Exhaust device of fuel cell vehicle

To achieve smooth drawing of air into a fuel cell, the air-flow resistance of an exhaust passage is reduced and intrusion of water into an exhaust duct is prevented. In the present invention, in an exhaust device of a fuel cell vehicle, an exhaust chamber is attached to a lower surface of the front hood, the exhaust duct extends upward in a vertical direction from a rear portion of a fuel cell case, an exhaust port at an upper end of the exhaust duct opens to an interior of the exhaust chamber, a penetrating hole through which the inside of the exhaust chamber communicates with the outside space, is formed in the front hood in a portion in front of the exhaust port in a vehicle front and rear direction, the penetrating hole is covered with a cover, and an opening portion opening toward a rear side of the vehicle and being positioned above and away from an upper surface of the front hood, is formed in the cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application filed under 35 U.S.C. 371 of International Application No. PCT/JP2012/055045, filed Feb. 29, 2012, which claims priority from Japanese Patent Application No. 2011-084160, filed Apr. 6, 2011, each of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to an exhaust device of a fuel cell vehicle. In particular, the present invention relates to an exhaust device of a fuel cell vehicle which can achieve smooth intake and exhaust of a fuel cell and can prevent intrusion of water.

BACKGROUND ART

In a kind of fuel cell vehicle, a fuel cell including a fuel cell stack, which is formed by stacking a plurality of fuel-cell cells, is used as a drive energy source. In this fuel cell vehicle, air used as a reaction gas is supplied to the fuel cell which is housed in a fuel cell case, by use of an intake duct. After that, the air is made to react with hydrogen. Excess air and excess hydrogen gas are discharged from the fuel cell, are discharged to the exterior of the vehicle through an exhaust passage which includes an exhaust duct of an exhaust device.

Exhaust of an air-cooled fuel cell which is discharged by the exhaust device, includes excess hydrogen and air hotter than the outside. As a result, the exhaust is lighter than air at normal temperature. Accordingly, flow of exhaust is facilitated in a case in which an exhaust port of the exhaust duct is directed upward. Furthermore, in order to reduce the air-flow resistance, the exhaust device is preferably configured such that the exhaust passage of the exhaust duct has few curves and has short length. However, when the exhaust port opens upward, water is likely to intrude into the exhaust port.

Regarding the exhaust device of a fuel cell vehicle, the following techniques are disclosed.

PTL 1 discloses that a hydrogen ventilation duct is provided in a hood of a fuel cell vehicle. PTL 2 discloses that a plurality of intake and exhaust ducts are joined to a cooling duct of a fuel cell unit.

CITATION LIST

Patent Literatures

SUMMARY OF INVENTION

Technical Problems

However, in the exhaust device disclosed in PTL 1, the hydrogen ventilation duct is interposed between an outer panel and an inner panel of the hood. As a result, the hydrogen ventilation duct has a small volume of the inner space, and the hydrogen ventilation duct is insufficient to function as the exhaust passage through which the excess air flows. Furthermore, the inner space of the hydrogen ventilation duct includes a plurality of tube portions, guide plates, and the like. As a result, the structure thereof is complicated, and pressure loss increases.

In the exhaust device disclosed in PTL 2, the cooling duct includes: a plurality of switching valves for switching a cooling air passage; a fan; temperature detecting means; and control means for the switching valves and the fan. As a result, the configuration of the exhaust device is complicated. Furthermore, an exhaust passage including the cooling duct and the intake and exhaust ducts becomes longer. As a result, pressure loss in exhaust is increased.

An object of the present invention is to provide an exhaust device of a fuel cell vehicle which can achieve smooth drawing of air into a fuel cell by reducing the air-flow resistance of an exhaust passage and can prevent intrusion of water into an exhaust duct.

Solution to Problems

The present invention is an exhaust device of a fuel cell vehicle comprising; a fuel cell case housing a fuel cell, the fuel cell case being arranged in a space which is formed on a front portion of the vehicle so as to be covered with a front hood from above; an intake duct and an exhaust duct which are connected to the fuel cell case; and a gas passage provided in the fuel cell; wherein the intake duct and the exhaust duct communicate with each other through the gas passage; wherein excess air and excess hydrogen gas which are discharged from the fuel cell, are discharged to an exterior of the vehicle through an exhaust passage which includes the exhaust duct; wherein an exhaust chamber is attached to a lower surface of the front hood; wherein the exhaust duct extends upward in a vertical direction from a rear portion of the fuel cell case; wherein an exhaust port is provided on an upper end of the exhaust duct, and the exhaust port opens to an interior of the exhaust chamber; wherein a penetrating hole is formed on a portion of the front hood which is positioned in front of the exhaust port in a vehicle front and rear direction, and the interior of the exhaust chamber communicates with an outer space through the penetrating hole; wherein the penetrating hole is covered with a cover; and wherein an opening portion is formed on the cover, the opening portion is positioned above an upper surface of the front hood so as to be away from the upper surface thereof, and the opening portion opens toward a rear end of the vehicle.

Advantageous Effects of Invention

Regarding the exhaust device of a fuel cell vehicle of the present invention, a downstream end portion of the exhaust passage opens above the front hood. As a result, the length of the exhaust passage including the exhaust duct can be reduced. Therefore, the air-flow resistance of the exhaust passage can be reduced. Accordingly, it is possible to smoothly discharge the excess air and the excess hydrogen from the fuel cell to the exterior of the vehicle, and it is possible to smoothly draw air into the intake duct.

Regarding the exhaust device of a fuel cell vehicle of the present invention, a portion of the exhaust passage which extends from the exhaust port of the exhaust duct to the opening portion of the cover, is curved, and the opening portion is positioned above the upper surface of the front hood so as to be away from the upper surface thereof. Accordingly, intrusion of water into the exhaust duct from the outside can be prevented.

DESCRIPTION OF EMBODIMENT

An Embodiment of the present invention is described below based on the drawings.

Embodiment

FIGS. 1 to 5illustrate the Embodiment of the present invention. InFIGS. 1 and 2, reference numeral “1” denotes a fuel cell vehicle, reference numeral “2” denotes a front bumper, reference numeral “3” denotes a front grille, reference numeral “4” denotes a right side panel, reference numeral “5” denotes a left side panel, reference numeral “6” denotes a dash panel, reference numeral “7” denotes a front hood, and reference numeral “8” denotes a front compartment. The fuel cell vehicle1is a four-wheel vehicle. The fuel cell vehicle1is provided with the front compartment8in a space which is formed on a front portion of the vehicle, this front portion is surrounded by the front bumper2, the front grille3, the right side panel4, the left side panel5, and the dash panel6, and furthermore, the front portion is covered with the front hood7from above. A fuel cell case10housing fuel cells9is arranged in the front compartment8.

The fuel cell case10is formed in a substantially-square box shape, this substantially-square box shape is thin in a front and rear direction, is longer in an upper and lower direction than in a right and left direction, and the fuel cell case10has a case space11. The fuel cell case10is arranged in the front compartment8such that a front portion12of the fuel cell case10is directed to a front end of the vehicle and a rear portion13of the fuel cell case10is directed to a rear end of the vehicle. In the fuel cells9, multiple fuel-cell cells are stacked, and as a result, fuel cell stacks are formed. Each fuel cell9is formed in a substantially-square box shape, this substantially-square box shape is thin in the front and rear direction, and is longer in the right and left direction than in the upper and lower direction, and a gas passage14is provided in an interior of each full cell9(seeFIG. 4). Two fuel cells9are installed in the case space11of the fuel cell case9while being arranged one on top of the other in the vehicle upper and lower direction, air drawing surfaces15of the fuel cells9is directed to the front end of the vehicle, and air discharging surfaces16of the fuel cells9is directed to the rear end of the vehicle.

The fuel cell vehicle1includes an intake device17and an exhaust device18. As shown inFIG. 2, in the intake device17, two intake ducts19are attached to the front portion12of the fuel cell case10while being arranged one on top of the other in the vehicle upper and lower direction. An intake duct space20is provided in an interior of each intake duct19, the intake duct space20communicates with the case space11of the fuel cell case9, and an air drawing port21opening toward a lower end of the vehicle is provided in a lower portion of the intake duct space20. Each intake duct19draws in air which flows into the front compartment8from the front grille3, from the air drawing port21. Each intake duct19guides the air to the case space11of the fuel cell case10through the intake duct space20. Air outside the vehicle is supplied to the air drawing surfaces15of the fuel cells9as a reaction gas as well as air used for cooling, by an intake passage22which is formed of the intake duct spaces20of the intake ducts19and the case space11of the fuel cell case10.

Air supplied to the air drawing surface15of each fuel cell9is sent from an interior of the gas passage14to a cathode, and then, the air reacts with hydrogen at an anode to generate electric power. Excess air which has not reacted with hydrogen cools the fuel cell9while flowing through the gas passage14. Excess hydrogen is mixed into the excess air, and the excess air is discharged from the air discharging surface16. Therefore, the fuel cells9are configured as air-cooled fuel cells.

The exhaust device18is arranged in the rear portion13of the fuel cell case10. As shown inFIGS. 1 and 2, in the exhaust device18, exhaust fans23are provided to face the air discharging surfaces16of fuel cells9. Two exhaust ducts24are attached to the rear portion13of the fuel cell case10so as to cover the exhaust fans23while being arranged side by side in the vehicle width direction. Each exhaust duct24is formed in a tubular shape extending in a vertical direction. An exhaust duct space25is provided in an interior of each exhaust duct2, the exhaust duct space25communicates with the air discharging surfaces16of the fuel cells9. An exhaust port26opening upward is provided at an upper end of each exhaust duct24. The exhaust ducts24guide the excess air and the excess hydrogen which are discharged from the air discharging surfaces16of the fuel cells9, to a lower surface side of the front hood7which is positioned above the exhaust ducts24.

As shown inFIGS. 2 and 4, in the exhaust device18of the fuel cell vehicle1, an exhaust chamber27is attached to the lower surface of the front hood7, and the front hood7has such a shape that the height thereof in the vehicle upper and lower direction is decreased toward the front end of the vehicle. A chamber space30is provided in an interior of the exhaust chamber27. This chamber space30communicates with the exhaust ports26, and the chamber space30is formed in a box shape by a plate-shaped bottom surface portion28and an annual peripheral wall portion29. The height of the plate-shaped bottom surface portion28in the vehicle upper and lower direction is decreased toward the front end of the vehicle along the lower surface of the front hood7. The annular peripheral wall portion29surrounds an outer periphery of the bottom surface portion28, and the annular peripheral wall portion29is attached to the lower surface of the front hood7. Two insertion hole portions31are formed on the bottom surface portion28of the exhaust chamber27, and the exhaust ports26of the exhaust ducts24are inserted into the insertion hole portion31. As shown inFIG. 4, the two exhaust ducts24extend linearly upward in the vertical direction from the rear portion13of the fuel cell case10. Upper ends of the exhaust ducts24are inserted into the exhaust chamber27from the insertion hole portions31, and as a result, the exhaust ports26open to the inside of the chamber space30of the exhaust chamber27.

As shown inFIGS. 3 and 4, in the front hood7, a plurality of penetrating holes32are formed in a portion in front of the exhaust ports26of the exhaust ducts24in the vehicle front and rear direction, and the interior of the exhaust chamber27communicates with the space outside the vehicle through the penetrating hole32. Four penetrating holes32are formed on the vehicle front side of the exhaust ports26of the exhaust ducts24at positions which are shifted therefrom in the vehicle width direction, when the front hood7is seen from above. The excess air and the excess hydrogen, having flowed into the exhaust chamber27, are guided to the penetrating holes32on the vehicle front side.

As shown inFIGS. 4 and 5, a cover33covering the penetrating holes32is provided on an upper surface of the front hood7. The cover33has a cover space34between the cover33and the upper surface of the front hood7, and the cover space e34communicates with the penetrating holes32. An opening portion35is formed in an end portion of the front hood7on the vehicle rear side, the opening portion35opens toward the rear side of the vehicle, and the opening portion35is positioned above the upper surface of the front hood7so as to be away from the upper surface thereof. A vertical wall portion36protruding upward over the entire width of the opening portion35is provided on the upper surface of the front hood7below the opening portion35. As a result, the opening portion35can be positioned above and away from the upper surface of the front hood7. The excess air and the excess hydrogen, having entered the cover space34of the cover33from the penetrating holes32, are discharged toward the rear side of the vehicle from the opening portion35. The excess air and the excess hydrogen, which are discharged from the fuel cells9, are discharged to the exterior of the vehicle through an exhaust passage37. Note that the exhaust passage37is formed of the exhaust duct spaces25of the exhaust ducts24, the chamber space30of the exhaust chamber27, and the cover space34of the cover33.

In the exhaust device18of the fuel cell vehicle1, the opening portion35of the cover33opens toward the rear end of the vehicle, and the opening portion35is positioned above the upper surface of the front hood7so as to be away from the upper surface thereof, while the exhaust ports26of the exhaust ducts24and the penetrating holes32of the front hood7are shifted from each other in the vehicle front and rear direction and in the vehicle width direction on the top view. Accordingly, water is less likely to enter the exhaust ducts24.

Accordingly, in the exhaust device18, the length of the exhaust passage37is less than that of a structure in which the exhaust ducts24are curved in a labyrinth shape to prevent intrusion of water. As a result, it is possible to reduce the length of the exhaust passage37including the exhaust ducts24, and it is possible to reduce the air-flow resistance of the exhaust passage37. The exhaust device18can smoothly discharge the excess air and the excess hydrogen from the fuel cells9to the outside of vehicle, and as a result, air can be smoothly drawn into the intake ducts19.

In addition, in the exhaust device18of the fuel cell vehicle1, a portion of the exhaust passage37extends from the exhaust ports26of the exhaust ducts24to the opening portion35of the cover33via the exhaust chamber27and the penetrating holes32of the front hood7This portion of the exhaust passage37is curved, and a lower edge portion of the opening portion35is positioned away from the upper surface of the front hood7by the vertical wall portion36which extends upward from the upper surface of the front hood7. Accordingly, as shown in the arrows ofFIG. 5, intrusion of water into the exhaust ducts24from the outside can be prevented.

As shown inFIGS. 3 to 5, in the exhaust device18of the fuel cell vehicle1, hydrogen gas discharging portions38are provided on the vehicle rear side of the opening portion35of the cover33, on the upper surface of the front hood7. The hydrogen gas discharging portions38forms a hydrogen gas discharging ports39. The hydrogen gas discharging ports39penetrate the front hood, and the outer space and a rear portion of the interior of the exhaust chamber27communicate with each other through the hydrogen gas discharging ports39. In the exhaust device18, the hydrogen gas discharging ports39are formed to open toward the rear side, at positions shifted from the positions of the exhaust ports26of the exhaust ducts24in the vehicle width direction, when the front hood7is seen from above. The hydrogen gas discharging pots39penetrate the front hood7, and the outer space and the interior of the exhaust chamber27communicate with each other through the hydrogen gas discharging ports39.

Accordingly, when the hydrogen gas is accumulated at a high position on a rear portion of the chamber space30in the exhaust chamber27, the exhaust device18can discharge this hydrogen gas rearward to the exterior of the vehicle from the hydrogen gas discharging ports39in a condition in which the fuel cells9are not operating.

As shown inFIGS. 2 and 4, in the exhaust device18of the fuel cell vehicle1, the bottom surface portion28of the exhaust chamber27has such a shape that the height thereof in the vehicle upper and lower direction becomes lower toward the front side of the vehicle. Furthermore, a water drain port41is formed in a front portion of the bottom surface portion28in which the height of the bottom surface portion28is lowest, by a water drain portion40protruding downward. A drain pipe42, which guides water flowing out from the water drain port41downward, is provided below the water drain port41. In an upper end of the drain pipe42, a funnel-shaped receiving portion43opening to expand upward is provided, and the drain pipe42is attached to the front portion12of the fuel cell case10which corresponds to a component arranged below the front hood7. The water drain portion40of the exhaust chamber27is separated from the receiving portion43of the drain pipe42when the front hood7is opened, and the water drain portion40is inserted into the receiving portion43of the drain pipe42when the front hood7is closed.

Therefore, in the exhaust device18, when water intrudes into the exhaust chamber27, the water is guided to the front side and made to flow out from the water drain port41by the bottom surface portion28which has such a shape that the height thereof becomes lower toward the front side of the vehicle, the water is received by the receiving portion43of the drain pipe42, and then, the water is guided downward. Accordingly, the intrusion of water into the exhaust ducts24is prevented.

INDUSTRIAL APPLICABILITY

The present invention is the exhaust device of a fuel cell vehicle which can achieve smooth drawing of air into the fuel cells by reducing the air-flow resistance of the exhaust passage and can prevent intrusion of water into the exhaust ducts. The present invention can be applied not only to a fuel cell vehicle but also to a cooling exhaust duct which discharges gas from an upper surface of a hood of a car.

REFERENCE SIGNS LIST

1Fuel cell vehicle

10Fuel cell case

21Air drawing port

28Bottom surface portion

36Vertical wall portion

39Hydrogen gas discharging port

41Water drain port