JPH10274041A - Engine exhaust passage switching device - Google Patents

Abstract

(57) Abstract: To provide an engine exhaust passage switching device capable of shortening a switching time, preventing a temporary decrease in output at the time of switching, and improving drivability. An engine and an exhaust pipe for a low rotation range and a high rotation range are connected via a switching valve 8, and the exhaust from the engine is changed to a low rotation range or a high rotation range exhaust pipe by the switching valve 8. In the exhaust passage switching device that can be switched, the switching valve 8
Has a valve body 12 connected to the engine, and a rotating body rotatably disposed on the valve body 12. The valve body 12 has two outlets 12 b and 12 c connected to each exhaust pipe. A bifurcated exhaust passage 12d is formed while the rotating body has a cylindrical shape with a communication passage formed therein.
An exhaust port formed in the cylinder body of the engine by being rotatably disposed at a branch portion of the two forked exhaust passages 12d and being rotated about a cylindrical central axis O;
The outlets 12b and 12c of the valve body 12 are set so as to be connected to each other through a communication passage, and further, the two exhaust pipes can be switched at an angle of rotation of the rotating body smaller than 180 °.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine and an exhaust pipe for a low rotation speed region and an exhaust pipe for a high rotation speed region, which are connected via a switching valve. Also, the present invention relates to an exhaust passage switching device for an engine that can switch to an exhaust pipe for a high rotation range.

[0002]

2. Description of the Related Art Conventionally, as an exhaust device capable of obtaining a high output by utilizing a pressure wave of exhaust over a wide range of an engine rotation range, for example, there is an exhaust device described in Japanese Utility Model Laid-Open No. 60-143125. . This is because a switching valve for switching the flow direction of exhaust gas to one of two directions is provided in an exhaust passage of a single cylinder engine, and one of the two outlets of the switching valve is adapted to a low rotation speed range which is adapted to a low rotation speed range. An exhaust pipe is connected, and a high-speed exhaust pipe suitable for a high-speed range is connected to the other end.

In this switching valve, an exhaust passage is formed in a valve body by forming two branch passages having a common inlet in a forked shape, and a rotating body having a curved communication passage at a branch portion of the exhaust passage. Are fitted rotatably about a central axis. An exhaust pipe for a low rotation range is connected to one exhaust passage, and an exhaust pipe for a high rotation range is connected to the other exhaust passage.

[0004] By rotating the rotating body about a central axis, a curved communication passage is moved to select one of the exhaust passages.

[0005]

However, in such a conventional apparatus, the rotating body is moved around the center axis.
By rotating by 80 °, the exhaust pipe for the low rotation range and the exhaust pipe for the high rotation range are selectively switched, so that the switching time becomes longer, and a temporary decrease in output at the time of switching occurs. However, there is a problem that the drivability is reduced.

Accordingly, an object of the present invention is to provide an engine exhaust passage switching device capable of shortening the switching time, preventing a temporary decrease in output at the time of switching, and improving drivability. .

[0007]

In order to achieve the above object, according to the first aspect of the present invention, an engine is connected to an exhaust pipe for a low revolution range and an exhaust pipe for a high revolution range via a switching valve. An exhaust passage switching device configured to be able to switch exhaust from the engine to a low rotation range or high rotation range exhaust pipe by the switching valve, wherein the switching valve includes a valve body connected to the engine; A rotating body rotatably disposed in the valve body, wherein the valve body is formed with a bifurcated exhaust passage having two outlets connected to the exhaust pipes, The rotator has a cylindrical shape with a communication passage formed therein, is rotatably disposed at a branch portion of the bifurcated exhaust passage of the valve body, and is rotated about a cylindrical central axis. An exhaust port formed in a cylinder body of the engine, and the valve body An exhaust passage switching device for an engine, wherein one of the outlets is set to be continuous through the communication passage, and further, the rotation angle of the rotating body can be switched between the two exhaust pipes at an angle smaller than 180 °. It is characterized by having.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the outlet of the communication passage of the rotating body is connected to both branches of the exhaust passage of the valve body during switching between the two exhaust pipes. It is characterized by straddling a passage.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the area where the communication passage outlet of the rotating body and the branch passage communicate with each other during switching between the two exhaust pipes is the same as that of the first embodiment. It is characterized by being at least 50% of the area of the branch passage.

[0010]

Embodiments of the present invention will be described below.

1 to 7 show an embodiment of the present invention.

First, the structure will be described. Reference numeral 1 in FIGS. 1 and 2 denotes a water-cooled two-cycle single-cylinder engine of a motorcycle. In this single-cylinder engine 1, a cylinder head 3 is fixed to a cylinder body 2; Inside, a connecting rod 5 whose lower end is connected to the crankshaft 4 is disposed.
A piston 6 is attached to the upper end of the connecting rod 5.

[0013] The single-cylinder engine 1 is connected to a low-rotation-range exhaust pipe 9 and a high-rotation-range exhaust pipe 10 through a switching valve 8.
Is connected.

Specifically, the switching valve 8 has a valve body 12 fixed to the cylinder body 2 and a rotating body 13 rotatably disposed on the valve body 12.

The valve body 12 has one inlet 12a,
A bifurcated exhaust passage 12d is formed by connecting the two outlets 12b and 12c, and the cylinder body 2 is bolted by bolts 14 so that the inlet 12a is connected to the exhaust port 2a formed in the cylinder body 2. It is fixed to. The exhaust pipes 9 and 10 are fixed to the valve body 12 by bolts (not shown). The exhaust pipe 9 for the low rotation range is provided at one outlet 12b of the valve body 12 and at the other outlet 12c. The high-speed exhaust pipes 10 are connected to each other (see FIG. 3).

As shown in FIGS. 2 and 3, the rotating body 13 has a cylindrical shape with a curved communication passage 13a formed therein, and is rotatable about a central axis O. Is fitted. Inlet 13b of this communication passage 13a
Is connected to the exhaust port 2a of the cylinder body 2, and the outlet 13c of the communication passage 13a is connected to both outlets 12b and 12c of the valve body 12 by rotating the rotating body 13. I have.

Further, an exhaust passage 12d of the valve body 12 is provided.
Are branch passages 12e, 12e having outlets 12b, 12c.
As shown in FIG. 2, the direction of the axis P of f is inclined downward by an angle θ from the central axis O of the rotating body 13. Then, both outlets 12 of both branch passages 12e and 12f of the valve body 12 are formed.
As shown in FIG. 4, b and 12c are located below the central axis O of the rotating body 13, and these two outlets 12b and 12c
Is that the angle α formed by the line connecting the centers of the outlets 12b and 12c and the central axis O is smaller than 180 °,
It is set to 0 °. Thereby, it is set such that the two exhaust pipes 9 and 10 can be switched at a rotation angle of the rotating body 13 smaller than 180 °.

Further, while the two exhaust pipes 9 and 10 are being switched, the outlet 13c of the communication passage 13a of the rotating body 13 is connected to the branch passage 12e of the valve body 12 as shown by a two-dot chain line in FIG. 12f so that both outlets 13c
And the diameters of the branch passages 12e and 12f are set. Moreover, in a state where the outlet 13c of the communication passage 13a of the rotating body 13 straddles the two branch passages 12e and 12f of the valve body 13, as shown schematically in FIG. 7, the communication passage outlet 13c and the two branch passages 12e and 12e, The area (indicated by the hatched portion in FIG. 7) communicating with the branch passage 12f is 50% of the area of each branch passage 12e, 12f.
% Is set.

The rotating body 13 is driven by a driving device 17.
It is set to be rotationally driven by. More specifically, as shown in FIG.
3 is provided with a rotating shaft 18 protruding therefrom.
As shown in FIG. 1, a first gear 19 having a small diameter is fixed, and a second gear 20 having a large diameter is meshed with the first gear 19 as shown in FIG. The second gear 20 is connected to the motor 21
, The rotating body 13 is rotated about the central axis O. The driving device 17 is connected to the control device 23.

The exhaust port 2a of the cylinder body 2
As shown in FIG. 2, a displacement member 25 for vertically displacing the position of the upper edge of the exhaust port 2a is disposed on the upper side of the exhaust port 2a. The displacement member 25 is disposed rotatably about a shaft 25a, and is rotated by a motor 26 shown in FIG. 1 to displace the position of the upper edge of the exhaust port 2a. Then, the motor 26 is connected to the control device 23 to be driven and controlled.

The control device 23 is connected to a sensor 27 provided at a portion where the crankshaft 4 is provided.
The number of revolutions of the single-cylinder engine 1 is detected, a signal from the sensor 27 is input, and the motor 21 of the switching valve 8 and the motor 26 of the displacement member 25 are driven according to the number of revolutions. ing.

Next, the operation of the exhaust passage switching device having the above configuration will be described.

The rotation speed of the single-cylinder engine 1 is detected by a sensor 27, and a signal from the sensor 27 is transmitted to a controller 23.
When the rotation speed at this time is smaller than a predetermined value, the rotating body 13 of the switching valve 8 is set at the position shown by the solid line in FIG. 3 and the exhaust gas is discharged through the exhaust port 2 a of the cylinder body 2. The gas passes through the communication passage 13a of the rotating body 13 and flows from the outlet 12b of the valve body 12 into the low-speed exhaust pipe 9 to be exhausted.

When the rotation speed exceeds a predetermined value, the control device 23 drives the motor 21 to rotate the rotating body 13 about the center axis O through the first and second gears 19 and 20 and the like. , And is switched to the high-speed exhaust pipe 10 for exhaust.

In this case, the switching can be performed by rotating the rotating body 13 by 120 ° as shown in FIG. 4, so that the switching time can be reduced as compared with the conventional 180 ° rotation. Thus, a temporary decrease in output at the time of switching can be suppressed more than before, and operability can be improved.

At the time of this switching, the outlet 13c of the communication passage 13a of the rotating body 13 is connected to one branch passage 12e, (12f) of the valve body 12 from the other branch passage 12f, (12f).
e), the two branch passages 12e, 12e
As shown by the arrow X in FIG. 6, the air flows into the exhaust pipes 9 and 10 and is exhausted. Therefore, even at the time of switching, the exhaust is not temporarily shut off, and a temporary decrease in output can be suppressed as compared with the conventional case, so that drivability can be improved.

Further, in a state where the outlet 13c of the communication passage 13a of the rotating body 13 straddles both branch passages 12e and 12f of the valve body 13, as shown schematically in FIG. The area of communication between the passages 12e and 12f (shown by hatching in FIG. 7) is
Since the area is set to 50% or more of the area of f, it is possible to further suppress a temporary decrease in output due to being narrowed, and to prevent a so-called breathing phenomenon.

In the above embodiment, the rotation of the rotating body 13 by 120 ° enables the switching between the two exhaust pipes 9 and 10;
Of course, it may be larger or smaller than 0 °.
In the above-described embodiment, the present invention is applied to a two-cycle engine. However, the present invention is not limited to this, and can be applied to a four-cycle engine.

[0029]

As described above, according to the first aspect of the present invention, both exhaust pipes can be switched at a rotation angle of the rotating body smaller than 180 °.
The switching time can be reduced as compared with the conventional case of rotating by 180 °, the temporary decrease in output at the time of switching can be suppressed more than before, and the drivability can be improved.

According to the invention described in claim 2, according to claim 1
In addition to the effects described in (1), at the time of switching of the exhaust pipe, the outlet of the communication passage of the rotating body straddles both exhaust passages while moving from one exhaust passage to the other of the exhaust passages of the valve body. Since the exhaust gas is exhausted through the pipe, even at the time of switching, the exhaust gas is not temporarily shut off, a temporary decrease in output can be suppressed more than before, and the drivability can be improved. it can.

According to the invention of claim 3, according to claim 2,
In addition to the effects described in the above, in the state where the outlet of the communication passage of the rotating body straddles both branch passages of the valve body, the area where the communication passage outlet and both branch passages communicate is 50% of the area of each branch passage.
With the above setting, a temporary beneficial decrease in the output due to the narrowing can be further suppressed, and the so-called breathing phenomenon can be prevented, which has a practically useful effect.

[Brief description of the drawings]

FIG. 1 is a front view showing an engine and an exhaust pipe according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the engine and the like according to the embodiment taken along a vertical direction.

FIG. 3 is a sectional view taken along line AA of FIG. 2 according to the embodiment;

FIG. 4 is a view of FIG. 2 according to the embodiment viewed from a direction of an arrow B;

FIG. 5 is a perspective view showing a valve body according to the embodiment.

FIG. 6 is a perspective view showing a rotating body and the like according to the embodiment.

FIG. 7 shows an outlet of a communication passage of the rotating body according to the embodiment,
It is an explanatory view of a state straddling both branch passages of the valve body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single cylinder engine 2a Exhaust port 8 Switching valve 9 Exhaust pipe for low rotation range 10 Exhaust pipe for high rotation range 12 Valve body 12a Inlet 12b, 12c Outlet 12d Exhaust passage 12e, 12f Branch passage 13 Rotating body 13a Communication passage 13b Inlet 13c Outlet 17 Drive O Central axis α Angle

Claims (3)

[Claims] An engine is connected to an exhaust pipe for a low rotation range and an exhaust pipe for a high rotation range through a switching valve, and the switching valve is used to extract exhaust from the engine for a low rotation range or a high rotation range. In an exhaust passage switching device that can be switched to an exhaust pipe, the switching valve has a valve body connected to the engine, and a rotating body rotatably disposed on the valve body. A bifurcated exhaust passage having two outlets connected to the respective exhaust pipes is formed in the main body, while the rotating body includes:
The cylinder body of the engine has a cylindrical shape in which a communication passage is formed, is rotatably disposed at a branch portion of a bifurcated exhaust passage of the valve body, and is rotated about a cylindrical central axis. And the one outlet of the valve body is set to be continuous through the communication passage, and further, the two exhaust pipes have a rotation angle of the rotating body smaller than 180 °. An exhaust passage switching device for an engine, wherein the switching of the exhaust passage is enabled. 2. The exhaust passage of an engine according to claim 1, wherein the outlet of the communication passage of the rotating body straddles both branch passages of the exhaust passage of the valve body while the two exhaust pipes are being switched. Switching device. 3. An area where the communication passage outlet of the rotating body and the branch passage communicate with each other while the two exhaust pipes are being switched is at least 50% of the area of the branch passage. 3. The exhaust passage switching device for an engine according to 2.