JP4030172B2 - Exhaust system with catalyst in internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust apparatus with a catalyst in an internal combustion engine, particularly an internal combustion engine suitable for driving a motorcycle or a tricycle.
[0002]
[Prior art]
Conventionally, a catalyst-equipped exhaust system in which a cylindrical catalyst is disposed in an exhaust system of an internal combustion engine for a motorcycle and exhaust gas from the engine is reacted and purified is known (see Japanese Patent Laid-Open No. 9-53441). )
[0003]
[Problems to be solved by the invention]
However, in the conventional exhaust system apparatus with a catalyst, the cylindrical catalyst disposed in the exhaust pipe is supported in close contact with a buffer made of glass wool or the like provided along the inner surface of the exhaust pipe. The flow of exhaust gas flowing between the catalyst and the cylindrical catalyst is hindered by the buffer, which slightly increases the flow resistance of the exhaust gas, and further reduces the contact area between the exhaust gas and the catalyst, thereby reducing the reaction of the exhaust gas. There is a problem of causing a decrease in efficiency.
[0004]
The present invention has been made in view of such circumstances, and the flow resistance of the exhaust gas flowing through the catalyst can be reduced as much as possible while supporting the cylindrical catalyst in the exhaust pipe through the buffer. An object of the present invention is to provide a catalyst-equipped exhaust system in a new internal combustion engine.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is provided with a cylindrical catalyst in an exhaust pipe connected to an exhaust port of an internal combustion engine, and the catalyst is supported by a buffer provided in the exhaust pipe. In an exhaust system device with a catalyst in an internal combustion engine, a catalyst holder having an annular buffer body is provided in an exhaust pipe, and a long diameter portion of a stay made of a hollow cylindrical body having an oblong cross section is formed on the inner peripheral surface of the buffer body . The outer peripheral surface is supported so as to be slidable in the axial direction, and the outer peripheral surface of the catalyst is fixed to the inner peripheral surface of the short diameter portion of the stay, and the inner peripheral surface of the long diameter portion and the catalyst corresponding to the long diameter portion An exhaust gas flow passage is formed between the exhaust pipe and the outer peripheral surface. According to this feature, the exhaust gas flowing through the exhaust pipe is supported while the cylindrical catalyst is slidably supported by the exhaust pipe. Without being disturbed by the buffer, the outer periphery of the catalyst has little resistance, and the circle It is possible to achieve the improvement of the reaction purification efficiency of exhaust gas by improving and catalyst of the output of the internal combustion engine flows into.
[0006]
The invention of claim 2 is characterized in that, in addition to the feature of the invention of claim 1, the exhaust pipe is covered with a heat insulation cylinder, and according to this feature, the heat insulation cylinder keeps the catalyst warm. It is possible to enhance the reaction purification performance and to suppress the diffusion of heat from the exhaust pipe to the outside.
[0007]
According to a third aspect of the invention, in addition to the feature of the second aspect of the invention, in the heat retaining cylinder, a part of the exhaust pipe is covered with a discoloration preventing cylinder, and an inner peripheral surface of the discoloration preventing cylinder is provided. Air gaps are formed between the outer peripheral surface of the exhaust pipe and between the outer peripheral surface of the same color-preventing cylinder and the inner peripheral surface of the heat retaining cylinder, and exhaust gas in the portion covered with the discoloration-preventing cylinder of the exhaust pipe. According to this feature, a part of the exhaust gas flowing through the exhaust pipe passes through the exhaust gas bypass hole and flows backward between the exhaust pipe and the heat insulation cylinder. Thus, the exhaust resistance of the exhaust gas can be reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.
[0009]
In the following description, front and rear, left and right, and top and bottom refer to the traveling direction of the motorcycle.
[0010]
First, referring to FIGS. 1 to 10, a description will be given of a first embodiment in which the apparatus of the present invention is applied to a motorcycle. FIG. 1 is a side view of a motorcycle equipped with the apparatus of the present invention, and FIG. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2, FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. 2, and FIG. 6 is a sectional view taken along line 6-6 of FIG. 5, FIG. 7 is a longitudinal sectional view of a silencer of the exhaust system, and FIG. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 7, and FIG. 10 is a cross-sectional view taken along line 10-10 in FIG.
[0011]
In FIG. 1, a traveling internal combustion engine E is mounted on a body frame F of a motorcycle. An exhaust port Pe is opened in front of the head of the internal combustion engine E, and an exhaust system EX is connected to the exhaust port Pe.
[0012]
When the internal combustion engine E is multi-cylinder, an exhaust system EX is connected to the exhaust port via an exhaust manifold.
[0013]
The exhaust system EX extends from the front of the internal combustion engine E to one side of the internal combustion engine E to the rear of the vehicle body frame F, and its rear end passes through the side of the rear wheel Wr of the motorcycle. The outlet is open to the atmosphere toward the rear. Moreover, a hanger Ha is welded to a silencer M, which will be described later, constituting the rear part of the exhaust system EX, and the silencer M, that is, the rear part of the exhaust system EX is connected to the vehicle body frame F via the hanger Ha. Suspended and supported by a fastener such as a nut.
[0014]
Next, the structure of the exhaust system EX will be described in detail mainly with reference to FIGS. 2 to 10. This exhaust system EX is a rear part of the exhaust pipe P that is integrally connected to the exhaust port Pe of the internal combustion engine E. Further, the silencer M is integrally connected.
[0015]
A cylindrical metal catalyst C, which will be described in detail later, is mounted in the exhaust pipe P. Exhaust gas discharged from the internal combustion engine E is HC, CO, After harmful components such as NOx are reacted and purified, they are released to the atmosphere through the silencer M.
[0016]
The exhaust pipe P is composed of an upstream exhaust pipe 1 and a downstream exhaust pipe 2 connected to the downstream end thereof. Upstream exhaust pipe 1 downward and is curved concavely, at its upstream end is secured is connecting flange, the connecting flange 1 _1, the exhaust port Pe which opens in front of the internal combustion engine E It is fixed to the mounting seat with a fixing tool 3 such as a bolt. The downstream end of the upstream side exhaust pipe 1 is inserted into the upstream end of the downstream side exhaust pipe 2 and is integrally connected by welding or the like. The downstream exhaust pipe 2 is configured by integrally connecting a longer downstream portion 2d to the rear end of a short upstream portion 2u by welding or the like.
[0017]
The downstream portion 2d of the downstream exhaust pipe 2 is formed in a straight shape, and a cylindrical metal catalyst C that is also formed in a straight shape is mounted therein. The metal catalyst C is to support the catalyst elements on the inner and outer surfaces of the catalyst body 9 formed in a cylindrical open ends by punching plate bored a number of small holes 9 ₁ a refractory metal plate of SUS plate or the like It is configured.
[0018]
As shown in FIGS. 2 and 3, the front portion of the cylindrical metal catalyst C is supported by the downstream exhaust pipe 2 in a fixed state via a front stay 4. The front stay 4 is constituted by a transverse surface length circular hollow cylinder, the inner peripheral surface of the minor axis portion 4 ₁ is secured by welding or the like on the front outer peripheral surface of the metal catalyst C, also the major axis the outer peripheral surface of the part 4 ₂ is fixed by welding or the like to the front inner peripheral surface of the downstream side exhaust pipe 2. Therefore, the front part of the cylindrical metal catalyst C is fixedly supported on the front part of the downstream exhaust pipe 2 via the stay 4, and an annular exhaust gas is interposed between the downstream exhaust pipe 2 and the metal catalyst C. A passage is formed.
[0019]
As shown in FIGS. 2, 5, and 6, the rear portion of the metal catalyst C is supported by the downstream exhaust pipe 2 through the catalyst holder Hc so as to be slidable in the longitudinal direction. The catalyst holder Hc is interposed in the middle of the downstream side portion 2d of the downstream side exhaust pipe 2, and is buffered in the annular gap of the short cylindrical holder case 5 formed with a larger diameter than the downstream side portion 2d. The body 6 is loaded, and an annular support cylinder 7 having the same diameter as that of the downstream portion 2d of the downstream exhaust pipe 2 is provided along the inner peripheral surface of the buffer body 6. The holder case 5 is integrally fixed by welding or the like between the front part and the rear part of the downstream part 2d of the downstream exhaust pipe 2 which are divided into the front and rear, and a plurality of the support cylinders 7 are attached to the peripheral wall. The vent hole 8 is formed so that exhaust gas can be circulated through the buffer hole 6 through the vent hole 8 to absorb and reduce the exhaust gas sound. The buffer body 6 is formed in a mesh shape with SUS wool.
[0020]
As clearly shown in FIGS. 5 and 6, the outer peripheral surface of the portion corresponding to the catalyst holder Hc at the rear end of the metal catalyst C is formed of a hollow cylinder having an elliptical cross section like the front stay 4. the inner peripheral surface of the short diameter portion 10 ₁ of the rear stays 10 are fixed by welding or the like to be, the outer peripheral surface of the diameter portion 10 ₂ of the rear stay 10 is axially on the inner peripheral surface of the support tube 7 of the catalyst holder Hc It is slidably supported on. Therefore, the rear part of the cylindrical metal catalyst C can slide in the longitudinal direction with respect to the downstream exhaust pipe 2 by the catalyst holder Hc, and expansion and contraction due to the heat of the metal catalyst C with respect to the downstream exhaust pipe 2 In addition, the metal catalyst C is bufferedly supported by the downstream exhaust pipe 2 via the buffer body 6, and the rear outer peripheral surface of the metal catalyst C and the buffer body 6 of the catalyst holder Hc are separated from each other. Thus, the exhaust gas flow passage 11 is formed. Thereby, the exhaust gas flowing through the metal catalyst C flows through the flow passage 11 with less resistance without being obstructed by the buffer body 6.
[0021]
As clearly shown in FIGS. 2 and 4, most of the downstream side exhaust pipe 2 is covered with a heat insulating cylinder 12. The heat insulating tube 12, the rear end of the front heat insulating tube 12 ₁ and the rear heat insulating tube 12 ₂ is constructed by connecting together by welding or the like, the front end by welding or the like downstream the upstream end of the exhaust pipe 2 A crushed portion 13 having a U-shaped cross-section that forms a pair with a phase difference of about 180 ° is formed at the rear end of the heat insulating cylinder 12, and the inner surface of the crushed portion 13 is downstream exhaust. The pipe 2 is in close contact with the outer peripheral surface of the rear portion, and the rear end of the heat insulating cylinder 12 is supported by the downstream exhaust pipe 2.
[0022]
Thus, the heat retaining cylinder 12 retains the metal catalyst C to improve its reaction purification performance, and suppresses the heat from the exhaust pipe P from being radiated to the outside, and heat to the outer cylinder 18 of the silencer M, which will be described later. Helps reduce harm.
[0023]
As shown in FIG. 2, a short hollow cylindrical discoloration preventing cylinder 15 is fixed to the upstream portion 2u of the downstream exhaust pipe 2 by welding or the like. The discoloration preventing cylinder 15 is interposed between the downstream exhaust pipe 2 and the heat retaining cylinder 12, and a gap is formed between them. An exhaust gas bypass hole 16 made up of a plurality of small holes is formed in a portion of the downstream exhaust pipe 2 covered with the discoloration prevention cylinder 15 at intervals in the circumferential direction. A part of the exhaust gas flowing from the internal combustion engine E through the upstream exhaust pipe 1 and the downstream exhaust pipe 2 bypasses the downstream exhaust pipe 2 and the heat retaining cylinder 12 backward through the exhaust gas bypass hole 16. As a result, the exhaust resistance of the exhaust gas is reduced, thereby contributing to an increase in the output of the internal combustion engine E, in particular, an increase in the output in the low speed operation region.
[0024]
The downstream exhaust pipe 2 and the heat retaining cylinder 12 are inserted into the silencer M constituting the latter half of the exhaust system EX from the inlet side, and the inlet end of the silencer M is the front heat retaining cylinder 12 _1. The downstream portion 2d of the downstream side exhaust pipe 2 extends to the middle of the silencer M.
[0025]
As shown in FIGS. 7 and 8, the outer cylinder 18 of the silencer M has a truncated conical front outer cylinder 18 f that expands toward the rear and a cylindrical shape fixed to the rear end thereof by welding or the like. The rear outer cylinder 18r is configured. An inner cylinder 19 is provided in the rear outer cylinder 18r with an annular gap. The inner cylinder 19 is partitioned into a first chamber 23, a second chamber 24, and a third chamber 25 by a first partition wall 20, a second partition wall 21, and a rear wall 19 ₁ of the inner cylinder 19. The chamber 23 and the third chamber 25 are connected to each other by a first communication pipe 26 that is bridge-connected between the first partition wall 20 and the second partition wall 21, and the third chamber 25 and the second chamber 24 are connected to the second partition wall. 21 to communicate with each other by the second communicating pipe 27 that is cantilevered, further third communication pipe with the atmosphere the second chamber 24 is bridged supported between the rear wall 18 ₁ of the second partition wall 21 and the outer cylinder 18 28.
[0026]
The exhaust gas reacted and purified from the downstream exhaust pipe 2 through the metal catalyst C flows into the silencer M, where it enters the third chamber 25 from the first chamber 23 through the first communication pipe 26. The third chamber 25 enters the second chamber 24 through the second communication pipe 27 and is further released from the second chamber 24 through the third communication pipe 28 to the atmosphere. During this time, the exhaust gas flows through the first, third and second chambers 23, 25 and 24 in the silencer M while repeating expansion and contraction in the silencer M, and is effectively reduced in sound. Released.
[0027]
Next, the operation of the first embodiment will be described. Exhaust gas generated by the operation of the internal combustion engine E now flows from the exhaust port Pe to the downstream exhaust pipe 2 via the upstream exhaust pipe 1, and the downstream exhaust. The tubular metal catalyst C provided in the pipe 2 reacts and removes harmful components contained therein, and then flows to the silencer M, where the sound is reduced and released to the atmosphere.
[0028]
By the way, the metal catalyst C and the buffer body 6 of the catalyst holder Hc that supports this in a buffering manner are separated from each other and an exhaust gas flow passage 11 is formed between them, so that the exhaust gas flowing outside the metal catalyst C is It is not disturbed by the buffer body 6 and flows smoothly without disturbing the flow, thereby reducing exhaust resistance and contributing to improving the output of the internal combustion engine E, as well as contact between the exhaust gas and the metal catalyst C. The exhaust gas purification efficiency by the catalyst C can be increased by increasing the area.
[0029]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0030]
FIG. 11 is a cross-sectional view of the catalyst mounting portion of the exhaust system, and FIG. 12 is a cross-sectional view taken along the line 12-12 in FIG. 11. The same members as those in the first embodiment are denoted by the same reference numerals. The
[0031]
In the second embodiment, the structure of the catalyst holder Hc is different from that of the first embodiment, and the catalyst holder Hc includes a holder case 5 and a buffer body 6 loaded in the holder case 5. The inner surface of the buffer body 6 is in direct contact with the outer peripheral surface of the rear stay 10 having an elliptical cross section fixed to the metal catalyst C in the downstream side exhaust pipe 2, and is slidable in the axial direction thereof. It is supported. In the second embodiment, the support cylinder of the first embodiment is omitted.
[0032]
By the way, the rear part of the cylindrical metal catalyst C is also supported by the buffer body 6 of the catalyst holder Hc so as to be slidable in the axial direction, and the metal catalyst C is separated from the buffer body 6. The exhaust gas flow passage 11 can be formed between them, and the same effect as that of the first embodiment can be obtained, and the number of parts can be reduced by omitting the support cylinder (first embodiment). As a result, the cost of the exhaust system can be reduced.
[0033]
As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention. For example, in the above-described embodiment, the case where the apparatus of the present invention is implemented in the exhaust system of an internal combustion engine for a motorcycle has been described. However, this may be implemented in the exhaust system of an internal combustion engine for another vehicle or other equipment. In the above-described embodiment, the case where the metal catalyst C is used as the cylindrical catalyst has been described. However, instead of the metal catalyst C, another non-metallic catalyst may be used. Furthermore, in the said Example, although SUS wool is used as a buffer, it may change to this and may use another conventionally well-known buffer.
[0034]
【The invention's effect】
As described above, according to the present invention, in the exhaust system with a catalyst, the exhaust pipe is provided with the catalyst holder provided with the annular buffer body, and the hollow cylinder having an elliptical cross section is formed on the inner peripheral surface of the buffer body. And supporting the outer peripheral surface of the long diameter portion of the stay slidably in the axial direction, and fixing the outer peripheral surface of the catalyst to the inner peripheral surface of the short diameter portion of the stay, and the inner peripheral surface of the long diameter portion, Since the exhaust gas flow passage is formed between the catalyst and the outer peripheral surface corresponding to the long diameter portion , the exhaust gas flowing in the exhaust pipe is not obstructed by the buffer supporting the catalyst, and the outer periphery of the catalyst has less resistance. It can flow smoothly to reduce exhaust resistance, improve the output of the internal combustion engine, and improve the reaction purification efficiency of the exhaust gas by the catalyst.
[0035]
In particular, according to the invention of claim 2, since the exhaust pipe is covered with the heat insulation cylinder, the catalyst is kept warm by the heat insulation cylinder to improve its reaction purification performance and to suppress the diffusion of heat from the exhaust pipe to the outside. Is possible.
[0036]
In particular, according to the invention of claim 3, in the heat retaining cylinder, a part of the exhaust pipe is covered with the discoloration preventing cylinder, and between the inner peripheral surface of the discoloration preventing cylinder and the outer peripheral surface of the exhaust pipe, and Air gaps are formed between the outer peripheral surface of the same discoloration prevention cylinder and the inner peripheral surface of the heat insulation cylinder, and an exhaust gas bypass hole is provided in a portion of the exhaust pipe covered with the discoloration prevention cylinder. Part of the flowing exhaust gas flows through the exhaust gas bypass hole and bypasses the space between the exhaust pipe and the heat insulation cylinder to the rear, thereby reducing the exhaust resistance of the exhaust gas.
[Brief description of the drawings]
FIG. 1 is a side view of a motorcycle equipped with the device of the present invention. FIG. 2 is a longitudinal sectional view of a catalyst mounting portion of an exhaust system. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2 is an enlarged sectional view taken along line 4-4 [FIG. 5] An enlarged sectional view taken along line 5-5 in FIG. 2 [FIG. 6] A sectional view taken along line 6-6 in FIG. FIG. 8 is a sectional view taken along line 8-8 in FIG. 7. FIG. 9 is a sectional view taken along line 9-9 in FIG. 7. FIG. 10 is a sectional view taken along line 10-10 in FIG. 11 is a cross-sectional view of a catalyst mounting portion of an exhaust system. FIG. 12 is a cross-sectional view taken along the line 12-12 in FIG.
6 ... Buffer 10 ... Stay (rear stay)
10 ₁ ・ ・ Short diameter part
10 ₂ ..Long diameter part 11 ... Flow passage
12 ... Insulation tube
15 ... Discoloration prevention cylinder
16 ... exhaust gas bypass hole C ... catalyst (metal catalyst)
E ... Internal combustion engine Hc ... Catalyst holder P ... Exhaust pipe Pe ... Exhaust port

Claims (3)

Exhaust pipe connected to an exhaust port of an internal combustion engine (E) (Pe) of the circular cylindrical catalyst in (P) (C) provided, cushion provided with the catalyst (C) in the exhaust pipe (P) ( In the exhaust system with catalyst in the internal combustion engine, which is supported by 6),
A catalyst holder (Hc) provided with an annular buffer (6) is provided in the exhaust pipe (P), and a stay (10) made of a hollow cylinder having an elliptical cross section is formed on the inner peripheral surface of the buffer (6). diameter section outer peripheral surface (10 ₂₎ with axially slidably supported in), fixed to the outer peripheral surface of the catalyst (C) on the inner peripheral surface of the short diameter portion of the stay (10) (10 ₁₎ Te, and the inner peripheral surface of the major diameter portion (10 _2), and characterized by forming flow passage of the exhaust gas (11) between the outer peripheral surface of the catalyst (C) corresponding to the major diameter portion (10 ₂₎ An exhaust system with a catalyst in an internal combustion engine. The exhaust system with a catalyst in an internal combustion engine according to claim 1, wherein the exhaust pipe (P) is covered with a heat insulating cylinder (12). In the heat retaining cylinder (12), a part of the exhaust pipe (P) is covered with the discoloration preventing cylinder (15), and the inner peripheral surface of the discoloration preventing cylinder (15) and the outer peripheral surface of the exhaust pipe (P). And between the outer peripheral surface of the anti-discoloration cylinder (15) and the inner peripheral surface of the heat retaining cylinder (12),
The exhaust system with a catalyst in an internal combustion engine according to claim 2, wherein an exhaust gas bypass hole (16) is provided in a portion of the exhaust pipe (P) covered with the discoloration prevention cylinder (15).

Images