JPS60142009A - Exhaust device of two-cycle engine - Google Patents

Abstract

PURPOSE:To facilitate the exhaust action and improve the mixture ratio of air and fuel by connecting a small-diameter pipe, a diffuser, a large-diameter pipe, a rear cone, and a tail pipe to the exhaust port of a 2-cycle engine and by providing the large-diameter pipe with a gas exhaust opening. CONSTITUTION:An exhaust pipe, which is to be connected to an exhaust port 2 of a 2-cycle engine 1, is formed with a small-diameter pipe 4, a diffuser 5, a large-diameter pipe 6, a rear-cone 7 which gradually reduces its diameter toward its end, and a small-diameter tail pipe 10, and a tip 11 of the tail pipe 10 is closed. In the wall surface of the large-diameter pipe 6, an opening 12 is formed and connected to a muffler 14 via a guide tube 13. The pressure waves emitted from the exhaust port 2 are depressured through the diffuser 5 and the large- diameter pipe 6 and send reflected negative pressure waves to the exhaust port 2, facilitating the exhaust action. The reflected positive pressure waves from the tip 11 of the tail pipe 10 prevent the mixed gas, which flows into the cylinder from the exhaust port, from being released through the exhaust port 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a two-stroke engine 4J1. It is related to air equipment.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF A typical air conditioner is shown in FIG. 1 at 0°. That is, a υ1" trachea 3 connected to the 4Jl air port 2 of the engine 1, a small diameter pipe 4, a diffuser 5 that gradually expands, a large diameter pipe 6, a gradual 1;
It consists of a small-diameter tail vibrator 8, and an extinguisher 9 is connected to the tip of the tail vibrator 8.

Here, the pressure wave discharged from the exhaust port 2 into the trachea 3 at U1 is decelerated and depressurized within the tiff user 5 and the large diameter 1 degree V6. At this time, a negative reflected pressure wave (reflected negative pressure wave) is applied to the exhaust port 2, and the Ij1 air 1]2 portion is brought into a negative pressure state to promote scavenging. Further advancing pressure wave (J rear cone 7
The gas converges and becomes a high pressure state, and a positive reflected pressure wave (reflected positive pressure wave) is applied to the J1 air port 2 (by 3 degrees, the filling ratio of the new JJt unburned gas in the cylinder is increased).

By the way, according to the experimental results, when the ratio of the opening + N1 area of the tail vibe 8 to the opening area of 411 air 1-12, that is, the aperture ratio is 0.5 to 1.0, the pressure wave 50% is directly discharged to the outside from the tail vibe 8, and effective use of the reflected positive pressure waves is one of the ten inventions.The present invention was made in view of these points.

An object of the present invention is to obtain an exhaust system for a two-stroke engine that can improve the output performance of the engine by effectively utilizing pressure waves emitted from an exhaust port.

Summary of the Invention The present invention connects a small diameter pipe, a diffuser that gradually expands, a large diameter pipe, a rear cone that gradually reduces its diameter, and a small diameter tail pipe in sequence, and connects the small diameter pipe to the exhaust port of a two-stroke engine. By depressurizing and decelerating the pressure waves emitted from the diffuser and large-diameter pipes, negative reflected pressure waves (reflected negative pressure waves) are applied to the exhaust port, and by bringing the exhaust port into a negative pressure state, the four parts are By blocking the tip of the tail vibe, the pressure wave is prevented from being discharged to the outside as it is, and the positive reflected pressure wave (reflected positive pressure wave) is effectively applied to the S lower eye, creating a new By increasing the filling ratio of unburned gas in the cylinder and providing an opening for exhaust gas release in communication with the large-diameter pipe, the 4Vj configuration suppresses the release of pressure waves and reflected pressure waves to a low value. This is what I did.

Embodiment of the Invention A first embodiment of the present invention will be described with reference to FIGS. 2 to 4. In addition, the 11th? Parts that are the same as those explained in "J" are designated by the same reference numerals and explanations are omitted (the same applies hereafter).A small-diameter tail pipe 1 is attached to the tip of the rear cone 7.
0 is connected, and the tip of this tail pipe 10 is closed by a closing surface 11. An opening 12 is formed in the wall of the small diameter tube 6, a conduit 13 is connected to the opening 12, and a muffler 14 is connected to the tip of the conduit 13.

In such a configuration, the pressure wave emitted from the exhaust port 2 is decelerated and depressurized within the diffuser 5 and the large diameter pipe 6, and at this time, a reflected negative pressure wave is applied to the exhaust gas 12, causing the exhaust port 2 to become under negative pressure. Promote scavenging as a condition. The pressure waves that advance further are converged at the rear cone section 7 and are suddenly accelerated and pressurized. Therefore, the reflected positive pressure wave returns to the exhaust port 2, and this reflected positive pressure wave has a sufficiently high pressure so that the pressure wave is not released from the tip of the tail vibe 10 to the outside. Then, this high-pressure reflected positive pressure wave is transmitted to the cylinder 1 from the scavenging port (not shown).
The new unburned gas flowing into the cylinder is prevented from being released from the exhaust port 2, the filling ratio of the new unburned gas into the cylinder is increased, and the output performance of the engine is improved.

Next, the release of 11゛ gas into the atmosphere will be explained. The loss gas released from the loss gas (2) following the pressure wave is released into the atmosphere from the opening 12 through the conduit 13 and the muffler 14.Here, the opening 12 faces into the large diameter pipe 6. The inside of this large-diameter pipe 6 is a place where pressure waves and reflected positive pressure waves are reduced in pressure and the pressure difference with the outside is minimized.

Therefore, compared to the case where the opening I2 is formed in other parts such as the rear cone 7 or the tail vibe 10, less pressure waves and reflected positive pressure waves are released to the outside, and the pressure waves can be generated without hindering the release of exhaust gas into the atmosphere. can be effectively used to improve the output performance of the engine 1.

FIG. 3 shows a graph of test results obtained using a shock wave tube to stationarily examine 12 reflected pressure waves per month. Pressure waves (
a) is generated, and while this pressure wave advances inside the small diameter pipe 4, a reflected pressure wave (b) reaches the exhaust port 2. When the pressure wave reaches the diffuser 5 and large diameter pipe 6, it is reflected L[-
The force wave (c) gradually decreases to a negative pressure state. When the pressure wave reaches the rear cone 7, the reflected pressure wave (d) gradually rises,
Therefore, the reflected pressure wave (e) remains at a substantially constant value while moving forward within the tail pipe lO. When the reflected pressure wave (f) reaches the closed surface 11 of the tail vibrator 10, the maximum reflected pressure wave (f) is obtained. Note that the waveforms after (f) are residual pulsating waves in the pipe. Point B in the graph indicates 1 o'clock when the scavenging port is open, and point 0 indicates 1 o'clock when the scavenging port is open.
The internal filling ratio increases, and the output performance of the engine 1 improves.

On the other hand, at point 8, the scavenging port closes, and at point 0, the exhaust is 1:I.
Maximum output is obtained when the rotation speed of engine 1 is set so that 2 is closed.

By the way, the reflected pressure wave (e) is generated when the pressure wave advances inside the tail bar 10, and by changing the length of the tail pipe 10, the reflected pressure wave (e) is generated.
) duration changes. Therefore, the maximum anti-11J
The position I11 of the pressure wave (f) moves, and the 111 air 2 closed position (0 point) to obtain the maximum output moves, and as a result,
The rotation speed at which maximum output is obtained changes. That is, by adjusting the length of the tail pipe 10, the number of times ili/i at which the maximum output is reduced to 11 can be adjusted.

The graph shown in Figure 4 shows the relationship between the reflected positive pressure wave and the aperture ratio. l-1 rate in this example (solid line) and in the conventional example (dashed line)
1, and from this graph 4], the reflectance is approximately 40% at each aperture ratio compared to the conventional example.
1 degree, the filling ratio of new unburned gas in the cylinder 15 increases accordingly, and the output direction of the engine 1 is achieved.Next, a second embodiment of the present invention is shown in FIG. The explanation will be based on. In this embodiment, the tip of the tail pipe 10 is closed with a closed surface 1G.
A conduit 17 is provided between both ends by passing through the closed surface 16, and a conduit 17 is provided between the two ends.
8 is located inside the large diameter pipe 6, and a silencer 14 is connected to the other opening 1-1. This example is based on the first implementation 7.
As explained in the example, the output performance of the engine 1 can be improved by promoting the scavenging action by the reflected negative pressure waves and by improving the filling ratio of new unburned gas in the cylinder 15 by the reflected positive pressure waves. The exhaust gas is released into the atmosphere from the opening 8 through the conduit 17 and the muffler I4, and the inside of the large diameter pipe 6 where the opening 18 is located is depressurized by both pressure waves and reflected positive pressure waves. Because the area is located in a location where there are many Therefore, the pressure waves can be effectively used to improve the output performance of the engine 1 without hindering the release of loss-of-gas gas into the atmosphere.

6 and 7121 show a modification of the first embodiment, in which the axis of the tail pipe 10 does not coincide with the axis of the small diameter pipe 4 and the diffuser 5 (the sixth
(Fig. 7) or bent (Fig. 7).

Effects of the Invention The present invention, configured as described above, can promote the scavenging action by reflected negative pressure waves and increase the filling ratio of new unburned gas in the cylinder by reflected positive pressure waves, thus improving the output performance of the engine. It can be improved, and Jl-
The gas is discharged to the outside through an opening provided in communication with the large-diameter pipe, and the pressure waves and reflected positive pressure waves are This has the effect of minimizing emissions, making effective use of pressure waves, and further improving the output performance of the engine.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the conventional example, Fig. 2 is a sectional view showing the first embodiment of the present invention, Fig. 3 is a rough view showing reflected pressure waves reaching the exhaust port, and Fig. 4 is a sectional view showing the reflected pressure wave reaching the exhaust port. This embodiment and the conventional example;
FIG. 5 is a cross-sectional view showing the second embodiment of the present invention. Days 6 and 7 are modified examples of the first embodiment. FIG.

Claims (1)

[Claims] J) 11 of the 2-cycle engine; a small-diameter pipe connected to the 11 air port; a tiff user connected to the tip of this small-diameter pipe that gradually expands; and a large-diameter pipe connected to the tip of this tiff user. A rear cone that is connected to the tip of this large diameter tube and whose diameter is gradually reduced, and a small diameter tail vibe that is connected to the tip of this rear cone are sequentially arranged, and the tail bar (
Close the end of the pipe with the key 1;
Exhaust system for 2-cycle engine with 'I' characteristic.