;
3 and 3 are enlarged longitudinal cross-sectional views of the main parts showing the operating state, FIG. 4 is a cross-sectional view of the main parts, and FIG. 5 is a view taken in the direction of the arrow in FIG. 4. E...Internal combustion engine, 6...Exhaust port, 13...Exhaust port, 16...Combustion chamber, 17...Starting pressure reduction hole,
18...Stop pressure reducing hole, 20...Valve, 24...Operating position, 25...Starting position, 26...Stop position.

Claims (1)

[Scope of utility model registration request] The exhaust port 13 is connected to the combustion chamber 16 of the active thermal atmosphere combustion type two-stroke internal combustion engine E through either the start pressure reduction hole 17 or the stop pressure reduction hole 18, in addition to the exhaust port 6. The cross-sectional area of the passage is larger than that of the starting pressure reducing hole 17, and the starting pressure reducing hole 17 is opened above the exhaust port 6 opened in the side wall of the combustion chamber 16, and a stop pressure reducing hole is formed above the starting pressure reducing hole 17. 18 is opened, and the start pressure reduction hole 17 and the stop pressure reduction hole 18 are connected to one valve 20.
The valve 20 is configured to be switchable between a starting position 25, an operating position 24, and a stopping position 26 of the internal combustion engine E. When the valve 20 is operated to the starting position 25, the stop pressure reducing hole 18 is closed, the starting pressure reducing hole 17 is opened, and a relatively small part of the air-fuel mixture and combustion gas in the combustion chamber 16 is released from the starting pressure reducing hole 17 to the exhaust port 13 during the compression process to lighten the internal combustion engine E. When the valve 20 is operated to the operating position 24, both the stop pressure reduction hole 18 and the start pressure reduction hole 17 are closed, and the air-fuel mixture and combustion gas in the combustion chamber 16 are allowed to flow through the holes 17, 18. When the valve 20 is operated to the stop position 26 and the valve 20 is operated to the stop position 26, the stop depressurization hole 18 is opened, and a large amount of the mixture and combustion gas in the combustion chamber 16 flows from the stop depressurization hole 18 to the exhaust port 13. 1. An activated thermal atmosphere combustion type two-stroke internal combustion engine characterized in that the internal combustion engine E is in a state in which the internal combustion engine E is stopped.