JPH0735717U - Engine exhaust system - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the operation failure and function deterioration due to carbon deposition of the on-off valve provided in the engine exhaust system, and to promote the purification of exhaust gas. [Configuration] A noble metal catalyst 53 is supported on at least a part of the valve body 48.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust system for an engine having an on-off valve that controls exhaust.

[0002]

[Prior art]

 Conventionally, there is known an engine in which an opening / closing valve is provided in the exhaust system in order to change the output characteristic and the exhaust gas characteristic of the engine. Has a chamber provided in the middle of an exhaust pipe connected to an exhaust hole of an engine, rotatably pivotally mounts a butterfly valve having a gap around the chamber, and opens and closes by interlocking the butterfly valve with a throttle valve. Is done.

[0003]

[Problems to be solved]

 However, carbon in the exhaust gas is apt to adhere to the on-off valve provided in the exhaust pipe as described above, and as a result, the valve sticks and fails to operate, or the gap between the valve body and the exhaust pipe inner wall surface is increased. The clearance will change and the valve will not function properly.

[0004]

[Means and Actions for Solving the Problems]

 The present invention has been made in view of such circumstances. In the present invention, an exhaust gas of an engine equipped with an on-off valve provided in an exhaust passage communicating with an exhaust port of an engine and having an opening area of the passage variable is provided. In the apparatus, a noble metal catalyst is supported on at least a part of the valve body of the on-off valve.

According to the present invention, the catalytic action of the noble metal catalyst raises the temperature in the vicinity of the on-off valve, making it difficult for carbon to adhere to the valve, thus preventing the above-mentioned malfunction or malfunction of the valve. .

Further, since the unburned substances in the exhaust gas are burned by the catalytic action, the exhaust gas is purified.

[0007]

【Example】

 FIG. 1 is an overall side view of a motorcycle 1 equipped with an exhaust device according to the present invention. Reference numeral 2 denotes a vehicle body frame, which includes a main frame 4 extending obliquely downward and rearward from a head pipe 3 above the front portion, a rear frame 5 extending obliquely upward and rearward from a lower rear portion of the main frame 4, and an intermediate portion of the main frame 4. It is composed of a seat rail 6 and the like, which extends rearward and whose rear end is connected to the rear portion of the rear frame 5.

At the front of the vehicle body, a front fork 8 pivotally supported by the head pipe 3 and rotated by a handle 7 extends vertically, and a front wheel 9 is pivotally supported at the lower end thereof. A rear fork 11 is pivotally supported vertically on a lower end of the rear of the main frame 4 via a pivot shaft 10, and a rear wheel 12 is pivotally supported on a rear end of the main frame 4 via a rear axle 13. Reference numeral 14 is a rear cushion provided between the rear fork 11 and the seat rail 6. An engine 15 is suspended and mounted on the main frame 4 between the front wheels 9 and the rear wheels 12. Then, a drive chain 19 is stretched between a drive sprocket 17 provided on the output shaft 16 of the engine 15 and a driven spoket rocket 18 provided on the rear axle 13, and the rear wheels 12 are passed through the drive chain 19. Driven by the engine 15.

The outside of the vehicle body is covered with a cowling 20 from its front surface to both side surfaces, and its rear portion is covered with a rear vehicle body cover 21. 22 is a fuel tank, 23 is a seat, and 24 is a radiator arranged in front of the engine 15.

The engine 15 is a two-cycle engine, and an intake system 26 having a carburetor 25 communicates with a crankcase in a crankcase 27. The exhaust system 29 connected to the exhaust port of the cylinder 28 descends in front of the engine 15 and then bends to extend below the engine 15 to the rear, and then extends diagonally upward to the side of the rear wheel 12, It opens toward the rear of the vehicle. The exhaust system 29 is formed by sequentially connecting an expansion pipe 31, a connection pipe 32, a silencer 33, and a discharge pipe 34 to an exhaust pipe 30 extending from a cylinder 28.

FIG. 2 is an enlarged view of only the exhaust system 29 of FIG. 1, and FIGS. 3 to 5 are sectional views of respective portions thereof. As shown in FIG. 2, a catalytic converter 35 for purifying exhaust gas is provided in the expansion pipe 31, and secondary air for assisting the catalytic reaction of the catalytic converter 35 is further provided in the exhaust pipe 30. The exhaust gas is added from the secondary air supply pipe 36 on the upstream side and in the vicinity of the cylinder exhaust port. The secondary air supply pipe 36 is attached to the exhaust pipe 30 by a flange 37 (see FIG. 3), and also has a reed valve 38 at the upstream air intake so that when the inside of the exhaust pipe 30 becomes a negative pressure, the lead is supplied. The valve 38 is opened, and external air is introduced as secondary air into the exhaust pipe 30 via the secondary air supply pipe 36.

The exhaust pipe 30 has a double pipe structure including an inner pipe 39 and an outer pipe 40. The inner tube 39 and the outer tube 40 are separated from each other by spacers 41 inserted in places, and the spacers 41 are made of a stainless steel mesh body and have excellent heat insulating properties and vibration damping properties. It is possible to effectively prevent the high temperature of the exhaust gas from being transmitted to the outer pipe 40 and causing the outer pipe 40 to vibrate and cause noise due to the vibration of the exhaust gas.

The exhaust pipe 30 is divided into an upstream side portion 30a and a downstream side portion 30b, and a valve chamber 42 is formed at a connecting portion between these two portions 30a and 30b. FIG. 6 is a partially enlarged view of the valve chamber 42 portion. The valve chamber 42 is fixed to the end portion of the exhaust pipe portion 30a on the upstream side, and the flange 43 is formed on the end surface opposite to the portion 30a. Then, the flange 43 fixed to the exhaust pipe portion 30b on the downstream side is brought into contact with the flange 43, and the exhaust pipe portions 30a and 30b are connected by fastening them with a bolt 45.

An opening / closing valve 46 is provided in the valve chamber 42. The on-off valve 46 is for varying the opening area of the exhaust passage, and includes a rotatable valve shaft 47 penetrating the valve chamber 42 in the diameter direction, and a disc-shaped valve shaft fixed to the valve shaft 47. It is a butterfly valve composed of a valve element 48 and is urged in a direction to fully close the exhaust passage as shown.

A pulley 49 is fixed to one end of the valve shaft 47 protruding from the valve chamber 42 to the outside (see FIG. 7). A wire 50 is wound around the pulley 49 and the end is fixed to the pulley 49. There is. The wire 50 is passed through a sleeve 52 having one end fixed to a bracket 51 fastened to the flange 43 by the bolt 45. As shown in FIG. 1, the sleeve 52 extends to the vaporizer 25, and the other end is fixed in the vicinity thereof. The other end of the wire 50 is connected to a throttle valve (not shown) provided in the carburetor 25. Therefore, the on-off valve 46 changes the exhaust passage area in conjunction with the throttle valve, and changes the output endurance and exhaust endurance of the engine according to the throttle valve opening.

By the way, carbon in the exhaust gas is apt to adhere to the valve body 48 exposed to the exhaust gas. Particularly, when such carbon adheres to the outer peripheral portion of the valve body 48, the carbon is separated from the inner wall surface of the valve chamber 42. The interference may impede the operation of the valve body 48, or the clearance between the outer peripheral edge of the valve body and the inner wall surface may be changed to prevent accurate control.

In order to prevent this, the outer periphery of the valve body 48 is coated with a precious metal catalyst 53. In this way, the catalytic action of the noble metal catalyst 53 carried on the outer peripheral portion of the valve body 48 promotes the combustion of the unburned components in the exhaust gas passing therethrough, so that the temperature of the outer peripheral portion rises, Carbon no longer adheres.

Further, along with this, the exhaust gas itself is also purified. That is, the noble metal catalyst 53 exerts the effect of purifying exhaust gas in addition to the effect of preventing the function of the on-off valve 46 from being deteriorated.

Although the noble metal catalyst 53 is supported only on the outer peripheral portion of the valve body 48 in the above embodiment, the noble metal catalyst 53 may be supported on the entire surface of the valve body 48. In this way, the exhaust gas purification effect is increased.

8 to 10 show another embodiment of the present invention. In these figures, the same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The valve body 54 of the on-off valve 46 in the present embodiment has a three-dimensional outer circumference in which a plurality of discs 55, 55 having different diameters are arranged in parallel with each other at a predetermined interval, and the peripheral edges of the discs 55 are connected. The surface 56 is assembled so that it forms a spherical surface. As shown in FIGS. 8 and 9, the valve body 54 is in a fully closed state when the disk 55 is perpendicular to the axis of the exhaust pipe 30, that is, the flow direction a of the exhaust gas. As shown in FIG. 10, the exhaust pipe 30 is fully opened when the disc 54 is rotated to a position where the discs 55 are parallel to the flow direction a. That is, when fully opened, the exhaust gas passes between the discs 55 along the discs 55.

In this valve body 54, the noble metal catalyst 53 is carried on both front and back surfaces of each disk 55. Since the exhaust gas flows along each disk 55 as described above, a good contact state is maintained between the exhaust gas and the noble metal catalyst 53, and the exhaust gas purification effect by the catalytic action is further improved.

[0023]

[Effect of device]

 ADVANTAGE OF THE INVENTION According to this invention, while preventing the operation | movement obstacle and functional decline by carbon attachment of the on-off valve provided in the exhaust system of an engine, it can promote purification of exhaust gas.

[Brief description of drawings]

FIG. 1 is an overall side view of a motorcycle including an exhaust device according to the present invention.

FIG. 2 is an enlarged view of only the exhaust system of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a partially enlarged view of FIG.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a view similar to FIG. 6 showing another embodiment of the present invention.

FIG. 9 is a perspective view showing a fully closed state of the on-off valve of the embodiment.

FIG. 10 is a perspective view showing a fully opened state of the on-off valve.

[Explanation of symbols]

1 ... Motorcycle, 2 ... Body frame, 3 ... Head pipe, 4 ... Main frame, 5 ... Rear frame, 6 ... Seat rail, 7 ... Handle, 8 ... Front fork, 9 ...
Front wheel, 10 ... pivot shaft, 11 ... rear fork, 12 ... rear wheel,
13 ... rear axle, 14 ... rear cushion, 15 ... engine, 16 ...
Output shaft, 17 ... Drive sprocket, 18 ... Driven sprocket rocket, 19 ... Drive chain, 20 ... Cowling, 21 ... Rear body cover, 22 ... Fuel tank, 23 ... Seat, 24 ... Radiator, 25 ... Vaporizer, 26 ... Intake System, 27 ... Crank case, 28
... Cylinder, 29 ... Exhaust system, 30 ... Exhaust pipe, 31 ... Expansion pipe, 32
... Connection pipe, 33 ... Silencer, 34 ... Exhaust pipe, 35 ... Catalytic converter, 36 ... Secondary air supply pipe, 37 ... Flange, 38 ... Reed valve, 39 ... Inner pipe, 40 ... Outer pipe, 41 ... Spacer, 42 ... valve chamber,
43, 44 ... Flange, 45 ... Bolt, 46 ... Open / close valve, 47 ... Valve shaft, 48 ... Valve body, 49 ... Pulley, 50 ... Wire, 51 ... Bracket, 52 ... Trouser, 53 ... Precious metal catalyst, 54 ... Valve Body, 55 ... disk,
56 ... Outer surface.

Claims (1)

[Scope of utility model registration request] 1. An exhaust system for an engine, comprising an opening / closing valve provided in an exhaust passage communicating with an exhaust port of an engine, the opening area of the passage being variable, wherein a precious metal catalyst is provided on at least a part of a valve body of the opening / closing valve. An exhaust system for an engine, which is carried.