JPH05141249A - Exhaust valve device for two-cycle engine - Google Patents

Abstract

PURPOSE:To form a valve driving mechanism into a simple structure by independently providing systems for driving a main exhaust valve and a subexhaust valve. CONSTITUTION:A main exhaust valve 13 of changing exhaust timing and an almost column-shaped subexhaust valve 14 formed with a partitioning part 15a for closing an auxiliary exhaust passage 12 are provided. The subexhaust valve 14 is placed toward a direction orthogonal to a cylinder axial line and turnably supported to a cylinder. Both the valves are connected to a shaft in parallel to the subexhaust valve 14 and driven. Since an opening/closing direction of a main exhaust passage 11 is equal to an opening/closing direction of the auxiliary exhaust passage 12, a simple material can be used in a member for connecting both the valves to the shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust valve device for a two-cycle engine in which an exhaust valve faces an exhaust port.

[0002]

2. Description of the Related Art Conventionally, as this type of exhaust valve device, a main exhaust passage communicating with a main exhaust port of an engine cylinder and an auxiliary exhaust passage communicating with auxiliary exhaust ports on both sides of the main exhaust port are respectively provided. There is one in which valves are provided and the cross-sectional area of all the exhaust passages is changed by these valves (for example, refer to JP-A-63-173817).

In the conventional exhaust valve device shown in this publication, when the engine is rotating at a low speed, both valves are closed to reduce the cross-sectional area of the exhaust passage, and both valves are operated as the engine speed increases. It had an open structure.

The main exhaust valve provided in the main exhaust passage has a structure in which a substantially plate-shaped valve element is supported so as to be vertically swingable above the main exhaust passage, and an end thereof is exposed to the main exhaust port. As a secondary exhaust valve provided in the auxiliary exhaust passage, a rotary valve that rotates around an axis parallel to the cylinder axis has been used.

Further, the sub exhaust valves are driven by a rack and pinion type drive mechanism, and the main exhaust valve has a structure in which power is transmitted from a rotating shaft of the sub exhaust valve so as to interlock with the sub exhaust valve. Met. Then, the main exhaust valve and the auxiliary exhaust valve were configured to open at the same time.

[0006]

However, the structure of the conventional exhaust valve device is complicated. This is because the valve drive mechanism has a structure in which the main exhaust valve drive system is combined with the drive system of the sub exhaust valve, and the direction in which the main exhaust passage is opened and closed is in the cylinder axis direction. This is because the direction in which the exhaust passage is opened and closed is the cylinder radial direction, which is the direction orthogonal to each other.

That is, it is necessary to mount, together with the valve body of the auxiliary exhaust valve, a member for converting the rotational operation into a reciprocating operation and transmitting it to the main exhaust valve on the rotary shaft of the auxiliary exhaust valve.

[0008]

An exhaust valve device for a two-cycle engine according to the present invention includes a main exhaust valve that faces a main exhaust port and has a protruding amount that can be changed according to an engine speed, and a main exhaust valve on the side of the main exhaust valve. The auxiliary exhaust valve is provided with a pair of auxiliary exhaust valves, and the auxiliary exhaust valve is provided with a partition part for closing an auxiliary exhaust passage communicating with the auxiliary exhaust port and a cutout part forming an inner wall of the passage. The main exhaust valve and the sub-exhaust valve are formed in a substantially columnar shape and are rotatably supported by the cylinder with the axis of rotation orthogonal to the axis of the cylinder.
The rotation axis is parallel to the rotation axis of the auxiliary exhaust valve and is connected to a control shaft that is rotatably supported by the cylinder.

[0009]

The direction in which the main exhaust passage is opened and closed by the main exhaust valve and the direction in which the auxiliary exhaust passage is opened and closed by the auxiliary exhaust valve are the same as the cylinder axis direction, and the auxiliary exhaust valve is the control shaft. Because it rotates in the same direction,
A simple interlocking mechanism that connects each valve to the control shaft is sufficient. Further, since the main exhaust valve can be connected to the control shaft via a connecting member different from the auxiliary exhaust valve connecting member, the drive system of the auxiliary exhaust valve is simplified.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 is a sectional view of a two-cycle engine equipped with an exhaust valve device according to the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a side view of the exhaust valve device according to the present invention, and FIG. It is sectional drawing for demonstrating operation | movement of an auxiliary | assistant exhaust valve, the figure (a) shows a fully open state, and the figure (b) shows a fully closed state. FIG. 5 is a perspective view showing a valve drive mechanism of the exhaust valve device according to the present invention.

In these figures, 1 is for a motorcycle 2
In a cycle engine, a cylinder body 3 is mounted on a crankcase 2 of the engine 1, and a cylinder head 4 is further mounted on the cylinder body 3.

A piston 5 is slidably provided in the cylinder of the cylinder body 3, and the piston 5 is connected to a crank arm 8 of a crank shaft 7 via a connecting rod 6. The crank arm 8 is housed in the crank chamber 9 of the crankcase 2. The crank chamber 9 communicates with a scavenging port 10a opened in the middle of the cylinder body 3 through a scavenging passage 10 formed in the cylinder body 3. is doing.

An intake passage (not shown) communicating with the crank chamber 9 is formed in the cylinder body 3 below the scavenging port 10a.

Reference numeral 11 denotes a main exhaust passage, which is the main exhaust passage 11.
Is the main exhaust port 1 opened in the cylinder of the cylinder body 3.
It is communicated with the cylinder via 1a. Auxiliary exhaust passages 12 are provided on both sides of the main exhaust passage 11.

The auxiliary exhaust passage 12 has one end communicating with the inside of the cylinder through an auxiliary exhaust port 12a opened in the cylinder, and the other end communicating with the main exhaust passage 11.

In the valve mounting hole 3a formed on the upper side of the main exhaust passage 11 (on the side of the cylinder head 4), the main exhaust valve 13 for changing the exhaust timing and the main exhaust passage sectional area according to the engine speed. Is installed.

The main exhaust valve 13 is, as shown in FIG.
The valve body 13a has a substantially plate-like shape and a rod-shaped valve shaft 13b. The valve shaft 13b is supported by the valve body 13c so as to be movable back and forth on the cylinder body 3.

The main exhaust valve 13 has a valve shaft 1
It is connected to a valve drive mechanism, which will be described later, through a pin 13d provided upright on 3b. Further, the exhaust passage side end portion (tip 13e) of the valve body 13a is formed in a shape matching the shape of the main exhaust passage 11.

By advancing / retreating the main exhaust valve 13 thus constructed with respect to the main exhaust passage 11 to change the valve stroke amount, the exhaust timing and the passage cross-sectional area of the main exhaust passage 11 can be changed. .. And the main exhaust valve 1
The direction in which the main exhaust passage 11 is opened and closed by 3 is the cylinder axis direction.

Further, a circular through hole 3b which is opened in a side wall of the auxiliary exhaust passage 12 is formed in a portion of the cylinder body 3 adjacent to the auxiliary exhaust passage 12, and the auxiliary exhaust gas, which will be described later, is formed in the through hole 3b. The valve 14 is installed. The through hole 3b is formed in the cylinder body 3 so that its axis is in a direction orthogonal to the cylinder axis and parallel to the axis of the crankshaft 7.

The sub exhaust valve 14 is, as shown in FIG.
A valve body 15 is formed into a substantially columnar shape having a size to fit into the through hole 3b, and a front end portion thereof faces the auxiliary exhaust passage 12, and the valve body 15 is formed integrally with the valve body 15 and pivots to the valve body 3 via a valve guide 16. The valve shaft 17 is rotatably supported on the valve body 3 by being inserted into the through hole 3b. An arm 18 connected to a valve drive mechanism described later is fixed to the valve shaft 17.

A partition portion 15a for closing the auxiliary exhaust passage 12 and a cutout portion 15b forming an inner wall of the auxiliary exhaust passage 12 are formed in a portion of the valve body 15 facing the auxiliary exhaust passage 12. Has been done.

That is, when the auxiliary exhaust valve 14 is rotated, the position of the partition 15a gradually changes in the auxiliary exhaust passage 12, so that the auxiliary exhaust passage 12 of the auxiliary exhaust passage 12 is changed by changing the rotational angle of the auxiliary exhaust valve 14. It becomes possible to change the passage cross-sectional area. The direction in which the auxiliary exhaust passage 12 is opened and closed by the auxiliary exhaust valve 14 is the cylinder axis direction.

Reference numeral 21 is a valve drive mechanism for driving the main exhaust valve 13 and the auxiliary exhaust valve 14. The valve drive mechanism 21 is formed as shown in FIG. 5, and opens each valve at a predetermined timing by changing the rotation angle of one shaft 22 as a control shaft according to the engine speed. Is configured.

The shaft 22 is disposed at a position above the main exhaust passage 11 and is rotatably supported by the cylinder body 3. The axis of the auxiliary exhaust valve 14 is
It is parallel to the axis of. In other words, it is oriented so as to be orthogonal to the cylinder axis and parallel to the axial direction of the crankshaft 7.

Two drive forks 23, with which the pin 13d of the main exhaust valve 13 is engaged, and an arm 24 for driving the auxiliary exhaust valve 14, are fixed to the shaft 22.

A drive device (not shown) for changing the rotation angle of the shaft 22 according to the engine speed is connected to the shaft end of the shaft 22.

The drive fork 23 is a main exhaust valve 1
A groove 23a into which the third pin 13d is fitted is formed, and the main exhaust valve 13 is advanced and retracted by changing the rotational operation of the shaft 22 into a reciprocating operation.

The arm 24 includes two auxiliary exhaust valves 1
4 are respectively arranged on both shaft ends of the shaft 22 so as to drive the shafts 4. Each arm 24 is provided with a pin 24a at its rotating end, and is connected to the sub exhaust valve 14 via a connecting rod 25 which is pierced by the pin 24a and pivotally supported. The end portion of the connecting rod 25 on the side of the sub exhaust valve is pivotally supported by a pin 18 a provided upright on the arm 18.

The valve drive mechanism 21 configured as described above
According to the above, by rotating the shaft 22, the main exhaust valve 13 and the auxiliary exhaust valve 14 operate in an interlocking manner.

In FIG. 1, reference numeral 26 is a cover for covering the main exhaust valve drive portion of the valve drive mechanism 21, which is fixed to the cylinder body 3 of the engine 1. The auxiliary exhaust valve drive unit of the valve drive mechanism 21 is arranged laterally of the cylinder body 3 as shown in FIG.

Next, the operation of the main exhaust valve 13 and the auxiliary exhaust valve 14 will be described. When the engine speed is in the low speed range equal to or lower than the set speed, the shaft 22 of the valve drive mechanism 21 is rotated right in FIGS. 1 and 3, and the main exhaust valve 13 and the sub exhaust valve 14 are fully closed.

That is, the main exhaust valve 13 has a pin 13d.
Is pushed by the drive fork 23, and its tip 13e
Moves to the position shown by the chain double-dashed line a in FIGS. 1 and 2. The exhaust timing of the engine 1 at this time is set relatively late so as to be suitable for low speed operation.

The auxiliary exhaust valve 14 rotates in the same direction as the shaft 22 because the rotational movement of the arm 24 is transmitted to the arm 18 via the connecting rod 25. FIG. 4A shows a state in which the sub exhaust valve 14 is fully closed.
In the fully closed state, the partition portion 15a of the valve body 15 closes the auxiliary exhaust passage 12. The positions of the arm 24 and the connecting rod 25 when the auxiliary exhaust valve 14 is fully closed are
The position is indicated by the chain double-dashed line in FIG.

When the engine speed exceeds the set speed and the engine rotates at a medium speed, the shaft 22 rotates counterclockwise. At this time, the main exhaust valve 13 and the sub exhaust valve 14 are opened together with the rotation operation of the shaft 22. That is, the pin 13 of the main exhaust valve 13
d is pulled by the drive fork 23, and the main exhaust valve 13 retracts. The sub exhaust valve 14 rotates in the same direction as the shaft 22 when the connecting rod 25 retracts.

The opening operation of the main exhaust valve 13 widens the passage cross-sectional area of the main exhaust passage 11 and accelerates the exhaust timing in the main exhaust passage 11. Further, by opening the auxiliary exhaust valve 14, the partition portion 15a of the valve body 15 is opened.
Moves to the position shown by the chain double-dashed line b in FIG. 4A, and a part of the exhaust gas is made to flow into the auxiliary exhaust passage 12. At this time, the cross-sectional area of the entire exhaust passage has a width suitable for medium speed rotation.

When the shaft 22 further rotates counterclockwise as the engine speed increases, the main exhaust valve 13 is fully opened as shown by the solid line in FIG.
The sub exhaust valve 14 is fully opened as shown in FIG. When fully opened, the tip portion 13e of the main exhaust valve 13 is in series with the upper wall of the main exhaust passage 11, and the sub exhaust valve 14
Then, the cutout portion 15b of the valve body 15 is in series with the inner wall surface of the auxiliary exhaust passage 12. The rotation angle when the sub exhaust valve 14 is changed from the fully closed state to the fully opened state is an angle indicated by θ in FIG. 3.

When the valve is fully opened, the exhaust timing becomes earliest and the total exhaust passage cross-sectional area becomes maximum, so that high output can be easily obtained when the engine is fully opened.

When the engine speed decreases from the fully open operation state, the shaft 22 is rotated clockwise in FIG.
Each valve begins to close at the same time. Then, the engine is fully closed when the engine speed falls to a low speed range below the set speed.

Therefore, according to the exhaust valve device of the present invention, the direction in which the main exhaust passage 11 opens and closes the main exhaust passage 11 and the direction in which the auxiliary exhaust passage 14 opens and closes the auxiliary exhaust passage 12 are in the cylinder axis direction. In the same direction, and the auxiliary exhaust valve 14 is attached to the shaft 22.
Since it rotates in the same direction as that of the drive fork 23 and the pin 13 as an interlocking mechanism for connecting each valve to the shaft 22,
d, the arms 24, 18 and the connecting rod 25 may have a simple structure.

Further, since the main exhaust valve 13 can be connected to the shaft 22 via a connecting member (drive fork 23) different from the auxiliary exhaust valve connecting member, the main exhaust valve 13 can be connected to the drive system of the auxiliary exhaust valve 14. Since the drive system does not coexist, the drive system of the sub exhaust valve 14 is simplified.

[0042]

As described above, in the exhaust valve device for a two-cycle engine according to the present invention, the main exhaust valve which faces the main exhaust port and whose protrusion amount is changed according to the engine speed, and the side of the main exhaust port are provided. A pair of sub-exhaust valves facing the auxiliary exhaust port, and the sub-exhaust valve is provided with a partition part for closing an auxiliary exhaust passage communicating with the auxiliary exhaust port and a cutout part forming an inner wall of the passage. Formed into a substantially cylindrical shape,
The rotation axis is orthogonal to the cylinder axis, and is rotatably supported by the cylinder. The main exhaust valve and the sub exhaust valve are rotated around the cylinder with the rotation axis parallel to the rotation axis of the sub exhaust valve. Since it is connected to a control shaft that is movably supported, the direction in which the main exhaust passage is opened and closed by the main exhaust valve and the direction in which the auxiliary exhaust passage is opened and closed by the auxiliary exhaust valve are in the cylinder axis direction and are in the same direction. Moreover, since the sub exhaust valve rotates in the same direction as the control shaft, the interlocking mechanism that connects each valve to the control shaft can have a simple structure. Further, since the main exhaust valve can be connected to the control shaft via a connecting member different from the auxiliary exhaust valve connecting member, the drive system of the auxiliary exhaust valve is simplified.

Therefore, the valve drive mechanism can be made to have a simple structure, the cost can be reduced and the weight of the engine can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a two-cycle engine equipped with an exhaust valve device according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a side view of an exhaust valve device according to the present invention.

4A and 4B are sectional views for explaining the operation of the auxiliary exhaust valve, in which FIG. 4A shows a fully open state and FIG. 4B shows a fully closed state.

FIG. 5 is a perspective view showing a valve drive mechanism of the exhaust valve device according to the present invention.

[Explanation of symbols]

 1 Engine 11 Main Exhaust Passage 12 Auxiliary Exhaust Passage 13 Main Exhaust Valve 14 Sub-Exhaust Valve 15 Valve Disc 15a Partition 15b Notch 21 Valve Drive Mechanism 23 Drive Fork 24 Arm 25 Connecting Rod

Claims (1)

[Claims] 1. An auxiliary exhaust valve comprising: a main exhaust valve which faces the main exhaust port and whose amount of protrusion is changed according to the engine speed; and a pair of auxiliary exhaust valves which face the auxiliary exhaust port on the side of the main exhaust port. The valve is formed in a substantially columnar shape provided with a partition portion that blocks the auxiliary exhaust passage that communicates with the auxiliary exhaust port and a cutout portion that forms the inner wall of the passage, and the rotation axis is orthogonal to the cylinder axis. The cylinder is rotatably supported,
A two-cycle engine characterized in that the main exhaust valve and the sub-exhaust valve are connected to a control shaft that is rotatably supported by a cylinder with a turning axis parallel to the turning axis of the sub-exhaust valve. Exhaust valve device.