JPH0826788B2 - Exhaust control valve device for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control valve device applied to a vehicle in which an exhaust control valve is provided below an engine mounted near the center of a vehicle body.

(Background of the Invention) There is an engine in which an exhaust system is provided with an exhaust control valve for changing an exhaust passage area. For example, by providing this near the opening end of the exhaust pipe to the expansion chamber, the exhaust flow passage area is reduced in the rotational speed range where dynamic effects such as the inertial effect and the pulsating effect of the exhaust system act to reduce the volume efficiency. , A method for eliminating the influence of the dynamic effect and improving the output characteristics has already been proposed (Japanese Patent Application No. 60-263752). It has also been proposed to close the exhaust control valve in a multi-cylinder engine in a speed range where exhaust interference between the cylinders adversely affects (Japanese Patent Application No. 60-263753).

Further, there is also one in which an exhaust control valve is provided in order to improve the combustion by controlling the back pressure of the exhaust pipe or to use as an exhaust brake.

On the other hand, in vehicles such as motorcycles in which the engine is mounted near the center of the vehicle body, it is conceivable to arrange the exhaust control valve below the engine. In this case, the exhaust control valve is apt to be hit by a road surface obstacle, and in particular, if the drive unit for opening and closing the exhaust control valve is damaged, the opening and closing cannot be smoothly performed.

Therefore, it is conceivable to cover this drive unit with a cover to protect it from obstacles, but since the exhaust control valve is always exposed to high-temperature exhaust gas, in this case, trouble due to heat is likely to occur near the drive unit. The problem arises.

(Object of the Invention) The present invention has been made in view of such circumstances,
When the exhaust control valve is installed below the engine mounted near the center of the vehicle body, the drive unit on the exhaust control valve side is reliably protected from road surface obstacles, and the cooling performance in the vicinity of this drive unit is enhanced to improve heat. It is an object of the present invention to provide an exhaust control valve device for a vehicle that can prevent the occurrence of troubles due to the above.

According to the present invention, an object of the present invention is to provide a vehicle equipped with an engine mounted near a center of a vehicle body and an exhaust control valve arranged below the engine to change an exhaust flow passage area. A wire connected to the valve-side drive unit is extended rearward from the exhaust control valve, and a cover that covers the drive unit is fixed to the exhaust control valve, and is provided between the exhaust control valve and the cover. Is achieved by an exhaust control valve device for a vehicle, characterized in that at least a front-directed cooling air inlet and a rear-directed cooling air outlet are formed around the wire.

(Embodiment) FIG. 1 is an exploded perspective view of an embodiment of the present invention, FIG. 2 is a plan sectional view of an exhaust control valve, FIG. 3 is a left side view thereof, and FIG. FIG. 5 is a left side view showing a state, and FIG. 5 is a side view of a motorcycle using the same.

In FIG. 5, reference numeral 10 is a 4-cycle 4-cylinder engine, which is mounted near the center of the vehicle body. This engine 10
Is a cylinder 14 that extends diagonally upward and forward from the crankcase 12.
Have. 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.
An exhaust control valve (20) connected to the rear end of the exhaust pipe (16) and collecting exhaust gas from each exhaust pipe (16) and guiding it to the silencer (18).

As shown in FIG. 2, a body 22 of the exhaust control valve 20 is connected to each of the four exhaust pipes 16 and forms branch pipes 24 (24a to 24d) together with the exhaust pipes 16, and the branch pipes 24. Expansion chamber 26 in which the downstream open ends 16A to 16D of 24 and one collecting pipe section
27 and 27, which are integrally cast from stainless cast steel. Each branch end of the branch pipe portion 24 on the upstream side is connected to each exhaust pipe 16. Further, the downstream opening ends 16A to 16D of the branch pipe portion 24 have a vertically long rectangular opening shape, and the expansion chamber 26
It opens in parallel with. A connecting pipe 27 is provided in the collecting pipe portion 27.
a is integrally connected, and the muffler 18 is detachably connected to the rear end of the connecting pipe 27a by a fastener so that only the muffler 18 can be replaced.

Reference numeral 28 denotes a crank-shaped valve body, and both ends of the valve body 28 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. ing.
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. The valve shafts 28a and 28b at both ends of the valve body 28 are axially supported by bearing plates 32 and 34, respectively, and the left valve shaft 28a penetrates through the bearing plate 32 and projects outward, and the exhaust control valve 20 A pulley 36 as a drive unit on the side is fixed. The intermediate portion 30 of the valve element 28 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 exhaust pipe 16
The downstream open ends 16A to 16D are formed in an arc shape centered on the valve shafts 28a and 28b and are close to each other. The pulley 36 is rotated by a servomotor (not shown) via two Bowden wires 38, 38 in accordance with the rotation speed of the engine 10, and the exhaust control valve 20 is closed in the low and medium speed range of the engine 10, for example. Controlled to open at high speeds. Here, the Bowden wires 38, 38 extend rearward and upward from the pulley 36.

The bearing plate 32 on the left side of the exhaust control valve 20 has a wire support
40 is fastened together, and the end of the outer tube 38a of the Bowden wire 38 is attached to the wire receiver 40 via a metal wire guide 42. Ie this wire guide
42 is made relatively long, and radiates the heat transmitted from the wire receiver 40 to the outer tube 38a here to prevent overheating of the outer tube 38a. The wire guide 42 is the outer tube 38a.
It is reversely caulkedly coupled to the end portion to reduce heat transfer from the wire guide 42 to the outer tube 38a. The wire guide 42 is attached as shown in FIG. 4, and is attached to the wire receiver 40 in a freely movable manner by a stopper 42a formed on the wire guide 42 and a clip 44 attached to the annular groove 42b. This is also to reduce heat transfer.

As shown in FIG. 4, the Bowden wire 38 is
The two inner wires 38b, 38b are permanently attached and locked to the pulley 36. As described above, the other ends of the inner wires 38b, 38b are connected to the servomotor. Reference numeral 46 is a metal cover that covers the pulley 36, and is screwed to the three bosses 32a that project from the bearing plate 32. The boss 32a protrudes from the side surface of the bearing plate 32, and the cover 4
Between the mating surfaces of 6 and the bearing plate 32, a gap is formed which is directed forward and upward and downward, and the gap forms a cooling air intake 48. Further, the cover 46 surrounds a connecting portion between the wire receiver 40 and the wire guide 42 with a gap, and this gap serves as a cooling air outflow port 50 directed rearward.

In FIG. 5, 52 is a front wheel, 54 is a steering wheel,
56 is a fuel tank, 58 is a driving seat, and 60 is a rear wheel.

Therefore, when the diameter and length of the exhaust pipe 16 are set so that the engine 10 has high volume efficiency in the high speed range,
The exhaust control valve 20 is driven by a 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 20 located near the open ends 16A to 16D is closed, a positive pressure wave due to the opening of the exhaust valve will cause this exhaust control valve 20
It is reflected by and returns to the exhaust valve at the speed of sound as a positive pressure wave.
Therefore, the exhaust control valve 20 is designed to reduce the exhaust flow passage area to about 1/2 in the medium speed range where the dynamic effect works in reverse to reduce the volume efficiency.
If the control is performed, the sum of the negative pressure wave generated by the open end of the exhaust pipe and returning and the positive pressure wave reflected by the exhaust control valve 20 becomes zero. 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 20 is used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valve 20 may be closed in the rotation region where the torque reduction due to the exhaust interference is remarkable.

A running wind enters the cover 46 from a cooling air intake 48 formed between the bearing plate 32 and the cover 46, cools high-temperature parts such as the pulley 36 and the Bowden wire 38, and the cooling air outlet 50.
Is discharged from the rear. Here, the cooling air outflow port 50 has a suction effect by the traveling air passing through the outside of the cover 46, so that the cooling air inside the cover 46 is more favorably discharged. Further, at this time, the wire 38 can be favorably cooled by the high-speed cooling air discharged from the cooling air outlet 50. Since the cover 46 is made of metal, its heat dissipation is good.

In the present embodiment, the cooling air intake not only directed forward but also downward between the mating surfaces of the bearing plate 32 and the cover 46.
Since 48 is also provided, even if pebbles or muddy water enters the inside of the cover 46, it can be effectively discharged. Further, the cooling air outflow port is not limited to one directed to the upper rear as in the present embodiment, but may be one directed to the rear substantially horizontally or one directed to the lower rear.

As described above, the present invention provides the exhaust control valve with the cover that covers the drive unit on the exhaust control valve side, and directs at least the front between the surfaces of the cover and the exhaust control valve. Since the traveling wind inlet and the cooling air outlet that surrounds the wire extending rearward and is directed rearward are formed, the drive unit can be well protected from the road surface obstacle. In addition, since the traveling air flows favorably inside the cover, the drive unit and the wires are well cooled, and troubles due to heat are less likely to occur.

[Brief description of drawings]

1 is an exploded perspective view of an embodiment of the present invention, FIG. 2 is a plan sectional view of an exhaust control valve, FIG. 3 is a left side view thereof, and FIG. 4 is a left side showing a state in which a cover is also removed. A front view and FIG. 5 are side views of a motorcycle using the same. 10 …… Engine, 20 …… Exhaust control valve, 36 …… Pulley as drive unit, 38 …… Boden wire, 46 …… Cover, 48 …… Cooling air intake, 50 …… Cooling air exhaust.

Claims (1)

[Claims] 1. A vehicle equipped with an engine mounted in the vicinity of the center of a vehicle body and an exhaust control valve which is disposed below the engine and changes an exhaust flow passage area, and which is connected to a drive unit on the exhaust control valve side. While extending the wire rearward from the exhaust control valve, a cover that covers the drive unit is fixed to the exhaust control valve, and a cooling wind that directs at least forward between the surfaces of the exhaust control valve and the cover. An exhaust control valve device for a vehicle, wherein an intake port and a cooling air outflow port that surrounds the wire and is directed rearward are formed.