JPH11343852A - Exhaust system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system capable of reducing the number of cut-off poppet valves or exhaust pipes and the weight thereof, preventing side vibration, contributing to the improvement of a car body strength, supporting the same by a small number of supporting points and effectively lengthening an exhaust system even in the case of a multi-cylinder internal combustion engine. SOLUTION: An exhaust pipe 2 has a branch part 2a connected to each cylinder and a collected part 2b, a cut-off poppet valve 3 connected to a pipe has a valve main body 7 connected to the collected part 2b and a rotor 8 disposed in the valve main body 7, a yoked exhaust passage 7d having two exits 7b connected to a low/high revolution exhaust pipe 4 is formed in the valve main body 7, the rotor 8 is formed in a cylindrical columnar shape where a communication route 8a is formed, the rotor 8 is disposed freely rotatably in the branch part of the yoked exhaust passage 7d of the valve main body 7 and rotated around a center axis 10, the exists of the collected part 2b and the valve main body 7 are set to be continuous via the communication route 8a, the center axis of the rotor 8 is extended forward through the collected part 2b, and a driving device 9 for rotating the rotor 8 is disposed in a part protruded to the front of a vehicle from the collected part 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine connected to a low-speed exhaust pipe and a high-speed exhaust pipe via a switching valve. The present invention relates to an exhaust device that can be switched to an exhaust pipe for an area or a high rotation area.

[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 rotation of an internal combustion engine, for example, an exhaust device described in Japanese Utility Model Laid-Open No. 60-143125 is known. There is. 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 the 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, such a conventional engine is provided with one switching valve, two low-speed exhaust pipes and a high-speed exhaust pipe per single cylinder engine. Therefore, in the case of a multi-cylinder engine, the number of switching valves and the number of exhaust pipes increase accordingly, making the structure complicated and increasing the weight. In addition, the switching valve is directly connected to the engine, and the two exhaust pipes for the low rotation range and the high rotation range are extended from the switching valve. It has been
It is easy to roll and does not contribute much to the rigidity of the vehicle body, and each exhaust pipe must be supported at many support points,
Further, there is a limit in increasing the total length of the exhaust system.

Therefore, the present invention can reduce the number and weight of the switching valves and the respective exhaust pipes even in the case of a multi-cylinder internal combustion engine, prevent the roll, and contribute to the improvement of the strength of the vehicle body. It is an object of the present invention to provide an exhaust device for an internal combustion engine that can support an exhaust pipe at a support point and effectively increase the overall length of an exhaust system.

[0007]

In order to achieve the above object, according to the present invention, an exhaust pipe is connected to each cylinder of a multi-cylinder internal combustion engine, and the exhaust pipe is connected to the exhaust pipe via a switching valve. An exhaust device in which a rotation range exhaust pipe and a high rotation range exhaust pipe are connected, and the switching valve can switch exhaust from the multi-cylinder internal combustion engine to a low rotation range or high rotation range exhaust pipe. The exhaust pipe has a branch portion provided with the same number as the number of cylinders and connected to each of the cylinders, and a collecting portion in which each of the branch portions is gathered into one. A valve body connected to the collecting portion, and a rotating body rotatably disposed on the valve body. The valve body includes a low-rotation range or high-rotation range exhaust pipe. A forked exhaust passage having two outlets connected thereto is formed, The rotating body has a columnar 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 columnar central axis. The collecting portion and one outlet of the valve body are set to be continuous through the communication path, and a central axis of the rotating body extends forward from the rotating body and penetrates through the collecting portion. An exhaust device for an internal combustion engine, wherein a drive device for rotating the rotating body is provided at a portion of the central shaft projecting forward of the vehicle from the gathering portion.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the plurality of branch portions located on the front side of the gathering portion of the exhaust pipe are located between the respective branch portions. It is characterized in that the device extends so as to be exposed when viewed from the front.

[0009]

Embodiments of the present invention will be described below.

[First Embodiment of the Invention] FIGS. 1 to 4 show a first embodiment of the present invention.

First, the structure will be described. Reference numeral 1 in FIGS. 1 and 4 designates 2 as a “multi-cylinder internal combustion engine” of a motorcycle.
In the cylinder engine, an exhaust pipe 2 is connected to the two-cylinder engine 1, and an exhaust pipe 4 for a low rotation range that is suitable for a low rotation range and a high rotation range for the exhaust pipe 2 via a switching valve 3. An exhaust pipe 5 for a high rotation range that is sometimes suitable is connected.

More specifically, the exhaust pipe 2
Has a plurality of, here, two branch portions 2a, and an aggregation portion 2b in which these branch portions 2a are gathered, and the two branch portions 2a are connected to each cylinder of the two-cylinder engine 1. The switching valve 3 is connected to the collecting portion 2a.

As shown in FIG. 3, the switching valve 3 has a valve body 7 fixed to the collecting portion 2b, and a rotating body 8 rotatably disposed on the valve body 7.

The valve body 7 has a bifurcated exhaust passage 7 formed by connecting one outlet 7a to two outlets 7b and 7c.
d is formed, the inlet 7a of which is connected to the collecting portion 2b.
5 is bolted to one outlet 7b of the valve body 7
The exhaust pipe 4 for the low rotation range is connected to the other, and the exhaust pipe 5 for the high rotation range is connected to the other outlet 7c (see FIGS. 2, 3 and the like).

Further, as shown in FIG. 3, the rotating body 8 has a cylindrical shape in which a curved communication path 8a is formed.
The valve body 7 is rotatably fitted to a branch portion of the exhaust passage 7d. The inlet 8b of the communication path 8a is connected to the exhaust port of the collecting portion 2b, and the outlet 8c of the communication path 8a is connected to the outlet 7b or 7c of the valve body 7 by the rotation of the rotating body 8. Has become.

The rotating body 8 is provided with a central shaft 10 which is connected to the driving device 9 and
The driving device 9 is set so that the rotating body 8 is rotationally driven via the central shaft 10. Specifically, the center shaft 10 has a flange portion 10a formed on the rear end side,
The flange portion 10a is fixed to the rotating body 8 with a screw 21, and the rear end portion 10b is attached to the valve body 7 by the bearing portion 22.
Is supported through. The center shaft 10 extends obliquely downward at the front of the vehicle through the communication passage 8a of the rotating body 8 and the collection portion 2b of the exhaust pipe 2. And this central axis 10 is
The protruding portion is supported by the bearing portion 23, and the gear 11, which is a component of the driving device 9, is attached to the center shaft 10 on the front side. Although not shown, the driving device 9 is equipped with a motor for rotating the gear 11 and the like, and the driving device 9 is connected to a control device (not shown).

As shown in FIG. 2 and the like, this driving device 9
A branch portion 2a on the front side of the gathering portion 2b of the exhaust pipe 2 is expanded left and right, and the branch portion 2 expanded right and left.
a, and is exposed when viewed from the front.

This control device is connected to a sensor provided on the crankshaft arrangement portion of the two-cylinder engine 1, which detects the number of revolutions of the two-cylinder engine 1 and inputs a signal from this sensor. The motor of the driving device 9 is driven according to the rotation speed.

The exhaust pipe 4 for the low revolution range and the exhaust pipe 5 for the high revolution range are branched right and left from the switching valve 3 and extend rearward of the vehicle. As shown in FIG. The low-range exhaust pipe 4 is bent halfway toward the high-rotation range exhaust pipe 5, and the rear end 4 a of the low-range exhaust pipe 4 is arranged along the vicinity of the high-rotation range exhaust pipe 5. Has been established.

A support piece 14 projects upward from the switching valve 3 and is bolted to a bracket 15 provided on the vehicle body side. Also, as shown in FIG. 1 and the like, a support piece 16 protrudes from an intermediate portion in the longitudinal direction of the exhaust pipe 4 for the low rotation range and the exhaust pipe 5 for the high rotation range, and this support piece 16 is provided on the vehicle body side. Bolted to the bracket. Further, a support piece 18 is fixed to the mufflers 4b, 5b of the exhaust pipe 4 for the low rotation range and the exhaust pipe 5 for the high rotation range, and the support piece 16 is provided on the bracket 1 provided on the vehicle body side.
9 bolted. In this manner, the exhaust pipe 2, the switching valve 3, the exhaust pipe 4 for the low rotation range, and the exhaust pipe 5 for the high rotation range are supported by the vehicle body.

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

The rotational speed of the two-cylinder engine 1 is detected by a sensor, and a signal from the sensor is input to a control device.
When the rotation speed at this time is smaller than a predetermined value, the switching valve 3
3 is set at the position shown by the solid line in FIG. 3, and the exhaust gas passes from the combustion chamber of each cylinder of the two-cylinder engine 1 through the branch portion 2a and the collecting portion 2b of the exhaust pipe 2 to be connected to the rotary body 8. After passing through the passage 8a, the gas flows from the outlet 7b of the valve body 7 into the exhaust pipe 4 for the low rotation range and is exhausted.

When the number of revolutions exceeds a predetermined value, the control device drives the motor to drive the gear 11.
The rotating body 8 is rotated about the central axis O via the above-mentioned means, and is switched to the high-speed exhaust pipe 5 for exhaust.

In such an exhaust system, an exhaust pipe 2, a switching valve 3, an exhaust pipe 4 for a low rotation range, and an exhaust pipe 5 for a high rotation range are connected, and a substantially X-shaped crossing at the switching valve 3 portion. Since it has an integral rigid structure, it can be mounted on the vehicle body to reduce the roll and reduce the rigidity of the vehicle body compared to the conventional two separate exhaust pipes. Contribute to improvement.

Further, when such an integral rigid structure is attached to a vehicle body, the number of attachment points can be reduced as compared with a conventional arrangement in which two separate exhaust pipes are provided. Moreover, in this embodiment, since the relatively heavy switching valve 3 is directly supported on the vehicle body via the support piece 14 and the like, vibration can be effectively suppressed. In addition, by disposing the switching valve 3 at the center portion in the vehicle width direction, the weight of the switching valve 3 is not excessively biased to either of the left and right sides, can be supported in a well-balanced manner, and at the same time, twisting or the like hardly occurs. The car width itself can be reduced.

Furthermore, since the exhaust pipe 2, the switching valve 3, the exhaust pipe 4 for the low rotation range and the exhaust pipe 5 for the high rotation range are connected in an X-shape, they can be simply extended backward as in the conventional case. As compared with the exhaust system, the overall length of the exhaust system can be increased. Further, the exhaust pipe 4 for the low revolution range and the exhaust pipe 5 for the high revolution range are branched right and left from the switching valve 3 and extended to the rear of the vehicle, and as shown in FIG. Is bent in the middle toward the high-speed exhaust pipe 5, and the rear end 4 a of the low-speed exhaust pipe 4 is disposed along the vicinity of the high-speed exhaust pipe 5. In particular, the entire length of the exhaust system on the side of the exhaust pipe 4 for the low rotation range can be effectively increased. In addition, the exhaust pipe 4 for the low rotation range and the exhaust pipe 5 for the high rotation range
And the rear end can be aligned, and the appearance quality can be improved.

Further, as shown in FIG. 2 and the like, the branch portion 2a on the front side of the collecting portion 2b of the exhaust pipe 2 is
Since the driving device 9 is spread right and left so as to be exposed when viewed from the front, the traveling wind directly hits the driving device 9, so that the cooling performance of the driving device 9 is secured without disposing a forced cooling device. it can.

Further, the center axis 10 of the rotating body 8 extends forward through the collecting portion 2b of the exhaust pipe 2,
Since the driving device 9 such as the gear 11 is provided at a portion protruding from the collecting portion 2b, the rotational position of the rotating body 8 can be easily adjusted. That is, assuming that the center shaft 10 is extended to the rear of the rotating body 8 and a drive device is provided in this extended portion, the position of the drive device is below the two-cylinder engine 1. At the same time, it is located between the exhaust pipe 4 for the low rotation range and the exhaust pipe 5 for the high rotation range. On the other hand, according to the present invention, the center axis 10 is extended forward, and the driving device 9 is divided into right and left branches 2.
a, the operation is easy, and the rotational position of the rotating body 8 is easily adjusted. In addition, since the driving device 9 is exposed toward the front of the vehicle, the driving device 9 is susceptible to traveling wind, so that the cooling performance of the driving device 9 is improved.

Further, by extending the center shaft 10 forward, the center shaft 10 can be supported by the pair of bearing portions 22 and 23 which are spaced apart in the vehicle front-rear direction. The backlash of the shaft 10 and thus the rotating body 8 can be prevented. On the other hand, when the center shaft 10 is extended rearward, the center shaft 10 is supported only by the rear bearing portion 22, so that the backlash is easily generated and the bearing portion 22 is enlarged. You also need to do it.

[Second Embodiment of the Invention] FIG. 5 shows a second embodiment of the present invention.

The second embodiment differs from the first embodiment in the configuration of the switching valve 33. That is, the switching valve 33 has a valve body 34, and the inlet 3 to which the collecting portion 2b of the exhaust pipe 2 is connected to the valve body 34.
4a are formed, and outlets 34b, 34c, 34d are formed, through which exhaust gas entering from the inlet 34a is selected and exhausted through a communication passage of a rotating body in the valve body 34. Although not shown, an exhaust pipe for a low rotation range, an exhaust pipe for a middle rotation range, and an exhaust pipe for a high rotation range are connected to these three outlets 34b, 34c, 34d.

If three types of exhaust pipes can be selected as described above, smooth performance can be exhibited from a low rotation speed range to a high rotation speed range. In addition, for example, when it is not necessary to use the engine up to the high speed range, the use of the low speed range exhaust pipe and the middle speed range exhaust pipe without using the high speed range exhaust pipe makes it easier to drive and fuel economy. Only the good area can be used.

Other configurations and operations are the same as those of the first embodiment.

In the above embodiment, the present invention is described as follows.
Although applied to the cycle engine, the invention is not limited to this, and can be applied to a four-cycle engine.

[0035]

As described above, according to the first aspect of the present invention, the exhaust pipe, the switching valve, the exhaust pipe for the low rotation range and the exhaust pipe for the high rotation range are connected to each other, and the switching valve is provided. Since it has an integral X-shaped rigid body structure that intersects at a portion, the structure is simpler and the weight can be reduced as compared with the case where a switching valve and two exhaust pipes are required for each cylinder. . Further, by attaching the integral rigid structure to the vehicle body, it is possible to prevent the roll and to contribute to the improvement of the rigidity of the vehicle body, as compared with the conventional arrangement in which two separate exhaust pipes are provided.

Further, when such an integral rigid structure is attached to a vehicle body, the number of attachment points can be reduced as compared with a conventional arrangement in which two separate exhaust pipes are provided.

Furthermore, since the exhaust pipe, the switching valve, the exhaust pipe for the low rotation range and the exhaust pipe for the high rotation range are connected in a substantially X-shape, they are simply extended rearward as in the prior art. By comparison, the overall length of the exhaust system can be increased.

Furthermore, the central axis of the rotating body extends forward through the gathering portion of the exhaust pipe, and the driving device is disposed at a portion protruding from the gathering portion.
It is easy to adjust the rotational position of the rotating body. In addition, since this driving device is located on the front side of the collecting portion, it is easy to receive the traveling wind, so that the cooling performance of the driving device can be improved.

Further, by extending the center axis forward, the center axis can be supported by a pair of bearings spaced apart in the vehicle longitudinal direction, so that the center axis and the rotating body can be prevented from rattling. .

According to the second aspect of the present invention, in addition to the above-described effects, the plurality of branch portions located on the front side of the collection portion of the exhaust pipe can be viewed from the front by a drive device located between these branch portions. Since it spreads right and left so as to be exposed, the traveling wind can be directly applied to the driving device, and the cooling performance can be secured without the necessity of disposing a forced cooling device. Further, by expanding the branching portion to the left and right, it is possible to increase the total length of the exhaust system.

[Brief description of the drawings]

FIG. 1 is a side view showing an arrangement state of an exhaust device according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of the exhaust device according to the first embodiment.

FIG. 3 is a cross-sectional view of the switching valve according to the first embodiment.

FIG. 4 is a side view of a front portion of the exhaust device according to the first embodiment.

5A and 5B are views showing a switching valve according to Embodiment 2 of the present invention, wherein FIG. 5A is a front view and FIG. 5B is a right side view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Two-cylinder engine (multi-cylinder internal combustion engine) 2 Exhaust pipe 2a Branch part 2b Collecting part 3,33 Switching valve 4 Low-speed exhaust pipe 5 High-speed exhaust pipe 7,34 Valve body 7a, 34a Inlet 7b, 7c , 34b, 34c, 34d Outlet 7d Exhaust passage 8 Rotating body 8a Communication passage 8b Inlet 8c Outlet 9 Drive 10 Central axis

Claims (2)

[Claims] An exhaust pipe is connected to each cylinder of a multi-cylinder internal combustion engine, and an exhaust pipe for a low rotation range and an exhaust pipe for a high rotation range are connected to the exhaust pipe via a switching valve. An exhaust device capable of switching exhaust from the multi-cylinder internal combustion engine to a low-speed or high-speed exhaust pipe, wherein the number of the exhaust pipes is equal to the number of the cylinders and is provided in each of the cylinders. A branch portion to be connected, and a collecting portion in which the respective branch portions are gathered together, wherein the switching valve is rotatably disposed on the valve body connected to the gathering portion and the valve body. A rotating body provided, and a bifurcated exhaust passage having two outlets connected to the exhaust pipe for the low rotation range or the high rotation range is formed in the valve body. The body has a cylindrical shape in which a communication passage is formed, and the valve body has a forked shape. The collecting portion and one outlet of the valve body are connected to each other through the communication passage by being rotatably disposed at a branch portion of the exhaust passage and being rotated about a cylindrical central axis. The central axis of the rotating body extends forward from the rotating body, penetrates the inside of the gathering portion, and rotates the rotating body at a portion of the central axis protruding forward of the vehicle from the gathering portion. An exhaust device for an internal combustion engine, wherein a drive device for causing the internal combustion engine to be disposed is provided. 2. A method according to claim 1, wherein the plurality of branch portions located forward of the gathering portion of the exhaust pipe are widened so that the driving device located between the branch portions is exposed when viewed from the front. The exhaust device for an internal combustion engine according to claim 1.