Exhaust gas systems for motorcycles

Abstract

1. An exhaust gas system (1) for an internal combustion engine (2) of a saddle-ride type vehicle (20), comprising: a first pipe section (3) having one or more primary catalysts (6) arranged therein; a second pipe section (4) having one or more secondary catalysts (6') arranged therein; a third pipe section (5) having a number of secondary catalysts (6') arranged therein that is less than the number of secondary catalysts arranged inside the second pipe section (4); and at least one outlet (16, 17) for discharging exhaust gas to the atmosphere, wherein the first pipe section (3) extends from a first end (11) connectable to an outlet of the internal combustion engine (2) and branches into the second and third pipe sections (4, 5) at a branch point (19), and the exhaust gas system (1) further comprises at least one valve (7) configured to deflect exhaust gas flow coming from the engine (2) from the first pipe section (3) to one or both of the second and third pipe sections (4, 5).

Description

[Technical field]

[0001] The present invention is in the field of internal combustion engines, in particular in the field of internal combustion engines for saddle-type vehicles, and more particularly in the field of exhaust gas systems for internal combustion engines of the aforementioned type of vehicle. [Background technology]

[0002] According to the most current and current legal regulations in terms of environmental protection, both the noise generated by an internal combustion engine and the amount of pollutants contained in the exhaust gases produced by said engine and entering the environment must be kept below very strict limits and values.

[0003] In order to meet the aforementioned legal restrictions, solutions have been proposed by manufacturers of internal combustion engines, the most common of which uses one or more catalysts arranged in the exhaust gas system, in particular inside one or more of the exhaust gas pipes or exhaust gas lines of the exhaust gas system, to capture pollutants contained in the exhaust gases produced by combustion before said exhaust gases are discharged into the environment.

[0004] One example of a prior art exhaust gas system is known from U.S. Patent Application Publication No. 2020 / 0056519, which arises from PTC application PCT / IB2017 / 0566881, filed on November 3, 2017 in the name of the same applicant as the present application.

[0005] Although the amount of pollutants captured by the catalyst with the exhaust gas system according to US Patent Application Publication No. 2020 / 0056519 has proven to be satisfactory, said exhaust gas system suffers from drawbacks which the Applicant of the present application aims to overcome or at least reduce with the present invention.

[0006] In practice, it must be taken into account that said legal restrictions may vary from region to region or even from area to area of ​​the same region or country, for example said legal restrictions may be stricter in urban areas than outside urban areas.

[0007] Furthermore, it must be taken into account that catalysts have an effect on engine performance, e.g. increasing the number and / or size of catalysts will reduce engine performance, particularly in terms of the power generated and therefore in terms of vehicle speed and / or acceleration.

[0008] Prior art exhaust gas systems do not allow the catalyst performance to be tuned to the engine performance, resulting in, for example, a very high performance catalyst set resulting in a lack of power in situations where more power would be advantageous (e.g. outside urban areas), while a poorer performance catalyst set (which has a reduced impact on engine performance) would prevent the vehicle from being used in urban areas. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 0056519 Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE PRESENT EMBODIMENT It is therefore a primary object of the present invention to overcome the shortcomings affecting prior art exhaust gas systems.

[0011] In particular, it is a further object of the present invention to provide an exhaust gas system comprising a catalyst set, the performance of which (and therefore the effect of the catalyst set on the performance of the engine) can be adjusted in response to prevailing conditions.

[0012] A further goal of the present application is to provide an exhaust gas system that can reduce the impact of the catalyst set on the performance of the engine when the engine (and therefore the vehicle) is used in areas where more engine power is required and where more lenient anti-pollution regulations are planned and / or in effect, and can again increase the catalyst performance when the engine (and therefore the vehicle) is used in areas where stricter anti-pollution regulations are in effect.

[0013] A further object of the present invention relates to providing an exhaust gas system which is adapted to be manufactured and installed on a number of different vehicles with simple and rapid operations, thus reducing or at least limiting costs. [Means for solving the problem]

[0014] The present invention arises out of the consideration that the above outlined goals may be achieved (thus overcoming the drawbacks affecting prior art exhaust gas systems) by means of an exhaust gas system capable of deflecting exhaust gas along at least two different flow paths which result in correspondingly different catalytic performance, e.g. by providing a correspondingly different number of catalysts and / or catalysts which are of different types and / or sizes.

[0015] In view of the above considerations and taking into account the drawbacks affecting prior art exhaust gas systems together with the above outlined aims and / or objectives, according to the present invention there is provided an exhaust gas system as claimed in claim 1 and a motorcycle as claimed in claim 15, further embodiments of the system and motorcycle according to the invention being defined by the dependent claims.

[0016] Disclosed in the present application is an exhaust gas system, in particular an exhaust gas system for an internal combustion engine of a saddle-type vehicle, comprising: - a first pipe section having one or more primary catalysts disposed therein; - a second pipe section having one or more secondary catalysts disposed therein; a third pipe section having a number of catalysts disposed therein that is less than the number of catalysts disposed therein of the second pipe section; - At least one outlet for discharging exhaust gases to the atmosphere; Equipped with the first pipe section extends from a first end connectable to an outlet of the internal combustion engine and branches into the second and third pipe sections at a branch point; The exhaust gas system further includes at least one valve configured to divert exhaust gas flow from the engine from the first pipe section to one or both of the second and third pipe sections.

[0017] According to one embodiment, two of the primary catalysts are arranged inside the first line to improve pollution reduction.

[0018] According to one embodiment, two of the secondary catalysts are arranged inside the second line to further improve the reduction of pollution.

[0019] According to one embodiment, the at least one valve is a three-way valve arranged at the branch point where the first line section branches into the second line section and into a third line section for selecting a setting of the exhaust system.

[0020] According to one embodiment, the three-way valve is configured to be switched between a first operating position, in which the valve diverts the exhaust gas flow completely from the first line section to the second line section, and a second operating position, in which the valve diverts the exhaust gas flow from the first line section partially to the second line section and partially to the third line section, thus providing two preferred exhaust gas system configurations.

[0021] According to one embodiment, the valve is configured to be further switched to a third operating position in which the valve diverts the exhaust gas flow completely from the first duct section to the third duct section, thus achieving better engine performance.

[0022] According to one embodiment, the at least one valve is a butterfly valve arranged in the second pipe section and configured to be switched between a number of operating positions in order to select the most favorable setting of the exhaust gas system.

[0023] According to one embodiment, the at least one valve is a butterfly valve arranged in the third pipe section and configured to be switched between a number of operating positions in order to select the most favorable setting of the exhaust gas system.

[0024] According to one embodiment, the second pipe section further comprises a first muffler section to reduce generated noise.

[0025] According to one embodiment, the third pipe section further comprises a second muffler section to further reduce generated noise.

[0026] According to one embodiment, in order to improve the exhaust gas system from an aesthetic point of view, the first and second muffler parts are enclosed in a common casing or in respective casings.

[0027] According to one embodiment, in order to maximize noise reduction, the at least one outlet of the exhaust gas system is at the distal end of the second pipeline section or the distal end of the third pipeline section, and the second and third pipeline sections are fluidly connected to each other.

[0028] According to one embodiment, the at least one outlet of the exhaust gas system comprises two outlets corresponding to the distal ends of the second and third pipe sections, respectively, in this way the two pipe sections function as two independent exhaust gas systems.

[0029] According to one embodiment, the second duct section has a smaller cross-sectional area than the third duct section, or vice versa, in order to regulate the proportion of gas flow going to the second section and therefore reduce contamination.

[0030] According to one embodiment, the number of catalysts arranged inside the third pipe section is zero in order to use only the catalysts arranged upstream of the third pipe section.

[0031] Further disclosed in the present application is a motorcycle comprising an internal combustion engine having an outlet and an exhaust gas system according to one disclosed embodiment, the exhaust gas system being connected to the outlet for discharging an exhaust gas flow coming from the internal combustion engine.

[0032] According to one embodiment, the motorcycle comprises: - a speed sensor configured to measure a speed of the motorcycle; - a throttle position sensor configured to measure the angular position of a throttle valve; - an engine speed sensor configured to measure the number of revolutions of a crankshaft of the engine; and The exhaust gas system further comprises a control unit operatively connected to the valves of the exhaust gas system and to one or more of the sensors, such that the valves of the exhaust gas system are controlled based on parameters of engine performance, in particular parameters allowing to distinguish between regions of low performance and regions of high performance.

[0033] According to one embodiment, the control unit is adapted to issue commands to switch the valve from one operating position to another operating position depending on one or more values ​​measured by the sensor.

[0034] According to one embodiment, when a first speed threshold and / or a first angular position of the throttle valve and / or a first number of revolutions of the crankshaft is reached, said control unit is adapted to issue a command to switch the valve from a single-way operating position to a two-way operating position and vice versa, the single-path operating position is an operating position of the valve in which exhaust gas flows only through the first and second pipe sections or only through the first and third pipe sections; The two-way operating position is an operating position of the valve in which exhaust gas flows from the first line section partly through the second line section and partly through the third line section.

[0035] In this way, the performance of the vehicle can be tailored and improved.

[0036] The invention will become more apparent from the following detailed description of an embodiment of the invention as shown in the drawings, in which it is pointed out, however, that the scope of the invention is not limited to the embodiment described below and as shown in the drawings, but rather is defined by the appended claims. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 illustrates a schematic of an engine and exhaust system according to one embodiment. [Figure 1A] FIG. 4 is a schematic diagram of a second duct section of an exhaust gas system according to an embodiment; [Figure 1B] FIG. 2 is a schematic diagram of a first duct section of an exhaust gas system according to an embodiment; [Figure 1C] 5 shows a schematic diagram of a branch of a pipe section of an exhaust gas system according to a further embodiment; [Figure 1D] 5 shows a schematic diagram of a branch of a pipe section of an exhaust gas system according to a further embodiment; [Figure 1E] 5 shows a schematic diagram of a branch of a pipe section of an exhaust gas system according to a further embodiment; [Figure 1F] FIG. 4 is a schematic diagram of a third duct section of an exhaust gas system according to an embodiment; [Figure 1G] 3 shows a schematic diagram of a distal end of an exhaust gas system according to a further embodiment; FIG. [Diagram 2] 1 shows a schematic representation of a motorcycle adapted to be equipped with an exhaust gas system according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The exhaust gas system according to the invention has proven to be particularly advantageous and convenient when applied to saddle-type vehicles having one or two front steering wheels, such as motorcycles, motorbikes, scooters, etc. For this reason, in the following the exhaust gas system according to the invention is finally disclosed with particular reference to the aforementioned types of vehicles. It is pointed out, however, that the application of the exhaust gas system according to the invention is not limited to the aforementioned vehicles, but on the contrary any type of internal combustion engine may be equipped with the exhaust gas system according to the invention.

[0039] 1, an exhaust gas system according to an embodiment of the invention is shown comprising a first (or main) conduit 3 having an end 11 adapted to be connected to an exhaust gas outlet of an engine 2. The manner in which the end 17 of the first conduit part 3 is connected to the outlet of the engine 2 does not fall within the scope of the invention and therefore a detailed description thereof has been omitted for the sake of brevity.

[0040] As further shown, the first duct section 3 branches into a second duct section 4 and a third duct section 5 at a branch point 19 (see FIGS. 1A and 1B ). That is, said second duct section 4 and third duct section 5 extend from the first duct section 3 at the branch point 19. As further shown (in FIG. 1F ), the second duct section 4 and the third duct section 5 define an outlet 17 and an outlet 16, respectively, and exhaust gases come from the first duct section 3 and flow through the second duct section 4 and the third duct section 5, from where they are discharged through the outlet 17 and the outlet 16, respectively.

[0041] With reference to Figures 1A, 1B and 1F, it can be seen that catalysts 6, 6' are arranged in one or more of said first pipe section 3, second pipe section 4 and third pipe section 5. According to the embodiment shown in Figures 1A, 1B and 1F, one or two primary catalysts 6 are arranged inside the first pipe section 3, one or more secondary catalysts 6' are arranged inside the second pipe section 4 and one or none secondary catalyst 6' is arranged inside the third pipe section 5. By secondary catalyst is meant a catalyst that is arranged downstream of the primary catalyst and thus catalyzes a gas flow already catalyzed by the primary catalyst.

[0042] However, it should be noted that the number, type, size, etc. of each of the catalysts 6, 6' arranged in the first pipe section 3, the second pipe section 4, and the third pipe section 5 can be selected according to the needs and / or surrounding circumstances. For the purposes of the present invention and for reasons that will become clear below, according to at least one preferred embodiment of the exhaust gas system according to the present invention, the number of catalysts 6' arranged inside the third pipe section 5 is less than the number of catalysts 6' arranged inside the second pipe section 4. That means, according to at least one embodiment, if one catalyst 6' is arranged inside the second pipe section 4, no catalyst 6' can be arranged inside the third pipe section 5. According to at least one additional embodiment, it means that if the second pipe section 4 comprises two catalysts 6', one catalyst 6' is arranged inside the third pipe section 5. Similarly, by way of a further non-limiting example, n catalysts 6' may be disposed within the second pipe section 4, and n-1 catalysts 6' may be disposed within the third pipe section 5, respectively.

[0043] As would be expected, the catalyst in the exhaust gas system affects the performance of the engine 2, so that the catalyst may result in a situation where the power produced by the engine is too low or not enough.

[0044] However, as further anticipated, the exhaust gas system 1 according to the present invention allows one to select (even automatically, see below) the path along which the exhaust gases flow from the inlet 11 to the outlets 17 and / or 16, and thus to select the number of catalysts used (through which the gases are forced to flow), and thus to vary the amount of engine power available.

[0045] For this purpose, according to the invention, deflection means are provided for deflecting the flow of exhaust gas inside the exhaust gas system 1 .

[0046] In particular, according to the embodiment of the invention shown in Fig. 1E, the deflection means comprises a three-way valve 7A arranged inside the exhaust gas system 1, i.e. at the branch point 19 of the first duct section 3. The valve 7A can be switched between three different operating positions. In a first operating position 7A', the valve 7A closes the third duct section 5 and opens the second duct section 4, i.e. the entire gas flow coming from the first duct section 3 is deflected into the second duct section 4 and discharged through the outlet 17. In a second operating position 7A'' the valve 7A opens both the third duct section 5 and the second duct section 4, i.e. the exhaust gas flow coming from the first duct section 3 is deflected partly into the third duct section 5 and partly into the second duct section 4 and discharged either through both outlets 17 and 16 or only through outlet 16 (see below). In the third operating position 7A''', the valve 7A closes the second line section 4 and opens the third line section 5. This means that the gas flow coming from the first line section 3 is generally deflected into the third line section 5 and discharged through the outlet 16.

[0047] According to a further embodiment of the invention, shown in FIG. 1C, the deflection means comprises at least one butterfly valve 7B arranged inside the second pipe section 4, i.e. downstream with respect to the branching point 19. The butterfly valve 7B can be switched between an open first operating position 7B' and a closed second operating position 7B''. When the butterfly valve 7B is in the open position 7B', the exhaust gas coming from the first pipe section 3 flows partly into the third pipe section 5 and partly into the second pipe section 4. When the butterfly valve 7B is in the closed position 7B'' the exhaust gas coming from the first pipe section 3 can only flow into the third pipe section 5.

[0048] According to a further embodiment of the invention, shown in Fig. 1D, the deflection means comprises at least one butterfly valve 7C arranged inside the third pipe section 5, i.e. downstream with respect to the branching point 19. The butterfly valve 7C can be switched between an open first operating position 7C' and a closed second operating position 7C''. When the butterfly valve 7C is in the open position 7C', the exhaust gas coming from the first pipe section 3 flows partly into the third pipe section 5 and partly into the second pipe section 4. When the valve 7C is in the closed position 7C'' the exhaust gas coming from the first pipe section 3 can only flow into the second pipe section 4.

[0049] For clarity, it is noted that in accordance with the present invention, one or both of butterfly valves 7B and 7C may be used, and one or both of butterfly valves 7B and 7C may be used either alternatively or in addition to three-way valve 7A.

[0050] It follows from the above that by switching one or both of the butterfly valves 7B and 7C between their respective open and closed positions, and / or by switching the three-way valve 7A between its respective three operating positions, it is possible to select through which of the second and third pipe sections 4 and 5 the exhaust gases may flow, and thus through which of the catalyst or catalysts 6, if any 6'.

[0051] Further details of the exhaust gas system of the present invention can be seen in Figure 1G. As shown in Figure 1G, one or both of the second duct section 4 and the third duct section 5 may comprise a first muffler 8 and a second muffler 9, respectively, with the end of the second duct section 4 (near the outlet 17) extending through the first muffler 8 and the end of the third duct section 5 (near the outlet 16) extending through the second muffler 9.

[0052] As further shown, a first casing 10' and / or a second casing 10'' may be provided (both first casing 10' and second casing 10'' are shown in FIG. 1G), with a first muffler 8 enclosed (disposed) within the first casing 10' and / or a second muffler 9 enclosed (disposed) within the second casing 10''.

[0053] Alternatively, a common casing 10 may be provided, in which case the first muffler 8 and the second muffler 9 are both enclosed (disposed) within the common casing 10 .

[0054] Furthermore, when a common casing 10 is provided, a first solution is envisaged in which both the end or distal end of the third conduit section 5 and the end or distal end of the second conduit section 4 extend across the wall of the common casing 10, i.e. both the outlet 16 of the third conduit section 5 and the outlet 17 of the second conduit section 4 terminate directly in the atmosphere and outside the common casing 10.

[0055] Furthermore, when a common casing 10 is provided, an alternative solution is envisaged in which either the end or distal end of the third duct section 5 or the end or distal end of the second duct section 4 extends across the wall of the common casing 10 (as shown), i.e. in this case either the outlet 16 of the third duct section 5 or the outlet 17 of the second duct section 4 terminates directly in the atmosphere and outside said common casing 10.

[0056] In this last case, either the third pipe section 5 or the second pipe section 4 may be provided with a number of through holes 21 (as shown), preferably upstream of the muffler 9 or muffler 8, respectively, so that gas discharged through the outlet 17 of the second pipe section 4 either passes through the holes 21 into the third pipe section 5 (and is eventually discharged through the outlet 16 of the third pipe section), or gas discharged through the outlet 16 of the third pipe section 5 passes through the holes 21 into the second pipe section 4 (and is eventually discharged through the outlet 17 of the second pipe section).

[0057] Referring now to Figure 2, a motorcycle is identified by reference numeral 20. As shown, motorcycle 20 is equipped with a speed sensor 13 configured to measure a speed of said motorcycle, a throttle position sensor 14 configured to measure an angular position of a throttle valve, and an engine speed sensor 15 configured to measure a rotational speed of a crankshaft of the engine. Motorcycle 20 further comprises a control unit 12 operatively connected to each of said speed sensor 13, throttle position sensor 14 and engine speed sensor 15, such that instantaneous values ​​of motorcycle speed, instantaneous position of said throttle valve and instantaneous engine speed, respectively, are collected and transmitted or forwarded to said control unit 12 by said sensors 13, 14 and 15. Furthermore, the control unit 12 is also connected to one or more of the three-way valve 7A, butterfly valve 7B, and butterfly valve 7C, so that one or more of the three-way valve 7A, butterfly valve 7B, and butterfly valve 7C are switched between their respective operating positions upon receiving an impulse issued by the control unit 12.

[0058] Thus, the most favorable path for the exhaust gas flow is automatically selected based on the foreseeing conditions and / or needs. Indeed, by way of non-limiting example, if the motorcycle 2 is traveling outside of urban areas where more engine power is required and more lenient anti-pollution regulations are foreseen, an exhaust gas flow with a reduced number of catalysts 6, 6' is automatically selected. For example, the second pipe section 4 is closed and the gas flows only inside the third pipe section 5, which has less or no catalyst 6'.

[0059] Conversely, assuming by way of non-limiting example that the motorcycle 2 is traveling in an urban area where less engine power is required and stricter anti-pollution regulations are scheduled, an exhaust gas flow with an increased number of catalysts 6, 6' is automatically selected. For example, both the second duct section 4 and the third duct section 5 are opened and the exhaust gas flows both inside the third duct section 5 (where there is at least one catalyst 6') and inside the second duct section 4 (where there is less or no catalyst 6').

[0060] It should therefore be evident, using the above description of an embodiment of the invention shown in the drawings, that the invention makes it possible to overcome or at least reduce the drawbacks affecting exhaust gas systems according to the prior art.

[0061] In particular, the present invention can be used to The performance of the catalyst suite (and therefore its effect on the performance of the engine) can be adjusted in response to contingency; The effect of the catalyst set on the performance of the engine can be reduced when the engine (and therefore the vehicle) is used in areas where more engine power is required and where more lenient anti-pollution regulations are planned and / or in effect, and the performance of the catalyst can be increased again when the engine (and therefore the vehicle) is used in areas where more strict anti-pollution regulations are in effect; An exhaust gas system is provided which can be manufactured and installed on a number of different vehicles in a simple and rapid manner, thus reducing or at least limiting costs.

[0062] Although the invention has been elucidated by means of the above description of an embodiment of the invention shown in the drawings, the invention is not limited to the embodiment described above and shown in the drawings.

[0063] In this regard, it is pointed out that the embodiments described above and illustrated in the drawings should not be understood as representative of different alternative embodiments, but rather each of the disclosed embodiments is adapted to be implemented in combination with one or more of the further embodiments.

[0064] Therefore, the scope of the invention is defined by the claims.

Claims

1. An exhaust gas system (1) for an internal combustion engine (2) of a saddle-type vehicle (20), comprising: a first pipe section (3) having one or more primary catalysts (6) disposed therein; a second pipe section (4) having one or more secondary catalysts (6') disposed therein; a third pipe section (5) in which secondary catalysts (6') are arranged, the number of which is less than the number of secondary catalysts arranged in the second pipe section (4); At least one outlet (16, 17) for discharging exhaust gases to the atmosphere; Equipped with the first pipe section (3) extends from a first end (11) connectable to an outlet of the internal combustion engine (2) and branches into the second and third pipe sections (4, 5) at a branching point (19); the exhaust gas system (1) further comprises at least one valve (7) configured to divert an exhaust gas flow coming from the internal combustion engine (2) from the first duct section (3) to one or both of the second and third duct sections (4, 5); The second pipe section (4) further includes a first muffler section (8), The third pipe section (5) further includes a second muffler section (9), An exhaust gas system (1), wherein said first and second muffler parts (8, 9) are enclosed in a common casing (10) or in respective casings (10', 10'').

2. 2. The exhaust gas system according to claim 1, wherein no catalyst (6') is arranged inside the third pipe section (5).

3. 3. The exhaust gas system (1) according to claim 1 or 2, wherein two of the primary catalysts (6) are arranged inside the first pipe section (3).

4. 4. The exhaust gas system (1) according to claim 1, wherein two of the secondary catalysts (6') are arranged inside the second pipe section (4).

5. 5. An exhaust gas system (1) according to claim 1, wherein the at least one valve (7) is a three-way valve (7A) arranged at the branching point (19) where the first pipe section (3) branches into the second pipe section (4) and the third pipe section (5).

6. 6. The exhaust gas system (1) of claim 5, wherein the three-way valve (7A) is configured to be switched between a first operating position (7A') in which the valve (7A) completely deflects the exhaust gas flow from the first pipe section (3) to the second pipe section (4) and a second operating position (7A'') in which the valve (7A) deflects the exhaust gas flow from the first pipe section (3) partially to the second pipe section (4) and partially to the third pipe section (5).

7. 7. The exhaust gas system (1) of claim 6, wherein the valve (7A) is further configured to be switched to a third operating position (7A''') in which the valve (7A) completely deflects the exhaust gas flow from the first pipe section (3) to the third pipe section (5).

8. 5. An exhaust gas system (1) as claimed in any one of claims 1 to 4, wherein the at least one valve (7) is a butterfly valve (7B) arranged in the middle of the second pipe section (4) and configured to be switched between a plurality of operating positions.

9. 5. An exhaust gas system (1) as claimed in any one of claims 1 to 4, wherein the at least one valve (7) is a butterfly valve (7C) arranged in the middle of the third pipe section (5) and configured to be switched between a plurality of operating positions.

10. 10. An exhaust gas system (1) as claimed in any one of claims 1 to 9, wherein the at least one outlet (16, 17) of the exhaust gas system (1) is a distal end (17) of the second pipe section (4) or a distal end (16) of the third pipe section (5), and the second and third pipe sections (4, 5) are fluidly connected to each other.

11. 10. An exhaust gas system (1) as claimed in any one of claims 1 to 9, wherein the at least one outlet (16, 17) of the exhaust gas system (1) comprises two outlets corresponding to distal ends (16, 17) of the second and third pipe sections (4, 5), respectively.

12. 12. An exhaust gas system (1) according to any one of the preceding claims, wherein the second duct section (4) has a smaller cross-sectional area than the cross-sectional area of ​​the third duct section (5) or vice versa.

13. 13. A motorcycle (20) comprising an internal combustion engine (2) having an outlet and an exhaust gas system (1) according to one or more of claims 1 to 12, said exhaust gas system (1) being connected to said outlet for discharging an exhaust gas flow coming from said internal combustion engine (2).

14. a speed sensor (13) configured to measure the speed of the motorcycle; a throttle position sensor (14) configured to measure the angular position of the throttle valve; an engine speed sensor (15) configured to measure the rotational speed of a crankshaft of the internal combustion engine; and 14. The motorcycle (20) of claim 13, further comprising a control unit (12) operatively connected to the valve (7) of the exhaust gas system and to one or more of the sensors (13, 14, 15).

15. 15. The motorcycle (20) according to claim 14, wherein the control unit (12) is configured to issue a command to switch the valve (7) from one operating position to another operating position depending on one or more values ​​measured by the sensors (13, 14, 15).

16. said control unit (12) is adapted to issue a command for switching said valve (7) from a single-path operating position (7A', 7A''', 7B'', 7C'') to a two-path operating position (7A'', 7B', 7C') and vice versa when a first speed threshold and / or a first angular position of said throttle valve and / or a first number of revolutions of said crankshaft is reached, the single-path operating positions (7A', 7A''', 7B'', 7C'') are operating positions of the valve (7) in which the exhaust gas flows only through the first and second pipe sections (3, 4) or only through the first and third pipe sections (3, 5); 16. The motorcycle (20) according to any one of claims 14 and 15, wherein the two-way operating positions (7A'', 7B', 7C') are operating positions of the valve (7) in which the exhaust gas flows from the first pipe section (3) partly through the second pipe section (4) and partly through the third pipe section (5).

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