JPH07111137B2 - Vehicle exhaust control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exhaust control device applied to a vehicle such as a motorcycle equipped with a V-type multi-cylinder engine.

(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) are particularly effective when the exhaust pipe is set to an appropriate length corresponding to the engine speed, and this effect also changes depending on the engine rotation speed. Therefore, if the dynamic effect is maximized in the high speed region to increase the volumetric efficiency, the dynamic effect acts in the other low and medium speed regions to the contrary, and the volumetric efficiency is significantly reduced. 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 installed in this exhaust pipe to reduce the flow passage area in the low / medium speed range where volume efficiency decreases and increase the flow passage area in other high speed areas. Is being considered. In this case, it is necessary to control the exhaust passage area with high accuracy.

Further, in a multi-cylinder engine, if the downstream side of each exhaust pipe is joined in the expansion chamber, the volume efficiency and 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. In this case, it is necessary to control the exhaust passage area with high accuracy.

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 volume efficiency, improvement of combustion, and control of exhaust components. However, in vehicles such as motorcycles equipped with a V-type multi-cylinder engine, providing a separate exhaust control valve for each exhaust pipe of each cylinder leads to an increase in size of the device, including its drive device, and secures space for its installation. Becomes difficult. In particular, in the front and rear V-type engine in which the crankshaft is arranged in the vehicle width direction, the exhaust pipes of the banks forming the V-shape are connected to the expansion chamber through different routes that are far apart from each other. Become.

(Object of the invention) The present invention has been made in view of the above circumstances, and can control the exhaust flow passage area with high accuracy, downsize the exhaust control valve and its drive device, and improve their mountability. It is an object of the present invention to provide an exhaust control device for a vehicle, which does not require a separate space for mounting an exhaust control valve and does not impair the appearance.

(Structure of the Invention) According to the present invention, the object is to provide a V-type multi-cylinder engine mounted near the center of a vehicle body, a plurality of exhaust pipes connected to each cylinder of the engine, and a rear end of the engine. In a vehicle provided with one expansion chamber connected to the downstream side of each of the exhaust pipes, the downstream side of each of the exhaust pipes is extended into the expansion chamber, and each exhaust gas is attached to one body fixed in the expansion chamber. While holding each open end of the pipe close to each other, a single valve body that integrally controls the exhaust flow passage area of each open end is held in the body, and the expansion is performed according to the engine rotation speed. This is achieved by a vehicle exhaust control device characterized in that the opening degree of the valve body is controlled by a drive device provided outside the chamber.

(Embodiment) FIG. 1 is a plan view of an exhaust system for a motorcycle according to a first embodiment of the present invention, and FIG. 2 is a side view of a motorcycle using the same.
3 and 4 are sectional views taken along line III-III and line IV-IV in FIG. 1, respectively, and FIG. 5 is line V-V in FIG.
It is a line sectional view.

In FIG. 2, reference numeral 10 is a four-cycle two-cylinder V-type engine, which is mounted near the center of the vehicle body. This engine
10, a crankshaft (not shown) is arranged in the vehicle width direction,
The two banks 12 and 14 forming the V-type are divided in the front-rear direction to form a so-called front-rear V-type engine. The engine 10 is attached to the vehicle body frame 18 by the upper ends of the banks 12, 14 and the rear end of the crankcase 16.

The exhaust system of the engine 10 includes an exhaust pipe 20 that extends rearward from the front of the front bank 12 through the lower right of the crankcase 16, and extends downward from the rear of the rear bank 14 and loops to the right of the vehicle behind the engine 10. Exhaust pipe 22 that extends backward while drawing
And the expansion chamber to which the downstream sides of these exhaust pipes 20 and 22 are connected.
24 and two exhaust mufflers 26, 28. Expansion chamber
24 is located at the lower rear of the engine 10. Also exhaust muffler
26 and 28 are integrally connected to each other by a bracket 30 (see FIG. 1), and the front end of the upper muffler 26 is connected to the expansion chamber by a connecting pipe 32.
The right end of the expansion chamber 24 is directly connected to the front left side surface of the lower muffler 28 (see FIG. 3). The downstream sides of the exhaust pipes 20 and 22 extend into the expansion chamber 24 from the right front portion of the expansion chamber 24, as shown in FIG. Exhaust pipes 20 and 22 are arranged in the expansion chamber 24 in the vicinity of their open ends in parallel and adjacent to each other.
34 are provided.

The exhaust control valve 34 includes a cast body 70 having a U-shape in plan view. The body 70 is fixed to the front wall and the rear wall of the expansion chamber 24, and the open ends of the exhaust pipes 20 and 22 are retained while penetrating the body 70, and one valve body facing the open ends. A body 36 is rotatably held by bearing plates 38, 40 fixed to the front and rear end surfaces of the body 70. The intermediate portion of the valve element 36 is formed in an arcuate cross section as shown in FIG.
The open ends of 0 and 22 are cut out in an arc shape so as to closely face and oppose the intermediate portion. One end of the valve element 36 penetrates the bearing plate 38 and projects forward, and the pulley 42 is fixed to this projecting end. A wire (not shown) is wound around the pulley 42, and the pulley 42 and the valve element 36 are rotated by a driving device such as a servo motor (not shown) via the wire. As a result, the exhaust flow passage area at the downstream open ends of the exhaust pipes 20 and 22 is controlled.

In FIG. 2, 50 is a front fork, 52 is a front wheel, 54 is a handlebar, 56 is a rear wheel, 58 is a fuel tank, and 60 is an operating seat.

Next, the operation of this embodiment will be described. When the diameter and length of the exhaust pipes 20 and 22 are set so that the volumetric efficiency of the engine 10 is high in the high speed range, the exhaust control valve 34 is closed in the low and medium speed range and opened in the high speed range. It is driven by a servo motor.

The positive pressure wave due to the opening of the exhaust valve of the engine 10 propagates in the exhaust pipes 20 and 22 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end reverses the exhaust pipes 20 and 22 at the speed of sound. Propagates in the direction and returns to the exhaust valve of the engine 10. When the exhaust control valve 34 is closed, the positive pressure wave generated by opening the exhaust valve is reflected by the exhaust control valve 34 and returns to the exhaust valve as a positive pressure wave at the speed of sound. Therefore, if the exhaust control valve 34 is controlled so that the exhaust flow passage area becomes approximately 1/2 in the low and medium speed range where the dynamic effect acts in reverse, the exhaust pipes 20 and 22 generate and turn back. The negative pressure wave and the positive pressure wave reflected by the exhaust control valve 34 cancel each other out. At this time, the pulsating effect is canceled out, and a decrease in volume efficiency (occurrence of a torque valley) in the medium speed range can be suppressed.

Further, when the exhaust control valve 34 is used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valve 34 may be closed in a rotation region where the torque reduction due to the exhaust interference is remarkable.

The downstream open ends of the exhaust pipes 20 and 22 are fixed to the expansion chamber 24.
Since it is held in each body 70 and is opened and closed by one valve body 36 held in this body 70, it is possible to reduce the size and weight as compared with providing exhaust control valves for the exhaust pipes 20 and 22 separately. . Here, since the open ends of the exhaust pipes 20 and 22 and the valve body 36 are held by the common body 70, the relative positioning accuracy between them is improved, and the control accuracy of the exhaust flow passage area can be sufficiently increased. . Further, only one drive device such as a servo motor for opening and closing the exhaust control valve 34 is required, and the size and weight of the entire device can be greatly reduced.

Since the exhaust pipes 20 and 22 extend into the expansion chamber 24, the total length of the exhaust pipes 20 and 22 is sufficiently long to effectively utilize the dynamic effect of the exhaust system to increase the torque and output in the high speed range. You can

FIG. 6 is a plan view in which a part of the exhaust system of the second embodiment is sectioned,
FIG. 7 is a side view thereof, and FIG. 8 is an exploded view of the exhaust control valve 34A.

In the exhaust control valve 34A of this embodiment, the upper half of the expansion chamber 24A is a casting, and the upper half 72a of the body 72 that is divided into upper and lower parts is integrally molded therein, while the upper half 72a is formed with the lower half 72b. Is fixed from below. The exhaust pipe 20 is attached to the upper and lower halves 72a and 72b.
It holds the valve ends 36A of A and 22A and the butterfly valve. As shown in FIG. 8, the valve body 36A has an oval valve plate 7 whose width in the valve shaft 74 direction is narrower than the opening end.
Equipped with 6, 76. By moving the valve plates 76, 76 to the right side of the open end in FIG. 8 to align the valve shaft 74 with the lower surface of the upper half 72a of the body 72, and moving the valve body 36A leftward, the valve shaft 7
4 is penetrated through the wall of the expansion chamber 24A to be projected to the outside, and then the lower half 72b is mounted. And this valve shaft 7
4 is rotated by a pulley 42A.

FIG. 9 is a plan view showing a partial cross section of an essential part of the exhaust system of the third embodiment, and FIG. 10 is an explanatory view of its principle.

The exhaust control valve 34B of this embodiment includes a body 78 that holds the open ends of the exhaust pipes 20B and 22B, and a slide-type plate-shaped valve body 36B that crosses these open ends, and links the rotation of the pulley 42B. The valve body 36B is reciprocated by changing the reciprocating motion via 80. The exhaust valve 20B is located near the left end of the valve element 36B.
Of the exhaust pipe 22B.
Facing the edge of.

FIG. 11 is an exploded perspective view of the exhaust system of the fourth embodiment, FIG. 12 is an enlarged plan view in which a main portion is sectioned, and FIG. 13 is its XIII-XIII.
Line cross-sectional view, FIG. 14 is an exploded view of the exhaust control valve 34 C.

In this embodiment, the two exhaust pipes 20 C and 22 C are arranged in the expansion chamber 24 C in the vehicle body width direction, and the respective open ends are adjacent to each other in the front-rear direction. The exhaust control valve 34 C includes a central body 96 fixed to the bottom surface of the expansion chamber 24 C by welding or the like, bearing plates 98 and 100 sandwiching the central body 96 from the front and rear, and a butterfly valve type valve body held by these. With 36 C. The open ends of the exhaust pipes 20 C and 22 C are sandwiched between the central body 96 and the bearing plates 98 and 100. The valve body 36 C is provided with a valve shaft 102, 104 which are connected by a dividable joint axially near the center, and a valve plate 106 which is integrally formed on Kakubenjiku 102,104. This exhaust control valve 34
C , as shown in FIG. 14, connects the valve shafts 102 and 104 to the central body 96.
Attached is inserted from the front and rear, assembled by further fixing the bearing plate 98 and 100 in the front and rear wall of the expansion chamber 24 C. The exhaust control valve 34 C is rotated by a pulley 42 C fixed to the front end of the valve shaft 102, and both valve shafts 102, 104 and the valve plate are rotated.
106 and 108 rotate integrally.

Since the operation of the second to fourth embodiments is almost the same as that of the first embodiment, the description thereof will not be repeated.

(Effect of the invention) As described above, the present invention extends each exhaust pipe into the expansion chamber,
Since the open ends of the exhaust pipes are held adjacent to each other in one body fixed in the expansion chamber, the opening and closing of these open ends is controlled by one valve body held in this body.
The space for mounting the exhaust control valve is smaller than that in the case where an individual exhaust control valve is provided for each exhaust pipe, and only one drive unit is required. Further, since the exhaust control valve is located in the originally necessary expansion chamber, it is not necessary to separately prepare a mounting space for the exhaust control valve, and it is possible to greatly reduce the size and weight of the entire device. Furthermore, since the exhaust control valve is in the expansion chamber,
It does not spoil the appearance. Further, since the downstream opening end of each exhaust pipe and the valve body are held in the same one body, the relative positioning accuracy between them is improved, and the exhaust flow passage area can be controlled with high accuracy. In particular, the high accuracy required for utilizing the pulsation of the pressure wave of exhaust gas can be easily obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing an exhaust system of a first embodiment of the present invention, FIG. 2 is a side view of a motorcycle using the same, and FIG.
III-III line sectional drawing, FIG. 4 is a IV-IV line sectional view, and FIG. 5 is a VV sectional view in FIG. FIG. 6 is a plan view in which a part of the exhaust system of the second embodiment is sectioned,
FIG. 7 is a side view thereof, and FIG. 8 is an exploded view of the exhaust control valve 34A. FIG. 9 is a plan view of a partial cross section of an essential part of the exhaust system of the second embodiment, and FIG. 10 is an explanatory view of its principle. FIG. 11 is an exploded perspective view of the exhaust system of the fourth embodiment, FIG. 12 is an enlarged plan view in which a main portion is sectioned, and FIG. 13 is its XIII-XIII.
14 is an exploded view of the exhaust control valve 34C. 10 ... V type multi-cylinder engine, 20,20A- C , 2,22A- C ... Exhaust pipe, 24,24A- C ... Expansion chamber, 34,34A- C ... Exhaust control valve, 36,36A- C …… Valve, 70,72,78,96 …… Body.

Claims (1)

[Claims] 1. A V-type multi-cylinder engine mounted near the center of a vehicle body, a plurality of exhaust pipes connected to each cylinder of the engine, and a downstream side of each exhaust pipe arranged behind the engine. In a vehicle including one connected expansion chamber, a downstream side of each exhaust pipe is extended into the expansion chamber, and one open body of each exhaust pipe is brought close to one body fixed in the expansion chamber. On the other hand, a single valve element for integrally controlling the exhaust flow passage area at each of the opening ends is held in the body, and is held by a drive device provided outside the expansion chamber according to the engine rotation speed. An exhaust control device for a vehicle, which controls the opening of the valve body.