JPS5974325A - Exhaust device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain enough output power over the entire operating region of an internal combustion engine ranging from the low-speed region to the high-speed region, by providing a plurality of mufflers different in output characteristics and by changing the connection of the mufflers to exhaust pipes depending on the load on the engine operating. CONSTITUTION:The exhaust pipes 3a-3d of an internal combustion-engine 1 are gathered at 1 in an exhaust chamber 4 whose downstream end is divided into two sections. Dividing pipes 5, 6 are placed at both the sides of a rear wheel 19 and connected to mufflers 7, 8. The flow resistance of the muffler 8 is higher than that of the other muffler 7. The muffler 8 has a construction appropriate to the slow rotation region of the engine, while the other muffler 7 has a construction appropriate to the rapid rotation region of the engine. When a controller has detected from ignition pulses from an igniter 16 that the engine has reached 5,000rpm, a pulse motor 18 is driven to close a control valve 20 and open another control valve 15 to change the muffler 8 for the other 7.

Description

[Detailed description of the invention] The present invention relates to an exhaust system for an internal combustion engine.

In general, it goes without saying that in internal combustion engines, the exhaust system, especially the muffler, has a large effect on the output characteristics.
It is extremely difficult to fully bring out both low-speed and high-speed performance with a single muffler, and either low-speed or high-speed performance is often sacrificed.

The present invention was made based on these circumstances, and
The object of the present invention is to provide an exhaust system for an internal combustion engine that can obtain sufficient output performance over the entire operating range from low speed range to high speed range.

That is, in order to achieve the above object, the present invention connects an exhaust pipe led out from a cylinder to a plurality of mufflers having different output characteristics, and connects this exhaust pipe to at least one of the above mufflers. The present invention is characterized in that a control valve is provided to open and close the communication passage, and by controlling the opening and closing of this control valve according to the operating load of the internal combustion engine, exhaust gas is guided to a muffler that is optimal for the operating load.

An embodiment of the present invention will be described below based on drawings in which it is applied to a motorcycle.

1 in the figure is a 4-cylinder internal combustion engine, and each cylinder 2 a +
2b + 2c and 2d have exhaust pipes, :la.

J b + 3c and 3d are connected. The rear ends of the exhaust pipes 3h, 3b, 3c, and 3d are gathered together in the exhaust chamber 4, and the downstream end of the exhaust chamber 4 is branched into two pipes. Mufflers 7 and 8 are connected to each of these branch portions 5 and 6 on both sides of the rear wheel 19. These mufflers 7 and 8 have the same external shape 9 and are composed of a plurality of partition walls 11 and a strut tube 12 on the downstream side of the expansion chambers 9 and 10, respectively. It has chambers 13 and 14. Sound deadening chamber 1 of one silencer 9
No. 3 has a small number of partition walls 11 and pierced pipes 12, and has an internal structure with extremely low exhaust resistance. On the other hand, the muffling chamber 14 of the other muffler 10 has a large number of partition walls 11 and pipes 12, and has an internal structure with greater resistance than the muffler 9. Therefore, one silencer 9 has a structure that emphasizes performance in the high rotation range, and the other silencer 1θ has a structure that emphasizes performance in the low and medium rotation range, so that the output characteristics of each are different. It's different.

In the communication portion between each silencer 9, 10 and the exhaust chamber 4,
Control valves 15 and 20 are provided to open and close this communication passage. The control valves 15 and 20 are controlled to open and close depending on the operating status of the internal combustion engine 1. That is, one of the control valves 20 is of a normally open type that is opened from the start of the internal combustion engine 1 to the time of medium load operation. When this detection signal reaches a predetermined level, for example, 5000 rpm relative to the rotation speed of the internal combustion engine 1, the control unit 17 sends an activation signal to the pulse smoke 18, which is the drive source of the control valve 20. This activation signal causes the control valve 20 to be closed.

The other control valve 15 is a normally closed type that is opened when the internal combustion engine 1 shifts from low-load or medium-load operation to high-load operation. The opening operation is performed by the A-rus motor 18 which receives an activation signal from the A-rus motor 18.

Next, the operation of the above configuration will be explained.

During low/medium load operation of the internal combustion engine 1, the control valve 15 closes;
And since the control valve 20 is open, each cylinder 2a, 2b
, 2c and 2d into the exhaust chamber 4, the exhaust gas is directed into the other muffler 8 as shown by the solid arrow in the figure.
Flow inward. Since this muffler 8 has an internal structure emphasizing low and medium speed performance, the exhaust gas is sufficiently expanded by the effect of exhaust pulsation, and high torque can be obtained during low and medium load operation.

On the other hand, the internal combustion engine 1 shifts to high-load operation, and the rotational speed of the internal combustion engine 1 increases to 50.
00 rpm, the control valve 15 is opened by an actuation signal from the control unit 17, while the control valve 2 is opened.
0 is closed, from this point on the exhaust chamber 4 and one of the mufflers 7 are communicated with each other, and the exhaust gas flows into one of the mufflers 7 as shown by the dashed arrow. This muffler 7 has an internal structure that has less resistance than the other muffler 8 and emphasizes high-speed performance, so when high-load operation is reached, the exhaust efficiency is increased accordingly, resulting in high torque and high-speed performance. I get the output. Therefore, according to this configuration, the exhaust gas can be guided to the silencers 7 and 8 that have optimal output characteristics according to the operating load, so high torque and high output can be achieved over the entire operating range from low speed range to high speed range. characteristics are obtained.

In the above-described embodiment, the state of transition to high-load operation was detected from the rotational speed of the internal combustion engine, but it may also be detected from, for example, the exhaust pressure, and the means for detecting the rotational speed of the internal combustion engine may also be electrical. It is not limited to a type, but may be a mechanical type.

Furthermore, the control valve is not limited to being provided in the communication path between each muffler and the exhaust pipe, but may be provided only in the communication path between one high-speed muffler and the exhaust pipe, for example, and in short, the control valve may be provided only in the communication path between one of the high-speed mufflers and the exhaust pipe. It is sufficient if the communication path with at least one of the silencers can be opened and closed.

Further, in the above-described embodiment, there are two silencers, a low-medium speed type and a high-speed type, but it is also possible to use three silencers, for example, a low-speed type, a medium-speed type, and a high-speed type.

Further, the internal combustion engine according to the present invention is not limited to a multi-cylinder internal combustion engine such as a four-cylinder engine, but can be similarly implemented even if it is a single-cylinder internal combustion engine.

As detailed above, according to the present invention, an exhaust pipe is connected to a plurality of mufflers having different output characteristics, and a communication path between the exhaust pipe and at least one of the mufflers is opened and closed. Since a control valve is provided and the control valve is controlled to open and close according to the operating load of the internal combustion engine, exhaust gas can be guided to a silencer with optimal output characteristics according to the operating load, and low-speed It has the advantage of being able to provide high torque and high output characteristics over the entire operating range from high speed to high speed.

[Brief explanation of the drawing]

The drawings are schematic configuration diagrams showing one embodiment of the present invention. 1... Internal combustion engine, 2a-2d... Cylinder, 3a-3d
...exhaust pipe, 7.8...silencer, 15,2θ...
Control valve O Applicant's agent Patent attorney Takehiko Suzue 7-

Claims (1)

[Claims] The exhaust pipe led out from the cylinder is connected to a plurality of mufflers having different output characteristics, and a control valve is provided for opening and closing a communication path between the exhaust pipe and at least one of the above-mentioned mufflers. An exhaust system for an internal combustion engine, characterized in that the control valve is controlled to open and close according to the operating load of the internal combustion engine.