JPH0825508B2 - Exhaust control device for motorcycles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control device applied to a motorcycle having an exhaust control valve in the middle of an exhaust system.

(Background of the Invention) In a 4-cycle engine, a 2-cycle engine, etc., it is known that exhaust gas is intermittently guided to an exhaust pipe by opening and closing an exhaust valve, and an inertial effect and a pulsating effect of the exhaust gas are generated in the exhaust pipe. . These effects (called dynamic effects) change depending on the engine speed. Therefore, if the dynamic effect is maximized and the volumetric efficiency is increased at a certain rotation speed, the dynamic effect is adversely affected and the volumetric efficiency is significantly reduced at other rotation speeds. For this reason, when the exhaust system specifications (exhaust pipe length, exhaust pipe diameter, etc.) are set so that this dynamic effect is optimal in the high rotation range, the torque is significantly reduced in the middle speed range (torque valley). There was a problem that occurs.

Therefore, an exhaust control valve that changes the exhaust flow passage area is provided near the opening end of the exhaust pipe to the expansion chamber, and the flow passage area is reduced in the rotational speed range where the volumetric efficiency is reduced, and the flow passage area is changed in other rotational speed regions. It is considered to increase.

Further, in a multi-cylinder engine, if the downstream side of each exhaust pipe is joined in the expansion chamber, the volume efficiency and the torque may be reduced due to exhaust interference between the cylinders. Therefore, it is considered that an exhaust control valve is provided for each exhaust pipe and the exhaust flow passage area is reduced by closing this control valve in a rotational speed range where adverse effects due to exhaust interference occur.

It is also considered to improve combustion by controlling the back pressure of the exhaust pipe or to control the exhaust gas component by controlling self-EGR (exhaust gas recirculation).

Thus, it is conceivable to provide the exhaust pipe with an exhaust control valve for changing the exhaust passage area for various purposes such as improvement of volumetric efficiency, improvement of combustion, and control of exhaust components.

However, particularly in the exhaust system of a motorcycle, it is usually arranged long in the front and rear so as to extend from the front of the engine to the lower part of the engine to the rear of the vehicle body. For this reason, if a relatively heavy exhaust control valve is interposed in the middle of the process, the stability of the exhaust system is poor and vibrations tend to occur. Further, when the exhaust pipe is directly connected to the exhaust control valve, it is difficult to maintain a high relative positional accuracy between the exhaust pipe and the exhaust control valve, and there is a problem that productivity is deteriorated.

(Object of the Invention) The present invention has been made in view of such circumstances,
When an exhaust control valve is provided in the exhaust system of a motorcycle, the stability of the exhaust system is good and vibration is suppressed well, and the relative positioning accuracy between the exhaust pipe and the exhaust control valve is significantly improved, and the assemblability is also improved. An object is to provide an exhaust control device for a motorcycle.

(Constitution of the Invention) According to the present invention, an object of the present invention is to provide an exhaust control valve for an exhaust pipe that is guided from the front of an engine mounted near the center of a vehicle body or the front of an engine mounted near the center of the vehicle body to the lower side of the engine. In a motorcycle including an exhaust system connected to an exhaust muffler extending to the upper rear part of the vehicle body through an expansion chamber, the exhaust control valve includes a branch pipe part connected to the exhaust pipe and a downstream opening end of the branch pipe part. A body in which an expansion chamber opening is formed, and a wire for controlling the exhaust flow passage area corresponding to the engine rotation speed facing the downstream opening end of the branch pipe portion from the expansion chamber side. An exhaust control valve assembly having a valve body driven by a motor, wherein the upstream end of the exhaust pipe is fixed to the engine and the exhaust muffler is fixed to the upper rear part of the vehicle body. Bo The exhaust control device for a motorcycle is characterized in that the day is disposed at the lowest position of the exhaust system and is fixed to the vehicle body side.

(Embodiment) FIG. 1 is a partially sectional plan view of an exhaust control valve assembly according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II thereof.
Fig. 3 is a view from the same arrow III, Figs. 4 and 5 are sectional views taken along the line IV-IV and end views taken along the line VV in Fig. 1, and Fig. 6 is a motorcycle using this exhaust control valve. Side view of the exhaust system,
FIG. 7 is a plan view of the same, and FIG. 8 is a side view of a motorcycle using this exhaust system.

In FIGS. 6 and 8, reference numeral 10 is a 4-cycle 4-cylinder engine, which is mounted near the center of the vehicle body. The engine 10 has a cylinder 14 extending obliquely upward and forward from a crankcase 12. The exhaust system includes four exhaust pipes 16 (16a to 16d, extending from the front surface of the cylinder 14 to the lower side of the crankcase 12).
(See FIG. 7) and each exhaust pipe 16 connected to the rear end of the exhaust pipe 16.
Exhaust control valve assembly that collects the exhaust of the vehicle and guides it to the exhaust muffler 18.
With 20 and.

As shown in FIG. 1, a body 22 of the exhaust control valve assembly 20 is provided with branch pipe portions 24 (24a to 24d) which are connected to each of the four exhaust pipes 16 and form an exhaust pipe together with the exhaust pipes 16. Branch pipe section 24
The downstream side open ends 16A to 16D are provided with an expansion chamber 26 that opens and a single collecting pipe portion 28, which are integrally cast from casting stainless steel. Each branch end of the branch pipe portion 24 is formed in a circular cross section as shown in FIG. 5 and is connected to each exhaust pipe 16. Also, the downstream opening end of the branch pipe section 24
As shown in FIG. 4, 16A to 16D have a vertically long quadrangular opening shape and open in parallel with the expansion chamber 26. As shown in FIG. 5, since the branch pipe portions 24 are arranged so that the front ends thereof form an inverted trapezoid, an appropriate space is provided between the branch pipes, and the workability with the exhaust pipe 16 is improved. The silencer 18 is detachably connected to the collecting pipe portion 28.

28 is a crank-shaped valve body (Fig. 1), and this valve body 28
Both ends thereof are rotatably supported by the left and right walls of the expansion chamber 26 behind the open ends 16A to 16D, and the intermediate portion 30 is formed in an arc shape in cross section. Circular openings are formed in the left and right walls of the expansion chamber 26, and these openings are closed by bearing plates 32 and 34. Disc
Shafts 28a and 28b at both ends of 28 are axially supported by bearing plates 32 and 34, respectively, and one shaft portion 28b penetrates the bearing plate 34 and projects outward,
A pulley 36 is fixed to this protruding end. The intermediate portion 30 faces the downstream opening of the branch pipe portion 24, that is, the downstream opening ends 16A to 16D of the exhaust pipe 16. The outer peripheral surface of the intermediate portion 30 and the downstream open ends 16A to 16D of the exhaust pipe 16 are the second,
As shown in FIG. 3, they are formed in an arc shape around the center of rotation of the valve body 28 and are close to each other. An exhaust control valve 20A is formed by the valve element 28, the downstream open ends 16A to 16D, the vicinity of the center of the body 22 surrounding them, and the bearing plates 32 and 34. The pulley 36 is a servo motor (both not shown) via a wire.
The exhaust control valve 20A is rotated by the engine 10 in accordance with the rotation speed of the engine 10, and is controlled so as to close in the low and medium speed range of the engine 10 and open in the high speed range.

The exhaust system formed by the exhaust pipe 16, the exhaust control valve assembly 20, the exhaust muffler 18, etc. is formed in a substantially U shape in a side view, and the front upper end thereof, that is, the upper end of the exhaust pipe 16 is the engine.
Fixed to 10 exhaust ports. Further, the rear part of the exhaust system, that is, the exhaust muffler 18, is provided with a stay 40 fixed to the body frame 40.
It is fixed to the lower end of a (Fig. 8).

The exhaust control valve assembly 20 is mounted near the lowest position near the center of the exhaust system, that is, the body 22 is attached to the vehicle body frame 40 as shown in FIGS. That is, the body frame 40 is provided with a pair of left and right hanging parts 42 (only one is shown) extending downward along the rear part of the engine 10.
A bracket 46 is fixed to a cross member 44 connecting the 42. A link 48 and a hanging plate 50 are fastened together to the bracket 46, and a bracket 52 fixed to the body 22 is fixed to the lower end of the hanging plate 50.

In FIG. 6, 54 is a rear arm, the front end of which is pivotally supported by the hanging portion 42 of the vehicle body frame 40, and the rear wheel 56 is attached to the rear end (FIG. 8). The pivot end of the link 48 is connected to the rear arm 54 by a pair of left and right links 58, 58 (FIG. 7). A support arm 60, on which the lower end of a shock absorber (not shown) is rotatably supported, is provided at the rotating end of the link 48.

In FIG. 8, 62 is a front wheel, 64 is a steering wheel,
66 is a fuel tank and 68 is an operation seat.

Therefore, when the diameter and length of the exhaust pipe 16 are set so that the volume efficiency of the engine 10 is high in the high speed range,
The exhaust control valve 20A is driven by the servo motor so as to close in the low and medium speed range and open in the high speed range.

The positive pressure wave due to the opening of the exhaust valve of the engine 10 propagates in the exhaust pipe 16 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the opening ends 16A to 16D causes the exhaust pipe 16 to travel in the opposite direction at the speed of sound. And propagates back to the exhaust valve of the engine 10. If the exhaust control valve 20A located near the open ends 16A to 16D is closed, the positive pressure wave due to the opening of the exhaust valve causes the exhaust control valve
It is reflected at 20A and returns to the exhaust valve at the speed of sound as a positive pressure wave. Therefore, exhaust control valve 2
If 0A is controlled, the sum of the negative pressure wave generated and returned by the open end of the exhaust pipe and the positive pressure wave reflected by the exhaust control valve 20A becomes zero. At this time, the pulsating effect is canceled out, and a decrease in volumetric efficiency (occurrence of a torque valley) in the medium speed range can be suppressed.

Further, when the exhaust control valve 20A is used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valve 20A is operated in the rotation region where the torque reduction due to the exhaust interference is remarkable.
Just close. When closing the exhaust control valve 20A in the low speed range, the exhaust control valve 20A has an exhaust flow passage area of 70 to 90
It is possible to use those that are squeezed to about 30% to about 30%.

Further, in this embodiment, four exhaust pipes 16 are gathered in the expansion chamber 24, but the present invention also includes one exhaust pipe connected to the expansion chamber. In this case, the branch pipe portion is one pipe. Will be formed.

Note that the exhaust system and the engine 10 or the vehicle body frame 40 are fixed to each other by using a tensile force of a spring or via a rubber damper.

(Effects of the Invention) As described above, the present invention fixes the exhaust pipe upstream end of the front part of the exhaust system to the engine and the exhaust muffler at the rear part of the exhaust system to the upper part of the rear part of the vehicle body. The body of the exhaust control valve provided near the lower position is fixed to the vehicle body. That is, the front and rear parts of the exhaust system long in the front-rear direction are fixed to the engine and the vehicle body, while the heavy exhaust control valve is arranged near the center of the exhaust system and fixed to the vehicle body side. Therefore, the vibration of the exhaust system in the left-right direction is satisfactorily damped in the vicinity of its center, and the stability of the exhaust system is improved. Further, since the branch pipe portion and the expansion chamber on the downstream side are integrally formed in the body of the exhaust control valve, the branch pipe portion that substantially forms a part of the exhaust pipe and the exhaust control valve are The relative positioning control is improved and the assembly accuracy is also improved.

[Brief description of drawings]

FIG. 1 is a plan view in which an exhaust control valve according to an embodiment of the present invention is partially sectioned, FIG. 2 is a sectional view taken along the line II-II, FIG. 3 is a view taken along arrow III, FIG. 4 and FIG. Figure 5 shows IV-IV in Figure 1.
FIG. 6 is a side view of the exhaust system of the motorcycle using this exhaust control valve, FIG. 7 is a plan view of the same, and FIG. 8 is this exhaust system. It is a side view of a motorcycle. 10 …… Engine, 16 …… Exhaust pipe, 18 …… Exhaust muffler, 20
...... Exhaust control valve assembly, 20A ...... Exhaust control valve, 22 ...... Body, 24 ...... Branch pipe section, 26 ...... Expansion chamber, 28 ...... Valve body, 40
a …… Stays on the body frame side for fixing the exhaust muffler, 16
A, 16B, 16C, 16D …… The downstream open end of the branch pipe.

Claims (2)

[Claims] 1. An exhaust system in which an exhaust pipe, which is installed in the vicinity of the center of a vehicle body and which is guided from the front of the engine to the lower side of the engine, is connected to an exhaust muffler extending to the upper rear part of the vehicle through an exhaust control valve and an expansion chamber. In the motorcycle, the exhaust control valve includes a body in which a branch pipe part connected to the exhaust pipe and an expansion chamber having a downstream opening end of the branch pipe part are formed, and a downstream side of the branch pipe part. An exhaust control valve assembly having an opening end facing from the expansion chamber side and a valve body driven by a motor through a wire so as to control an exhaust flow passage area corresponding to an engine rotation speed, While fixing the upstream end of the exhaust pipe to the engine and the exhaust muffler to the upper rear part of the vehicle body, the body of the exhaust control valve assembly is disposed at the lowest position of the exhaust system and fixed to the vehicle body side. Featuring Exhaust control device for motorcycles. 2. The exhaust control device for a motorcycle according to claim 1, wherein the branch pipe portion and the expansion chamber are integrally formed by casting in a body of the exhaust control valve.