JPS6312824A - Exhaust control device for engine - Google Patents

Abstract

PURPOSE:To enable opening and closing of plural exhaust pipes through a single drive control device, by a method wherein valve bodies, rotated around an axis extending across a space between adjoining exhaust pipes, and moved in and out from each exhaust pipe, are situated to an exhaust control valve varying the flow passage areas of plural exhaust pipes. CONSTITUTION:An engine has plural exhaust pipes 16 (16a-16d), an exhaust control valve 18 connected to the rear end of each exhaust pipe 16, and an expansion chamber 22, through which exhaust gas is guided to a muffler 20. In this case, the exhaust control valve 18 is formed with a body 34, to which opening ends 16A-16D of each exhaust pipe 16 are open, a single valve stem 36, extending horizontally across a space between upper and lower opening ends, making a pair, and valve plates 38 (38a-38d), secured to the valve stem 36 and serving as plural valve bodies. The valve stem 36 is driven by a servo motor 44 through transmission means 40 and 42, and the servo motor 44 is controlled by a control circuit 48 based on the number of revolutions of an engine detected by means of an ignition device 46.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine exhaust control device in which exhaust control valves are provided in each of a plurality of exhaust pipes extending from an exhaust port of the engine to an expansion chamber.

(Background of the Invention) It is known that in 4-stroke engines, 2-stroke engines, etc., exhaust gas is intermittently guided into the exhaust pipe by opening and closing the exhaust valve, causing an inertial effect and a pulsation effect of the exhaust gas in the exhaust pipe. . These effects (referred to as dynamic effects) vary depending on engine speed. Therefore, if this dynamic effect is maximized to increase the volumetric efficiency at the rotational speed, the dynamic effect acts in the opposite direction at other rotational speeds, resulting in a significant decrease in the volumetric efficiency. Therefore, if the specifications of the exhaust system (exhaust pipe length, exhaust pipe system, etc.) are set so that this dynamic effect is optimal in the high speed range, the torque will be significantly reduced (torque valley) in the medium speed range. ) occurred, it was very problematic.

Therefore, an exhaust control valve that changes the area of the exhaust flow path is installed near the opening end of the exhaust pipe to the expansion chamber, reducing the flow path area in the rotation speed range where volumetric efficiency is low, and reducing the flow path area in other rotation speed ranges. It is being considered to increase the

Furthermore, in a multi-cylinder engine, if the downstream sides of the exhaust pipes are merged in an expansion chamber, the volumetric efficiency and torque may decrease due to exhaust interference between the cylinders. Therefore, it has been considered to provide an exhaust control valve for each exhaust pipe and close this control valve in a rotational speed range where the adverse effects of exhaust interference occur to reduce the exhaust flow path area.

It is also being considered to improve combustion by controlling the back pressure in the exhaust pipe, and to control exhaust components by controlling self-EGR (exhaust gas recirculation).

In this way, it is conceivable to install an exhaust control valve in the exhaust pipe to change the exhaust flow path area for various purposes such as improving volumetric efficiency, improving combustion, and controlling exhaust components. In this case, each exhaust pipe must be provided with an exhaust control valve, and if each is controlled independently, the problem arises that the control device becomes complicated.

Further, if the valve stem of each exhaust control valve becomes excessively long, a problem arises in that the valve stem expands due to heat.

(Objective of the Invention) The present invention was made in view of the above circumstances, and it is possible to simplify the control device when each exhaust control valve is provided in a plurality of exhaust pipes, and also to reduce the elongation of the valve stem due to heat. The purpose of the present invention is to provide an engine exhaust control device that can perform the following steps.

(Structure of the Invention) According to the present invention, the object is to provide a plurality of exhaust pipes each having one end connected to an exhaust port of the engine and the other end opening to an expansion chamber, and each exhaust pipe being provided with In an engine equipped with an exhaust control valve that changes a road area, the exhaust control valve includes a valve body that rotates about an axis that intersects between two adjacent exhaust pipes and that moves forward and backward into the two exhaust pipes. This is achieved by an engine exhaust control device characterized by:

(Example) Fig. 1 is a side view of an exhaust system of a motorcycle that is an embodiment of the present invention, Fig. 2 is a plan view of the same, and Fig. 3 is a side view of a motorcycle using this exhaust system. Fig. 4 is a side view of the exhaust control valve cut at the center, Figs. 5 and 6 are its v-V and Vl-Vl sectional views, and Fig. 7 is the FIG.

In FIG. 1.3, reference numeral 10 is a 4-stroke, 4-cylinder engine, which is mounted near the center of the vehicle body. This engine 10 has a cylinder 14 extending diagonally upward and forward from a crankcase 12. The exhaust system consists of four exhaust pipes 16 extending from the front of the cylinder 14 to the bottom of the crankcase 12.
(16a to 16d), an exhaust control valve 18 connected to the rear end of the exhaust pipe 16, and an expansion chamber 22 connected to the rear surface of the exhaust control valve 18 to guide exhaust gas to the muffler 20.

In FIG. 3, 24 is a front wheel, 26 is a steering handle, 28 is a rear wheel, 3o is a cover that covers an intake air cleaner and a fuel tank, and 32 is a driver's seat.

The exhaust control valve 18 is located at each open end 1 of the four exhaust pipes 16.
Pode 34 with 6A-16D arranged in a rectangular opening
and the opening end 1 forming the upper F pair of the opening ends 16A to 160.
6A, 16B and 16G, 16D, one valve shaft 36 that crosses the water pipe, and four valve plates 38 (38a to 38d) fixed to this valve shaft 36 are fixed to the valve shaft 36. Be prepared. Each valve plate 38 opens at each opening end t as the valve shaft 36 rotates.
The bottom of the hill is formed almost symmetrically so that it faces 6A to 160. That is, each valve plate 38 narrows the opening area of each opening end 16A to 160 to about 50% in its vertical position (practical position in FIG. 4.7), and in its horizontal position (in the imaginary line position in FIG. 7). Fully open the opening area.

A pulley 40 is fixed to the externally protruding end of the valve shaft 36a, and the pulley 40 is forcibly rotated in both directions by a servo motor 44 via a wire 42. This servo motor 4
4 is controlled by a control circuit 48 to close the control valve 18 in a rotation range where the volumetric efficiency deteriorates and to open it in other rotation ranges, based on the engine rotation speed detected from, for example, an ignition device 46 (see FIG. 2). Ru.

Therefore, the diameter and length of the exhaust pipe 16 are determined by the engine 10.
When the volumetric efficiency is set to be high in the high speed range, the control circuit 48 drives the servo motor 44 to close the exhaust control valve 18 in the medium speed range. Since each valve plate 38 is fixed vertically symmetrically to one valve shaft 36, the valve plates 38 are synchronously controlled to have the same opening degree.

A positive pressure wave caused by the opening of the exhaust valve of the engine 10 propagates inside the exhaust pipe 16 at the speed of sound, and a negative pressure wave generated by rapid expansion at the open ends 16A to 16D propagates through the exhaust pipe 16.
propagates in the opposite direction at the speed of sound and returns to the exhaust valve of the engine 10. If the exhaust control valve 18 located near the opening ends 16A to 16D is closed, the positive pressure wave caused by the opening of the exhaust valve is reflected by the exhaust control valve 18 and returned to the exhaust valve at the speed of sound as a positive pressure wave. . Therefore, if the exhaust control valve 18 is controlled so that the exhaust flow path area is 1/2, the negative pressure wave generated by the open end of the exhaust pipe and returned, and the exhaust control valve 18
The sum with the positive pressure wave reflected by 8 becomes zero. At this time, the pulsation effect is canceled out, and a decrease in volumetric efficiency (occurrence of torque valley) in the medium speed range can be suppressed.

Further, when this exhaust control valve 18 is used for the purpose of preventing torque reduction due to exhaust interference between cylinders, it is sufficient to close this exhaust control valve 18 in a rotation range where torque reduction due to exhaust f interference is significant. Note that when the exhaust control valve 18 is closed in a low speed range, it is possible to use an exhaust control valve 18 that reduces the exhaust flow path area by about 90% to about 10%.

Although the embodiment described below is applied to an engine 10 having four exhaust pipes 16, the present invention also includes an application to an engine having two exhaust pipes.

In this case, it is desirable that the open ends of the two exhaust pipes be located symmetrically across the valve shaft. It is preferable that the opening ends be arranged symmetrically with the valve stem in between.
The exhaust control valve 18A may be arranged asymmetrically as in the embodiment shown in FIG. 8. In FIG. 8, the same parts as in FIGS.

FIG. 9 is an exploded perspective view of an exhaust control valve 18B according to a third embodiment, FIG. 10 is a sectional view taken along the line X-X, and FIG.
It is a sectional view taken along the line XI-XIX in the figure.

In these figures, 134 is a pode, and this pode 134
The open ends 16A to 16D of the four exhaust pipes are opened so as to form a square.

Moreover, this podium 134 has an upper and lower pair of open ends 16A,
A valve body 138 is loaded that traverses between the vicinity of 16B and 16C116D. This valve body 138 is a cylinder having an outer diameter approximately equal to the center distance between the upper and lower exhaust pipes 16a, 16b, and has arc-shaped notches 138 facing each of the exhaust pipes 16a to 16d.
a to 138d are formed. A valve shaft 136 is integrally formed at one end of this valve body 138.

It rotates around an axis that crosses between the open ends of the upper and lower exhaust pipes.

This valve body 138 is inserted into the pode 134 from one side (the left side in FIG. 11) of the pode 134. At this time, the valve shaft 136 is passed through the side wall 134a on the other side (the right side in FIG. 11) of the valve shaft 134, and a pulley 142 is fixed to the protruding end of the valve shaft 136 with a collar 140 sandwiched between it and the side wall 134a. ing. Also, the valve body 138 has a pulley 1.
A stopper pin 144 is provided protruding in the radial direction near the periphery on the opposite side from 42, and this pin 144 engages with a notch 146 (FIG. 11) provided in the body 134 to stop the rotation of the valve body 138 by 90'. be regulated within the scope of

As shown in FIG. 11, appropriate lightening holes α, β, and γ are formed in the valve body 138 to reduce the weight and thermal deformation of the valve body 138.

If the number of exhaust pipes arranged across the axis of the valve body is the same as in each of the above embodiments, the exhaust pressure exerted by the exhaust to cause the valve body to rotate around the axis is canceled out. The effect of reducing the driving force of the valve body is obtained. However, the present invention also includes exhaust pipes in which the number of exhaust pipes disposed across the axis is not the same.

FIG. 12 is a cross-sectional view of an exhaust control valve 18c according to a fourth embodiment, and FIG. 13 is a cross-sectional view taken along the line 7--7. This embodiment includes a pod 234 in which the open ends of three exhaust pipes 16a to 16c are arranged in a triangular shape, and a valve body 2 inserted through the pod 234.
38, and valve shafts 236 and 236 that are formed integrally with this valve body 238 and protrude on both sides. Similarly to the third embodiment, the valve body 238 is made of a cylinder with cutouts 238a to 238C formed in the portion facing each exhaust pipe 16a to 16c.
Each valve shaft 236 has a bearing plate 240 fixed to the podium 234.
．． 242. One side of the valve shaft 236 projects outward from the bearing plate 240, and a pulley 244 is fixed thereto.

(Effects of the Invention) As described above, the present invention is provided with a valve body that rotates around an axis that intersects between two adjacent exhaust pipes and moves forward and backward within each exhaust pipe. Therefore, a plurality of exhaust percentage control valves can be controlled by a single drive stage such as a servo motor, and the control device becomes simple. Further, since the valve 1h11 is shortened, measures against elongation of the valve stem due to exhaust heat become simple or unnecessary.

[Brief explanation of the drawing]

Fig. 1 is a side view of an exhaust system for a motorcycle that is an embodiment of the present invention, Fig. 2 is a plan view of the same, Fig. 3 is a side view of a motorcycle using this exhaust system, and Fig. 4 is an exhaust A side view of the control valve taken in section at the center, Figures 5 and 6 are cross-sectional views taken along lines V-V and VT-Vl, and Figure 7 is a cross-sectional view of
■ Line sectional view, and Figure 8 is the layout diagram of the second embodiment, Figure 9 is the layout diagram of the second embodiment.
The figure is an exploded perspective view of the third embodiment, FIG. 10 is a cross-sectional view taken along line X-X, FIG. 11 is a cross-sectional view taken along line XI-X in FIG. 10, and FIG. 12 is a cross-sectional view of fourth embodiment. FIG. 13 is a cross-sectional view of the store along a single-layer line. 10... Engine, 16... Exhaust pipe, 18.18A, 18B, 18C... Exhaust control valve, 22
...Expansion chamber, 38...Valve plate as a valve body, 138.238...Valve body. Patent Applicant Yamaha Motor Co., Ltd. Attorney Yamaha 1) Fumio Figure 4 Figure 5 Figure 6 Figure 7 Figure 6 Figure 10 Figure 11 Figure 1? Figure 13 Procedural Techniques 1 Official Book (Spontaneous) 24th October 1986

Claims (3)

[Claims] (1) An engine that includes a plurality of exhaust pipes, one end of which is connected to the exhaust port of the engine and the other end of which opens into an expansion chamber, and an exhaust control valve that is provided in each of the exhaust pipes and changes the exhaust flow path area of each exhaust pipe. An engine exhaust control device, wherein the exhaust control valve includes a valve body that rotates about an axis that crosses between two adjacent exhaust pipes and moves forward and backward within the two exhaust pipes. (2) A patent claim characterized in that four exhaust pipes are arranged symmetrically around one axis, and the valve body is formed of four valve plates that rotate around the axis. The exhaust gas control device for an engine according to item 1. (3) The engine exhaust control device according to claim 1, wherein the valve body is formed of a cylinder whose portion facing each exhaust pipe is cut out in a substantially arc shape.