Title:
Fuel Cell Vehicle and Vehicle
Kind Code:
A1


Abstract:
The object of the present invention is to provide a fuel cell vehicle capable of generating running noise that does not feel unnatural based on the driving situation by noting and effectively utilizing the fact that a muffling section is provided on a gas piping line of a fuel cell system. In a fuel cell vehicle (1) in which a fuel cell system (3) equipped with a muffling section (20) on a gas piping line (5) is mounted, the muffling capability of the muffling section (20) is variable based on the driving situation of the fuel cell vehicle (1). In a low-speed driving situation, the muffling capability of the muffling section (20) is lowered. For example, the muffling section (20) has a direction control valve (24) that changes over between a muffler (21) and a bypass passage (23), based on the driving situation. The direction control valve (24) may be mechanically operated based on the gas flow speed, or its changeover operation may be controlled by means of a control device (51).



Inventors:
Aso, Shinji (Toyota-shi, JP)
Application Number:
11/660861
Publication Date:
10/25/2007
Filing Date:
09/14/2005
Primary Class:
International Classes:
F01N1/24
View Patent Images:
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Primary Examiner:
PHILLIPS, FORREST M
Attorney, Agent or Firm:
OLIFF PLC (ALEXANDRIA, VA, US)
Claims:
We claim:

1. A fuel cell vehicle in which a fuel cell system having a muffling section on a gas piping line is mounted, wherein the muffling capability of the muffling section can be lowered in a driving situation where the fuel cell vehicle runs at low speeds or in an urban area and the muffling capability of the muffling section can be increased in a driving situation where the fuel cell vehicle runs at high speeds or in a suburban area.

2. (canceled)

3. (canceled)

4. The fuel cell vehicle according to claim 1, wherein the muffling section comprises a muffler that is capable of muffling sound by introducing gas from the gas piping line, and the interior of the muffler has at least two muffling spaces of different muffling capability, and changeover means that changes over the at least two muffling spaces based on the driving situation.

5. The fuel cell vehicle according to claim 1, wherein the muffling section comprises a muffler which muffles sound by introducing gas from the gas piping line, a bypass passage that bypasses the muffler, and changeover means that changes over to either of the muffler or the bypass passage based on the driving situation.

6. The fuel cell vehicle according to claim 1, wherein the muffling section comprises at least two mufflers capable of muffling sound by introducing gas from the gas piping line, the at least two mufflers having mutually different muffling capability, and changeover means that changes over the at least two mufflers based on the driving situation.

7. The fuel cell vehicle according to any of claims 4 to 6, further comprising detection means that detects the driving situation and a control device that controls the changeover action of the changeover means based on the detection means.

8. The fuel cell vehicle according to claim 7, wherein the detection means is a flow meter that detects the gas flow rate and is provided in the gas piping line.

9. The fuel cell vehicle according to claim 7, wherein the detection means is a vehicle speedometer that detects the speed of the fuel cell vehicle.

10. The fuel cell vehicle according to claim 7, wherein the detection means detects the position of the fuel cell vehicle.

11. The fuel cell vehicle according to claim 10, wherein the detection means detects the position of the fuel cell vehicle using a GPS signal.

12. The fuel cell vehicle according to any of claims 4 to 6, further comprising a pressurizing device provided on the gas piping line, the pressurizing device delivering oxidizing gas under pressure to a fuel cell, and a control device that controls the pressurizing device based on the driving situation, wherein the control device controls the changeover action of the changeover means based on the flow rate of oxidizing gas estimated from a control instruction value supplied to the pressurizing device.

13. The fuel cell vehicle according to any of claims 4 to 6, further comprising detection means that detects the driving situation, reporting means that reports to an occupant of the vehicle the detection result obtained by the detection means, and manual control means capable of manually controlling changeover of the changeover means by manual control performed by the occupant of the vehicle.

14. The fuel cell vehicle according to any of claims 4 to 6, wherein the changeover means performs changeover mechanically based on the flow speed of gas flowing therethrough.

15. The fuel cell vehicle according to any of claims 4 to 14, wherein the changeover means is a direction control valve.

16. The fuel cell vehicle according to any of claims 4 to 15, wherein the muffler is provided on the downstream side of a fuel cell in the gas piping line.

17. The fuel cell vehicle according to claim 1, further comprising detection means that detects the driving situation and a control device that varies the muffling capability of the muffling section based on the detection means.

18. The fuel cell vehicle according to claim 17, wherein the detection means is a flow meter that detects the gas flow rate and is provided in the gas piping line.

19. The fuel cell vehicle according to claim 17, wherein the detection means is a vehicle speedometer that detects the speed of the fuel cell vehicle.

20. The fuel cell vehicle according to claim 17, wherein the detection means detects the position of the fuel cell vehicle.

21. The fuel cell vehicle according to claim 20, wherein the detection means detects the position of the fuel cell vehicle using a GPS signal.

22. The fuel cell vehicle according to claim 1, further comprising a pressurizing device provided on the gas piping line, the pressurizing device delivering oxidizing gas under pressure to a fuel cell, and a control device that controls the pressurizing device based on the driving situation, wherein the control device varies the muffling capability of the muffling section based on the flow rate of oxidizing gas estimated from a control instruction value supplied to the pressurizing device.

23. The fuel cell vehicle according to claim 1, further comprising detection means that detects the driving situation, reporting means that reports to an occupant of the vehicle the detection result obtained by the detection means, and manual control means capable of manually varying the muffling capability of the muffling section by manual control performed by the occupant of the vehicle.

24. A vehicle comprising: a drive source that generates drive energy by being supplied with gas by means of gas piping; an exhaust system that discharges gas from the drive source; and a muffling section provided in the exhaust system, wherein the muffling capability of the muffling section can be lowered in a driving situation where the fuel cell vehicle runs at low speeds or in an urban area and the muffling capability of the muffling section can be increased in a driving situation where the fuel cell vehicle runs at high speeds or in an suburban area.

Description:

BACKGROUND

The present invention relates to a fuel cell vehicle and vehicle with quiet running noise.

The running noise of an electric vehicle typified by an electric automobile is less than that of an engine vehicle in which an internal combustion engine is mounted. Pedestrians and others may therefore not notice the presence of an electric automobile running at low speed, even if this automobile is close to. Proposals have therefore been made, in view of safety aspects, to mount a simulated sound generating device that generates an engine simulation sound on an electric automobile, the simulated sound being generated from a speaker of the simulated sound generating device based on the driving situation of the electric automobile (see for example Laid-open Japanese Patent Application No. 2001-282263 (page 3 and FIG. 1) and Laid-open Japanese Patent Application No. H. 7-32948 (FIG. 1)).

Such a conventional electric automobile is useful in that the attention of for example pedestrians can be attracted by the simulated sound depending on the driving situations. However, it was necessary to install the simulated sound generating device such as a speaker separately. Also, since the sound is a simulated sound, it is different from the actual operational sound and therefore seemed unnatural to the driver and pedestrians and others.

SUMMARY

A first object of the present invention is to provide a fuel cell vehicle wherein running noise can be generated that does not seem unnatural, in accordance with the driving situation by noting and effectively utilizing the fact that a muffling section is provided on the gas piping line of a fuel cell system.

Also, another, second object of the present invention is to provide a vehicle that is capable of transmitting the proximity of the vehicle to subjects outside the vehicle by running noise that does not seem unnatural by noting and effectively utilizing the fact that a muffling section is provided on an exhaust system.

In order to achieve the first object, in a fuel cell vehicle according to the present invention in which a fuel cell system comprising a muffling section on a gas piping line is mounted, the muffling capability of the muffling section is variable based on the driving situation of the fuel cell vehicle.

With such a construction, since the muffling capability of the muffling section is varied based on the driving situation, the sound can be emitted dependent on the driving situation. In this way, by effectively utilizing the muffling section of the gas piping line that is provided in an ordinary fuel cell system, structural simplification can be achieved in that a simulated sound generating device or the like to provide a source of simulated sound becomes unnecessary and sound that does not seem unnatural dependent on the driving situation can be generated.

The fuel cell system that is mounted in the fuel cell vehicle may be a system wherein raw fuel such as natural gas is reformed on-board to fuel gas whose chief constituent is hydrogen, or may be a system wherein a high-pressure tank or occlusion alloy that stores fuel gas is mounted on-board. Fuel cells for fuel cell vehicles are chiefly of the solid polymer type, but there is of course no restriction to this and the fuel cell could be for example a phosphoric acid type fuel cell. Also, as examples of fuel cell vehicles, there may be mentioned four-wheel or two-wheel automobiles, electric trains, or bicycles. Furthermore, regarding the position of the muffling section on the gas piping line, this could be for example on the upstream side of the fuel cell or on the downstream side.

Here, “driving situation” means for example: quantitative conditions relating to driving (movement) of the fuel cell vehicle (vehicle operating conditions such as speed, acceleration, deceleration or turning condition); operating conditions (rate of generation of electricity, rate of flow of gas) of the fuel cell constituting the drive source for running of the vehicle; motor drive conditions (motor rotational speed, motor torque) of the motor that rotates the vehicle wheels; and environmental information regarding the environment in which the fuel cell vehicle is running (road surface μ, positional information such as an urban or suburb, height above sea-level, information regarding installations in the vicinity, whether there are any persons in the vicinity and whether there are any moving objects in the vicinity). Preferably the muffling capability of the muffling section is varied as below based on specific driving situations.

According to one embodiment of the present invention, the muffling section is preferably constructed such that its muffling capability can be lowered in a driving situation where the fuel cell vehicle runs at low speeds or in an urban area.

Typically, the flow rate of gas in the gas piping line drops at low speeds, so satisfactory muffling sound is achieved by a muffling section whose muffling capability does not vary. Accordingly, the amount of noise generated at low speeds can be increased by lowering the muffling capability of the muffling section as in the construction described above. In this way, it is possible to enable for example pedestrians or other users of vehicles such as bicycles to recognize the approach of the fuel cell vehicle at low speeds.

On the other hand, in typical urban areas, low-speed running may be necessitated by various circumstances such as the presence of a large number of persons such as pedestrians, congestion and reduced road width. By adopting the above construction, it is possible to make pedestrians and others aware of the approach of the fuel cell vehicle.

Accordingly, a fuel cell load is typically low during low-speed running of the fuel cell vehicle and the fuel cell load is typically high during high-speed running.

Likewise, according to one embodiment of the present invention, preferably the muffling section is constructed such that its muffling capability can be increased in a driving situation wherein the fuel cell vehicle runs at high speeds or in a suburban area.

With this construction, in contrast to the case described above, a considerable amount of noise tends to be generated by increase in the flow rate of the gas during high-speed running, but noise that is more than required can be attenuated by a muffling section of raised muffling capability. Also, no more noise that is required is generated in the suburban area where the fuel cell vehicle is surrounded by nature and there is little point in giving notice of its approach.

According to one embodiment of the present invention, preferably the muffling section comprises a muffler that is capable of muffling sound by introducing gas from the gas piping line. The interior of the muffler has at least two muffling spaces of different muffling capability, and changeover means that changes over the at least two muffling spaces based on the driving situation.

With this construction, gas that is introduced into the muffler is directed by the changeover means into one of the muffling spaces based on the driving situation. In this way, noise dependent on the driving situation can be suitably generated or attenuated. Also, since two or more muffling spaces and changeover means are provided within a single muffler, the space occupied in the fuel cell vehicle by the muffling section as a whole can be reduced.

Here, the muffler may be constituted as for example an inverted type or multi-stage expansion type muffler. For example, at least the two muffling spaces may be constructed so as to have different flow path cross-sectional area. It is also possible to adopt a construction in which the muffling capability of one of the muffling spaces is substantially zero. Also, the muffler could have a sound absorbing material such as glass wool, or could have a resonance section to attenuate the noise by resonance.

Likewise, in one embodiment of the present invention, preferably the muffling section comprises a muffler which muffles sound by introducing gas from the gas piping line, a bypass passage that bypasses the muffler, and changeover means that changes over to either of the muffler or the bypass passage based on the driving situation.

With this construction, changeover is effected by the changeover means based on the driving situation, so that gas introduced into the muffling section is introduced into the muffler or bypass passage. In this way, gas can be introduced into the muffler when muffling sound is required, as for example in the driving situation. Also, gas can be introduced into the bypass passage when generation of noise in the driving situation is required. It should be noted that taking into consideration such a specification, a muffler may be designed such as to obtain a sufficient muffling effect for the case of a large gas flow rate.

Also likewise, according to one embodiment of the present invention, preferably the muffling section comprises at least two mufflers capable of muffling sound by introducing gas from the gas piping line and having mutually different muffling capability, and changeover means that changes over the at least two mufflers based on the driving situation.

With this construction, since gas introduced into the muffling section is directed by the changeover means into one of the mufflers, depending on the driving situation, noise can be suitably generated or attenuated depending on the driving situation. Also, since no more is involved than the provision of changeover means within the muffler, excessive complication of the structure is avoided. Such a construction is advantageous in that there is considerable latitude regarding the mounting space of the muffling section.

According to an embodiment of the present invention, preferably the fuel cell vehicle further comprises detection means that detects the driving situation, and a control device that controls the changeover action of the changeover means based on the detection means.

With this construction, the control device performs control based on the driving situation, so the changeover action of the changeover means can be performed in an appropriate manner.

In this case, preferably the detection means is a flow meter that detects the gas flow rate and is provided in the gas piping line.

With this construction, since the flow rate of gas, that has a close relationship with noise in the gas piping line, is detected, noise can be generated or attenuated in an even more suitable way, dependent on the driving situation. Preferably, the flow meter is provided on the upstream side of a fuel cell on the gas piping line. Although water is generated by the gas reaction in the fuel cell, by providing the flow meter in the gas piping line on the upstream side of the fuel cell, the flow meter is not subjected to the effects of this generated water.

In a preferred embodiment of the present invention, the detection means may be a vehicle speedometer that detects the speed of the fuel cell vehicle.

With this construction, noise dependent on the speed of the fuel cell vehicle can be suitably generated or attenuated.

Also likewise, according to a preferred embodiment of the present invention, the detection means may detect the position of the fuel cell vehicle using a GPS signal.

With this construction, noise dependent on the position of the fuel cell vehicle can be suitably generated or attenuated, so the condition of the noise can be altered in for example urban areas and suburban areas. It should be noted that it would also be possible to arrange to detect the position of the fuel cell vehicle using road-to-vehicle communication or vehicle-to-vehicle communication.

Also in the above case, in a preferred embodiment of the present invention, the fuel cell vehicle further comprises a pressurizing device provided on the gas piping line that delivers oxidizing gas under pressure to a fuel cell, and a control device that controls the pressurizing device based on the driving situation. The control device may control the changeover action of the changeover means based on the flow rate of oxidizing gas estimated from a control instruction value supplied to the pressurizing device.

With this construction, noise dependent on the driving situation can be generated or attenuated in an even more suitable fashion, being based on the estimated flow rate of the oxidizing gas, which is closely related to the noise in the gas piping line. In particular, it becomes unnecessary to employ a flow rate meter or speedometer as referred to above.

Also likewise, according to a preferred embodiment of the present invention, the fuel cell vehicle further comprises detection means that detects the driving situation, reporting means that reports to an occupant of the vehicle the detection result obtained by the detection means, and manual control means capable of manually controlling changeover of the changeover means by manual control performed by the occupant of the vehicle.

With this construction, since the driving situation is transmitted to an occupant of the vehicle by the reporting means, the occupant of the vehicle can suitably alter the muffling capability using the manual control means. In this way, it is possible to make pedestrians or others aware of the approach of the fuel cell vehicle by running noise that does not seem unnatural, without the driver for example needing to use a horn or like.

It would be possible for the reporting means to report the detection result to the occupant of the vehicle audibly or visually using a display such as a lamp or a noise such as a buzzer, or reporting could even be effected using for example vibration or the sense of touch. The “occupant” of the vehicle includes not only the driver but also persons in seats other than the driver's seat of the vehicle, such as for example a co-driver.

Also likewise, in a preferred embodiment of the present invention, the changeover means of the fuel cell vehicle may perform changeover mechanically based on the flow speed of gas flowing therethrough.

With this construction, the changeover means is mechanically changed over based on the flow speed of the gas, so the muffling capability can be altered without employment of for example a sensor.

In these cases, the changeover means is preferably a direction control valve.

With this construction, muffling capability can be altered by means of a simple construction.

In an embodiment of the present invention, the muffler is preferably provided on the downstream side of the fuel cell in the gas piping line.

With this construction, the effect in terms of pressure loss of the gas with respect to the fuel cell can be reduced compared with the case where the muffler is provided on the upstream side of the fuel cell.

Also, in a preferred embodiment of the present invention (according to any of claim 1 to claim 3), the fuel cell vehicle may further comprise detection means that detects the driving situation, and a control device that varies the muffling capability of the muffling section based on the detection means.

With this construction, the control device performs control based on the driving situation, so the muffling capability of the muffling section can be altered based on the driving situation.

It is also possible for the control device to alter the muffling condition continuously. As an example of a muffling section of this type, a construction may be mentioned by way of example in which the magnitude of a variable volume chamber or degree of opening of a valve is continuously varied. In the former case, the volume may be varied using for example an electric motor. In the latter case, duty control of for example a linear electromagnetic valve or on-off electromagnetic valve may be employed.

Likewise in this case, the detection means may be a flow meter that detects the gas flow rate or may be a vehicle speedometer that detects the speed of the fuel cell vehicle. Also the detection means may detect the position of the fuel cell vehicle and for this a GPS signal or road-to-vehicle communication or vehicle-to-vehicle communication may be employed.

Likewise, according to a preferred embodiment of the present invention, the fuel cell vehicle may further comprise a pressurizing device provided on the gas piping line that delivers oxidizing gas under pressure to a fuel cell, and a control device that controls the pressurizing device based on the driving situation. The control device may vary the muffling capability of the muffling section based on the flow rate of oxidizing gas estimated from a control instruction value supplied to the pressurizing device.

With this construction, the muffling capability of the muffling section can be varied based on the driving situation, by control of the control device based on the estimated flow rate of oxidizing gas.

Likewise, according to a preferred embodiment of the present invention, the fuel cell vehicle may further comprise detection means that detects the driving situation, reporting means that reports to an occupant of the vehicle the detection result obtained by the detection means, and manual control means capable of manually varying the muffling capability of the muffling section by manual control performed by the occupant of the vehicle.

With this construction, since the driving situation is transmitted to an occupant of the vehicle by the reporting means, the occupant of the vehicle can suitably alter the muffling capability using the manual control means.

In order to achieve the above second object, in a vehicle according to the present invention comprising a drive source that generates drive energy by being supplied with gas by means of gas piping, an exhaust system that discharges gas from the drive source, and a muffling section provided in the exhaust system. The muffling capability of the muffling section is variable based on the driving situation of the vehicle.

With this construction, it is possible to emit noise dependent on the driving situation, since the muffling capability of the muffling section is varied based on the driving situation. In this way, the construction can easily be simplified since for example a simulated noise generating device or the like is not required and noise with little unnatural feeling dependent on the driving situation can be generated by effectively utilizing the muffling section that is normally provided in the exhaust system of a vehicle that generates drive energy using gas.

Here, the drive source may be a fuel cell as described above, an internal combustion engine such as a gasoline engine or diesel engine, or hydrogen internal combustion engine. Specifically, a vehicle for achieving the second object need not necessarily be a fuel cell, but could also be an engine vehicle using an internal combustion engine as the drive source for running. In the case of a hydrogen internal combustion engine, this may be used for supplementing drive of a fuel cell.

In this connection, “driving situation” means for example: quantitative conditions relating to running of the fuel cell vehicle; operating conditions of the drive source for running (for example rate of flow of gas); motor drive conditions (motor rotational speed, motor torque) of the motor that rotates the vehicle wheels; and environmental information regarding the environment in which the vehicle is running.

With a fuel cell vehicle according to the present invention as described above, by effectively utilizing the muffling section of the gas piping line, running noise that does not seem unnatural can be generated based on the driving situation.

With a vehicle according to the present invention as described above, it is possible to communicate approach of the vehicle to persons outside the vehicle by running noise that does not seem unnatural, by effectively utilizing the muffling section of the exhaust system.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the construction of a fuel cell vehicle according to a first embodiment;

FIG. 2 is a block diagram showing the construction of a detail of a fuel cell vehicle according to a second embodiment;

FIG. 3 is a block diagram showing the construction of a detail of a fuel cell vehicle according to a third embodiment;

FIG. 4 is a block diagram showing the construction of a detail of a fuel cell vehicle according to a fourth embodiment;

FIG. 5 is a block diagram showing the construction of a fuel cell vehicle according to a fifth embodiment;

FIG. 6 is a block diagram showing the construction of a fuel cell vehicle according to a sixth embodiment; and

FIG. 7 is a side view showing the construction of an engine vehicle according to a seventh embodiment.

DETAILED DESCRIPTION

Preferred embodiments of the present invention are described below with reference to the appended drawings. A characteristic feature of the present invention is that the muffling capability of a muffling section is altered and thereby various types of vehicle generate noise, which does not seem unnatural, depending on the driving situation. Hereinbelow, first of all a fuel cell automobile will be described as an example of a fuel cell vehicle. In the first to third embodiments, modified examples of the muffling section are chiefly described; in the fourth to fifth embodiment, examples of control of the muffling section are chiefly described. And in the remaining embodiments, examples of application are described. It should be noted that, in the second and subsequent embodiments, parts that are the same as in the case of the construction of the first embodiment are given the same reference symbols as in the first embodiment and further description thereof is dispensed with.

FIRST EMBODIMENT

As shown in FIG. 1, a fuel cell automobile 1 has a fuel cell system 3 that is mounted on the vehicle body 2. The fuel cell 4 in the fuel cell system 3 is linked with a drive motor, not shown, through an inverter, not shown, and the drive motor rotates a shaft, not shown. A fuel cell vehicle of this type, apart from a four wheeled fuel cell automobile 1 as shown in FIG. 1, could be a two wheeled automobile or an electric train or bicycle, for example.

The fuel cell 4 is of a stack construction, in which a large number of single cells are stacked. The fuel cell 4 generates power (drive energy) by receiving supply of air constituting oxidizing gas and hydrogen gas constituting fuel gas. There are various types of fuel cell 4, such as the phosphoric acid type, but in this case the fuel cell 4 is of the solid polymer electrolyte type. As a method for supplying hydrogen gas to the fuel cell 4, the method may be employed of reforming hydrogen gas from fuel gas such as natural gas in the vehicle body 2, or the method may be employed of mounting a high-pressure tank in which hydrogen gas is accumulated in the vehicle body 2.

A gas piping line 5 in the fuel cell system 3 has a fuel gas supply line 11 for supplying hydrogen gas to the fuel cell 4 through a regulator from for example a high-pressure tank, a fuel gas discharge line 12 for discharging hydrogen off gas from the fuel cell 4, and oxidizing gas supply line 13 for supplying oxidizing gas to the fuel cell 4, and an oxidizing gas discharge line 14 for discharging oxidizing off gas from the fuel cell 4. The fuel gas discharge line 12 merges with the oxidizing gas discharge line 14 and the hydrogen off gas merges with the oxidizing off gas and is finally discharged to outside the vehicle body 2.

The oxidizing gas supply line 13 has a compressor 17 (pressurizing device) for supplying oxidizing gas under pressure to the fuel cell 4. The compressor 17 takes in and compresses atmospheric air and supplies the air as oxidizing gas to the fuel cell 4 through a humidifier, not shown. The flow rate of the oxidizing gas that is supplied under pressure to the fuel cell 4 is adjusted by controlling the rotational speed of a motor constituting the drive source of the compressor 17. When the fuel cell 4 is under high load such as for example when the fuel cell automobile 1 runs at high speeds, there is a high flow rate of oxidizing gas. On the other hand, when the fuel cell 4 is under low load, such as for example when the fuel cell automobile 1 runs at low speeds, the flow rate of oxidizing gas is small.

The oxidizing gas discharge line 14 has a muffling section 20 that is enclosed by a broken line in FIG. 1. As will be described, the muffling section 20 is constructed so as to be capable of varying its muffling capacity based on the driving situation of the fuel cell automobile 1. Also, although not shown, the oxidizing gas discharge line 14 has a pressure regulating valve, which adjusts the pressure of the oxidizing gas in the fuel cell 4, on the upstream side of the muffling section 20, and a fuel gas discharge line 12 is connected on the downstream side of the pressure regulating valve.

The muffling section 20 has a muffler 21 into which mixed gas i.e. oxidizing off gas and hydrogen off gas is introduced and that effects muffling sound, a main flow passage 22 on which the muffler 21 is provided, a bypass passage 23 that bypasses the muffler 21, being provided in parallel with the main flow passage 22, and a direction control valve 24 that changes over the flow path of the mixed gas either to the main flow passage 22 on the side of the muffler 21 or to the bypass passage 23, based on the driving situation of the fuel cell automobile 1.

The muffler 21 may be for example of the expansion type that exhibits the muffling effect by expanding the mixed gas within the muffler 21 or may be of the inverting type that exhibits the muffling effect by inverting the mixed gas within the muffler 21. For the interior of the muffler 21, a construction may be adopted in which sound absorbing material such as glass wool is provided. The muffler 21 of this embodiment is constructed so as to be capable of muffling oxidizing off gas or mixed gas chiefly under high flow rate conditions. It should be noted that a construction could also be adopted in which the muffler 21 is directly attached to a discharge port in the direction control valve 24 on the side of the main flow of passage 22.

The upstream end of the bypass passage 23 is connected with a discharge port in the direction control valve 24 and the downstream end therein is connected on the downstream side of the muffler 21 in the main flow passage 22. The bypass passage 23 is constituted by a pipe of similar internal diameter or smaller internal diameter than the main flow passage 22. No auxiliary equipment (such as for example a filter) having a muffling action is provided in the bypass passage 23. Consequently, mixed gas passing through the bypass passage 23 is discharged to the outside from the downstream side of the main flow passage 22 without undergoing any muffling action.

The direction control valve 24 (changeover means) is constituted by a three-way valve and its supply port is connected with the main flow passage 22 on the side of the fuel cell 4. The direction control valve 24 is constituted so as to perform a mechanical changeover action in response to the flow rate of gas (specifically, mixed gas) flowing therethrough.

Specifically, when the fuel cell automobile 1 is in a high-speed driving situation in which the flow rate of mixed gas is large, the flow of the mixed gas becomes high-speed. When the flow rate of the mixed gas becomes high-speed, the direction control valve 24 is actuated to effect a mechanical changeover to the side of the muffler 21. In this way, the mixed gas is discharged to the outside through the muffler 21 and thus undergoes muffling. That is, in the case of a high-speed driving situation, the muffling capability of the muffling section 20 is increased overall.

In contrast, when the fuel cell automobile 1 is in a low-speed driving situation in which the flow rate of mixed gas is small, the flow of the mixed gas becomes low-speed. When the flow of the mixed gas becomes low-speed, the direction changeover valve 24 is actuated to effect a mechanical changeover to the side of the bypass passage 23. The mixed gas is thereby discharged to the outside through the bypass passage 23 without passing through the muffler 21. Specifically, since the mixed gas is not subjected to muffling sound in the muffling section 20, the muffling capability of the muffling section 20 in the case of a low-speed driving situation drops overall, becoming substantial zero.

As described above, with the fuel cell automobile 1 according to this embodiment, the muffling capability of the muffling section 20 is mechanically altered in response to the driving situation. Consequently, generation of noise above what is needed can be prevented when the muffling capability of the muffling section 20 is raised in high-speed running. Also, when the muffling capability of the muffling section 20 is lowered during low-speed running, gas flow noise is generated based on the flow rate of the mixed gas. Pedestrians or other vehicles such as bicycles can thereby be alerted of the approach of the fuel cell automobile 1 by its operating noise, during low-speed running.

In other words, if, contrary to the present embodiment, fully effective muffling of the gas flow noise (gas discharge noise) were to be performed even during low-speed running when the mixed gas is introduced into the muffler 21, it would be difficult to recognize the approach of the fuel cell automobile 1. In contrast, with the present embodiment, the gas discharge noise can be increased, albeit only relatively, by arranging that the mixed gas does not pass through the muffler 21 during low-speed running. It is thereby possible to alert pedestrians and others to the approach of the fuel cell automobile 1 in a suitable manner during low-speed running.

Thus, with this embodiment, even though the fuel cell automobile 1 is quiet in terms of running noise compared with ordinary engine vehicles, it is possible to emit noise corresponding to the driving situation by altering the muffling capability of the muffling section 20 based on the driving situation, by effectively utilizing the muffling section 20 of the oxidizing gas discharge line 14. In this way, it becomes unnecessary to separately provide for example a simulated noise generating device, as conventionally, thereby achieving a constructional simplification and making it possible to generate operating noise that does not seem unnatural.

It should be noted that although, in the present embodiment, the muffling section 20 is provided on the oxidizing gas discharge line 14, it would also be possible to provide the muffling section 20 on the oxidizing gas supply line 13. Of course, in view of the effect of pressure loss of the oxidizing gas delivered under pressure to the fuel cell 4 by the compressor 17, it is preferable to provide the muffler section 20 on the downstream side of the fuel cell 4 as in the present embodiment.

Also, although the fuel gas discharge line 12 is connected with the oxidizing gas discharge line 14 on the upstream side of the muffling section 20, there is of course no restriction to this position. For example, this connection position could be on the downstream side of the muffling section 20 or could be on the main flow passage 22 between the direction control valve 24 and muffling section 21. In the latter case, the direction control valve 24 performs changeover operation in response to the flow rate of oxidizing gas rather than the flow rate of mixed gas.

Also, the direction control valve 24 that functions as the changeover means may be so constituted that, rather than the gas flow speed, the gas pressure or flow rate, for example, may constitute the setting element for the changeover operation. Also, the direction control valve 24 may be constituted as a valve capable of pressure application and the direction control valve 24 may be constructed so as to perform a mechanical changeover action by applying a prescribed pressure. For example, the pressure of oxidizing gas of the oxidizing gas supply line 13, the pressure of oxidizing off gas of the oxidizing gas discharge line 14, the pressure of hydrogen gas of the fuel gas supply line 11, or the pressure of hydrogen off gas of the fuel gas discharge line 12 may be made to act on the direction control valve 24.

It should be noted that the direction control valve 24 need not be constituted so as to effect complete changeover either to the side of the muffler 21 or to the side of the bypass passage 23, but could be constructed as a distributor that distributes the flow rate of the discharged mixed gas respectively in prescribed rates to the side of the muffler 21 and to the side of the bypass passage 23. For example, it is possible for the distributor to distribute a greater flow rate of the mixed gas to the side of the bypass passage 23 rather than the muffler 21 during low-speed running, and so to distribute a greater flow rate of mixed gas to the muffler 21 rather than the bypass passage 23 in the case of high-speed running.

SECOND EMBODIMENT

Next, a fuel cell automobile 1 according to a second embodiment will be described with reference to FIG. 2, focusing on the differences with regard to the first embodiment. FIG. 2 shows a fuel cell system 3 mounted on a fuel cell automobile 1. The points of difference from the first embodiment concern the construction of the muffler section 20.

The muffling section 20 comprises a muffler 21 that is capable of muffling the noise produced by introduction of mixed gas of the oxidizing gas discharge line 14. The interior of the muffler 21 is partitioned into two muffling spaces 31a, 31b of different muffling capability. On the gas introduction side of the interior of the muffler 21, there is provided a direction control valve 24 that changes over the two muffling spaces 31a, 31b, acting as a passage for directing the mixed gas to one or other of these muffling passages. The direction control valve 24 has the same construction as in the case of the first embodiment. The direction control valve 24 is actuated mechanically based on the driving situation of the fuel cell automobile 1, to effect changeover to one of these two muffling spaces 31a, 31b.

One muffling space 31a has a muffling capability corresponding to mixed gas of large flow rate during high-speed running of the fuel cell automobile 1, to muffle this large flow rate of mixed gas so that no more noise than necessary is generated. The other muffling space 31b has a muffling capability corresponding to mixed gas of small flow rate during low-speed running of the fuel cell automobile 1. This muffling space 31b may present a function corresponding to the bypass passage 23 of the first embodiment, and may be constructed such that the muffling capability thereof is substantially zero, or may be constructed so as to effect a slight muffling.

In this way, the muffling section 20 is constructed such that, in the driving situation where the fuel cell automobile 1 runs at high speeds, the direction changeover valve 24 changes over to the side of the muffling space 31a, thereby elevating the overall muffling capability. Furthermore, the muffling section 20 is constructed such that, in the driving situation the fuel cell automobile 1 runs at low speeds, the direction changeover valve 24 changes over to the side of the muffling space 31b, thereby lowering the overall muffling capability.

It should be noted that the muffling spaces 31a, 31b exhibit their muffling function by appropriate setting of for example the magnitude (length, cross-sectional area) of their volume and the shape of their space. Construction of the muffling spaces 31a, 31b can be achieved by for example expansion molding or inversion molding and they can be suitably designed by arrangement of sound absorbing material only within the muffling space 31a, for example. Also for example the muffling space 31b may be constituted simply by a passage. In more detail, the muffling spaces 31a, 31b may be suitably set up based on the frequency band of the gas discharge noise that it is desired to muffle.

Consequently, even with the present embodiment, the muffling capability of the muffling section 20 is changed based on the driving situation where the fuel cell automobile 1 runs, so it is possible to emit a suitable operating noise based on the driving situation. In particular, in the present embodiment, since two muffling spaces 31a, 31b and a direction control valve 24 are provided within a single muffler 21, the muffling section 20 as a whole does not need to occupy much space within the fuel cell automobile 1.

It should be noted that the number of muffling spaces 31 is not restricted to two spaces and for example three spaces could be employed. In this case, these could be constituted for example by a muffling space for very low speed, a muffling space for low speed and a muffling space for use at high speeds other than these. Also, the number of ports on the discharge side of the direction control valve 24 may be increased corresponding to the increase in number of muffling spaces 31: for example in the case of three muffling spaces 31 there may be three discharge ports.

In addition, as described with reference to the first embodiment, the present embodiment may also be applied to modifications of various types of construction such as for example in regard to position of the muffling section 20 on the gas piping line 5 or a construction in which the direction control valve 24 is substituted by a distributor. In this respect, the present embodiment may also be applied to the following embodiments, where constructionally possible.

THIRD EMBODIMENT

Next, a fuel cell automobile 1 according to a third embodiment is described with reference to FIG. 3, focusing on differences from the first embodiment. FIG. 3 shows a fuel cell system 3 mounted on a fuel cell automobile 1. The points of difference with regard to the first embodiment lie in the construction of the muffling section 20.

A muffling section 20 comprises two mufflers 21a, 21b capable of introduction of mixed gas from the oxidizing gas discharge line 14 and muffling sound, and a direction control valve 24 that changes over between these two mufflers 21a, 21b.

The muffler 21a is provided on the main flow passage 22, while the muffler 21b is provided on a branch passage 41 that is provided in parallel with the main passage 22. The upstream end of the branch passage 41 is connected with the direction control valve 24, while its downstream end is connected with the downstream side of the muffler 21a of the main flow passage 22. The direction control valve 24 is mechanically actuated in the same way as in the embodiments described above based on the driving situation where the fuel cell automobile 1 runs. The direction control valve 24 changes over the flow path whereby the mixed gas is directed to the passage where either the muffler 21a or the muffler 21b is located.

The two mufflers 21a, 21b have different muffling capabilities and function in the same way as the two muffling spaces 31a, 31b of the second embodiment. Specifically, the muffler 21a on the side of the main flow passage 22 has a muffling capability corresponding to a large flow rate of mixed gas such as is obtained during high-speed running of the fuel cell automobile 1 and performs muffling of this mixed gas of large flow rate so that it generates no more than the required amount of noise. The muffler 21b on the side of the branch passage 41 has a muffling capability corresponding to a small flow rate of mixed gas such as is obtained during low-speed running of the fuel cell automobile 1 and may be constructed such that the muffling capability thereof is substantially zero, or may be constructed so as to effect a slight muffling.

Consequently, with this embodiment also, the muffling capability of the muffling section 20 is altered based on the driving situation where the fuel cell automobile 1 runs, so a suitable amount of operating noise can be emitted based on the driving situation. In the present embodiment in particular, in contrast to the second embodiment, no direction control valve 24 need be provided in the muffler 21, so the construction of the mufflers 21a, 21b can be simplified. Such a construction is useful in the case where there is a comparatively large margin regarding the space in the vehicle for mounting the muffling section 20.

It should be noted that, just as in the case of the second embodiment, the number of mufflers 21 of different muffling capability could be three or more: in this case, the number of discharge port of the direction control valve 24 may also be three or more. Also, although the downstream end of the branch passage 41 is connected with the main flow passage 22, it could of course be directly open to the outside.

FOURTH EMBODIMENT

Next, a fuel cell automobile 1 according to a fourth embodiment will be described with reference to FIG. 4, focusing on differences with respect to the first embodiment. FIG. 4 shows the control arrangement of the fuel cell automobile 1 whose main component is a fuel cell system 3. The difference from the first embodiment is that alteration of the muffling capability of the muffling section 20 is arranged to be controlled by a control device 51 (ECU).

In contrast to the embodiments described above, the direction control valve 24 of the present embodiment is not mechanically actuated for changeover in response to the flow rate of mixed gas but is connected with the control device 51, so that its changeover operation is controlled by an output signal from the control device 51. Such a direction control valve 24 may be for example of the electromagnetic valve type that is driven by a solenoid, or of an electrically operated valve type that is driven by a motor, or of the type that is driven by electricity or magnetism, such as a piezoelectric element or magnetostriction element.

Also, in the fuel cell automobile 1, a vehicle speedometer 52 on the vehicle body 2 and a flow rate meter 53 on the gas piping line 5 may be provided as detection means for detecting the driving situation of the fuel cell automobile 1. The vehicle speedometer 52 is connected with the control device 51. The speed of the fuel cell automobile 1 is measured by the vehicle speedometer 52.

The flow rate meter 53 is connected with the control device 51. Also, the flow rate meter 53 is provided on the upstream side of the compressor 17 in the oxidizing gas supply line 13. The flow rate of oxidizing gas supplied to the fuel cell 4 by the compressor 17 is measured by the flow rate meter 53.

It should be noted that, instead of this construction, the flow rate meter 53 could also be provided on the oxidizing gas discharge line 14. Of course, providing the flow rate meter 53 on the oxidizing gas supply line 13 on the upstream side of the fuel cell 4 as in the present embodiment means that the flow rate meter 53 is not subject to the effect of water generated by the fuel cell 4.

The control device 51 (ECU) performs overall control of the entire fuel cell automobile 1, including operation of the fuel cell 4. Although none of these are shown, the control device 51 comprises a CPU, a ROM that stores the control program and control data that is processed by the CPU, RAM that is chiefly employed to provide working areas of various types for the control processing, and an input/output interface, these being mutually connected via a bus. Various types of drivers that drive for example the motor of the compressor 17 and the direction control valve 24, and, in addition, various types of sensors such as the vehicle speedometer 52 and flow rate meter 53 are connected with the input/output interface.

Also, in accordance with the above construction, the CPU inputs the detection signals of the vehicle speedometer 52 and flow rate meter 53 through the input/output interface based on the control program in the ROM and processes for example various types of data in the RAM. After this, the CPU outputs control signals to the various drivers through the input/output interface and thereby controls the entire fuel cell automobile 1 so as to alter the muffling capability of the muffling section 20 based on the driving situation of the fuel cell automobile 1.

For example, the control device 51 decides from the output signal of the vehicle speedometer 52 whether or not the condition of the low-speed driving situation that the vehicle speed is no more than a threshold value is satisfied. Then, if this condition is satisfied, the control device 51 outputs a control signal to produce changeover of the direction control valve 24 to the bypass passage 23; on receipt of this, the direction control valve 24 executes changeover operation to the side of the bypass passage 23. In contrast, if the vehicle speed is larger than the threshold value, for example in high-speed driving situation, the control device 51 outputs a control signal to produce changeover of the direction control valve 24 to the muffler 21. On receipt of this signal, the direction control valve 24 then executes changeover operation to the side of the muffler 21.

Likewise, the control device 51 decides whether or not the condition that the flow rate of oxidizing gas is no more than a threshold value is satisfied, from the output signal of the flow rate meter 53. Then, if the flow rate of oxidizing gas is no more than the threshold value, the control device 51 concludes that the vehicle is in low-speed driving situation, and so outputs a control signal to produce changeover of the direction control valve 24 to the bypass passage 23. In contrast, if the flow rate of oxidizing gas is larger than the threshold value, the control device 51 concludes for example that the vehicle is in high-speed driving situation, and so outputs a control signal to produce changeover of the direction control valve 24 to the muffler 21.

Also, for example the control device 51 controls the rotational speed of the motor of the compressor 17 based on the degree of opening of the accelerator pedal or these detection means (52, 53). Specifically, the control device 51 determines the load required by the fuel cell 4 and based on the result of this determination decides what the rotational speed of the motor of the compressor 17 should be.

The control device 51 outputs a control signal to the compressor 17 based on this decision and estimates the flow rate of gas (oxidizing off gas or mixed gas) to the muffling section 20 based on this control instruction value. Also, the control device 51 controls the changeover operation of the direction control valve 24 by outputting a changeover signal to the direction control valve 24 based on this estimation.

As described above, with the fuel cell automobile 1 according to the present embodiment, the muffling capability of the muffling section 20 can be altered by changeover operation of the direction control valve 24 by the control device 51 based on the vehicle speedometer 52 or flow rate meter 53, or based on the gas flow rate estimated from the control instruction value to the compressor 17. In this way, operating noise that is even more appropriate to the driving situation of the fuel cell automobile 1 can be emitted.

It should be noted that, although the control device was described with reference to an example of application to the muffling section 20 of FIG. 1, it would of course be possible to apply this also to the muffling section 20 of FIG. 2 or FIG. 3. Also, although, as the detection means for detecting the driving situation of the fuel cell automobile 1, a vehicle speedometer 52 and flow rate meter 53 were described by way of example, there is of course no restriction to these. For example, the rotary speed of the drive motor that drives the vehicle shaft of the fuel cell automobile 1 could be detected.

FIFTH EMBODIMENT

Next, a fuel cell automobile 1 according to a fifth embodiment is described with reference to FIG. 5, focusing on the difference with regard to the first embodiment. The difference with regard to the first embodiment lies in the fact that the fuel cell automobile 1 is equipped with a control device 51 (CPU) and navigation device 61, and that alteration of the muffling capability of the muffling section 20 is arranged to be controlled with reference to the detection result obtained by the navigation device 61.

The navigation device 61 is mounted on the vehicle body 2 and receives a GPS signal, constituting position information relating to the position of the fuel cell automobile 1. The navigation device 61 is connected with the control device 51 and delivers the received GPS signal to the control device 51. Specifically, the navigation device 61 functions as detection means that detects the driving situation of the fuel cell automobile 1 by acquiring position information of the fuel cell automobile 1.

The control device 51 is constructed in the same way as in the case of the fourth embodiment, inputs a signal from the navigation device 61, and controls the changeover operation of the direction control valve 24 of the muffling section 20. Specifically, the control device 51 decides whether the fuel cell automobile 1 is running in an urban or suburban area by input from the navigation device 61.

When the control device 51 decides that the fuel cell automobile 1 is running in an urban area, the control device 51 outputs a signal to change over the direction control valve 24 to the bypass passage 23, so as to increase the running noise of the fuel cell automobile 1. Specifically, muffling capability of the muffling section 20 is lowered. In contrast, when it is decided that the automobile 1 is running in a suburban area, the control device 51 outputs a signal to change over the direction control valve 24 to the muffler 21, so that the running noise of the fuel cell automobile 1 is muffled so as not be greater than necessary: specifically, the muffling capability of the muffling section 20 is increased.

As described above, with the fuel cell automobile 1 according to the present embodiment, the muffling capability of the muffling section 20 is altered based on the driving situation in relation to the location where this automobile is traveling, so that suitable operating noise can be emitted based on whether the automobile runs in an urban area or suburban area. In this way, the running noise can be increased in urban areas where there are comparatively many pedestrians and others, so that these pedestrians and others can easily be alerted to the approach of the fuel cell automobile 1. In contrast, in suburban areas surrounded by nature where there are comparatively few pedestrians and others, no more noise than necessary is generated with the aim of alerting pedestrians and others to the approach of the fuel cell vehicle.

It should be noted that although the description was given taking as an example application to the muffling section 20 of FIG. 1, this could of course also be applied to the muffling sections 20 of FIG. 2 or FIG. 3. Also, as in the fourth embodiment shown in FIG. 4, detection means such as a vehicle speedometer 52 could be connected with the control device 51 so that the control device 51 can vary the muffling capability of the muffling section 20 taking into account both the detection result of the vehicle speedometer 52 or flow rate meter 53 and the detection result of the navigation device 61.

SIXTH EMBODIMENT

Next, a fuel cell automobile 1 according to a sixth embodiment will be described with reference to FIG. 6, focusing on the differences with regard to the first embodiment. The chief difference from the first embodiment is that the fuel cell automobile 1 comprises reporting means 71 and manual control means 72, so that alteration of the muffling capability of the muffling section 20 can be achieved by an occupant of the vehicle performing manual control in response to a report to the occupant of the vehicle (within the vehicle).

As shown in FIG. 6, in addition to the detection means 73, direction control valve 24 and compressor 17, reporting means 71 and manual control means 72 are connected with the control device 51. As shown in FIG. 4 and FIG. 5, the detection means 73 includes for example vehicle speedometer 52, flow rate meter 53 and navigation device 61: these are respectively connected with the control device 51.

The reporting means 71 is arranged so as to be capable of reporting the detection result obtained by the detection means 73 to an occupant of the vehicle. The reporting means 71 may be constituted by display means such as a lamp 81 that displays the detection result in a manner capable of being viewed by the occupant in the vehicle. Also, the reporting means 71 may be constituted by means that transmits the detection result audibly to an occupant of the vehicle, using for example a buzzer 82. Alternatively, the reporting means 71 may be constituted by means that transmits the detection result to the occupant of the vehicle by the sense of touch, such as for example slight vibration.

The manual control means 72 is constructed so as to make it possible to manually control changeover of the direction control valve 24 by manual control performed by an occupant of the vehicle. The manual control means 72 may comprise for example a key button or lever whereby an occupant of the vehicle can perform manual control. When the occupant of the vehicle operates the manual control means 72, this manual control signal is input to the control device 51, causing the control device 51 to control the changeover operation of the direction control valve 24. It should be noted that preferably the manual control means 72 is constituted so as to make it possible to adjust for example the setting of the amount of light of the lamp 81 in the reporting means 71 or the setting of the amount of sound produced by the buzzer 82.

With the construction according to the present embodiment, the driving situation of the fuel cell automobile 1 is suitably detected by the detection means 73 and this detection result is delivered to the control device 51. When the control device 51 decides from this detection result that the driving situation is for example low-speed running or urban running, it reports to that effect to the occupant of the vehicle by using the reporting means 71.

In this way, the occupant of the vehicle becomes able to select whether or not the muffling capability of the muffling section 20 should be altered, by using the manual control means 72. If the vehicle occupant wishes to lower the muffling capability of the muffling section 20, the occupant of the vehicle can then change over the direction control valve 24 by means of the control device 51 to the bypass passage 23, by operation of the manual control means 72. In this way, the occupant of the vehicle can ensure that pedestrians and others are made aware of the approach of the fuel cell automobile 1 by running noise that does not seem unnatural, without needing to use for example a horn mounted on the vehicle.

In contrast, if the control device 51 determines from the detection result that the automobile runs for example at high speeds or in a suburban area, the control device 51 exercises control such that no report is made by the reporting means 71 to the occupant of the vehicle. Of course, it would also be possible for the control device 51 to report to that effect to the vehicle occupant, using the reporting means 71.

In this way, with the fuel cell automobile 1 according to this embodiment, the vehicle occupant can suitably alter the muffling capability of the muffling section 20 by using the manual control means 72, so that suitable operating noise is emitted based on the driving situation. Here, the “occupant” of the vehicle includes not only the driver but also persons in seats other than the driver's seat of the vehicle, such as for example a co-driver.

SEVENTH EMBODIMENT

Next, an engine vehicle 91 according to a seventh embodiment is described with reference to FIG. 7. In the engine vehicle 91 of the present embodiment, an internal combustion engine 93 is mounted on the vehicle body 92. The internal combustion engine 93 (drive source), if constituted by a gasoline engine or diesel engine, is supplied with gas (mixed gas) by means of gas piping on the upstream side thereof and generates drive energy for running of the engine vehicle 91. It should be noted that the internal combustion engine 93 could also be constituted by a hydrogen internal combustion engine.

A gas exhaust system 94 for the internal combustion engine 93 has an exhaust pipe 95 for discharge to the outside of exhaust gas that is discharged from the internal combustion engine 93. The exhaust pipe 95 in the exhaust system 94 has a catalyst 96 that purifies the exhaust gas, and a muffling section 20 that muffles the discharge noise of the discharge gas, positioned on the downstream side of the catalyst 96. The major portion of this muffling section 20 is constituted comprising the construction of the muffling section 20 shown in FIG. 2. Since the construction of the muffling section 20 in FIG. 2 has already been described in the second embodiment, further description thereof is dispensed with.

Consequently, in the engine vehicle 91 of the present embodiment also, the muffling capability of the muffling section 20 is varied based on the driving situation thereof. In this case, the direction control valve 24 of the muffling section 20 is changed over so as to lower the muffling capability in a driving situation where the engine vehicle 91 runs at low speeds.

Consequently, during low-speed running, the running noise is increased. In this way, in particular when the running noise of the engine vehicle 91 is quiet, the running noise at low speeds can be increased, making it possible to alert pedestrians and others of the approach of the engine vehicle 91 with a noise that does not seem unnatural.

Also, by providing the engine vehicle 91 with a control device 51 and/or navigation device 61 as shown in FIG. 5 and subsequent Figures, it becomes possible to lower the muffling capability of the muffling section 20 even when the engine vehicle 91 is running in an urban area. Consequently, even in the case of an engine vehicle 91 whose running noise is quiet, by adoption of the construction applied in the fuel cell automobile 1 to the muffling section 20, safety in regard to pedestrians and others can be suitably guaranteed under driving situations such as at low speeds, without installing a simulated noise generating device.

It should be noted that the first to sixth embodiments could of course be suitably applied to the engine vehicle 91 of this embodiment. Description of such examples of application is dispensed with.