ITTO20060013A1 - EXHAUST SYSTEM FOR VEHICLE. - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

"Exhaust system for vehicle"

DESCRIPTION

The present invention relates to an exhaust system for a vehicle which comprises a catalytic converter.

In general, exhaust systems for motorcycles are known which comprise a silencer connected to an exhaust duct extending from an engine (refer, for example, to the Japanese patent published No. Hei 6-10,659). In this type of vehicle exhaust systems, a system of the type has been proposed in which a rear portion of the exhaust duct is inserted within the silencer, and the rear portion of the exhaust duct increases in diameter towards the rear at the aim to improve engine performance. In the traditional exhaust system mentioned above, a catalytic converter comprises a catalyst chamber, an introduction duct for feeding the exhaust gas into the catalyst chamber is connected to a first end side of the catalyst chamber, and an outlet duct for venting the exhaust gas from the catalyst chamber is connected to the other end side of the catalyst chamber.

However, when the catalytic converter is connected in series on the rearward extending exhaust duct, the exhaust duct is long in the front-to-rear direction, and it becomes difficult to compact the assembly.

Furthermore, in this configuration, it is impossible to achieve a diversification of the arrangement of the catalytic converter. For example, in the case where the catalytic converter is connected to an intermediate portion on the line of the exhaust pipe which extends in a given direction so that the catalytic converter is orthogonal to the direction of extension of the exhaust pipe, the traditional configuration is characterized in that the outlet duct of the catalytic converter moves away from the line of the exhaust duct which extends in the given direction and exits on the other end side of the catalytic converter. In this case, the outlet duct of the catalytic converter must be brought back to the line of the exhaust duct extending in the given direction, and, for this purpose, the exhaust duct must be arranged in a complicated shape, for example an approximately shape U-shaped

Furthermore, in the case where a catalyst is arranged in a silencer as in the prior art, the activation of the catalyst is delayed in the cold running condition of the engine immediately after the start of operation.

Accordingly, an object of the present invention is to solve the aforementioned problems encountered in the prior art and to provide an exhaust system for a vehicle by which it is possible to achieve a diversification of the arrangement of a catalytic converter and to accelerate the activation of a catalyst in the cold running condition of the engine.

The present invention is characterized in that, in an exhaust system for a vehicle which includes a silencer connected to an exhaust duct extending from an engine, a catalytic converter is arranged on an intermediate portion of the exhaust duct and / or in the muffler, and the catalytic converter has a configuration in which an inlet and an outlet duct for feeding an exhaust gas into and out of a catalyst chamber are collectively arranged on a single end side of the catalytic converter .

In the present invention, the inlet duct and the exhaust gas outlet duct are collectively arranged on a single end side of the catalyst chamber, so that the inlet duct and the outlet duct of the catalytic converter can be easily connected. to the exhaust duct without having to arrange the exhaust duct in a complicated shape, even if the catalytic converter is connected, for example, in a condition in which it is orthogonal to the direction of extension of the exhaust duct.

Thus, the ease in connecting the pipelines increases, and it is possible to achieve a diversification of the arrangement of the catalyst.

Furthermore, when the catalytic converter is integrated with the silencer, the diameter of the silencer can be kept substantially at the same value as a traditional silencer, and an increase in the size of the silencer is limited.

In this case, the catalyst chamber may comprise a first catalyst chamber in communication with the introduction duct, and a second catalyst chamber in communication with the outlet duct, and the first and second catalyst chambers can be placed in communicating with each other on the other end side of the catalyst chamber.

The catalytic converter can comprise an outer tube and an inner tube; and the first catalyst chamber can be internally provided with a first catalyst body surrounded by the inner tube, the second catalyst chamber can be internally provided with a second catalyst body surrounded by the inner tube and the outer tube, each of the catalyst bodies can be formed by wrapping a flat sheet and a corrugated sheet in a stratified condition, and, in each of the areas between the flat sheet and the corrugated sheet in each of the catalyst bodies, between the catalyst body and the inner tube, and between the body catalyst and the outer tube, it is possible to braze a joint region arranged on the outlet side in the direction of the exhaust gas outlet in the axial direction of each of the catalyst bodies.

Furthermore, in an exhaust system for a vehicle that includes a silencer connected to an exhaust duct extending from an engine, a catalytic converter may be disposed on an intermediate portion of the exhaust duct and / or in the muffler, and the converter catalytic can comprise a catalyst body having a honeycomb shape and can have a configuration in which an exhaust gas entering the catalyst body through an introducing duct can pass through pores in a first part of the honeycomb structure and also through pores in another part of the honeycomb structure, before reaching an outlet duct. The catalyst body having a honeycomb shape can be formed by wrapping a flat sheet and a corrugated sheet in a stratified condition, and, between the flat sheet and the corrugated sheet in correspondence with the pores in the first part, it is It is possible to braze only a joint region arranged on the outlet side in the direction of the exhaust gas outlet in the axial direction of the pores in the first part, while, between the flat sheet and the corrugated sheet in correspondence with the pores in the other part, it is possible brazing a joint region disposed on the outlet side in the exhaust gas outlet direction in the axial direction of the pores in the other part. Furthermore, the pores in the first or other part of the honeycomb structure may be pores in a central portion of the honeycomb structure, and the pores in the other or first part of the honeycomb structure. bee may be pores in a peripheral portion of the honeycomb structure.

Since the catalyst body having a honeycomb shape is used and the configuration is adopted in which the exhaust gas entering the catalyst body through the introduction duct passes through pores in a first part of the honeycomb structure and even through pores in another part of the honeycomb structure before reaching the outlet duct, a separation between the pores in a first part and the pores in another part is not necessary, and they are obtained with a configuration simple back and forth steps for the exhaust.

The catalytic converter connected to the exhaust line can be placed directly under the engine. According to this configuration, it is possible to arrange the catalytic converter using the space directly under the engine, i.e. the so-called dead zone, so that it is possible to obtain an improvement in the efficiency in the use of space, and it is possible to obtain a rationalization of the balancing of the vehicle weight. Furthermore, since the catalytic converter is located in the vicinity of the engine, the activation of the catalyst is accelerated by the heat developed by the engine located close to the catalytic converter even in the cold running condition of the engine after the start of operation.

In addition, the catalytic converter can be arranged on the front side of a footrest for the driver. With this arrangement, it is possible to achieve efficient utilization of the space on the front side of the footrest for the driver, and it is possible to achieve a rationalization of the vehicle weight balance.

The catalytic converter can be arranged inside a shield in the vehicle width direction. The heat developed by the engine is liable to accumulate inside the shield in the direction of the vehicle's width. In this configuration, in the condition after the engine is started but before the start of travel, the temperature inside the shield in the vehicle width direction increases in a short period of time, and the heating of the catalytic converter produced by this heat accelerates the activation of the catalytic converter.

Furthermore, it is possible to obtain an efficient utilization of the space inside the shield in the direction of the width of the vehicle, and it is possible to obtain a rationalization of the balance of the vehicle weight. An exhaust duct protection member may be disposed between an outlet duct of the catalytic converter and the exhaust duct. In this configuration, the open side of the exhaust duct is covered by the protective element, whereby the aesthetic quality is improved.

In the present invention, the introduction duct and the outlet duct for supplying the exhaust gas into and for exiting the catalyst chamber are collectively arranged on a single end side of the catalyst chamber, so that, even in the case wherein the catalytic converter is connected, for example, in an orientation in which it is orthogonal to the direction of extension of the exhaust duct, the introduction duct and the outlet duct of the catalytic converter can be easily connected to the exhaust duct without having to arrange the exhaust duct in a complicated form. Thus, the ease of connecting the pipelines increases, and a diversification of the arrangement of the catalytic converter is possible.

Furthermore, in the event that the catalytic converter is integrated in the silencer, the diameter of the silencer can be reduced substantially to the same value as a traditional silencer, and it is possible to limit an increase in the size of the silencer.

Furthermore, the catalytic converter can be easily arranged in a confined space, for example in the vicinity of the engine of a motorcycle or the like. This ensures that the catalyst activation is accelerated by the heat developed by the engine placed near the catalyst even in the cold running condition of the engine immediately after the start of operation.

An embodiment of the present invention will now be described below with reference to the attached drawings.

Figure 1 represents a side view of a vehicle according to an embodiment of the present invention.

Figure 2 is a bottom view of the vehicle illustrated in Figure 1.

Figure 3 represents a side view thereof. Figure 4 represents a structural view of a catalytic converter.

Figure 5 is a sectional view thereof.

Figure 6 represents a structural view of a catalytic converter showing another embodiment.

Figure 7 represents a structural view of a catalytic converter showing another embodiment.

Figure 8 represents a structural view of a catalytic converter showing a further embodiment.

Figure 9 represents a structural view of a catalytic converter showing yet another embodiment.

Figure 10 represents a structural view of a catalytic converter showing yet another embodiment.

Figure HA represents a sectional view showing a junction portion between a catalyst body and a connecting duct, Figure 11B represents a plan view showing a sealing element, and Figure 11C represents a view to illustrate the dimension sealing element.

Figure 12 represents a structural view of a catalytic converter showing yet another embodiment.

Figure 13A represents a sectional view along the P - P line of Figure 12, and Figure 13B represents a sectional view along the Q - Q line of Figure 12.

Figure 14 represents a structural view of a catalytic converter showing yet another embodiment.

Figure 15 is a sectional view thereof.

Figures 16A and 16B respectively represent a structural view and a sectional view showing yet another embodiment.

Figure 17 represents a view showing a flat sheet and a corrugated sheet.

Figure 18 represents a structural view showing yet another embodiment.

In figure 1, the symbol 1 indicates a motorcycle (vehicle), in which a front portion of a molded frame 7 is covered with a coating 2. A front fork 5 for supporting a front wheel 4 is supported by a head tube 3 arranged in the front portion of the molded frame 7.

Furthermore, an engine 6 is mounted at an intermediate lower portion of the liner 2, the molded frame 7 is externally connected to the rear side of the liner 2, with a fuel tank and the like (not shown) disposed therein, and a saddle 8 is arranged on the molded frame 7. A rear fork 10 for supporting a rear wheel 9 is supported in an oscillating manner by a lower portion of the molded frame 7, and a rear shock absorber assembly 11 is inserted between the rear fork 10 and a rear portion of the frame. A steering handlebar 12 is fixed on an upper portion of a steering shaft extending above the steering tube 3, a headlight assembly 13 is fixed on a central portion of the steering handlebar 12, and some turn indicators 14 are fixed in left portions and right of the steering handlebar 12.

A shield 15, which constitutes a front portion of the covering 2, is arranged in correspondence with left and right portions of a front part of the motorcycle 1, and the shield 15 is made in such a way as to integrally surround the area comprised between the lower left and right near the driver's feet and left and right portions of a portion on the upper side of the head tube 3. An intermediate portion of the shield 15 is curved backward to surround a rear portion of the head tube 3, a upper casing in the form of a vertical channel 16 is arranged in correspondence with a front portion of the steering tube 3 located in this position, and the upper casing 16 is fixed to the intermediate portion of the shield 15.

In this embodiment, the motor 6 is supported on a lower portion 7a of the molded frame 7 through two suspension bolts 21, as illustrated in Figure 3.

An end 23a of an exhaust duct 23 is connected to an exhaust port 6b of a cylinder head 6a of the engine 6 through a connecting flange 22. The exhaust duct 23 exits on the lower side of the engine 6, comprises an outlet portion 23b to pass on the rear side of the vehicle near a portion directly under the engine 6, so as to be connected to a catalytic converter 30, and a rear end portion 23c of the exhaust pipe 23 is connected to a muffler 25 which acts by so-called silencer.

The catalytic converter 30 forms a part of the exhaust duct 23, and extends in the left-right direction of the vehicle, with its axis L orthogonal to the line of the exhaust duct 23 which generally extends in a single direction. Furthermore, the catalytic converter 30 is arranged directly under the engine 6 so as to be substantially included in the width of the engine 6.

In this arrangement of the catalyst, the L axis of the catalytic converter 30 is arranged to be substantially orthogonal to the line of the exhaust duct 23 which generally extends in a single direction. Therefore, with respect to a catalyst arrangement in which the L axis of the catalytic converter 30 coincides with the direction of extension of the line of the exhaust duct 23, a catalytic converter 30 having a high capacity and a relatively large longitudinal dimension can be arranged in compact form in the short distance between the first end 23a and the rear end portion 23c of the exhaust duct 23, without increasing the size in the front-rear direction of the vehicle.

As illustrated in Figure 4, the catalytic converter 30 comprises a main body 51 of the generally tubular converter having the two ends closed, and a catalyst body 53 formed inside the main body of the converter 51. An introduction duct 55 for introducing the exhaust gas in the catalyst body 53 and an outlet duct 57 for the outlet of the exhaust gas which has passed through the catalyst body 53 are collectively arranged on the side of the first end 51a of the tubular main body 51 of the converter.

The catalyst body 53 comprises a first catalyst chamber 53a (indicated by broken dashes) in communication with the introduction duct 55 through a communication duct 61, and a second catalyst chamber 53b in communication with the outlet duct 57 The first and second catalyst chambers 53a and 53b can be made with an approximately equal cross-sectional area, as illustrated in Figure 5; alternatively, the ratio between the cross-sectional areas of the catalyst chambers 53a and 53b can be varied in an arbitrary manner, in consideration of the acoustic attenuation efficiency.

The first catalyst chamber 53a is arranged on the internal side in the catalyst body 53, and, as shown in Figure 4, one of its inlets A is in communication with the introduction duct 55 through the communication duct 61, and one of its outlet B it is in communication with an inversion chamber 63 formed on the side of the other end 51b of the main body 51 of the converter.

The inversion chamber 63 is in communication with an inlet C of the second catalyst chamber 53b arranged on the external side in the catalyst body 53, an outlet D of the catalyst chamber 53b is in communication with a collecting chamber 65 formed on the side of the first end 51a of the main body of the converter 51, and the outlet duct 57 is in communication with the collecting chamber 65.

The catalyst body 53 is composed of a porous honeycomb structure coated with platinum, palladium, rhodium or the like.

It constitutes a three-way catalyst having a honeycomb shape. The exhaust gas which has passed through the introduction duct 55 and the communication duct 61 entering the inlet A of the first catalyst chamber 53a is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, and then passes through the Exit B, reaching the inversion chamber 63, flows from the latter into the inlet C of the second catalyst chamber 53b, is again deprived therein of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, then passes through the outlet D in the collecting chamber 65, and exits through the outlet duct 57 in the silencer 25.

In the configuration described above, all the pores in the honeycomb pass through the catalyst body from one end to the other. Therefore, when the communication duct 61 is connected to a part (on the central side) of a first end of the catalyst body 53, this part directly performs the function of porous communication ducts (the first catalyst chamber 53a) to allow the passage of the exhaust gas in a first direction, and the exhaust gas which has reversed its direction in the reversing chamber 63 at the other end of the catalyst body 53 passes in the opposite direction through another porous part (the second catalyst chamber 53b ) of the honeycomb. In other words, the single honeycomb catalyst body 53 performs the function of bidirectional communication conduits.

Furthermore, since the catalyst body 53 is a three-way catalyst having a honeycomb shape composed of a set of intrinsically divided passages, a separation between the first and second catalyst chambers 53a and 53b is not necessary, favoring a simple configuration. Furthermore, since the passages in the single catalyst body 53 are used for flows in opposite directions of the exhaust gas, it is possible to obtain an efficient purification and a prompt activation.

The three-way catalyst generally has a low ability to purify hydrocarbons by reactions before an activation temperature (about 300 ° C) is reached, and the capacity improves after this temperature has been reached.

In this configuration, the catalytic converter 30 is arranged in the vicinity of the position directly under the engine 6, so that the heat developed by the engine 6 can easily bring the temperature of the three-way catalyst to the activation temperature. For example, even in the cold running condition of the engine immediately after the start of operation, the heat radiation from the engine 6 ensures that the temperature of the three-way catalyst rises in an extremely short time, and the catalyst is rapidly activated.

In this configuration, since the catalytic converter 30 is disposed on an intermediate portion of the aforementioned exhaust duct 23, it is not necessary to arrange a large capacity catalyst in the silencer 25.

Therefore, it is possible to obtain a reduction in the size of the silencer 25, with respect to a configuration in which a large capacity catalyst is arranged in the silencer 25. Furthermore, since the catalytic converter 30 is arranged to be substantially orthogonal to the direction in which it extends into the exhaust duct 23, the catalytic converter 30 can be arranged compactly and easily in the confined space in the vicinity of the engine, ensuring a capacity sufficient of the catalyst of the catalytic converter 30, without increasing the size in the front-to-rear direction of the motorcycle.

In this configuration, the catalytic converter 30 is arranged in the area directly under the engine 6, i.e. in the so-called dead zone, as shown in Figure 3. Thus, it is possible to achieve efficient use of space, and to arrange the catalytic converter 30 without increasing the overall width of the vehicle. Furthermore, since the catalytic converter 30 is arranged so as not to be easily visible from the outside, it is possible to ensure a good degree of freedom in the design of the vehicle.

Furthermore, since the catalytic converter 30 is arranged directly under the engine 6, the position of the center of gravity is lowered, and it is possible to obtain a rationalization of the balance of the vehicle weight.

In this case, a lower protection 39 is arranged directly under the catalytic converter 30 so as to substantially cover this entire area from the lower side. The lower guard 39 is fixed to an outer wall of the catalytic converter 30 by means of a bolt 39a. The lower shroud 39 is provided with a receiving groove 39b for receiving a head portion of the bolt 39a, so that the head portion of the bolt 39a does not protrude from the lower surface of the lower shroud 39.

In this configuration, the bottom shield 39 promotes a protection of the catalytic converter 30, and its heat preservation effect leads to an early activation of the catalyst.

As illustrated in Figure 2, a pivot of the footrests 41 is fixed to the lower surface of the motor 6 by means of screws, and the driver's footrests 43 are disposed on the two end portions of the pivot of the footrests 41.

In this configuration, the catalytic converter 30 is arranged on the front side relative to the driver's footrests 43. As a result, the driver's feet are prevented from touching the catalytic converter 30, the influence of heat on the driver is limited to a relatively low level , it is possible to obtain an efficient use of the space on the front side of the footrests 43, and it is possible to obtain a rationalization of the balance of the vehicle weight.

Furthermore, the catalytic converter 30 is arranged inside the shield 15 in the direction of the width of the vehicle. When parking, heat is likely to build up inside the shield 15 in the width direction of the vehicle. The air temperature inside the shield 15 in the vehicle width direction increases in a relatively short time after starting the engine 6, whereby the catalytic converter 30 is activated more efficiently. Furthermore, it is possible to obtain an efficient use of the space inside the shield 15 in the direction of the width of the vehicle, and it is possible to obtain a rationalization of the balancing of the weight of the vehicle.

In this configuration, the introduction duct 55 and the outlet duct 57 for the exhaust gas are collectively arranged on the side of the first end 51a of the tubular main body 51 of the converter. Therefore, as illustrated in Figure 2, a discontinuous portion of the exhaust duct 23 is formed between the introduction duct 55 and the outlet duct 57, and, near the discontinuous portion, a protective element of the exhaust duct 47 is arranged so as to cover the discontinuous portion. The protection element of the exhaust duct 47 is fixed to projections 23d by means of bolts 47a, and the projections 23d are said on the outer wall of the exhaust duct 23. The protection element of the exhaust duct 47 is provided with grooves receivers 47b for receiving head portions of the bolts 47a, so that the head portions of the bolts 47a do not protrude from the surface of the protection member of the exhaust duct 47.

In this configuration, since the discontinuous portion of the exhaust duct 23 is covered by the protective element of the exhaust duct 47, it is possible to obtain protection and thermal insulation of the exhaust duct 23. At the same time, since the discontinuous portion of the exhaust duct 23 is invisible from the outside, the exhaust duct 23 is seen from the outside of the vehicle as if it were continuous, so that the aesthetic quality improves and the appearance is pleasant.

The catalytic converter 30 is not limited to the above exemplary configuration. For example, as shown in Figure 6, the catalytic converter 30 may comprise a main body of the converter 151, a catalyst body (honeycomb body) 153 arranged inside the main body 151, and a separation wall 152 to achieve a separation between the spaces on the inlet and outlet side J and K with reference to the catalyst body 153. In consideration of the thermal expansion of the honeycomb body, it is possible to provide a predetermined clearance d between the separation wall 151 and the body catalyst 153. In this case, it is advantageous that d ≤ 5 mm. The catalyst body 153 may comprise first and second catalyst chambers 153a and 153b which have an approximately equal cross-sectional area; alternatively, the ratio between the cross-sectional areas of the chambers 153a and 153b can be varied in an arbitrary manner, in consideration of the acoustic attenuation efficiency.

In this case, the catalyst body 153 is composed of a three-way catalyst having a honeycomb shape comprising platinum, palladium, rhodium or the like. The exhaust gas, which has passed through an introduction duct 155 and an inlet side space J reaching an inlet A of a first catalyst chamber 153a (the right-hand portion of the catalyst body 153 in Figure 6) composed of a porous portion of the nest of bee connected with space J, is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, then passes through an outlet B reaching an inversion chamber 163, passes from the latter into an inlet C of a second catalyst chamber 153b (the left portion of the catalyst body 153 in Figure 6), is again deprived therein of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, and is subsequently released through an outlet D, an outlet side space K and an exhaust duct 157 reaching the silencer 25.

Furthermore, as illustrated in Figure 7, the catalytic converter 30 may comprise a main body of the converter 251 and have a configuration in which a first punched duct 252 disposed along the inner peripheral wall of the main body of the converter 251 and a second punched duct 254 arranged along the inner peripheral wall of an introducing duct 255 are arranged concentrically in the main body of the converter 251, and platinum, palladium, rhodium or the like are arranged on the punched ducts. In this case, the space in which the first punched duct 252 extends constitutes a first catalyst chamber 253a, while the space in which the second punched duct 254 extends constitutes a second catalyst chamber 253b. The first and second catalyst chambers 253a and 253b are composed of a three-way catalyst having a honeycomb shape. The exhaust gas which has reached, through the introduction duct 255, the first catalyst chamber 253a is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, then reaches an inversion space 263, passes through this last in the second catalyst chamber 253b, it is again deprived therein of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, and is made to exit through an outlet duct 257 reaching the silencer 25.

Although the main body of the above catalytic converter 30 has a hollow cylindrical shape in section, the shape is not limited thereto and can be, for example, a polygonal tubular shape or the like. In particular in the case of a motorcycle in which the catalytic converter 30 is arranged directly under the engine 6, it is advantageous for the thickness of the catalytic converter 30 to be reduced. In this case, for example, the shape could be a thin angled tubular cassette shape or the like.

Figure 8 shows another embodiment.

In this embodiment, a catalytic converter is arranged inside a silencer 325. The silencer 325 is a multiple chamber type silencer, in which a second, a first and a third expansion chamber N, M, 0 divided a first and a second separation wall 325a and 325b are formed in this order from the side of an introduction duct 355. On the first separation wall 325a, a catalytic converter 30 having this configuration is disposed which crosses the wall 325a.

The catalytic converter 30 comprises a tubular main body 351 of the converter, and a catalyst body 353 formed inside the main body of the converter 351. The introduction duct 355 for introducing the exhaust gas into the catalyst body 353 and an outlet duct 357 to release the exhaust gas which has passed through the catalyst body 353, they are collectively arranged on the side of the first end 351a of the tubular main body 351 of the converter.

The catalyst body 353 comprises a first catalyst chamber 353a which is in communication with the introduction duct 355 through a communication duct 361, and a second catalyst chamber 353b which is in communication with the outlet duct 357 through the second delivery chamber. expansion N. The first and second catalyst chambers 353a and 353b can be arranged to have an approximately equal cross-sectional area; alternatively, the ratio between the cross-sectional areas of the catalyst chambers 353a and 353b can be varied, in consideration of the acoustic attenuation efficiency. The first catalyst chamber 353a is arranged on the internal side in the catalyst body 353, one of its inlet A is put in communication with the introduction duct 355 through the communication duct 361, while one of its outlet B is put in communication with a inversion chamber 363 (the first expansion chamber M) formed on the side of the other end 351b of the main body of the converter 351. The inversion chamber 363 is communicated with an inlet C of the second catalyst chamber 353b disposed on an external side in the catalyst body 353, an outlet D of the second catalyst chamber 353b is communicated with a collecting chamber 365 (the second expansion chamber N) provided on the side of the first end 351a of the main body of the converter 351, and the outlet 357 is put in communication with the collecting chamber 365. The outlet duct 357 passes through the first and second separation walls 325a and 325b and is put in communication with the third expansion chamber 0, and the third expansion chamber 0 is put in communication with the outside through an exhaust duct 371.

The catalyst body 353 is composed of a honeycomb structure coated with platinum, palladium, rhodium or the like.

It constitutes a three-way catalyst having a honeycomb shape. The exhaust gas which has passed through the introduction duct 355 and the communication duct 361 reaching the inlet A of the first catalyst chamber 353a is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, then passes through the outlet B entering the inversion chamber 363 (the first expansion chamber M), passes from the latter into the inlet C of the second catalyst chamber 353b, and is again deprived therein of hydrocarbons, carbon monoxide and oxide of nitrogen by redox reactions, then passes through outlet D reaching the collecting chamber 365 (the second expansion chamber N), passes through the outlet duct 357 penetrating into the third expansion chamber 0, and exits outside through the duct exhaust 371.

According to this configuration, in the silencer of the multiple chamber type, the catalyst body 353 passes through the first separation wall 325a, and forms three paths.

Specifically, the first and second catalyst chambers 353a and 353b also function as two communication ducts in the traditional configuration, whereby a reduction in the number of component parts is obtained, with respect to the traditional configuration. Furthermore, the exhaust gas passes alternately in the passages in the single catalyst body 353, whereby it is possible to obtain an easy activation of the catalyst and to improve the purification efficiency. Furthermore, the communication ducts necessary in the prior art can be eliminated, so that an increase in the diameter of the silencer can be avoided, even in the case of a silencer having the catalyst body 353.

Figure 9 shows yet another embodiment.

In this embodiment, the catalytic converter 30 is arranged to pass through a second separation wall 325b. The catalytic converter 30 has a configuration equal to that of Figure 8, and comprises a tubular main body 351 of the converter, and a catalyst body 353 formed inside the main body of the converter 351. An introduction duct 355 for the introduction of the exhaust gas in the catalyst body 353 and an outlet duct 357 for the outlet of the exhaust gas which has passed through the catalyst body 353 are collectively arranged on the side of a first end 351a of the tubular main body 351 of the converter.

A silencer 325 is a multi-chamber type silencer, in which a third, second and first expansion chamber 0, N and M, divided by a first and a second separation wall 325a and 325b, are formed in this 'order from the side of the introduction duct 355.

The catalyst body 353 comprises a first catalyst chamber 353a in communication with the introduction duct 355 through a communication duct 361, and a second catalyst chamber 353b in communication with the outlet duct 357 through the second expansion chamber N. La first and second catalyst chambers 353a and 353b can be made with an approximately equal cross-sectional area, or the ratio between their cross-sectional areas can be varied arbitrarily in consideration of the acoustic attenuation efficiency. The first catalyst chamber 353a is arranged on the internal side in the catalyst body 353, one of its inlet A is in communication with the introduction duct 355 through the communication duct 361, and one of its outlet B is in communication with an inversion chamber ( the first expansion chamber M) formed on the side of the other end 351b of the main body of the converter 351.

The inversion chamber 363 is in communication with an inlet C of the second catalyst chamber 353b arranged on the external side in the catalyst body 353, an outlet D of the second catalyst chamber 353b is in communication with a collecting chamber 365 (the second expansion N) formed on the side of the first end 351a of the main body of the converter 351, and the outlet conduit 357 is in communication with the collecting chamber 365.

The outlet duct 357 is in communication with the third expansion chamber 0, the third expansion chamber 0 is in communication with an exhaust duct 371 which crosses the first and second separation walls 325a and 325b, and the exhaust duct 371 is in communication with the outside world.

The catalyst body 353 is composed of a honeycomb structure coated with platinum, palladium, rhodium or the like.

It constitutes a three-way catalyst having a honeycomb shape. The exhaust gas that has passed through the introduction duct 355 and the communication duct 361 reaching the first catalyst chamber 353a is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, then passes through the outlet B reaching the inversion chamber 363 (the first expansion chamber M) passes from the latter into the inlet C of the second catalyst chamber 353b, and is again deprived therein of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions , passes through the outlet D reaching the collecting chamber 365 (the second expansion chamber N), and is made to exit from the latter to the outside through the outlet duct 357, the third expansion chamber 0 and the exhaust duct 371.

Incidentally, in the above configuration, the catalytic converter 30 can be arranged to pass through each of the separation walls 325.

Figure 10 shows yet another embodiment.

In this embodiment, the catalytic converter 30 is arranged so as to pass through a first separation wall 325a. The catalytic converter 30 has the same configuration as that illustrated in Figure 8, and comprises a tubular main body 351 of the converter and a catalyst body 353 formed inside the main body 351. An introduction duct 355 for introducing a gas in the catalyst body 353 and an outlet duct 357 for the outlet of the exhaust gas which has passed through the catalyst body 353 are collectively arranged on the side of a first end 351a of the tubular main body 351 of the converter.

A silencer 325 is a multiple chamber type silencer, in which a third, a second and a first expansion chamber 0, N and M, divided by a first and a second separation wall 325a and 325b, are formed in this order from the side of the introduction duct 355.

The catalyst body 353 comprises a first catalyst chamber 353a in communication with the introduction duct 355 through a communication duct 361, and a second catalyst chamber 353b in communication with the outlet duct 357 through the third expansion chamber 0. first and second catalyst chambers 353a and 353b can be made to have an approximately equal cross-sectional area, or the ratio of the cross-sectional areas of the catalyst chambers can be varied in consideration of the sound attenuation efficiency.

The first catalyst chamber 353a is arranged on the internal side in the catalyst body 353, one of its inlet A is in communication with the introduction duct 355 through the communication duct 361, and one of its outlet B is in communication with an inversion chamber 363 (the first expansion chamber M) on the side of the other end 351b of the main body of the converter 351 through a communication conduit 362 which crosses the second separation wall 325b.

The inversion chamber 363 is in communication with the second expansion chamber N through a communication duct 364 which crosses the second separation wall 325b, the second expansion chamber N is in communication with an inlet C of the second catalyst chamber 353b arranged on the external side in the catalyst body 353, an outlet D of the second catalyst chamber 353b is in communication with a collecting chamber 365 (the third expansion chamber 0) on the side of the first end 351a of the main body of the converter 351, and a duct outlet 357 is in communication with the collecting chamber 365. The outlet duct 357 passes through the first and second separation walls 325a and 325b, and is in communication with an exhaust duct 371, which is in communication with the outside.

In the previous configuration, a sealing element 391 is interposed at a junction portion between the catalyst body 353 and the communication duct 361, as illustrated in Figures 1A to 11C.

As shown in Figure 11C, the sealing element 391 has a width W2 greater than the diameter W1 of the circumference circumscribed by the pores of the honeycomb of the catalyst body 353. The sealing element 391 can also be similarly arranged in correspondence with the junction portion between the catalyst body 353 and the communication duct 362. If the catalyst body 353 also acts as a communication duct for a silencer, the arrangement of the sealing element 391 makes it possible to safely feed the exhaust gas in the expansion chamber, whereby sufficient functionality as a communication conduit is achieved.

Furthermore, in the previous configuration, since the junction portion between the catalyst body 353 and the communication duct 361 is made watertight by means of the sealing element 391, the exhaust gas escaping from the communication duct 361 will not be directly laminated into the third expansion chamber 0, whereby an increase in exhaust noise is avoided.

Incidentally, the sealing element 391 does not constitute a limiting means, and the joining portions of the catalyst body 353 and the communication duct 361 can be joined by welding.

Figure 12 shows yet another embodiment.

In this embodiment, the catalytic converter 30 is arranged so as to pass through a first separation wall 325a. The catalytic converter 30 comprises a tubular main body 351 of the converter and a catalyst body 353 formed inside the main body 351. An introduction duct 355 for introducing an exhaust gas into the catalyst body 353 and an outlet duct 357 for the outlet of the exhaust gas which has passed through the catalyst body 353 are collectively arranged on the side of the first end 351a of the tubular main body 351 of the converter.

A silencer 325 is a multi-chamber type silencer, in which a second, first and third expansion chambers N, M and 0, divided by a first and a second separation wall 325a and 325b, are formed in this 'order from the side of the introduction duct 355.

The catalyst body 353 comprises a first catalyst chamber X in communication with the introduction duct 355 through a communication duct 361, a second catalyst chamber Y which realizes a communication between the first and the second expansion chamber M and N, and a third catalyst chamber Z which also acts as an outlet duct 357 for the exhaust gas. As illustrated in Figures 13A and 13B, the first catalyst chamber X and the second catalyst chamber Y have circular passage shapes in section, and the third catalyst chamber Z is arranged to surround the first catalyst chamber X and the second catalyst chamber Y.

An inlet A of the first catalyst chamber X is in communication with the introduction duct 355 through the communication duct 361, and one of its outlet B is in communication with an inversion chamber 363 (the first expansion chamber M) on the side of the the other end 351b of the main body of the converter 351. The inversion chamber 363 is in communication with an inlet C of the second catalyst chamber Y, an outlet D of the second catalyst chamber Y is in communication with a collecting chamber 365 (the second expansion chamber N) on the side of the first end 351a of the main body of the converter 351, and the collecting chamber 365 is in communication with an inlet E of the third catalyst chamber Z. An outlet F of the third catalyst chamber Z is in communication with a communication conduit 368 which crosses the second separation wall 325b, and the communication conduit 368 is in communication with a drain conduit load 371 through the third expansion chamber 0.

In the preceding catalyst body 353, as illustrated in Figure 12, the exhaust gas first passes through the first catalyst chamber X, as indicated by arrow 1, reverses its direction in the reversing chamber 363, then passes through the second chamber of catalyst Y, as indicated by arrow 2, reverses its direction in the collecting chamber 365, passes through the third catalyst chamber Z, as indicated by arrow 3, passes through the communication duct 368 reaching the third expansion chamber 0 , and is led out through the exhaust duct 371.

In this embodiment, since the single catalyst body 353 constitutes three paths in the silencer 325 and the first to third catalyst chambers X to Z also function as three communication conduits used in the prior art, the number of component parts is reduced. compared to the traditional configuration. In addition, since the exhaust gas undergoes one and a half reversal of flow in the passages in the single catalyst body, activation of the catalyst is facilitated, and purification efficiency is improved. Furthermore, since it is substantially possible to eliminate the communication ducts required in the prior art, it is also possible to increase the diameter of the silencer having the catalyst body 353.

Figures 14 and 15 show yet another embodiment.

In this embodiment, the same catalytic converter 30 illustrated in Figure 4 is covered with a complete coating 401 which acts as a protective element. If the catalyst body 53 of the catalytic converter 30 is exposed to water or the like, resulting in a rapid thermal change, a distortion could be generated between that body and the first end 51a of the main body of the converter 51 or the like. In this configuration, however, since the catalytic converter 30 is covered by the complete coating 401, the catalyst body 53 is provided with a waterproofing structure, it is possible to shield the heat coming from the catalyst body 53, and the catalyst body 53 is protected by stones. projected and the like.

Incidentally, the catalytic converter 30 within the complete liner 401 is not limited to the form illustrated in Figure 4, and can be any converter.

Figures 16A and 16B show yet another embodiment.

The catalytic converter 30 comprises a main body of the converter (outer tube) 551, which is coaxially provided in its interior with an inner tube 559 to divide it. A first catalyst body 561 is disposed in the inner tube 559, with an appropriate clearance 61 between them, and this portion constitutes a first catalyst chamber 553a. Furthermore, in an annular space surrounded by the outer tube 551 and the inner tube 559, a second catalyst 562 is arranged, with appropriate clearances 62 and 63 respectively on the side of the outer circumference and on the side of the inner circumference, and this portion constitutes a second chamber of catalyst 553b. As illustrated in Figure 17, both the first catalyst body 561 and the second catalyst body 562 are formed by layering a flat sheet 563 and a corrugated sheet 564, by wrapping the layered structure into a roll form from a first portion of end towards the other end portion, and then by brazing the flat sheet 563 and the corrugated sheet 564 onto each other as will be described below.

In this configuration, the exhaust gas that has passed through an introduction duct 555 into the first catalyst chamber 553a (the first catalyst body 561) is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by redox reactions, thus being purified , and then reaches an inversion space 563, passes from the latter into the second catalyst chamber 553b (the second catalyst body 562), is again deprived in this chamber of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions , being thus purified, and exits through an outlet duct 557 in the silencer 25.

The first catalyst body 561 is exposed to a relatively higher temperature on the inlet side 561a than the outlet side 561b, and the second catalyst body 562 is exposed to a relatively higher temperature on the inlet side 562a than the outlet side 562b. In general, when a high temperature portion is brazed, the thermal stress generated in the brazed portion increases, resulting in a reduction in life. In light of this phenomenon, in this configuration, between the flat sheet 563 and the corrugated sheet 564 in each of the catalyst bodies 561 and 562, only a junction region P (the hatched region) arranged on the outlet side 561b, 562b is brazed. in the exhaust gas outlet direction in the axial direction of each catalyst body 561, 562.

Furthermore, in this configuration, the outer periphery of the first catalyst body 561 and the inner periphery of the inner tube 559 (the clearance portion 61), the inner periphery of the second annular catalyst body 562 and the outer periphery of the inner tube 559 (the of clearance 63), and the outer periphery of the second annular catalyst body 562 and the inner periphery of the outer tube 551 (the clearance portion 62), are connected to each other by brazing. Again, based on the same previous considerations, only one region of junction Q (the region indicated by a thick line) arranged on the outlet side 561b, 562b in the direction of the exhaust gas outlet in the axial direction of each catalyst body 561, 562 is brazed.

Thus, the first catalyst body 561 is brazed inside the inner tube 559, the second catalyst body 562 is brazed in the annular space between the inner tube 559 and the outer tube 551, and a catalyst, for example platinum, palladium, rhodium or the like, is supported on each of the flat sheets 563 and of the corrugated sheets 564 which constitute the first catalyst body 561 and the second catalyst body 562.

In this configuration, the outer periphery on the inlet side 561a of the first catalyst body 561 and the inner periphery of the inner tube 559 are not brazed to each other, and clearance 61 remains between them. inlet 561a of the first catalyst body 561 is brought to high temperature by coming into contact with the exhaust gas, the heat of the inlet side 561a is not easily transmitted to the inner tube 559, and a reduction in the mechanical strength of the material is prevented due to 'temperature rise, so which material can be used a cheap material. Furthermore, the outlet side 562b of the second catalyst body 562 disposed around the outer periphery of the inner tube 559 can be heated by radiated heat or the like limiting extreme heating, whereby it is possible to accelerate the activation on the outlet side 562b at the moment. of a cold start.

Figure 18 shows yet another embodiment.

The catalytic converter 30 has a configuration in which a catalyst body 653 having a porous honeycomb shape coated with platinum, pailadium, rhodium or the like is disposed within a main body of the converter 651. The catalyst body 653 is formed by winding a flat sheet and a corrugated sheet (see Figure 17) in a stratification condition, and comprises a first catalyst chamber 653a composed of pores in a first part and in communication with an introduction duct 655 through a communication conduit 661, and a second catalyst chamber 653b composed of pores in another part and in communication with an outlet conduit 657. In this configuration, between the flat sheet and the corrugated sheet corresponding to the pores in the first part ( the first catalyst chamber 653a), only one region of the junction P1 (the hatched region) arranged on the outlet side in the outlet direction is brazed of the exhaust gas in the axial direction of the pores, while, between the flat sheet and the corrugated sheet in correspondence with the pores in the other part (the second catalyst chamber 653b), only a P2 junction region is brazed (the region hatched) arranged on the outlet side in the exhaust gas outlet direction in the axial direction of the pores in the other part. Furthermore, in this configuration, the catalyst body having a honeycomb shape 653 and the internal periphery of the main body of the converter 651 are connected together by brazing. In this case, only a junction region Q1 (the region indicated by a thick line) disposed on the outlet side in the exhaust gas outlet direction in the axial direction of the catalyst body 653 is brazed.

In this configuration, the exhaust gas which has passed through an introduction duct 655 and a communication duct 661 reaching an inlet A of the first catalyst chamber 653a is deprived of hydrocarbons, carbon monoxide and nitrogen oxide by means of redox reactions, being thus purified, it passes through an outlet B of the first catalyst chamber 653a into an inversion chamber 663, passes from the latter into an inlet C of the second catalyst chamber 653b, is again deprived in this chamber of hydrocarbons, monoxide carbon and nitrogen oxide by means of redox reactions, being thus purified, passes through an outlet D of the second catalyst chamber 653b into a collector chamber 665, and exits through the outlet duct 657 into the silencer 25.

In the previous configuration, all the pores of the honeycomb pass through the catalyst body 653 from a first end to the other end; therefore, when the communication duct 661 is connected to a first part (on the central side) of the first end of the catalyst body 653, this first part acts directly as a communication duct formed by pores (the first catalyst chamber 653a) allowing the passage of the exhaust gas through it in the first direction, and the exhaust gas that has changed direction in the reversing chamber 663 at the other end of the catalyst body 653 passes through the other part of the honeycomb pores (the second chamber of catalyst 653b) in the opposite direction. In particular, the single catalyst body having a honeycomb shape 653 performs the function of bidirectional communication conduits.

In this configuration, the outlet side in the exhaust gas outlet direction where the influence of heat is limited is brazed, without affecting the upstream portion of the exhaust gas where the temperature is high, so that it is possible to limit a reduction in the mechanical strength of the material due to an increase in temperature in the P and Q junction regions, and it is possible to use inexpensive materials for these regions.

Although the present invention has been previously described with reference to some embodiments thereof, it is evident that the invention is not limited to these embodiments. For example, although the arrangement of a catalyst in a motorcycle has been described in the previous embodiments, the invention is also applicable to the arrangement of a catalyst in other vehicles, such as three-wheeled vehicles and four-wheeled vehicles, classified as ATVs. ("all terrain vehicles" - off-road vehicles).

Claims (11)

CLAIMS 1. Exhaust system for a vehicle, comprising a silencer connected to an exhaust duct extending from an engine, in which a catalytic converter is arranged on an intermediate portion of the aforementioned exhaust duct and / or in the aforementioned silencer, and the aforementioned catalytic converter has a configuration in which an inlet conduit and an outlet conduit for supplying an exhaust gas into, and exiting the exhaust gas from, a catalyst chamber are collectively disposed on a single end side of the chamber of aforementioned catalyst. 2. Exhaust system for a vehicle according to claim 1, wherein the aforesaid catalyst chamber comprises a first catalyst chamber in communication with the aforesaid introduction duct, and a second catalyst chamber in communication with the aforesaid outlet duct. , and the aforementioned first and second catalyst chambers are in communication with each other on the other end side of the aforementioned catalyst chamber. 3. An exhaust system according to claim 2, wherein the aforementioned catalytic converter comprises an outer tube and an inner tube; And the aforementioned first catalyst chamber is internally provided with a first catalyst body surrounded by the aforementioned inner tube, the aforesaid second catalyst chamber is internally provided with a second catalyst body surrounded by the aforementioned inner tube and the aforementioned outer tube, each aforesaid catalyst body is formed by wrapping a flat sheet and a corrugated sheet in a stratified condition, and in each of the areas between the aforementioned flat sheet and the aforementioned corrugated sheet in each aforementioned catalyst body, between the aforementioned catalyst body and the aforementioned inner tube, and between the aforesaid catalyst body and the aforesaid outer tube, a junction region is brazed arranged on the outlet side in the direction of the exhaust gas outlet in the axial direction of each aforesaid catalyst body. 4. Exhaust system for a vehicle, comprising a silencer connected to an exhaust duct extending from an engine, in which a catalytic converter is arranged on an intermediate portion of the aforementioned exhaust duct and / or in the aforementioned silencer, and the aforementioned catalytic converter comprises a catalyst body having a honeycomb shape, and has a configuration in which an exhaust gas which has passed through an introduction duct reaching the aforementioned catalyst body passes through pores in a first part of the honeycomb and further through pores in another part of the honeycomb structure reaching an outlet duct. 5. Exhaust system for a vehicle according to claim 4, wherein said catalyst body having a honeycomb shape is formed by wrapping a flat sheet and a corrugated sheet in a layered condition, and, between aforesaid flat sheet and the aforesaid corrugated sheet in correspondence with the aforesaid pores in the aforesaid first part, only a junction region arranged on the outlet side in the outlet direction of the exhaust gas in the axial direction of the aforesaid pores in the aforesaid first part is brazed, while , between the aforesaid flat sheet and the aforesaid corrugated sheet in correspondence with the aforesaid pores in the other aforesaid part, a junction region is brazed which is arranged on the outlet side in the outlet direction of the exhaust gas in the axial direction of the aforesaid pores in the other aforementioned part. 6. An exhaust system for a vehicle according to claim 4 or 5, wherein the pores in the aforementioned first part or the other aforesaid part of the aforementioned honeycomb structure are pores in a central portion of the honeycomb structure aforesaid, and the pores in the aforesaid other part or in the aforesaid first part of the aforementioned honeycomb structure are pores in a peripheral portion of the aforesaid honeycomb structure. 7. Exhaust system for a vehicle according to any one of claims 1 to 6, wherein said catalytic converter is arranged directly under said engine. Exhaust system for a vehicle according to any one of claims 1 to 7, wherein said catalytic converter extends in the left-right direction of said vehicle. Exhaust system for a vehicle according to any one of claims 1 to 8, wherein the aforementioned catalytic converter is arranged on the front side of a driver's footrest. Exhaust system for a vehicle according to any one of claims 1 to 9, wherein said catalytic converter is arranged inside a shield in the vehicle width direction. 11. Exhaust system for a vehicle according to any one of claims 1 to 10, wherein an exhaust duct protection member is arranged between an outlet duct of said catalytic converter connected to said exhaust duct and the exhaust duct aforementioned.