WO2025083954A1 - Vehicle and exhaust component - Google Patents

Abstract

This vehicle comprises a lightweight fuel gas internal combustion engine and an exhaust component. The lightweight fuel gas internal combustion engine outputs a driving force obtained by burning lightweight gas fuel that is lighter than air. The exhaust component is connected to an exhaust pipe of the lightweight fuel gas internal combustion engine. The exhaust component includes a housing that bulges at least more upward than the exhaust pipe. An unburned gas outlet connecting an upper part of an internal space of the housing to an external space at a higher position is provided in the exhaust component.

Description

Vehicle and exhaust parts

This disclosure relates to exhaust from a light-duty fuel gas internal combustion engine in a vehicle equipped with such an engine.

Patent Document 1 discloses a moving body that obtains propulsion energy by receiving a supply of gas containing hydrogen. A pipe is formed in the exhaust gas passage from the energy source to discharge water that is produced as energy is generated.

JP 2008-137505 A

The exhaust gas passage in Patent Document 1 is provided with a pipe for discharging water, but there are cases where exhaust gas is not sufficiently discharged.

This disclosure has been made in consideration of the above circumstances, and its purpose is to promote exhaust gas emissions from exhaust components in lightweight fuel gas internal combustion engines.

The problem that this disclosure aims to solve is as described above. Next, we will explain the means for solving this problem and the effects of doing so.

According to a first aspect of the present disclosure, a vehicle having the following configuration is provided. That is, the vehicle includes a lightweight fuel gas internal combustion engine and an exhaust component. The lightweight fuel gas internal combustion engine outputs a driving force obtained by burning a lightweight gas fuel that is lighter than air. The exhaust component is connected to an exhaust pipe of the lightweight fuel gas internal combustion engine. The exhaust component includes a housing that bulges at least upward from the exhaust pipe. The exhaust component is provided with an unburned gas outlet that connects an upper portion of the internal space of the housing to an external space at a higher position.

According to a second aspect of the present disclosure, there is provided an exhaust part having the following configuration. That is, this exhaust part is used in a vehicle equipped with a lightweight fuel gas internal combustion engine that outputs driving force obtained by burning a lightweight gas fuel that is lighter than air. The exhaust part is connected to an exhaust pipe of the lightweight fuel gas internal combustion engine. The exhaust part has a housing that bulges at least upward from the exhaust pipe. The exhaust part is provided with an unburned gas outlet that connects an upper portion of the internal space of the housing to an external space at a higher position.

As a result, the unburned gas contained in the gas discharged from the internal combustion engine moves from the exhaust pipe to the upper space inside the housing due to the buoyancy effect. The unburned gas inside the housing moves out of the housing through the unburned gas outlet. This can promote the discharge of exhaust gas from exhaust components, for example, the housing, via the unburned gas outlet. By promoting exhaust in this way, it can, for example, prevent exhaust containing unburned gas from remaining inside the housing.

The present disclosure can promote the discharge of exhaust gas from exhaust components in a lightweight fuel gas internal combustion engine.

1 is a side view showing an overall configuration of a motorcycle according to an embodiment of the present disclosure; FIG. 1 is a perspective view showing a muffler according to a first embodiment. FIG. 6 is a perspective view showing a muffler according to a second embodiment. FIG. 11 is a perspective view showing a muffler according to a third embodiment. FIG. 13 is a perspective view showing a muffler according to a fourth embodiment. FIG. 13 is a schematic diagram showing a muffler according to a fifth embodiment. FIG. 13 is a schematic diagram showing a muffler according to a sixth embodiment.

Next, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a side view showing the overall configuration of a motorcycle 1 according to one embodiment of the present disclosure. FIG. 2 is a perspective view showing a muffler 23 of the first embodiment.

The motorcycle (saddle-type vehicle, vehicle) 1 of this embodiment includes a frame 3, a front wheel 6, a rear wheel 7, and a steering wheel 8. The frame 3, the front wheel 6, the rear wheel 7, and the steering wheel 8 form part of the vehicle body 2.

The driver drives the motorcycle 1 while straddling the body 2. In the following explanation, unless otherwise specified, front, rear, left, and right mean the front, rear, left, and right as seen by the driver while riding the motorcycle 1. The left-right direction corresponds to the vehicle width direction, and the front-rear direction corresponds to the vehicle length direction.

The frame 3 is a strength component that forms the skeleton of the body 2, and is made of, for example, metal pipes. The frame 3 supports the engine (lightweight fuel gas internal combustion engine) 22, which serves as the drive source for propelling the motorcycle 1.

The engine 22 functions as a power unit that drives the rear wheels 7, which are driving wheels. The engine 22 burns lightweight gas fuel to rotate a crankshaft (not shown) and obtain power. In this specification, lightweight gas means a gas that is lighter per unit volume than air at room temperature. In this embodiment, hydrogen is used as the fuel for the engine 22, but light gases such as methane and ammonia may also be used. The number of cylinders in the engine 22 is arbitrary, but in this embodiment, a multiple-cylinder engine 22 is used. The driving force generated by the engine 22 is changed in speed by a transmission (not shown) and transmitted to the rear wheels 7 via the drive chain 12.

A seat 14 on which the driver sits is provided at the top of the vehicle body 2. A steering wheel 8 operated by the driver is provided at the top front of the vehicle body 2.

A head pipe 15 is provided at the front of the frame 3. A front wheel 6 is supported on the head pipe 15 via a front fork 16. The rider can turn the front wheel 6 by operating a steering handle 8. A swing arm 17 is supported at the bottom of the central front-rear part of the frame 3 so as to protrude rearward. The rear wheel 7 is rotatably supported at the tip of the swing arm 17.

A gas tank 21 is attached to the rear of the frame 3. Hydrogen gas, which is a fuel, is stored in a compressed state in the gas tank 21. In this embodiment, a pair of gas tanks 21 are provided on the left and right, but the number of gas tanks 21 is arbitrary. Each gas tank 21 is formed in a cylindrical shape and is arranged with its axial direction facing the front-to-rear direction. A fuel supply pipe 26 is connected to the gas tank 21 via a valve device (not shown). Hydrogen gas is supplied from the gas tank 21 to the engine 22 via the fuel supply pipe 26.

A tank cover 25 is attached to the frame 3 so as to cover the gas tank 21. The tank cover 25 is hollow and protects the internal gas tank 21 from external impacts.

Depending on the layout of each part of the vehicle body 2, other vehicle-mounted parts may be placed above exhaust parts such as the muffler 23 described below, and these vehicle-mounted parts may have recesses that are open downward and recessed upward. Examples of places where such recesses are formed include, but are not limited to, the underside of the rear cowl, the bottom surface of the pannier case, and the underside of the tank cover 25. Figure 1 shows an example in which a non-penetrating recess 30 is formed on the underside of the tank cover 25.

The recess may be formed as a through hole formed in the underside of a hollow member. Examples of hollow members include, but are not limited to, a tank cover, a rear cowl, a seat cowl, or a pannier case. In this case, the upper part of the internal space of the hollow member is closed, and this internal space is connected to the lower space via the aforementioned through hole. A small gap may be formed in the hollow member to connect the internal space to the upper space.

A muffler 23, which is an example of an exhaust component, is disposed on one of the left and right sides of the rear wheel 7. The muffler 23 is connected to the engine 22 via an exhaust pipe 27. Exhaust gas generated by burning hydrogen gas in the engine 22 is discharged to the outside via the exhaust pipe 27 and the muffler 23. A sound-absorbing structure is configured inside the muffler 23, which reduces the exhaust noise generated when the exhaust gas is discharged to the outside. In this way, the muffler 23 functions as an exhaust sound-absorbing device.

Inside the muffler 23, an expansion chamber is formed in which the exhaust gas expands compared to the connected exhaust pipe 27. In this expansion chamber, the cross-sectional area in the direction perpendicular to the direction in which the exhaust gas flows is larger than that of the upstream exhaust pipe 27. As the exhaust gas expands inside the muffler 23, the energy of the exhaust gas is consumed, and as a result, the exhaust noise is silenced. The expansion chamber may be configured so that expansion is repeated multiple times in the muffler 23, or a resonance structure or sound-absorbing structure may be used in combination.

The muffler 23 includes a hollow housing 41. The housing 41 is configured, for example, in an elongated shape, and is arranged so that its longitudinal direction is generally along the front-to-rear direction in a plan view. The housing 41 is located below one of the pair of tank covers 25 arranged on the left and right.

As shown in FIG. 2, the exhaust pipe 27 is inserted from the front into the front part of the housing 41. In FIG. 2, the internal structure of the housing 41 is omitted. An exhaust inlet 43 is formed at the rear end of the exhaust pipe 27. The exhaust pipe 27 is connected to the internal space 42 of the housing 41 through the exhaust inlet 43. The axis of the exhaust pipe 27 is inclined upward as it approaches the exhaust inlet 43. An outlet pipe 44 is connected to the rear end of the housing 41, and an exhaust outlet 45 is formed at the rear end of this outlet pipe 44. Exhaust gas introduced from the exhaust pipe 27 into the internal space 42 of the housing 41 through the exhaust inlet 43 flows rearward and is discharged from the exhaust outlet 45 of the outlet pipe 44.

An expansion chamber (sound-absorbing chamber) is formed inside the housing 41. Therefore, the housing 41 is formed with an outer diameter larger than the exhaust pipe 27 and also larger than the outlet pipe 44. As a result, the housing 41 and its internal space 42 expand at least one way above, below, left, or right from either the exhaust pipe 27 or the outlet pipe 44. In other words, the exhaust pipe 27 and the outlet pipe 44 are recessed toward the center position of the housing 41 relative to the housing 41. Specifically, the upper surfaces of the exhaust pipe 27 and the outlet pipe 44 are positioned lower than the upper surface of the housing 41.

Sound-absorbing material such as metal wool or glass wool may be placed in the internal space 42 of the housing 41.

In this embodiment, a guide pipe 46 is provided at the upper rear of the housing 41 in addition to the outlet pipe 44. The guide pipe 46 is arranged so as to protrude diagonally upward and rearward from the housing 41. A gas vent passage (exhaust passage) 47 is formed inside the guide pipe 46. An unburned gas outlet 48 is formed at the end of the guide pipe 46 farther from the housing 41. The unburned gas outlet 48 is located at the downstream end of the gas vent passage 47. The gas vent passage 47 and the unburned gas outlet 48 are provided so as to connect the upper part (preferably the top) of the internal space 42 of the housing 41 to the external space at a higher position.

In this embodiment, the unburned gas outlet 48 is formed with a smaller passage cross-sectional area than the exhaust outlet 45. The guide pipe 46 protrudes upward from the upper surface of the housing 41. More specifically, the guide pipe 46 protrudes upward from the top surface of the housing 41.

In a motorcycle 1 equipped with a hydrogen gas engine 22, unburned hydrogen gas may be exhausted from the engine 22 and introduced into the muffler 23 through the exhaust pipe 27. If hydrogen gas remains in the internal space 42 of the housing 41 in which the muffler 23 is mounted, the hydrogen gas may burn within the muffler 23, causing abnormal noise. In this regard, in this embodiment, hydrogen gas, which is lighter than air, is promoted to be exhausted from the upper part of the internal space 42 of the housing 41 through the unburned gas outlet 48. This makes it possible to prevent unburned hydrogen gas from remaining in the muffler 23 and to prevent malfunctions caused by such retention.

The ceiling surface of the inner wall surfaces constituting the internal space 42 of the housing 41 is inclined from the horizontal so that the downstream side in the direction of exhaust gas flow is higher. For reference, a horizontal imaginary plane H1 is shown in FIG. 2. With this inclined arrangement, the unburned hydrogen gas in the internal space 42 flows rearward along the ceiling surface. Therefore, it can be said that the vicinity of the upper rear end of the internal space 42 is a retention portion where unburned hydrogen gas is likely to remain. The unburned gas outlet 48 is configured to guide unburned hydrogen gas from the upper rear end (the retention portion described above) of the internal space 42 of the housing 41 to the external space. Therefore, it is possible to effectively prevent unburned hydrogen gas from remaining in the upper part of the rear end portion of the housing 41. As in the third embodiment described below, the ceiling surface of the inner wall surfaces of the housing 41 may be arranged substantially horizontally.

The opening area of the exhaust outlet 45 is larger than the opening area of the unburned gas outlet 48. This prevents the unburned hydrogen gas from accumulating while preventing the flow resistance of the exhaust outlet 45 from becoming excessive.

In this embodiment, the tank covers 25 are arranged in a pair on the left and right. Therefore, the bottom surface 32 of the tank cover 25 arranged on one of the left and right sides and the unburned gas outlet 48 of the muffler 23 may be arranged so as to roughly correspond in the vertical direction. In this case, unburned hydrogen gas discharged from the unburned gas outlet 48 may enter the recess 30 of the bottom surface 32 from below, or enter the internal space of the tank cover 25 from below through a through hole from the bottom surface 32, and may remain there for a long time.

To prevent this, as shown in Figure 1, a guide portion 51 is disposed above the unburned gas outlet 48. The guide portion 51 is, for example, a plate-shaped member, and is disposed so as to block the gap between the unburned gas outlet 48 and the tank cover 25. This can guide the unburned hydrogen gas so that it does not enter the recess 30 on the underside of the tank cover 25 or the inside of the tank cover 25, thereby preventing the unburned hydrogen gas from accumulating in the tank cover 25. In the example of Figure 1, the guide portion 51 is attached to the frame 3, but it may also be attached, for example, to the top of the muffler 23 or the bottom of the tank cover 25.

As described above, the motorcycle 1 of this embodiment includes the engine 22 and the muffler 23. The engine 22 outputs driving force obtained by burning hydrogen gas fuel, which is lighter than air. The muffler 23 is connected to the exhaust pipe 27 of the engine 22. The muffler 23 includes a housing 41 that bulges at least upward from the exhaust pipe 27. The muffler 23 is provided with an unburned gas outlet 48 that connects the upper part of the internal space 42 of the housing 41 to an external space at a higher position.

As a result, the unburned hydrogen gas can be discharged from the unburned gas outlet 48 by the buoyancy of the unburned hydrogen gas without stagnation within the housing 41 of the muffler 23. Therefore, while the motorcycle 1 is in operation, the discharge of unburned hydrogen gas in the muffler 23 is promoted, and stagnation within the muffler 23 can be prevented.

In the motorcycle 1 of this embodiment, the muffler 23 has a gas vent passage 47 that is connected to the internal space 42. The gas vent passage 47 is inclined so that it slopes upward as it advances downstream in the exhaust direction. The unburned gas outlet 48 is located at the downstream end of the gas vent passage 47.

This allows the unburned hydrogen gas to be smoothly guided to the unburned gas outlet 48 and discharged using the inclined gas vent passage 47.

In this embodiment, the ceiling surface of the inner wall surface that forms the internal space 42 of the housing 41 is inclined so that it becomes higher as it approaches the rear. The unburned gas outlet 48 connects the upper part of the ceiling surface to the external space.

This allows gas that tends to accumulate near the ceiling surface of the housing 41 to be collected at the unburned gas outlet 48 and effectively discharged.

In the motorcycle 1 of this embodiment, the muffler 23 has an exhaust outlet 45 that discharges exhaust gas introduced into the muffler 23. The exhaust outlet 45 is formed in a position different from the unburned gas outlet 48.

As a result, the unburned gas outlet 48 is provided separately from the exhaust outlet 45, which mainly exhausts post-combustion gas, making it possible to realize appropriate outlets for each, taking into account the differences in the characteristics of the exhausted gas.

In the motorcycle 1 of this embodiment, the opening area of the exhaust outlet 45 is larger than the opening area of the unburned gas outlet 48.

This reduces the flow resistance of the combustion gas at the exhaust outlet 45, maintaining exhaust performance while preventing the accumulation of unburned hydrogen gas.

In the motorcycle 1 of this embodiment, a guide portion 51 is provided above the unburned gas outlet 48 to guide the unburned hydrogen gas that flows out from the unburned gas outlet 48 into the external space of the housing 41.

This makes it possible to prevent the unburned hydrogen gas discharged from the unburned gas outlet 48 from remaining in a specific location on the motorcycle 1.

In the motorcycle 1 of this embodiment, the internal space 42 of the housing 41 is a sound-absorbing chamber that reduces the exhaust noise of the engine 22.

This prevents unintentional combustion of unburned hydrogen gas in the muffler 23.

Next, a second embodiment will be described with reference to FIG. 3. In the following description of this embodiment, the same or similar components as those in the previous embodiment will be denoted by the same reference numerals in the drawings, and descriptions thereof may be omitted.

In the muffler 23a of this embodiment shown in FIG. 3, the aforementioned outlet pipe 44 and exhaust outlet 45 are omitted. The guide pipe 46 is configured with a large diameter equivalent to that of the outlet pipe 44 of the first embodiment. In this embodiment, the unburned gas outlet 48 formed in the guide pipe 46 serves both as an outlet for burned exhaust gas and an outlet for unburned hydrogen gas.

Even with this configuration, unburned hydrogen gas remaining in the internal space 42 of the housing 41 can be smoothly discharged from the unburned gas outlet 48.

Next, the third embodiment will be described with reference to Figure 4.

In the muffler 23b of this embodiment shown in Figure 4, the housing 41 is disposed substantially horizontally. Therefore, among the inner wall surfaces that form the internal space 42 in the housing 41, the ceiling surface is almost horizontal. In Figure 4, the housing 41, the guide tube 46, etc. are drawn see-through with dashed lines to explain the inside of the housing 41.

Two ring-shaped partitions 49 are provided to divide the internal space 42 of the housing 41 into multiple spaces in the longitudinal direction. The longitudinal direction of the housing 41 can also be said to be the direction in which the exhaust flows in the muffler 23b. Each partition 49 is disposed outside the outlet pipe 44, which is disposed elongated as described below. The number of partitions 49 into which the internal space 42 is divided is arbitrary, but in this embodiment, the internal space 42 is divided into three spaces. Below, the three spaces may be referred to as the first space 42a, the second space 42b, and the third space 42c, starting from the front. Dividing the internal space 42 unequally is preferable because it can effectively suppress noise over a wide range of frequencies.

A guide pipe 46 is provided on the upper surface of the housing 41. A gas vent passage 47 formed in the guide pipe 46 forms an opening in the ceiling surface of the longitudinal center of the housing 41. Therefore, the gas vent passage 47 is connected to the second space 42b located in the longitudinal center of the housing 41, among the three spaces divided by the partition 49.

In the muffler 23b of this embodiment, the outlet pipe 44 extends forward through the partition 49 and is directly connected to the exhaust pipe 27. A large number of small through holes are formed in the portion of the outlet pipe 44 that is located in the internal space 42 of the housing 41.

Each partition 49 is arranged to form a gap (flow passage) 50 between it and the ceiling surface. This gap 50 connects the partitioned spaces together. As a result, the flow of unburned hydrogen gas that has been introduced into the housing 41 and floated near the ceiling surface is not blocked by the partitions 49, so that the unburned hydrogen gas can be smoothly guided to the unburned gas outlet 48. In the example of FIG. 4, the gap 50 is configured by forming a flat recess in the top of the circular outer edge of the partition 49. However, the configuration of the flow passage is not limited to this, and for example, a circular through hole for circulating unburned hydrogen gas may be formed in the upper part of the partition 49.

As described above, in the motorcycle 1 of this embodiment, the internal space 42 of the housing 41 is divided into a plurality of spaces (first space 42a, second space 42b, and third space 42c) by partitions 49. The unburned gas outlet 48 is connected to the upper part of the second space 42b, which is located in the longitudinal center of the housing 41, among the plurality of spaces. A gap 50 is formed at the upper part of the partition 49 located between adjacent spaces, connecting the divided spaces to each other.

This allows the unburned hydrogen gas in each of the multiple partitioned spaces to be efficiently discharged from the unburned gas outlet 48.

Next, the fourth embodiment will be described with reference to FIG. 5.

In the muffler 23c of this embodiment shown in FIG. 5, the aforementioned outlet pipe 44 and exhaust outlet 45 are omitted. As in the third embodiment, the internal space 42 of the housing 41 is divided by two partitions 49, forming a first space 42a, a second space 42b, and a third space 42c.

The exhaust inlet 43, which is the downstream end of the exhaust pipe 27, is located in the first space 42a, which is the forward-most space of the three spaces. The rear end of the housing 41 is closed.

A cylindrical first passage tube 53 is arranged inside the housing 41 so as to pass through the two partitions 49. One opening of the first passage tube 53 is located in the first space 42a, and the opening on the opposite side is located in the third space 42c.

A cylindrical second passage tube 54 is disposed inside the housing 41 so as to pass through the partition 49 located between the second space 42b and the third space 42c. One opening of the second passage tube 54 is located in the third space 42c, and the opposite opening is located in the second space 42b.

A guide pipe 46 having the same configuration as in the third embodiment is provided on the upper surface of the housing 41. The guide pipe 46 is formed with a gas vent passage 47 and an unburned gas outlet 48. The gas vent passage 47 is connected to the second space 42b.

In this embodiment, the exhaust gas flowing through the exhaust pipe 27 is first introduced into the first space 42a. The exhaust gas from the first space 42a passes through the first passage pipe 53 and flows into the third space 42c. The exhaust gas from the third space 42c reverses its flow direction and flows into the second space 42b via the second passage pipe 54. As the exhaust gas flows through each space, the energy of the exhaust gas is attenuated, providing a silencing effect. Finally, the exhaust gas from the second space 42b passes through the gas vent passage 47 and is discharged to the outside of the housing 41.

In this manner, in this embodiment, as in the third embodiment, the unburned gas outlet 48 formed in the guide pipe 46 serves both as an outlet for burned exhaust gas and an outlet for unburned hydrogen gas.

In this embodiment, as in the third embodiment, a gap 50 is formed at the top of each partition 49. Therefore, unburned hydrogen gas remaining in the internal space 42 of the housing 41 can be smoothly discharged from the unburned gas outlet 48.

Next, the fifth embodiment will be described with reference to FIG. 6.

In the muffler 23d of this embodiment shown in Figure 6, the guide pipe 46 is omitted. A gas vent hole 52 is formed through the rear part of the upper surface of the housing 41. The gas vent hole 52 essentially functions as a short exhaust flow path. In this way, the unburned gas outlet can also be the outlet of a through hole simply formed in the housing 41.

Next, the sixth embodiment will be described with reference to FIG. 7.

In the muffler 23e of this embodiment shown in FIG. 7, an on-off valve 55 is disposed midway through the aforementioned gas vent passage 47. This on-off valve 55 is configured as, for example, a solenoid valve.

The on-off valve 55 is electrically connected to the control device 56. The control device 56 is a known computer equipped with a CPU, ROM, RAM, etc. The control device 56 may be realized by the same hardware as the ECU equipped in the motorcycle 1, or may be realized by different hardware.

As an example, the control device 56 monitors the traveling speed of the motorcycle 1, and controls the on-off valve 55 to close when the body 2 is substantially stopped, and to open when the body 2 is traveling. Information on the traveling speed can be obtained based on the detection results of a wheel speed sensor 57 provided on either the front wheel 6 or the rear wheel 7. However, this is not limited to this, and information on the traveling state of the body 2 can be obtained, for example, from an IMU sensor arranged at an appropriate position on the body 2. IMU is an abbreviation for inertial measurement unit.

When the motorcycle 1 is traveling, the area around the body 2 is usually open, but when the motorcycle 1 is stopped, the body 2 may be in a closed, narrow space, such as indoors. In this case, the control device 56 controls the on-off valve 55 to close. This makes it possible to prevent unburned hydrogen gas from being released into a closed space.

The control of opening and closing of the on-off valve 55 is not limited to the above, and can be performed by detecting various conditions of the vehicle body 2 and the engine 22. For example, the control device 56 can be configured to switch the opening and closing of the on-off valve 55 in response to the driver operating an operating switch provided on the steering wheel 8.

The on-off valve 55 can be placed anywhere in the gas vent passage 47. For example, the on-off valve 55 can be placed at the connection between the internal space 42 of the housing 41 and the gas vent passage 47, at a midway point in the gas vent passage 47, or at the unburned gas outlet 48.

The on-off valve 55 is not limited to being electrically operated (e.g., a solenoid valve) and can also be configured as a manually operated on-off valve.

As described above, in the motorcycle 1 of this embodiment, the gas vent passage 47 that connects the unburned gas outlet 48 and the internal space 42 of the housing 41 can be opened and closed.

As a result, for example, by allowing the discharge of unburned hydrogen gas from the unburned gas outlet 48 only when the motorcycle 1 is traveling, it is possible to prevent the unburned hydrogen gas discharged from the unburned gas outlet 48 from floating around the motorcycle 1 for a long period of time.

The motorcycle 1 of this embodiment includes an on-off valve 55 and a control device 56. The on-off valve 55 opens and closes the flow path connecting the unburned gas outlet 48 and the internal space 42. The control device 56 controls the opening and closing of the on-off valve 55 depending on the running state of the vehicle body 2.

This allows the emission of unburned hydrogen gas to be controlled depending on the situation.

The above describes a preferred embodiment of the present disclosure, but the above configuration can be modified, for example, as follows. A single modification may be made, or multiple modifications may be made in any combination.

Instead of the ceiling surface, an opening may be provided on the upper part of the rear surface of the inner wall surface of the housing 41 that constitutes the internal space 42. In this case, the guide pipe 46 can be provided so as to protrude rearward from the upper part of the rear end surface of the housing 41, and the above opening and the unburned gas outlet 48 can be connected by a gas vent passage 47.

In the first, second and fifth embodiments, the ceiling surface of the housing 41 may be arranged horizontally without being inclined.

The partition 49 shown in the third embodiment may be applied to the first embodiment. In this case, the outlet pipe 44 and the guide pipe 46 are each provided to connect the downstream end (rearmost) space of the multiple spaces divided by the partition 49 in the internal space 42 of the housing 41 to the outside. The partition 49 may be applied to the second or fifth embodiment.

In the third and fourth embodiments, the gas vent passage 47 may be connected to any of the multiple spaces divided by the partitions 49.

The housing 41 may be shaped to bulge, for example, only upward with respect to the exhaust pipe 27 or the outlet pipe 44.

The opening area of the exhaust outlet 45 may be smaller than the opening area of the unburned gas outlet 48. The two opening areas may be equal.

The guide portion 51 may be omitted.

The unburned gas outlet 48 may be connected to the engine 22 to return the unburned light gas to the intake side of the engine 22.

The inner wall surfaces of the housing 41, particularly the ceiling surface, may be made of a material that has the function of suppressing hydrogen embrittlement, or may be coated with such a material.

The unburned light gas exhaust structure described in each embodiment may be applied to exhaust parts with a large cross-sectional area of the exhaust passage, and may also be applied to exhaust parts other than the muffler, such as a secondary silencer provided upstream of the muffler. For example, in the case of a motorcycle, the unburned light gas exhaust structure may be applied to an exhaust chamber located in the space between the rear wheel and the body frame in the fore-and-aft direction.

Some vehicles are equipped with multiple silencers, such as both a muffler and a secondary silencer. In this case, an unburned gas outlet may be formed in both silencers, or an unburned gas outlet may be formed in only one of the silencers. If an unburned gas outlet is provided in only one of the silencers, it is preferable that the unburned gas outlet be formed in the silencer downstream, where the exhaust flow rate is relatively slow. This can promote the discharge of unburned gas that accumulates due to the slow flow rate.

The above-mentioned unburned light gas exhaust structure may be used in a sound deadening structure that utilizes Helmholtz-type resonance. In this case, an unburned gas outlet may be formed in the upper wall of the resonance chamber.

Catalysts that utilize an oxidation-reduction reaction are sometimes used as exhaust components to purify nitrogen oxides (NOx), which are formed when nitrogen contained in the air is oxidized by the combustion of a fuel mixture. In order to improve purification performance, the catalyst may be formed with a larger passage cross-sectional area than the exhaust passage upstream of the catalyst. In this configuration, the unburned gas outlet described in each of the above embodiments may be formed in the space that houses the catalyst, or in another space that communicates with that space. This promotes the discharge of unburned gas in the catalyst space, and makes it possible to suppress unburned gas remaining in the catalyst space.

The above-mentioned unburned lightweight gas emission structure can be applied not only to two-wheeled motor vehicles 1 (saddle-type vehicles, lean vehicles), but also to a wide range of vehicles such as three-wheeled vehicles, four-wheeled vehicles, ships, and aircraft. Vehicles include moving objects that move without a human on board.

The application of the unburned lightweight gas exhaust structure disclosed herein is not limited to mobile objects. In other words, this unburned lightweight gas exhaust structure can be applied to exhaust parts of a fixed lightweight fuel gas internal combustion engine. For example, the unburned lightweight gas exhaust structure may be applied to exhaust parts provided on a power generation device or an internal combustion engine as a hydraulic drive device that does not have a mobile propulsion source.

Claims (11)

a lightweight fuel gas internal combustion engine that outputs a driving force obtained by burning a lightweight gas fuel that is lighter than air;
an exhaust component connected to an exhaust pipe of the light fuel gas internal combustion engine;
A vehicle comprising:
The exhaust component includes a housing that extends at least upwardly beyond the exhaust pipe,
A vehicle, wherein the exhaust component is provided with an unburned gas outlet that connects an upper portion of the interior space of the housing with a higher exterior space. 2. The vehicle of claim 1,
The exhaust component includes an exhaust passage connected to the internal space,
The exhaust flow path is inclined upward as it proceeds downstream in the exhaust direction,
The unburned gas outlet is disposed at a downstream end of the exhaust flowpath. 2. The vehicle of claim 1,
In the housing, a ceiling surface of an inner wall surface that defines the internal space is inclined,
The unburned gas outlet is connected to an upper portion of the ceiling surface. 2. The vehicle of claim 1,
the exhaust component includes an exhaust outlet for discharging exhaust gas introduced into the exhaust component;
The exhaust outlet is formed at a different location from the unburned gas outlet. 5. A vehicle as claimed in claim 4,
The opening area of the exhaust outlet is larger than the opening area of the unburned gas outlet. 2. The vehicle of claim 1,
The unburned gas outlet or a flow path connecting the unburned gas outlet and the internal space is openable and closable. 7. A vehicle as claimed in claim 6,
an on-off valve that opens and closes the unburned gas outlet or a flow path that connects the unburned gas outlet and the internal space;
a control device that controls the opening and closing of the on-off valve in response to at least one of the conditions of the lightweight fuel gas internal combustion engine and the vehicle body;
A vehicle equipped with: 2. The vehicle of claim 1,
The internal space of the housing is divided into a plurality of spaces by partitions,
The unburned gas outlet is connected to an upper portion of any one of the plurality of spaces,
A vehicle, wherein a flow passageway connecting the partitioned spaces is formed in an upper portion of the partition located between adjacent spaces. 9. A vehicle as claimed in claim 8,
A guide portion is provided above the unburned gas outlet, for guiding the unburned gas that has flowed out from the unburned gas outlet into the external space. 2. The vehicle of claim 1,
The interior space of the housing is a sound-absorbing chamber that reduces exhaust noise from the light fuel gas internal combustion engine. An exhaust part for use in a vehicle equipped with a lightweight fuel gas internal combustion engine that outputs a driving force obtained by burning a lightweight gas fuel that is lighter than air, the exhaust part being connected to an exhaust pipe of the lightweight fuel gas internal combustion engine,
a housing that bulges at least upward from the exhaust pipe,
An exhaust component having an unburned gas outlet formed therein that connects an upper portion of the interior space of the housing with an exterior space at a higher position.

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