Exhaust hydrogen dilution device

Abstract

To provide an exhaust hydrogen diluter capable of performing appropriate purge hydrogen treatment regardless of the operating state of a vehicle.SOLUTION: An exhaust hydrogen diluter according to an embodiment of the present invention includes a purge space in which hydrogen is intermittently purged from a fuel cell is stored, an air flow path in which dilution gas flows adjacent to the purge space, and the dilution gas flows into the purge space from the air flow path through a first flow port, and mixed gas of the hydrogen and the dilution gas remaining in the purge space flows toward a second flow port, and the pressure loss is adjusted such that the ratio of hydrogen flowing out of the second flow port into the air flow path is 4% or less of the total amount of gas flowing through the air flow path, and the mixed gas flows into the air flow path from the purge space through the second flow port and is diluted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an exhaust hydrogen dilutor for a fuel cell system applied to, for example, a vehicle. [Background technology]

[0002] In a fuel cell mounted on a fuel cell vehicle, hydrogen supplied to the anode electrode and oxygen supplied to the cathode electrode undergo an electrochemical reaction to obtain electrical energy required, for example, to drive the vehicle.

[0003] In such fuel cells, the hydrogen concentration at the anode electrode decreases due to the electrochemical reaction described above, and so it is necessary to open the purge valve at a specified timing to discharge the hydrogen (hereinafter, such discharge process is also referred to as "hydrogen purging process" and the hydrogen discharged at this time is also referred to as "purged hydrogen"). For this reason, for example, Patent Documents 1 to 3 shown below propose a diluter that dilutes the hydrogen in the exhaust gas discharged outside the vehicle to a specified ratio (for example, 4% or less). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-193993 A [Patent Document 2] JP 2006-031998 A [Patent Document 3] JP 2003-132915 A Summary of the Invention [Problem to be solved by the invention]

[0005] Not only the above-mentioned patent documents, but current technologies do not adequately meet market needs, and the following problems exist. For example, in the above-mentioned Patent Document 1, it is assumed that hydrogen is diluted in space 43 to which purged hydrogen is supplied, and in order to achieve the above-mentioned predetermined ratio, it is necessary to take in a sufficient amount of dilution gas (air) into this space, which increases the volume of the diluter. Also, in Patent Document 2, it is assumed that hydrogen is diluted in dilution vessel 51 to which purged hydrogen is supplied, and as in Patent Document 1, the volume of the dilution vessel increases.

[0006] On the other hand, in Patent Document 3, although hydrogen dilution is carried out in a space (dilution space 10) different from the space (retention area 9) to which purged hydrogen is supplied, the structure of the flow section 14 disclosed in Patent Document 3 limits hydrogen dilution to diffusion and hydrogen movement due to pressure differences. For this reason, with the dilution of purged hydrogen in Patent Document 3, there is a risk that hydrogen may not be sufficiently diluted under certain operating conditions (for example, when the fuel cell is generating low power), and the desired dilution ratio may not be achieved.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an exhaust hydrogen dilution device that can perform appropriate purged hydrogen treatment regardless of the operating state of the vehicle. [Means for solving the problem]

[0008] In order to solve the above problems, an exhaust hydrogen diluter in one embodiment of the present invention is: (1) an exhaust hydrogen diluter provided in a fuel cell system, the exhaust hydrogen diluter having a purge space portion in which hydrogen intermittently purged from a fuel cell is temporarily stored, and an air flow path portion adjacent to the purge space portion through which a dilution gas flows, a first flow port is provided upstream of a boundary region between the purge space portion and the air flow path portion, and a second flow port is provided downstream of the boundary region, the pressure loss at the first flow port is equal to or greater than the pressure loss at the second flow port, the dilution gas flows from the air flow path portion through the first flow port, and a mixed gas of hydrogen remaining in the purge space portion and the dilution gas flows toward the second flow port, the pressure loss is adjusted so that the proportion of hydrogen flowing out of the second flow port in the air flow path portion is 4% or less of the total amount of gas flowing through the air flow path portion, and the mixed gas flows from the purge space portion to the air flow path portion through the second flow port to be diluted. A water intrusion prevention member is provided in the purge space and around the first flow port so that liquid generated in the purge space does not block the first flow port. do.

[0009] In the exhaust hydrogen dilution device described in (1) above, (2) the air flow path downstream of the first flow port Department It is preferred that the nozzle further comprises a turbulence generating member capable of generating turbulence therein.

[0010] In the exhaust hydrogen dilution device described in (1) or (2) above, (3) it is preferable that the purge nozzle for discharging the hydrogen into the purge space is connected to the purge space so that the tip of the purge nozzle is located downstream of the first flow port.

[0012] In addition, the above (1) to ( 3 In the exhaust hydrogen dilution device according to any one of the above, 4 ) The boundary region is The purge space further includes a water guide structure for directing the liquid generated in the purge space toward the second flow port. In the water guide structure, an inclination angle β of the boundary region downstream of the second flow port is set to be larger than an inclination angle α of the boundary region upstream of the second flow port. It is preferable that Effect of the Invention

[0013] According to the present invention, it is possible to discharge hydrogen purged from the fuel cell to the outside of the vehicle at an appropriate ratio, regardless of the operating state of the vehicle. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a fuel cell vehicle equipped with a fuel cell system according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a fuel cell system according to an embodiment; [Diagram 3] FIG. 2 is a schematic diagram showing the structure of an exhaust hydrogen diluter according to an embodiment. [Figure 4] FIG. 2 is a schematic diagram showing an example of the flow state of purge hydrogen and dilution gas in the exhaust hydrogen diluter. [Diagram 5] FIG. 2 is a schematic diagram illustrating the positional relationship between a first flow port and a purge nozzle in the exhaust hydrogen diluter, and the dilution mode performed based on this positional relationship. [Figure 6] FIG. 4 is a schematic diagram showing a comparison of changes over time in the hydrogen ratio (concentration) in exhaust gas between a conventional structure and an exhaust hydrogen dilutor according to an embodiment of the present invention. [Figure 7] FIG. 11 is a schematic diagram showing the structure of a fuel cell system and an exhaust hydrogen dilutor in a second embodiment. [Figure 8] FIG. 11 is a schematic diagram showing the structure of an exhaust hydrogen diluter in the third and fourth embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Next, preferred embodiments for carrying out the present invention will be described. Note that configurations other than those described in detail below may be supplemented as appropriate with elemental technologies and configurations related to known fuel cell systems, fuel cell vehicles, and exhaust hydrogen dilutors, including those listed in the above-mentioned patent documents.

[0016] A. First embodiment <Fuel cell system 200> First, the configuration of a fuel cell system 200 in a first preferred embodiment of the present invention will be described with reference to Figures 1 and 2. The fuel cell system 200 in this embodiment is mounted on, for example, a known fuel cell vehicle V. Below, the case of an automobile will be described as an application example of the fuel cell system 200, but the present invention is not limited to application to automobiles, and is also suitable for, for example, stationary battery systems such as residential facilities and mobile battery systems such as aircraft.

[0017] The fuel cell system 200 installed in the fuel cell vehicle V is composed of an electronic control unit ECU that controls each part of the vehicle, a fuel cell FC whose operation is controlled by this electronic control unit ECU, an exhaust hydrogen dilutor 100 that dilutes the hydrogen intermittently discharged (purged) from the fuel cell FC, an adjustment valve V1 that adjusts the flow rate of the purged hydrogen Hp, an adjustment valve V2 that controls the flow rate of the dilution gas DA described later, and a gas flow path that appropriately supplies gas to the exhaust hydrogen dilutor 100 using the exhaust from the fuel cell FC.

[0018] The electronic control device 50 is configured to include, for example, a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), electric circuits, and storage elements such as a RAM (Random Access Memory) or a ROM (Read Only Memory). Note that a part or all of the electronic control device 50 may be configured with updatable elements such as firmware, or may be a program module executed by commands from the CPU or the like.

[0019] <Flow path structure in fuel cell system 200> As an example, a gas flow path structure suitable for the fuel cell system 200 will be described below. 2, the fuel cell system 200 of this embodiment is configured to include a hydrogen supply flow path C1 that is connected to the fuel cell FC and a known hydrogen tank (not shown) and supplies hydrogen to the fuel cell FC. The fuel cell system 200 is also configured to include an air supply flow path C2 that is connected to, for example, the air compressor AP and supplies oxygen (air) to the fuel cell FC.

[0020] The fuel cell system 200 also includes a hydrogen circulation flow path C3 that is connected to the hydrogen supply flow path C1 and mixes the purged hydrogen Hp discharged from the fuel cell FC with hydrogen supplied to the fuel cell FC as necessary. The fuel cell system 200 also includes a hydrogen discharge flow path C4 that branches off from the hydrogen circulation flow path C3 and supplies the purged hydrogen Hp to the exhaust hydrogen dilutor 100, which will be described later.

[0021] The fuel cell system 200 is also configured to include a dilution gas supply passage C5 that is connected to the air compressor AP and supplies air to the exhaust hydrogen dilutor 100 described below. The fuel cell system 200 is also configured to include an air discharge flow passage C6 that connects the fuel cell FC to the dilution gas supply passage C5 and distributes air discharged from the fuel cell FC to the dilution gas supply passage C5. The fuel cell system 200 is also configured to include an exhaust flow passage C7 that is connected to the air flow passage section 20 of the exhaust hydrogen dilutor 100 and discharges diluted purged hydrogen Hp to the outside of the vehicle.

[0022] In this embodiment, as an example, when the air discharged from the fuel cell FC cannot be secured at a sufficient flow rate as dilution gas DA, the necessary and sufficient air may be supplied from the air compressor AP via the dilution gas supply path C5. The specific structure of each of the above-mentioned flow paths is not particularly limited as long as each function is performed, and known piping can be used.

[0023] The adjustment valve V1 that adjusts the flow rate of the purged hydrogen Hp can be a known valve mechanism such as an electromagnetic valve, and may be installed in the hydrogen discharge flow path C4. As an example, the electronic control unit ECU of this embodiment controls the opening and closing of the adjustment valve V1 to discharge the purged hydrogen Hp into the purge space 10 of the exhaust hydrogen dilution device 100 via the hydrogen discharge flow path C4.

[0024] The adjustment valve V2 that controls the supply amount of dilution gas can be a known valve mechanism such as an electromagnetic valve, and may be installed in the above-mentioned dilution gas supply passage C5. As an example, the electronic control unit ECU of this embodiment controls the opening and closing of the adjustment valve V2 to supply air (dilution gas) from at least one of the air compressor AP and the fuel cell FC to the air flow passage 20 of the exhaust hydrogen diluter 100 via the dilution gas supply passage C5.

[0025] <Exhaust hydrogen dilution device 100> Next, the configuration of the exhaust hydrogen dilutor 100 in this embodiment will be described with reference to FIGS. 3 and the like, the exhaust hydrogen dilution device 100 of this embodiment constitutes a part of the above-mentioned fuel cell system 200. The exhaust hydrogen dilution device 100 can be exemplified by a rectangular parallelepiped housing in which a purge space section 10 and an air flow path section 20 are defined.

[0026] There are no particular limitations on the material of the housing that constitutes the exhaust hydrogen dilution device 100, and for example, known metal materials such as aluminum and steel, or known resin materials such as plastic may be used. The shape of the exhaust hydrogen dilution device 100 is also not limited to the rectangular parallelepiped housing described above, and other known shapes may be adopted depending on the vehicle structure, vehicle model, etc.

[0027] The purge space 10 is provided as an upper space in the above-mentioned housing constituting the exhaust hydrogen diluter 100. This purge space 10 is configured to have the function of temporarily storing hydrogen that is intermittently purged from the above-mentioned fuel cell FC.

[0028] The air flow passage section 20 is provided as a lower space in the above-mentioned housing constituting the exhaust hydrogen diluter 100. This air flow passage section 20 also functions as a space for diluting the above-mentioned dilution gas DA and hydrogen contained in the below-mentioned mixed gas Hd in a portion directly below and downstream of a below-mentioned second flow port 31B. As can be seen from Fig. 3 and the like, the purge space section 10 and the air flow passage section 20 are partitioned within the housing by a boundary region 30.

[0029] The boundary region 30 is provided so as to be interposed between the purge space portion 10 and the air flow path portion 20. In this embodiment, the boundary region 30 functions as the bottom surface of the purge space portion 10 and also functions as the top surface of the air flow path portion 20. The purge space portion 10 and the air flow path portion 20 may each be formed as separate rectangular parallelepipeds, with the bottom surface of one portion and the top surface of the other portion being fixed together to form the exhaust hydrogen diluter 100, or they may be formed as an integral unit rather than as separate bodies as described above.

[0030] As can be understood from FIG. 2 and FIG. 3, the boundary region 30 of this embodiment has a flow port 31 (a first flow port 31A and a second flow port 31B) that communicates the purge space portion 10 and the air flow path portion 20 to allow gas to flow from one to the other. Such a flow port 31 is composed of a plurality of through holes that are adjusted in advance to have a predetermined hole diameter and opening rate, for example. In this embodiment, the flow port 31 is composed of a plurality of through holes, but the number and shape of the through holes are not important as long as the pressure loss described below can be adjusted. In addition, when the purge space portion 10 and the air flow path portion 20 are separate bodies, they may be composed of piping with adjusted pressure loss, and further, the inside of this piping may be filled with a known cotton-like filler.

[0031] Specifically, in the exhaust hydrogen dilutor 100 of this embodiment, a first flow port 31A is provided on the upstream side (the negative Y direction side in Figure 3) of the boundary region 30, and a second flow port 31B is provided on the downstream side (the positive Y direction side in Figure 3).

[0032] A purge nozzle PN is provided between the hydrogen discharge passage C4 and the purge space 10, and at least a portion of the purge nozzle PN, including its tip, is inserted into the purge space 10. As a result, the purged hydrogen Hp flowing through the hydrogen discharge passage C4 is discharged into the purge space 10 from the tip of the purge nozzle PN.

[0033] 5(a), it is preferable that the purge nozzle PN is connected to the purge space 10 so that the tip (e.g., based on the center PNc of the opening) of the purge nozzle PN for discharging the purge hydrogen Hp into the purge space 10 is located downstream of the first flow port 31A (e.g., based on the center 31Ac). This makes it easier for the purge hydrogen Hp discharged into the purge space 10 to ride on the air current going from the first flow port 31A to the second flow port 30B, as shown in FIG. 5(b), and it is possible to prevent the purge hydrogen Hp from unintentionally flowing back from the first flow port 31A within the purge space 10.

[0034] A dilution nozzle DN is provided between the dilution gas supply passage C5 and the air flow passage section 20, and at least a portion of the dilution nozzle DN, including the tip thereof, is inserted into the air flow passage section 20. As a result, the dilution gas (e.g., air) flowing through the dilution gas supply passage C5 is supplied from the tip of the dilution nozzle DN into the air flow passage section 20. A discharge nozzle MN is provided on the opposite side (downstream side) of the air flow passage section 20 from the dilution nozzle DN. Gas in which the proportion of hydrogen, described later, has reached an appropriate range (e.g., 4% or less, which is suitable for handling) is discharged from the exhaust hydrogen diluter 100 through the discharge nozzle MN.

[0035] <Pressure Loss Adjustment by First Flow Port 31A and Second Flow Port 31B> The flow states of the dilution gas DA and the purge hydrogen Hp in this embodiment are shown in FIGS. As described above, the dilution gas DA is supplied into the purge space 10 through the dilution nozzle DN. Thereafter, at least a portion of the dilution gas DA supplied into the air flow path 20 flows from the air flow path 20 through the first flow port 31A into the purge space 10 as the second gas, and the remainder flows through the air flow path 20 downstream (toward the discharge nozzle MN) as the first gas.

[0036] On the other hand, the purged hydrogen Hp discharged into the purged space 10 moves downstream while being guided by the second gas (dilution gas DA) that flows in from the air passage 20 through the first flow port 31A. As a result, the mixed gas Hd, which is a mixture of the purged hydrogen Hp discharged into the purged space 10 and the dilution gas DA, flows toward the second flow port 31B.

[0037] Next, the mixed gas Hd of the dilution gas DA and the purge hydrogen Hp flows into the air flow passage 20 through the second flow port 31B provided on the downstream side of the purge space 10. At this time, the mixed gas Hd flowing into the air flow passage 20 through the second flow port 31B is mixed with the first gas (dilution gas DA) flowing from the upstream inside the purge space 10. At this time, the hydrogen contained in the mixed gas Hd is diluted by being mixed with the first gas (dilution gas DA). Thereafter, the mixed gas of the mixed gas Hd and the first gas (dilution gas DA) is discharged to the outside from the exhaust hydrogen diluter 100 through the discharge nozzle MN.

[0038] In this embodiment, by adjusting the pressure loss described below, the proportion of hydrogen flowing out from the second flow port 31B into the air flow path section 20 (i.e., the proportion of hydrogen contained in the mixed gas Hd) is set to 4% or less of the total amount of gas flowing through the air flow path section 20 (i.e., the combined amount of the dilution gas DA flowing from upstream and the mixed gas Hd).

[0039] In this embodiment, after adjusting the pressure loss in this way, the mixed gas Hd flows from the purge space 10 into the air passage 20 via the second flow port 31B and is mixed with the dilution gas DA from upstream, thereby diluting the hydrogen in the gas to within an appropriate range. The reason for setting the appropriate range at 4% or less is based on the general technical knowledge that there is a risk of ignition when the hydrogen concentration exceeds 4%, which is the lower explosive limit of hydrogen.

[0040] Here, as an example of the above-mentioned pressure loss adjustment mode, it can be derived by experiment or simulation using the following method, for example. That is, if the pressure loss is defined as ΔP, the pressure loss coefficient specific to the flow path is defined as K, and the flow rate of the gas flowing through this flow path is defined as Q, it can be calculated using the following formula (1).

[0041] ΔP=K×Q 2 (1)

[0042] When the flow in the exhaust hydrogen dilutor 100 becomes steady, the flow rate of the first gas introduced from the dilution nozzle DN into the air passage section 20 and proceeding downstream is Q1, and the flow rate of the second gas introduced into the air passage section 20 and flowing into the purge space section 10 through the first flow port 31A is Q2. Then, the pressure loss of the first gas (ΔP1=K1×Q1 2 ) and the pressure loss of the second gas (ΔP2 = K2 × Q2 2 ) are equal to each other.

[0043] K1×Q1 2 =K2×Q2 2 (2)

[0044] Then, the above formula (2) can be transformed into the following formula (3), and the above flow rate ratio can be controlled by the pressure loss coefficient. In other words, the above flow rate ratio can be controlled by the shape of the flow path through which each gas flows.

[0045] JPEG0007659415000001.jpg1277

[0046] In consideration of the above, in this embodiment, the pressure losses at the first flow port 31A and the second flow port 31B are adjusted as follows, for example. First, the condition was set so that the pressure loss at the first flow port 31A was equal to or greater than the pressure loss at the second flow port 31B. More specifically, for example, the hole diameters of the first flow port 31A and the second flow port 31B may be different from each other to satisfy the above-mentioned condition, or the number of holes of the first flow port 31A and the second flow port 31B may be different from each other.

[0047] At this time, it is preferable that the pressure loss at the first flow port is set so that the purged hydrogen Hp does not flow back to the air flow passage 20 through the first flow port 31A when it is discharged into the purge space 10. In order to achieve such a setting, it is necessary that the pressure loss at the first flow port 31A is greater than that at least the second flow port 31B. As a result, when the purged hydrogen Hp is discharged into the purge space 10, the second flow port 31B becomes an escape route for the air pushed out of the purge space 10, and only the air downstream of the purge space 10 far from the purge nozzle PN is discharged to the air flow passage 20, so that the hydrogen dilution function can be maintained normally. In addition, it is preferable that the pressure loss at the second flow port is set so that the turbulent flow generated in the air flow passage 20 does not flow into the purge space 10. A specific example of setting these conditions is, for example, adjusting the aperture ratio based on the hole diameter and number of holes in each of the above-mentioned flow ports, but it may be realized by other known methods.

[0048] 3, a pressure loss adjusting section 21 may be provided in the purge space 10 to appropriately adjust the flow rate of the first gas introduced from the dilution nozzle DN into the air passage section 20 and proceeding downstream. Note that the pressure loss adjusting section 21 is not essential and may be omitted as appropriate. Specific examples of such pressure loss adjusting section 21 include known structures such as known throttle shapes. In this way, the pressure loss adjustment by the first flow port 31A and the second flow port 31B can be adjusted not only by adjusting the opening rate based on the hole diameter and number of holes at each flow port, but also by the shape (height and outer shape) of the pressure loss adjustment section 21.

[0049] The above-mentioned manner of adjusting the pressure loss is just one example, and the adjustment of the flow rate through the first flow port 31A and the second flow port 31B is not limited to the above, and can be set appropriately depending on the specifications of the fuel cell FC and the shape of each of the flow ports, and may be adjusted based on other known methods.

[0050] In the exhaust hydrogen diluter 100 of this embodiment having the above configuration, as shown in Figure 4 or Figure 5 (b), the flow path of the dilution gas DA is bifurcated in the purge space section 10, one part becomes the first gas and moves downstream, and the other part becomes the second gas and flows into the purge space section 10 through the first flow port 31A. On the other hand, the purge hydrogen Hp discharged into the purge space section 10 becomes the mixed gas Hd and flows into the air flow path section 20 from the second flow port 31B as guided by the second gas. In this way, the two air flow paths (the first gas flow and the second gas flow) separated in the air flow path section 20 finally merge downstream of the air flow path section 20.

[0051] At this time, in this embodiment, the pressure loss is adjusted so that the flow rate of the mixed gas Hd flowing into the air flow path section 20 through the second flow port 31B is, for example, 4 / 96 or less relative to the first gas. Therefore, in this embodiment, the ratio of hydrogen in the gas obtained by combining the mixed gas Hd and the first gas is always within an appropriate range (4% or less in this example) and is released to the outside through the release nozzle MN.

[0052] Specifically, as shown in Figure 6, when the conventional method is adopted, when the dilution gas DA cannot be supplied sufficiently, for example, during low power generation of the fuel cell FC, there is a risk that hydrogen gas with a concentration that temporarily exceeds the appropriate range will be released outside the system. On the other hand, according to the fuel cell system 200 including the exhaust hydrogen dilutor 100 in this embodiment, it is possible to keep the hydrogen purged from the fuel cell within an appropriate range (in this example, the concentration is 4% or less as described above) and discharge it outside the vehicle regardless of the operating state of the vehicle.

[0053] 3 to 5, the tip (e.g., the center PNc) of the purge nozzle PN in the purge space 10 is preferably located at a position higher than the first flow port 31A in the vertical (gravity) direction. This makes it possible to maintain the hydrogen ratio within an appropriate range without a large amount of purge hydrogen Hp flowing into the air flow path 20 when, for example, a sufficient amount of dilution gas DA is not supplied into the air flow path 20.

[0054] The volumes of the purge space 10 and the air flow path 20 may be set appropriately according to the class of the fuel cell vehicle V and the specifications of the fuel cell FC, but it is preferable that the volume of the purge space 10 is at least larger than the volume of one hydrogen purging process. This makes it possible to properly supply the dilution gas DA to the air flow path 20 even when hydrogen purging processes are performed continuously, and makes it possible to maintain the hydrogen ratio within the appropriate range without a large amount of hydrogen flowing out to the air flow path 20.

[0055] B. Second embodiment <Exhaust Hydrogen Diluter 101> Next, a second preferred embodiment of the present invention will be described with reference to Fig. 7. An exhaust hydrogen dilution device 101 of this embodiment is characterized in that it further includes a turbulence generating member 22 compared to the exhaust hydrogen dilution device 100 of the first embodiment. Therefore, the following description will focus on the differences from the first embodiment, and the same configurations as in the first embodiment will be given the same reference numerals and descriptions thereof will be omitted as appropriate (the same applies to the other embodiments described below).

[0056] Such a turbulence generating member 22 is provided so as to be capable of generating a turbulent flow in the air flow passage section 20 downstream of the first flow port 31A. In other words, the exhaust hydrogen diluter 101 of this embodiment may be configured to include a turbulence generating member 22 capable of generating a turbulent flow (e.g., a vortex flow) in the vicinity of or downstream of the second flow port 31B in the boundary region 30. Such a turbulence generating member 22 is provided with any of various known structures capable of generating turbulence in the air flow, such as a spiral fin, and is disposed in the air flow passage section 20.

[0057] As shown in FIG. 7, the turbulence generating member 22 of this embodiment may be disposed upstream of the second flow port 31B in the air flow path section 20.

[0058] In the exhaust hydrogen diluter 101 in the present embodiment described above, the dilution gas DA (first gas) introduced from the dilution nozzle DN into the air passage section 20 and moving downstream becomes turbulent as it passes through the turbulence generating member 22. Then, the mixed gas Hd that flows into the air passage section 20 through the second flow port 31B is efficiently mixed with the dilution gas DA (first gas). Therefore, according to the present embodiment, in addition to the effects of the first embodiment described above, the occurrence of unevenness in the hydrogen concentration when the mixed gas Hd is diluted with the dilution gas DA (first gas) is suppressed.

[0059] C. Third embodiment <Exhaust hydrogen dilution device 102> Next, a third preferred embodiment of the present invention will be described with reference to Fig. 8(a). The exhaust hydrogen dilution device 102 of this embodiment is characterized in that it further includes a water ingress suppression member 32, as compared with the exhaust hydrogen dilution device 100 of the first embodiment. Although components other than the exhaust hydrogen dilution device 102 are not shown in Fig. 8, it goes without saying that the fuel cell system 200 is similar to that of the first embodiment.

[0060] That is, in the exhaust hydrogen diluter 102 of this embodiment, a cylindrical water infiltration suppression member 32 is provided in the purge space 10 (on the boundary area 30) so as to surround the first flow port 31A of the boundary area 30. Such a water infiltration suppression member 32 is provided around the first flow port 31A so that liquid (such as water containing water droplets) generated in the purge space 10 does not block the first flow port 31A.

[0061] There are no particular limitations on the specific material of this water infiltration suppression member 32 so long as it can perform the above-mentioned functions. For example, metal materials such as steel or aluminum that have been subjected to rust prevention treatment, or resin materials such as plastic can be used.

[0062] The water intrusion suppression member 32 of this embodiment may have a cylindrical shape of uniform height surrounding the first flow port 31A, but may have a lower height on the downstream side (the side facing the second flow port 31B) than the other sides. The water intrusion suppression member 32 of this embodiment has a shape that rises vertically along the vertical direction around the first flow port 31A, but is not limited to this shape and may have a shape that is inclined obliquely toward the downstream side.

[0063] This helps the dilution gas DA (second gas) flowing into the purge space 10 through the first flow port 31A to flow downstream efficiently, and allows the water infiltration suppression member 32 to function as a wind straightening guide. According to the present embodiment described above, in addition to the effects of the first embodiment described above, blocking of the first flow port 31A due to the influence of moisture present in the purge space portion 10 and the like is suppressed.

[0064] D. Fourth embodiment <Exhaust hydrogen dilution device 103> Next, a fourth preferred embodiment of the present invention will be described with reference to Fig. 8(b). The exhaust hydrogen dilution device 103 of this embodiment is characterized in that it further includes a water guide structure 33 compared to the exhaust hydrogen dilution device 100 of the first embodiment.

[0065] That is, as shown in the figure, the exhaust hydrogen dilutor 102 of this embodiment has a water guide structure 33 through which liquid (water including water droplets) generated in the purge space portion 10 flows toward the second flow port 31B. More specifically, the water guide structure 33 of this embodiment has a structure in which the bottom of the purge space portion 10 (i.e., the boundary region 30 in this example) is inclined so that the second flow port 31B is positioned relatively lower in the vertical direction.

[0066] In this embodiment, the boundary region 30 has a shape that is uniformly inclined toward the second flow port 31B as the water-guiding structure 33, but is not limited to this shape and may have, for example, a stepped shape in which the second flow port 31B is at the bottom within the purge space 10. According to the present embodiment described above, in addition to the effects of the first embodiment described above, blocking of the first flow port 31A due to the influence of moisture present in the purge space portion 10 and the like is suppressed.

[0067] 8(b), it is preferable that the inclination angle β of the boundary region 30 downstream of the second flow port 31B in the purge space 10 is set to be larger than the inclination angle α of the boundary region 30 upstream of the second flow port 31B. This allows the purged hydrogen Hp discharged into the purge space 10 through the purge nozzle PN to flow more efficiently into the second flow port 31B.

[0068] Each of the above-described embodiments is a preferred example of the present invention, and new structures and controls may be realized by appropriately combining the elements of the embodiments without departing from the spirit of the present invention. The above describes preferred embodiments of the present invention with reference to the accompanying drawings. However, it is clear that a person having ordinary knowledge in the technical field to which the present invention pertains may attempt further modifications to these embodiments, and it is understood that these modifications also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0069] 10 Purge space 20 Air flow passage 30 Boundary area V fuel cell vehicle FC fuel cell ECU Electronic Control Unit

Claims

1. An exhaust hydrogen dilution device provided in a fuel cell system, comprising: a purge space portion in which hydrogen intermittently purged from the fuel cell is temporarily stored; an air flow path portion adjacent to the purge space portion and through which a dilution gas flows, a first flow port is provided upstream of a boundary area between the purge space portion and the air flow path portion, and a second flow port is provided downstream of the boundary area; a pressure loss at the first flow port is equal to or greater than a pressure loss at the second flow port; the dilution gas flows from the air flow passage into the purge space through the first flow port, so that a mixed gas of hydrogen remaining in the purge space and the dilution gas flows toward the second flow port; the pressure loss is adjusted so that a ratio of the hydrogen flowing out from the second flow port to the air flow passage portion is 4% or less with respect to a total amount of gas flowing through the air flow passage portion, and the mixed gas flows from the purge space portion to the air flow passage portion via the second flow port and is diluted; a water ingress prevention member is provided within the purge space and around the first flow port so that liquid produced in the purge space does not block the first flow port.

2. 2. The exhaust hydrogen dilution device according to claim 1, further comprising a turbulence generating member capable of generating a turbulent flow in the air flow passage portion downstream of the first flow port.

3. 3. The exhaust hydrogen dilution device according to claim 1, wherein a purge nozzle for discharging the hydrogen into the purge space is connected to the purge space such that a tip of the purge nozzle is located downstream of the first flow port.

4. The boundary region further has a water-conducting structure for directing liquid generated in the purge space portion toward the second flow port, 4. The exhaust hydrogen dilutor according to claim 1, wherein an inclination angle β of the boundary region downstream of the second flow port in the water guide structure is set to be larger than an inclination angle α of the boundary region upstream of the second flow port.

Images