JPS62197631A - Exhaust timing controller of two-cycle engine - Google Patents

Abstract

PURPOSE:To prevent the slidability drop of a piston ring, in a mechanism which the opening upper portion of an exhaust passage formed in a cylinder is closed by plate-like valves, by dividing an exhaust port with a rib into plural opening portions which are arranged in its circumferential directions. CONSTITUTION:A depression 10 is formed on the upper portion of an exhaust passage 3 and on the slightly downstream side of an exhaust port 4, and plate- like valves 16 which are oscillatable around an axis 11 are received in this depression 10. The axis 11 is connected with a drive source driving corresponding to the revolution speed of an engine via a valve driving mechanism 15. And the exhaust port 4 is divided with a rib 8 along the axial direction of a cylinder 2 into two opening portions 4a, 4b which are arranged in its circumferential directions. And two valves 16 are disposed corresponding to the two opening portions 4a, 4b of the exhaust port 4, the base end sides of them are stuck fast to each other while the free end sides of them are separated, and the rib 8 is located therebetween. Thus, the opening area of the exhaust port 4 can be increased without dropping the slidability of a piston ring.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to the inside of a cylinder of a two-stroke engine and υ1:
The present invention relates to an exhaust timing control device that changes the timing of continuous communication with an air passage using a valve body.

"Prior Art" This type of device ξ is disclosed in Japanese Patent Publication No. 47-36047. This device has a shaft perpendicular to the cylinder axis on the upper part of the inner wall of the exhaust passage, and a valve body that opens and closes the upper part of the υL air communication passage υ air port is attached to this shaft so that it can swing freely. By swinging and displacing the cylinder by a drive mechanism, the timing at which the piston in the cylinder communicates with the inside of the cylinder and the exhaust passage can be changed.

According to this, by substantially changing the degree of opening of the exhaust port according to the rotational speed of the engine, the return of the υF air reflection waves from the υF air communication passages and the opening/closing timing of the exhaust port are made to match. The blowhole effectively pushes the gas back into the cylinder, creating a problem with the air-fuel mixture.By the way, in order to increase the engine output in a two-stroke engine, it is essential to lower the exhaust resistance. .

One possible means for this is to make the exhaust passage thicker and to increase the opening area of the exhaust port, but simply increasing the opening area may reduce the slidability of the piston ring.

For this reason, there was a limit to the expansion of the opening area.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust timing control device that can increase the opening area of an air port, thereby increasing output.

"Means for Solving the Problems" In order to achieve the above object, the present invention divides the exhaust port into a plurality of openings lined up in the circumferential direction by ribs along the cylinder axis, and exhausts the air from each opening. It is equipped with a valve body for timing control.

"Embodiment" Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a υF air timing control σ11 device according to the present invention, and FIG. 2 is a cross-sectional view.

1 is a cylinder block, 2 is a cylinder, 3 is an exhaust passage, 4 is an exhaust port, 5 is a cylinder head, 6 is a piston, and 7 is a scavenging passage.

As shown in FIG. 2, the exhaust port 4 of the exhaust passage 3 is divided into two openings 4a and 4b arranged in the circumferential direction by a rib 8 extending in the axial direction of the cylinder 2. and,
The total area of both openings 4a and 4b is larger than the area of the conventional exhaust port. The rib 8 is integrally formed with the cylinder block I so that its inner circumference coincides with the inner layer surface of the cylinder 2. This rib 8 strengthens the exhaust port 49 and also strengthens the piston ring 12.
This prevents the exhaust port 4 from expanding outward in the radial direction and interfering with the upper and lower edges of the exhaust port 4.

Further, in the upper part of the exhaust passage 3, as shown in FIG. 1, a valve body storage recess 10 is located slightly downstream of the exhaust port 4.
is formed. A sleeve 11 is provided in this recess lO in a direction perpendicular to the center line of the cylinder 2.

As shown in FIG. 2, this shaft 11 has one end protruding outside from the entrance of a shaft insertion hole 12 formed in the cylinder block 1, and is positioned by a plug 13 and a sealing material 14 to drive the valve body. It is connected to the mechanism 15. The other end of the shaft 11 is fitted into and supported by the tip of a shaft insertion hole 12 formed in the inner wall of the exhaust passage 3. Further, the central portion of the shaft 11 has a square cross section, and the base end of a valve element I6 for exhaust timing control is fitted and fixed therein.

Since the valve bodies 16 are plate-shaped, two valve bodies 16 are disposed corresponding to the two openings 4a and 4b of the exhaust port 4, and both are symmetrical. The valve bodies 16, 16 are mutually detonated at the pivotally supported portions, but are separated from each other at the free ends, and the ribs 8 are located in these gaps. Even if a slight gap is formed over the entire circumference of the valve body 1G between the valve body 1G arranged in this way and the inner surface of the cylinder 2 and the circumferential surface of the rib 8, the valve body 1G will not hit the inner surface of the cylinder 1. This is the way to do it.

As shown in FIG. 1, the free end of the valve body I6 is formed with a collar that projects upward. The end of the collar is formed to have approximately the same curvature as the inner surface of the cylinder 2.

Furthermore, long and narrow through holes 17 and 18 are formed in the flat plate-shaped portion of the valve body 16, and these through holes 17 and 18 extend vertically.
The upper part of 18 is chamfered.

The rotation drive mechanism 15 is a mechanism that swings the valve body 16 according to the rotational speed of the engine, and includes one wire guide attached to the end of the tube II and a wire attached to the wire guide 19. It consists of a motor (not shown) connected via 26, and a shift controller (not shown) that operates the motor to rotate forward or backward according to the rotational speed of the engine. The end of the shaft 11 and the wire guide 19 are
Wire case attached to cylinder block l. Note that R in the figure indicates a passage through which cooling water passes.

Next, the operation of the exhaust timing control device configured as above will be explained.

When the engine is operated at low rotation speed, the valve body 1G is displaced downward by the drive mechanism 15.

As a result, the opening degree of the exhaust port 4 is substantially narrowed. Then, the exhaust port 4 is opened late and closed quickly in response to the slow vertical movement of the piston 6. As a result, the timing of opening and closing of the exhaust port 4 and the moment when the exhaust reflected wave returns is adjusted so that the gas in the atrium efficiently returns into the cylinder.

On the other hand, when the engine is rotating at high speed, the drive mechanism 1
5, the valve body 16 is oscillated upward and accommodated in the valve body accommodation recess IO. Then, the substantial opening degree of the exhaust port 4 is increased, and the exhaust port 4 is opened earlier and closed later in response to the faster vertical movement period of the piston 6. As a result, even in this case, the opening and closing of the exhaust port are synchronized with the moment when the exhaust reflected wave returns, so that the gas is efficiently forced into the cylinder through the atrium. Therefore, this device
Whether the engine is running at high speed or low speed, the filling efficiency of the air-fuel mixture into the cylinder 2 is increased and the output characteristics of the engine are improved.

In the exhaust timing control device of this embodiment having such a configuration, the rib 8 extending from the upper edge to the lower edge of the exhaust port 4
This prevents the piston ring 9 from expanding and interfering with the upper and lower edges of the exhaust port 4, improving the sliding performance of the piston ring 9 and reducing wear and noise generation. Therefore, the opening area of the exhaust port 4 can be expanded to any size without being restricted, and it is possible to reduce the exhaust resistance of the engine and increase the output.

Further, since the valve body IG is arranged for each of the openings 4a and 4b, these can be inserted and assembled separately, and there is no difficulty in inserting them.

In addition, in the device of this embodiment, the through hole 17.1 is provided in the valve body I6.
g, and its upper part is chamfered, so that carbon adhering to the upper surface of the valve body 16 is brushed off by the edge of the chamfered layer edge by the swinging of the valve body 16.
It flows into the exhaust passage 3 through the through holes 17,18. Also, through the through holes 17 and 18, the gas in the atrium flows through the valve body
It flows to the upper surface side and carbon is washed away. Therefore, carbon does not adhere and accumulate on the upper surface of the valve body 16, and the valve body 16 always operates stably.

The method of controlling the position of the valve body I6 by the drive mechanism 15 may be either step control such as two-position control in which the valve body I6 goes back and forth between two positions, upper and lower, or proportional control in which the valve body I6 is continuously displaced steplessly. It's okay.

Further, in the above embodiment, the υF air port 4 is divided into two openings 4a and 4b, and two corresponding valve bodies 1G are provided, but the present invention is limited to this. It's not a thing. For example, FIG. 3 shows another embodiment of the invention, in which the exhaust port 30 is formed by two ribs 31, 31 into three openings 30a, 30J30c.
The valve body 32 is divided into three opening parts 30a, 30b, and 3.
Three are provided corresponding to 0c. Therefore, in this embodiment, the exhaust port 30 is
The opening area can be made larger. In addition, the exhaust port 30 has the fastest exhaust gas flow rate and the most gas flow m.
Since there is no rib at the central position, this has the advantage that the exhaust resistance can be further reduced compared to the previous embodiment.

“Effects of the Invention” Exhaust timing control device for two-stroke engine of the present invention, 5 “
11, the exhaust port is divided into multiple openings lined up in the circumferential direction by a full rib in the cylinder axis direction, and a υV air timing control valve body is provided for each opening, which reduces the sliding performance of the piston ring. The opening area of the exhaust port can be increased without increasing the exhaust port. Therefore, it is possible to increase the opening area of the air port, thereby providing the significant effect of reducing exhaust resistance and increasing engine output.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof. Further, FIG. 3 is a sectional view similar to FIG. 2 showing another embodiment of the present invention. I...Cylinder block 2...Cylinder 4.30
...Exhaust ports 4a, 4b, 30a, 30b - opening II...
・Shaft I5...Valve body drive machine +1 is 16.32...
Valve body applicant: Honda Motor Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A shaft perpendicular to the cylinder axis is provided at the upper part of the exhaust passage having an exhaust port opening into the inner surface of the cylinder of the two-cycle engine, and the upper part of the exhaust port of the exhaust passage is attached to the swinging end of the shaft. By attaching a valve body that opens and closes depending on the part and making it swingable, and by using a drive mechanism to oscillate the valve body according to the engine speed, the timing of communication between the inside of the cylinder and the exhaust passage by the piston inside the cylinder can be controlled. In the exhaust timing control device, the exhaust port is divided into a plurality of openings aligned in the circumferential direction by a rib along the cylinder axis, and a plurality of the valve bodies are provided corresponding to each of the openings. 2 characterized by
Cycle engine exhaust timing control device.