JP2606309B2 - Exhaust control system for motorcycle - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to an exhaust gas control device for a motorcycle in which a reflected wave of exhaust pressure is appropriately controlled to improve engine output. .

(Prior art) In a high-speed, high-output four-stroke engine mounted on a motorcycle, the end of the exhaust stroke and the beginning of the intake stroke are overlapped in order to lengthen the intake and exhaust times. Is set. Since there is almost no movement of the piston in the stroke of the overlap portion, the suction and exhaust operations are performed by utilizing the inertia effect of the exhaust gas and the pulsation effect of the suction and exhaust gas.

However, the pulsation effect has an adverse effect when the cycle of the pulsation wave is determined according to the exhaust system conditions and does not match the engine speed. In the high-speed, high-output type, the exhaust system is set with the expectation of an appropriate effect in the high-speed range, so that a remarkable output drop (output valley) is likely to occur in the medium-speed range.

In order to prevent such a phenomenon, FIGS. 4 (A), (B),
As shown in (C) and (D), a technique of installing an exhaust pipe throttle valve b for changing the passage area in the exhaust pipe a in the middle of the exhaust pipe a and performing control related to the engine rotation speed has been conventionally performed. (For example, JP-A-62-206227).

When the passage area in the pipe is changed by the exhaust pipe throttle valve b, a change in the exhaust pulsation cycle is used to obtain an appropriate pulsation effect in the entire rotation range. In the figure, (A) shows a state during idling operation, (B) shows a state at low speed operation, (C) shows a state at medium speed operation, and (D) shows a state at high speed operation.

In this way, as shown in the horsepower characteristic of the line A in FIG. 5, the extreme output trough is eliminated. However, there is a limit in uniformly obtaining an appropriate pulsation effect in the entire rotation range, and this system has a problem that it is necessary to reduce the output in the high rotation range to some extent and add the output to the medium speed range.

(Problems to be Solved by the Invention) As described above, in a high-revolution, high-output type four-stroke engine, an exhaust pipe throttle valve is provided in order to eliminate a valley of output, and the flow path of the exhaust pipe is related to the number of revolutions. By changing the area,
Although a technique for optimizing the exhaust pulsation wave over the entire rotation range is used, in view of the point that sufficient suitability cannot be obtained, the present invention makes the use of the exhaust pulsation wave more effective to achieve full rotation. It is an object of the present invention to obtain a motorcycle exhaust control device that improves output over a range.

[Configuration of the invention]

(Means for Solving the Problems) In accordance with the above object, an exhaust emission control device for a motorcycle according to the present invention includes an exhaust pipe for a high-speed, high-output four-cycle engine mounted on the motorcycle. An expansion chamber is arranged in the middle and communicates via a rotary on-off valve, and an exhaust pipe throttle valve that protrudes and disappears in the exhaust pipe is formed integrally with the rotary on-off valve. This rotary on-off valve is related to the engine speed. At the idling operation speed, the rotary on-off valve is fully closed, the opening of the exhaust pipe throttle valve is minimized, and the opening of both valves is increased with the increase of the engine rotation speed. In the operating range, both valves are controlled to be fully opened.

(Function) In this way, the expansion chamber has a function of interfering with the exhaust pulsation wave, and the function is adjusted by the opening degree of the rotary valve, and is synergistic with the adjustment by changing the flow path area of the exhaust pipe throttle valve. By the action, the exhaust pulsation wave can be finely optimized over the entire rotation range, and the output from a low speed to a high speed range is improved.

Especially in the high speed range, the pulsation wave optimization range is wide,
As shown in the horsepower characteristic of FIG.

(Embodiment) A description will be given below with reference to the drawings showing an embodiment of the present invention.

FIG. 2 shows an automatic 2 equipped with an exhaust control device according to the present invention.
FIG. 3 is a side view of the wheel, and FIG. 3 is a perspective view of the exhaust pipe.

The engine 1 mounted in the center of the vehicle body is a high-speed, high-power, multi-cylinder four-cycle engine. The exhaust pipe 2 derived from each cylinder is guided rearward along the front and lower parts of the engine 1,
After being connected to the collecting pipe 3, it is opened to the atmosphere by left and right mufflers 4.

An expansion chamber 5 is provided in the middle of the exhaust pipe 2. Expansion room 5
Is communicated with the inside of the exhaust pipe 3 by a communication portion 6, and a valve 7 is interposed in the communication portion 6 so as to close the communication portion 6.

The valve body 7 includes a cylindrical rotary opening / closing valve 8 pivotally supported by a support shaft 9 and an exhaust pipe throttle valve extending in a fan shape.
10 and is provided so as to always slidably contact the peripheral wall 11 of the communication portion 6 and swing.

The rotary opening / closing valve 8 has a through hole 12 diametrically communicating with the inside of the expansion chamber 5 and the inside of the exhaust pipe 2, and one end of the through hole 12 has a valve seat 13 formed from a part of the peripheral wall 11. Are opposed to each other, and the opening degree thereof is changed by the swing displacement.

Further, the exhaust pipe throttle valve 10 protrudes and retracts in the exhaust pipe 2 due to the swing displacement of the rotary on-off valve 8, and changes the passage area S of the pipe.

The valve body 7 includes a driven pulley 14 fixed to the support shaft 9,
Oscillating displacement is provided via a belt 16 suspended between a drive pulley 15 on the motor drive shaft. The motor is computer-controlled on the basis of the engine speed, so that the valve element 7 is controlled in relation to the engine speed.

In an extremely low-speed rotation range such as during idling operation, the rotary on-off valve 8 is fully closed, and at the same time, the exhaust pipe throttle valve 10 is closed.
Project greatly into the exhaust pipe 2 to minimize the passage area S (the state of FIG. 1 (A)).

As the engine speed increases, the valve element 7 swings, the opening of the rotary on-off valve 8 increases, and the passage area S of the exhaust pipe throttle valve 10 increases (the state of FIG. 1 (B)). .

In the high-speed rotation range, the rotary on-off valve 8 is fully opened, and the exhaust pipe throttle valve 10 is retracted to have the original passage area of the exhaust pipe 2 (the state of FIG. 1 (C)).

In this manner, the cycle of the exhaust pulsation wave is adjusted by the interference effect of the passage area S of the exhaust pipe 2 and the interference effect of the expansion chamber 5 through the rotary on-off valve 8, so that the intake and exhaust overlap over the entire rotation range of the engine. The pressure reflected wave at the time is appropriately controlled to improve the output.

That is, in FIG. 1 (A), in the low-speed rotation region, the exhaust flow velocity is usually slow, and the exhaust pressure is also small. Therefore, the exhaust pipe passage area S is greatly reduced to forcibly change the exhaust pressure to improve the output.

In FIG. 1 (B), when the engine speed reaches a certain set value, the valve element starts to swing, the rotary on-off valve 8 starts to open, and communicates with the expansion chamber 5. Therefore, in this rotation range, the exhaust pulsation wave can be delayed according to the valve opening in combination with the reflected wave control by the exhaust pipe throttle valve 10, and the positive pressure wave applied to the intake valve portion at the time of overlap is reduced. To increase volumetric efficiency.

In the high rotation range, both the rotary on-off valve 8 and the exhaust throttle valve 10 are fully opened as shown in FIG. 1 (C), and operation can be performed with the set pulsation effect. Pulsation wave characteristics match this rotation range due to the interference action of the expansion chamber 5, and conversely, the output is improved (see FIG. 5).

〔The invention's effect〕

As described above, in the motorcycle exhaust control apparatus according to the present invention, in a high-speed, high-output four-stroke engine, an expansion chamber is provided in the middle of an exhaust pipe and communicated with a rotary on-off valve. The exhaust pipe throttle valve is extended integrally with the rotary valve, and both valves are controlled in relation to the engine speed. In the low-speed rotation range, the rotary valve is fully closed, and the passage area of the exhaust pipe throttle valve is set. The opening degree of both valves rises with the increase of the rotation speed in the middle speed range, and both valves are fully opened in the high speed range. Not only eliminates output valleys, but also improves output over the entire area.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust gas control device according to an embodiment of the present invention, in which (A) is a low-speed rotation region, (B) is a medium-speed rotation region,
(C) shows a state in a high-speed rotation range, FIG. 2 is a side view of a motorcycle provided with the exhaust control device of FIG. 1, and FIG.
FIG. 4 is a vertical cross-sectional view of a conventional exhaust control device provided with the exhaust control device shown in FIG. 4, (A) is idling, (B) is low speed, (C) is medium speed, (D) ) Shows the state of each high-speed rotation range, and FIG. 5 shows the relationship between the engine speed and the output. 2 ... exhaust pipe, 5 ... expansion chamber, 8 ... rotary on-off valve,
9 ... Support shaft, 10 ... Exhaust pipe throttle valve.

Claims (1)

(57) [Claims] 1. A high-speed, high-output four-stroke engine mounted on a motorcycle, in which an expansion chamber is arranged in the middle of an exhaust pipe and communicates via a rotary opening / closing valve, and protrudes and retracts in the exhaust pipe. The exhaust pipe throttle valve is formed integrally with the rotary on-off valve, and the rotary on-off valve is rotated and displaced in relation to the engine speed. At the idling operation speed, the rotary on-off valve is fully closed and the exhaust pipe throttle valve is closed. The exhaust control of a motorcycle is characterized in that the opening of both valves is minimized, the opening of both valves is increased with an increase in engine speed, and both valves are controlled to be fully opened in a high-speed operation range. apparatus.