Fuel cell stack

Abstract

A fuel cell stack is provided with: a cell stack (101); a pair of end units (102) disposed at both ends of the battery stack (101); a cooling medium discharge flow path (PA2) that is provided through the battery stack (101) in a predetermined direction and discharges the cooling medium introduced into the plurality of power generation batteries (1); and a substantially cylindrical pipe body (7) which is disposed in the cooling medium discharge flow path (PA2) and which is provided with, at one end and at the lower end, openings which communicate with the upstream side and the downstream side of the cooling medium discharge flow path (PA2), respectively. The end unit (102) is provided with a through-hole (102 g) communicating with an opening on the downstream side of the pipe body (7) and penetrating the end unit (102), and the end unit (102) is provided with a first support part (201) and a second support part (202) for supporting the peripheral edge part of the first end part and the peripheral edge part of the second end part of the pipe body (7). The second support section (202) has a tapered section (521) formed on the peripheral surface of the through-hole (102 g) so as to be tapered toward the outlet of the through-hole (102 g).

Description

Technical Field

[0001] The present invention relates to a fuel cell stack. Background Art

[0002] In recent years, in order to ensure that more people can use cost-effective, reliable, sustainable and advanced energy, the development of fuel cell technology that helps improve energy efficiency is underway. As a technology related to such fuel cells, there is a technology that is known to be arranged inside the refrigerant discharge manifold. A resin exhaust channel is arranged inside the refrigerant discharge manifold, and the air bubbles in the refrigerant discharge manifold are discharged to the outside through the exhaust channel. Such technology is described in Patent Document 1, for example. Figure 8 Patent Document 1 describes that an exhaust passage is joined or fixed to an inner side surface of a refrigerant discharge manifold within the refrigerant discharge manifold.

[0003] However, it is difficult to stably support the exhaust passage in a configuration that does not interfere with components such as the end unit in the refrigerant discharge manifold where the refrigerant flows.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-079779 (JP 2019-079779 A). Summary of the Invention

[0007] A fuel cell stack according to one embodiment of the present invention comprises: a cell stack formed by stacking a plurality of power generation cells including membrane electrode structures and separators in a predetermined direction; a first end unit and a second end unit disposed at one and the other ends of the cell stack in the predetermined direction; a coolant discharge passage extending through the cell stack in the predetermined direction for discharging the coolant introduced into the plurality of power generation cells; and a substantially cylindrical tube disposed in the coolant discharge passage, having a first opening and a second opening at one and a lower ends, respectively, communicating with the upstream and downstream sides of the coolant discharge passage. A through hole is formed in the second end unit, communicating with the second opening of the tube and extending through the second end unit. The first and second end units respectively have first and second support portions supporting the peripheral edges of the first and second ends of the tube. The second support portion has a tapered portion on the circumference of the through hole, the tapered portion having a tapered surface tapering toward the outlet of the through hole, centered about an axis extending substantially parallel to the predetermined direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present invention will be further clarified through the following description of the embodiments in conjunction with the accompanying drawings.

[0009] Figure 1is a perspective view schematically showing the overall structure of a fuel cell stack according to an embodiment of the present invention;

[0010] Figure 2 It shows Figure 1 A perspective view of the schematic structure of an integrated electrode assembly included in a fuel cell stack;

[0011] Figure 3 yes Figure 1 A rear view of a fuel cell stack;

[0012] Figure 4 It is along Figure 3 A cross-sectional view taken along line IV-IV;

[0013] Figure 5 yes Figure 4 Magnified view of the V part;

[0014] Figure 6 It is along Figure 4 A cross-sectional view taken along line VI-VI;

[0015] Figure 7 yes Figure 4 An enlarged view of Part VII;

[0016] Figure 8 2. FIG. 2 is a diagram showing another example of a rear support portion supporting the rear end portion of the communicating pipe;

[0017] Figure 9 yes Figure 8 IX-direction view;

[0018] Figure 10 It shows Figure 9 FIG. 1 is a diagram of a modified example of . DETAILED DESCRIPTION

[0019] Below, refer to Figures 1 to 10 The embodiments of the present invention will now be described. A fuel cell stack according to an embodiment of the present invention is a main component of a fuel cell. A fuel cell is installed in, for example, a vehicle and can generate electricity to drive the vehicle. First, the overall structure of the fuel cell stack will be briefly described.

[0020] Figure 1 This is a perspective view schematically illustrating the overall structure of the fuel cell stack 100 according to this embodiment. For convenience, the following description defines three mutually orthogonal axes as the front-to-back direction, the left-to-right direction, and the top-to-bottom direction, as shown in the figure. The structure of each component is described according to these definitions. The downward direction in the top-to-bottom direction corresponds to the direction of gravity, or approximately the direction of gravity. The front-to-back direction corresponds to the stacking direction of the fuel cell stack 100. The front-to-back direction and the left-to-right direction are not necessarily the same as those of a vehicle.

[0021] like Figure 1 As shown, the fuel cell stack 100 has a battery stack 101 formed by stacking a plurality of power generation cells 1 in the front-to-back direction, and end units 102 arranged at the front and rear ends of the battery stack 101. The fuel cell stack 100 is generally rectangular in shape. Although not shown, the battery stack 101 is surrounded by a roughly rectangular shell. The length of the battery stack 101 in the left-right direction is longer than the length in the up-down direction. For convenience, Figure 1 A single power generation cell 1 is shown in FIG.

[0022] The power generation cell 1 comprises a unitized electrode assembly 2 (UEA), which comprises a membrane electrode assembly (MEA) comprising an electrolyte membrane and electrodes; and separators 3, 3, arranged on the front and rear sides of the UEA 2, sandwiching the UEA 2. The UEA 2 and separators 3 are arranged alternately in the front-to-back direction. The UEA 2 may also be referred to as a membrane electrode structure, membrane electrode unit, or membrane electrode member.

[0023] The partition 3 has a pair of front and rear metal thin plates with a corrugated plate cross-section, and the outer peripheral edges of these thin plates are joined to each other to form a whole. The partition 3 uses a conductive material with good corrosion resistance, for example, titanium, titanium alloy, stainless steel, etc. A cooling flow channel for the flow of a cooling medium is formed inside the partition 3 (between a pair of thin plates), and the power generation surface of the power generation cell 1 is cooled by the flow of the cooling medium. For example, water can be used as a cooling medium. The surface (front surface and rear surface) of the partition 3 facing the UEA2 is formed into a concave and convex shape by stamping, so that a gas flow channel is formed between the membrane electrode assembly and the UEA2.

[0024] The separator 3 on the front side of the UEA 2 is, for example, an anode-side separator (anode separator). An anode flow channel for fuel gas (anode gas) is formed between the anode separator 3 and the membrane electrode assembly of the UEA 2. The separator 3 on the rear side of the UEA 2 is, for example, a cathode-side separator (cathode separator). A cathode flow channel for oxidant gas (cathode gas) is formed between the cathode separator 3 and the membrane electrode assembly of the UEA 2. For example, hydrogen can be used as the fuel gas, and air can be used as the oxidant gas. Fuel gas and oxidant gas are sometimes not distinguished and are referred to as reactant gases.

[0025] Figure 2 : is a perspective view showing the schematic structure of UEA2. Figure 2As shown, the UEA 2 includes a substantially rectangular assembly 20 (Membrane Electrode Assembly, hereinafter referred to as MEA) and a frame 21 supporting the MEA 20. The MEA 20 includes an electrolyte membrane, an anode electrode provided on the front surface of the electrolyte membrane, and a cathode electrode provided on the rear surface of the electrolyte membrane.

[0026] The electrolyte membrane is, for example, a solid polymer electrolyte membrane, and a thin film of perfluorosulfonic acid containing water can be used. The electrolyte is not limited to a fluorine-based electrolyte, and a hydrocarbon-based electrolyte can also be used.

[0027] The anode electrode includes an electrode catalyst layer formed on the front surface of the electrolyte membrane and serving as the reaction field for the electrode reaction, and a gas diffusion layer disposed on the front surface of the electrode catalyst layer and used to diffuse and supply the reactant gas. The cathode electrode includes an electrode catalyst layer formed on the rear surface of the electrolyte membrane and serving as the reaction field for the electrode reaction, and a gas diffusion layer disposed on the rear surface of the electrode catalyst layer and used to diffuse and supply the reactant gas. The electrode catalyst layer includes a catalyst metal that promotes the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas, an electrolyte with proton conductivity, and carbon particles with electron conductivity. The gas diffusion layer is composed of a gas-permeable conductive member, such as a porous carbon body.

[0028] At the anode electrode, fuel gas (hydrogen) supplied via the anode flow channel and gas diffusion layer is ionized by the catalyst and moves through the electrolyte membrane toward the cathode electrode. The electrons generated during this process are extracted as electrical energy through an external circuit. At the cathode electrode, oxidant gas (oxygen) supplied via the cathode flow channel and gas diffusion layer reacts with hydrogen ions introduced from the anode electrode and electrons transferred from the anode electrode, producing water. This generated water provides appropriate humidity to the electrolyte membrane, and the excess water is discharged to the outside of the UEA2.

[0029] The frame 21 is a roughly rectangular, film-like member made of insulating resin, rubber, or the like. A roughly rectangular opening 21a is provided in the center of the frame 21. The MEA 20 is positioned so as to completely cover the opening 21a and is supported by the periphery of the opening 21a. Three through-holes 211 to 213 are arranged vertically to the left of the opening 21a, extending longitudinally through the frame 21. Three through-holes 214 to 216 are arranged vertically to the right of the opening 21a, extending longitudinally through the frame 21.

[0030] like Figure 1As shown, the front and rear separators 3 of the UEA 2 have through-holes 311 to 316 extending through the separators 3 in the front-to-back direction, at positions corresponding to the through-holes 211 to 216 of the frame 21. These through-holes 311 to 316 are connected to the through-holes 211 to 216 of the frame 21, respectively. These interconnected through-holes 211 to 216 and 311 to 316 form flow passages PA1 to PA6 (indicated by arrows for convenience) that extend through the cell stack 101 in the front-to-back direction. These flow passages PA1 to PA6 are sometimes also referred to as manifolds. These flow passages PA1 to PA6 are connected to a manifold external to the fuel cell stack 100.

[0031] The flow channel PA1 (solid arrow) extending forward through through-holes 211 and 311 is the fuel gas supply channel. The flow channel PA6 (solid arrow) extending rearward through through-holes 216 and 316 is the fuel gas exhaust channel. The fuel gas supply channel PA1 and the fuel gas exhaust channel PA6 communicate with the anode channel, which is positioned facing the front surface of the MEA 20. As indicated by the solid arrows, fuel gas flows from left to right through the anode channel via the fuel gas supply channel PA1 and the fuel gas exhaust channel PA6. The anode channel is disconnected from the other channels PA2 to PA5 by a seal (not shown).

[0032] The flow channel PA4 (dashed arrow) extending forward through through-holes 214 and 314 serves as the oxidant gas supply channel. The flow channel PA3 (dashed arrow) extending rearward through through-holes 213 and 313 serves as the oxidant gas exhaust channel. The oxidant gas supply channel PA4 and the oxidant gas exhaust channel PA3 communicate with the cathode channel, which is positioned facing the rear surface of MEA 20. As indicated by the dashed arrows, the oxidant gas flows from right to left in the cathode channel through the oxidant gas supply channel PA4 and the oxidant gas exhaust channel PA3. The cathode channel is disconnected from the other channels PA1, PA2, PA5, and PA6 by a seal (not shown).

[0033] The flow channel PA5 (single-dash arrow) extending forward through through-holes 215 and 315 is the cooling medium supply channel. The flow channel PA2 (single-dash arrow) extending rearward through through-holes 212 and 312 is the cooling medium discharge channel. The cooling medium supply channel PA5 and the cooling medium discharge channel PA2 communicate with the cooling channel inside the partition 3. The cooling medium flows from right to left through the cooling channel PA5 and the cooling medium discharge channel PA2. The cooling channel is disconnected from the other flow channels PA1, PA3, PA4, and PA6 by a seal (not shown).

[0034] The end units 102, located on the front and rear sides of the battery stack 101, each include a terminal plate 4, an insulating plate 5, and an end plate 6. The front end unit 102 is sometimes referred to as a dry-side end unit, and the rear end unit 102 is sometimes referred to as a wet-side end unit. A pair of front and rear terminal plates 4, 4 are located on the front and rear sides of the battery stack 101, sandwiching the battery stack 101. A pair of front and rear insulating plates 5, 5 are located on the front and rear sides of the terminal plates 4, 4. A pair of front and rear end plates 6, 6 are located on the front and rear sides of the insulating plates 5, 5.

[0035] The terminal plate 4 is a generally rectangular plate-like member made of metal and has a terminal portion for extracting the electricity generated by the electrochemical reaction in the battery stack 101. The insulating plate 5 is a generally rectangular plate-like member made of non-conductive resin or rubber, which electrically insulates the terminal plate 4 from the end plate 6. The end plate 6 is a plate-like member made of metal or a high-strength resin. When assembling the fuel cell stack 100, a compressive load is applied to the battery stack 101 in the front-to-back direction. In this state, the housing surrounding the battery stack 101 and the front and rear end units 102 are combined together. Therefore, after the assembly of the fuel cell stack 100 is completed, the compressive load on the fuel cell stack 100 is maintained.

[0036] The rear end unit 102 is provided with a plurality of through holes 102a to 102f that penetrate the end unit 102 in the front-to-back direction. The through holes 102a to 102f include a through hole that penetrates the terminal plate 4, a through hole that penetrates the insulating plate 5, and a through hole that penetrates the end plate 6. Figure 1 In FIG. 1 , they are collectively represented as through holes 102 a to 102 f.

[0037] Through hole 102a is formed as an extension of fuel gas supply channel PA1 and communicates with fuel gas supply channel PA1. Through hole 102b is formed as an extension of coolant exhaust channel PA2 and communicates with coolant exhaust channel PA2. Through hole 102c is formed as an extension of oxidant gas exhaust channel PA3 and communicates with oxidant gas exhaust channel PA3. Through hole 102d is formed as an extension of oxidant gas supply channel PA4 and communicates with oxidant gas supply channel PA4. Through hole 102e is formed as an extension of coolant supply channel PA5 and communicates with coolant supply channel PA5. Through hole 102f is formed as an extension of fuel gas exhaust channel PA6 and communicates with fuel gas exhaust channel PA6.

[0038] A pump for supplying a cooling medium is connected to these through-holes 102a to 102f, particularly through-hole 102e, to supply the cooling medium to the fuel cell stack 100 through through-hole 102e. The cooling medium is discharged from through-hole 102b. The discharged cooling medium is cooled by heat exchange in the radiator and then supplied again to the fuel cell stack 100 through through-hole 102e.

[0039] The above is a schematic structure of the fuel cell stack 100. The fuel cell stack 100 is housed in a substantially box-shaped casing and mounted on a vehicle.

[0040] In such a fuel cell stack 100, after the fuel cell stack 100 is assembled, a cooling medium is injected into the interior of the fuel cell stack 100 through the through hole 102e. At this time, the air in the cooling channel moves upward and moves toward the cooling medium exhaust channel PA2 along the flow of the cooling medium. In addition, when air is mixed in the cooling medium supplied through the through hole 102e, the air also moves toward the cooling medium exhaust channel PA2 along the flow of the cooling medium. Therefore, air (bubbles) are easily retained in the upper area of ​​the cooling medium exhaust channel PA2, and the retained air needs to be discharged from the cooling medium exhaust channel PA2. The present embodiment is characterized in that the air retained in the cooling medium exhaust channel PA2 is discharged. This point is explained below.

[0041] Figure 3 is a rear view of the fuel cell stack 100, Figure 4 It is along Figure 3 Cross-sectional view taken along line IV-IV. Figure 3 The shape of the rear surface of the wet side end plate 6 (such as the arrangement of the through holes 102a to 102f) is further specifically shown in FIG. Figure 4 In FIG, individual illustrations of the power generation cells 1 of the cell stack 101 are omitted. Figure 3 、 Figure 4 In order to distinguish the structures of the front and rear end units 102, the terminal plate 40, the insulating plate 50 and the end plate 60 are used to represent the front side (dry side) end unit 102, and the terminal plate 41, the insulating plate 51 and the end plate 61 are used to represent the rear side (wet side) end unit 102.

[0042] like Figure 4 As shown, the cooling medium discharge flow channel PA2 extends in the front-to-back direction through the through-hole 102b of the front end cell 102, the through-holes 212 and 312 of the battery stack 101, and the through-hole 102b of the rear end cell 102. The through-hole 102b of the front end cell 102 includes the through-hole 40a of the terminal plate 40 and the through-hole 50a of the insulating plate 50. The front end of the cooling medium discharge flow channel PA2 is closed by the end plate 60.

[0043] The through-holes 102b of the rear end unit 102 include the through-holes 41a of the terminal plate 41, the through-holes 51a of the insulating plate 51, and the through-holes 61a of the end plate 61. More specifically, the insulating plate 51 is provided with a rearwardly projecting protrusion 510, which engages with the through-holes 61a of the end plate 61. Therefore, the through-holes 51a are located within the through-holes 61a.

[0044] Figure 3 The figure shows the pipe mounting parts 103a to 103f for mounting external pipes connected to the through holes 102a to 102f of the rear end unit 102. Figure 3 As shown, the pipe installation parts 103e and 103b for supplying and discharging the cooling medium are located on the left and right outside of the pipe installation parts 103a and 103d for supplying the fuel gas and the oxidant gas, and are located on the left and right outside of the pipe installation parts 103f and 103c for discharging the fuel gas and the oxidant gas.

[0045] In end unit 102, a through-hole 102g for air discharge is provided diagonally above and to the left of through-hole 102b for cooling medium discharge. Through-hole 102g is sometimes referred to as the first through-hole, and through-hole 102b is sometimes referred to as the second through-hole. A duct mounting portion 103g is mounted on through-hole 102g. Through duct mounting portion 103g, through through-hole 102g, an external duct for air discharge is connected. Figure 3 The dashed line in the figure shows the cooling medium discharge passage PA2 of the battery stack 101. Through holes 102b and 102g are both provided inside the cooling medium discharge passage PA2. More specifically, through hole 102b is located at the bottom of the cooling medium discharge passage PA2, while through hole 102g is located at the top of the cooling medium discharge passage PA2.

[0046] like Figure 4 As shown, through-holes 102b and 102g branch off from coolant discharge passage PA2 and are each provided on insulating plate 51. The periphery of through-hole 102b has a tapered surface 511 (reduced diameter portion) tapering to a tapered shape with its opening area gradually decreasing toward the rear, and a cylindrical surface 512 extending rearward from the rear end of tapered surface 511 to the outlet (rear end surface 513) at the rear end of through-hole 102b. Through-hole 102g extends rearward from tapered surface 511, penetrating insulating plate 51 in the front-to-back direction. Through-hole 102g (first through-hole) has a smaller diameter than through-hole 102b (second through-hole), i.e., cylindrical surface 512.

[0047] A connecting pipe 7 is provided along the upper surface of the coolant discharge passage PA2. The connecting pipe 7 is a slender pipe member with a roughly cylindrical cross-section, with openings (front opening 71a and rear opening 72a) on its front and rear faces 71 and 72, respectively. The connecting pipe 7 extends linearly in the front-to-back direction along the coolant discharge passage PA2. The front and rear ends of the connecting pipe 7 protrude forward and rearward from the battery stack 101.

[0048] The connecting tube 7 is formed of a material such as resin, rubber, or glass. However, considering vibration and temperature fluctuations in the fuel cell stack 100, the connecting tube 7 is preferably made of a flexible resin or rubber. Air (air bubbles) accumulated above the coolant discharge passage PA2 passes through the interior of the connecting tube 7. The cross-sectional area of ​​the connecting tube 7 is sufficiently smaller than that of the coolant discharge passage PA2.

[0049] The front end opening 71a of the connecting tube 7 is located within the interior space SP1 of the through-hole 102b of the front end unit 102. More specifically, the through-hole 40a of the terminal plate 40 and the through-hole 50a of the insulating plate 50 have approximately the same shape as the coolant discharge passage PA2 when viewed from the front-to-back direction. The front end opening 71a passes through the through-hole 40a and is located inside the through-hole 50a. Thus, the front end opening 71a communicates with the coolant discharge passage PA2 via the interior space SP1. Alternatively, a recessed portion may be provided on the rear surface of the insulating plate 50 in place of the through-hole 50a, with the front end opening 71a located inside the recessed portion and communicating with the coolant discharge passage PA2 via the interior space of the recessed portion.

[0050] The rear end of the communication pipe 7 is fitted into the through hole 102g of the insulating plate 51 , and the rear end opening 72a communicates with the through hole 102g.

[0051] Internal space SP1 is located upstream of coolant discharge passage PA2. The pressure in internal space SP1, upstream of the coolant flow, is higher than the pressure within through-hole 102g. Consequently, a pressure difference develops between the front opening 71a and rear opening 72a of connecting tube 7. This pressure difference causes bubbles to migrate from front opening 71a to rear opening 72a within connecting tube 7. Thus, by providing a long connecting tube 7 extending from the front end unit 102 to the rear end unit 102 in coolant discharge passage PA2, the pressure difference between the two ends of connecting tube 7 is increased, thereby promoting the migration of bubbles.

[0052] The front end portion of the communication pipe 7 is supported by a front support portion 201 of the end unit 102 provided on the front side, and the rear end portion of the communication pipe 7 is supported by a rear support portion 202 of the end unit 102 provided on the rear side. Figure 5 The structure of the rear support portion 202 is shown. Figure 4 The main part of the enlarged view ( Figure 4 (enlarged view of the V part of the image), Figure 6 It is along Figure 4 The cross-sectional view of the VI-VI line. Figure 5 、 Figure 6 As shown, the terminal plate 41 is in the through hole 41a ( Figure 4 ) has a protrusion 411 protruding toward the inside of the through hole 41a at the upper left corner of the periphery. A substantially circular through hole 411a is provided in the protrusion 411, and the rear end portion of the communicating pipe 7 passes through the through hole 411a.

[0053] The through hole 102g is centered around the axis CL1 extending in the front-to-back direction. The through hole 102g includes a tapered portion 521 having a tapered surface 521b tapered about the axis CL1 with the opening area gradually decreasing toward the rear; a small-diameter portion 522 connected to the rear end 521a of the tapered portion 521, having a smaller opening area than the rear end 521a and having a generally cylindrical shape about the axis CL1; and a large-diameter portion 523 connected to the small-diameter portion 522, having a larger opening area than the small-diameter portion 522 and having a generally cylindrical shape. The small-diameter portion 522 and the tapered portion 521, and the small-diameter portion 522 and the large-diameter portion 523, respectively, are connected in a stepped manner.

[0054] The large diameter portion 523 is connected to the pipe mounting portion 103g ( Figure 3 ) is connected to an external pipe. The top end of the external pipe is, for example, fitted into the large diameter portion 523, and the external pipe is mounted on the pipe mounting portion 103g in a shaft-sealed state. The opening area of ​​the large diameter portion 523 is larger than the opening area of ​​the rear end portion 521a of the tapered portion 521. In order to avoid interference between the external pipes, the center of the large diameter portion 523 ( Figure 3 The center of the pipe mounting portion 103g) is offset from the axis CL1 (refer to Figure 9 As long as there is no possibility of interference between external pipes, the center of the large diameter portion 523 may be aligned with the axis CL1.

[0055] More specifically, the rear end face 72 of the communicating tube 7 abuts the tapered portion 521 (tapered surface 521b) along its entire perimeter. For example, the rear end face 72 abuts the tapered portion 521 at a position forward of the tapered portion's rear end 521a. This aligns the axis CL1 of the through hole 102g with the centerline CL2 of the communicating tube 7, allowing the position of the rear end opening 72a of the communicating tube 7 to be precisely defined.

[0056] Figure 7 The structure of the front support portion 201 is shown. Figure 4 The main part of the enlarged view (Part VII enlarged view). Figure 7As shown, the front support portion 201 is also constructed in the same manner as the rear support portion 202. That is, the terminal plate 40 has a protrusion 410 that protrudes toward the inside of the through hole 40a. A substantially circular through hole 410a is formed in the protrusion 410, and the front end of the connecting pipe 7 passes through the through hole 410a. A retainer 505 is provided at the upper end of the periphery of the through hole 50a of the insulating plate 50. The retainer 505 is located at the axis CL1 ( Figure 5 ) is centered on the axis CL3 on the extension line of the connecting pipe 7 and is in a substantially cylindrical shape. The outer peripheral surface of the front end portion of the connecting pipe 7 is supported by the retainer 505.

[0057] A generally circular opening 505a is provided on the front wall of the retainer 505, and the front end opening 71a communicates with the internal space SP1 via the opening 505a. Alternatively, a notch may be provided in the lower portion of the retainer 505, and the front end opening 71a communicates with the internal space SP1 via the notch. The inner circumferential surface of the retainer 505 may not be cylindrical, but may be tapered, similar to the rear support portion 202.

[0058] Thus, in this embodiment, the rear and front ends of the connecting tube 7 are supported by the rear support portion 202 of the end unit 102, which has a tapered portion 521 that tapers rearward, and the front support portion 201 of the end unit 102, which has a substantially cylindrical retainer 505. This allows the connecting tube 7 to be stably held at a predetermined position at the upper end of the coolant discharge flow path PA2. As a result, the position of the front opening 71a relative to the opening 505a is restricted, allowing bubbles to be effectively introduced into the connecting tube 7 through the opening 505a. Furthermore, the position of the rear opening 72a relative to the through-hole 102g is restricted, allowing bubbles that have passed through the connecting tube 7 to be effectively discharged to the outside through the through-hole 102g.

[0059] However, in Figure 5 In the structure, at the abutment position Pa, the outer peripheral edge of the rear end portion of the connecting tube 7 abuts against the peripheral surface of the tapered portion 521 (tapered surface 521b) over the entire circumference. Therefore, at the abutment position Pa, there is no gap between the through hole 102g and the connecting tube 7. Therefore, when bubbles are generated around the rear end portion of the connecting tube 7 (for example, inside the through hole 102b) along the flow of the cooling medium, the distance from the bubbles to the front end opening 71a of the connecting tube 7 is long, making it difficult to discharge the bubbles to the outside through the connecting tube 7. In view of this, it is preferred as follows Figure 8 The support portion 202 is shown. Figure 8 Another example of the rear support portion 202 is shown. Figure 4 An enlarged view of the main part, Figure 9 yes Figure 8 IX direction view.

[0060] Figure 8 and Figure 5 The difference lies in the structure of the through hole 102g, especially the structure of the tapered portion 521. Figure 8 、 Figure 9 As shown, slit-like grooves 525 and 526 are provided at the upper and lower ends of the tapered portion 521. Grooves 525 and 526 extend concavely from the tapered surface 521b through a portion of the small-diameter portion 522 and extend in the front-to-back direction approximately parallel to the axis CL1. The bottom surface (upper end surface) of the upper groove 525 is located below the upper end surface of the large-diameter portion 523. The bottom surface (lower end surface) of the lower groove 526 is located above the lower end surface of the large-diameter portion 523.

[0061] The grooves 525 and 526 have a predetermined width in the left-right direction, extend beyond the contact position Pa of the rear end portion of the connecting pipe 7, and extend from the tapered surface 511 to the front end surface 523a of the large diameter portion 523. The positions of the bottom surfaces of the grooves 525 and 526, that is, the positions of the upper end surface of the groove 525 and the lower end surface of the groove 526, are constant throughout the entire front-to-back direction. The cross-sectional shape of the through hole 102g in the range from the tapered surface 511 to the front end surface 523a of the large diameter portion 523 is as follows: Figure 9 Therefore, the rear end portion of the connecting pipe 7 is in contact with the tapered portion 521 at both left and right ends, and the rear end surface 72 (shown by hatching for convenience) is exposed at both upper and lower ends.

[0062] Thus, a gap is generated between the connecting pipe 7 and the through hole 102g, from the through hole 102b on the front side of the tapered surface 511 to the inner space of the large diameter portion 523 at the rear of the connecting pipe 7. Therefore, air can flow in and out of the connecting pipe 7 as shown in FIG. Figure 8 The flow is as shown by the arrow in the middle, allowing bubbles to move rearward through the gaps (grooves 525, 526). As a result, even if bubbles are generated around the rear end of the connecting pipe 7 along the flow of the coolant, these bubbles can be effectively discharged to the outside of the fuel cell stack 100 through the through hole 102g.

[0063] The cross-sectional shape of the through hole 102g is not limited to an elliptical shape, but may be an elliptical shape that is elongated in the vertical direction. The bubbles are retained above the cooling medium discharge flow channel PA2. Therefore, it is also possible to provide the grooves 525 and 526 at the upper and lower ends of the tapered portion 521 instead of the grooves 525 and 526. Figure 10 As shown, the groove portion 527 is provided only at the upper end portion. Figure 10 In the embodiment, the width of the groove portion 527 is smaller than the diameter of the small-diameter portion 522. The width of the groove portion 527 may be the same as the width of the small-diameter portion 522, or may be larger than the diameter of the small-diameter portion 522.

[0064] The present invention can achieve the following effects.

[0065] (1) The fuel cell stack 100 comprises: a cell stack 101, which is formed by stacking a plurality of power generation cells 1 having UEAs 2 and separators 3 in the front-to-back direction; front and rear end units 102, 102, which are arranged at the front and rear ends of the cell stack 101; a cooling medium discharge flow path PA2, which is provided through the cell stack 101 in the front-to-back direction to discharge the cooling medium introduced into the plurality of power generation cells 1; and a connecting pipe 7, which is substantially cylindrical and is provided in the cooling medium discharge flow path PA2, and has a front end opening 71a and a rear end opening 72a, which are respectively provided at the front and rear ends and communicate with the upstream and downstream sides of the cooling medium discharge flow path PA2. Figure 1 、 Figure 2 、 Figure 4 The rear end unit 102 has a front end surface (tapered surface 511) facing the cooling medium discharge flow path PA2 and a rear end surface 513 ( Figure 4 The rear end unit 102 is provided with a through hole 102g (which is connected to the rear end opening 72a of the connecting pipe 7 and passes through the rear end unit 102). Figure 4 The front and rear end units 102, 102 respectively have a front support portion 201 and a rear support portion 202 that support the peripheral portion of the front end portion and the peripheral portion of the rear end portion of the connecting pipe 7. The rear support portion 202 has a tapered portion 521 on the peripheral surface of the through hole 102g. The tapered portion 521 has a tapered surface 521b ( Figure 5 ).

[0066] In this manner, the front end portion of the connecting tube 7 located forward of the cell stack 101 and the rear end portion of the connecting tube 7 located rearward of the cell stack 101 are supported by the front support portion 201 of the front end unit 102 and the rear support portion 202 of the rear end unit 102. Furthermore, the front end portion is supported via the tapered portion 521. This allows the connecting tube 7 to be positioned and retained within the coolant discharge passage PA2 with high precision. Consequently, when a compressive load is applied in the stacking direction of the power generation cells 1 during assembly of the fuel cell stack 100, thereby compressing the cell stack 101, the end unit 102 and the connecting tube 7 do not interfere with each other, and the connecting tube 7 can be stably retained at the upper end of the coolant discharge passage PA2, where the coolant flows.

[0067] (2) The tapered portion 521 has grooves 525 to 527 that are recessed from the tapered surface 521b and extend substantially parallel to the axis CL1 beyond the contact position Pa where the rear end of the connecting pipe 7 contacts. Figures 8 to 10When the rear end of the connecting tube 7 abuts the tapered portion 521, the gap between the connecting tube 7 and the through hole 102g is closed, potentially trapping air bubbles around the rear end of the connecting tube 7. This is addressed by providing grooves 525-527 in the tapered portion 521. This allows air to flow through the grooves 525-527, past the abutment position Pa, and toward the rear. This effectively discharges air bubbles trapped within the coolant discharge passage PA2.

[0068] (3) The connecting pipe 7 extends in a substantially horizontal direction ( Figure 4 Grooves 525 and 527 are provided on the upper portion of the tapered portion 521 ( Figure 9 、 Figure 10 Bubbles are retained above the cooling medium discharge flow path PA2. By providing grooves 525 and 527 above, only the bubbles can be efficiently discharged through the grooves 525 and 527.

[0069] (4) The rear end unit 102 includes a terminal plate 41 disposed adjacent to the battery stack 101, an insulating plate 51 disposed adjacent to the terminal plate 41, and an end plate 61 disposed adjacent to the insulating plate 51. Figure 4 ). The tapered portion 521 is provided on the insulating plate 51 ( Figure 5 、 Figure 8 ). Thus, the tapered portion 521 can be easily formed together with the grooves 525 to 527 .

[0070] The above embodiment can be modified in various ways. Several variations are described below. In the above embodiment, the dry-side end unit 102 (first end unit) is composed of the terminal plate 40 (collector plate), the insulating plate 50 (insulating plate), and the end plate 60 (end plate), while the wet-side end unit 102 (second end unit) is composed of the terminal plate 41 (collector plate), the insulating plate 51 (insulating plate), and the end plate 61 (end plate). However, the configuration of the first and second end units is not limited to that described above. The tapered portion 521 may also be provided on components other than the insulating plate 51.

[0071] In the above embodiment, the connecting tube 7 is positioned at the uppermost portion of the coolant discharge passage PA2. The connecting tube 7 is provided with a front opening 71a (first opening) and a rear opening 72a (second opening) at the front end (one end) and rear end (the other end), respectively, which communicate with the upstream and downstream sides of the coolant discharge passage PA2. However, the configuration of the generally cylindrical tube body is not limited to the above. In the above embodiment, the connecting tube 7 is positioned so as to extend generally horizontally, i.e., in a generally horizontal position. However, the position of the tube body is not limited to a generally horizontal position. In the above embodiment, a plurality of power generation cells 1 are stacked in the front-to-back direction (prescribed direction) to form the cell stack 101. However, the prescribed direction may also be a direction other than the front-to-back direction.

[0072] In the above embodiment, the front support portion 201 (first support portion) and the rear support portion 202 (second support portion) support the periphery of the front end portion of the communication tube 7 in front of the battery stack 101 (the periphery of the first end portion) and the periphery of the rear end portion of the communication tube 7 in rear of the battery stack 101 (the periphery of the second end portion). However, the configuration of the first support portion is not limited to the above configuration. Furthermore, the configuration of the second support portion may be any configuration as long as it has a tapered portion that tapers toward the outlet of the through-hole 102g (the outer end surface of the end unit) centered about the axis CL1 extending in the stacking direction of the power generation cells 1. In the above embodiment, grooves 525 and 526 are formed continuously at the upper and lower ends of the small-diameter portion 522 of the through-hole 102g. However, the configuration of the grooves may be any configuration as long as they extend beyond the contact position Pa with which the distal end of the communication tube 7 contacts and are substantially parallel to the axis CL1.

[0073] One or more of the above-described embodiments and modifications may be arbitrarily combined, and modifications may be combined with each other.

[0074] According to the present invention, the exhaust pipe body can be stably supported in the cooling medium discharge flow path without interfering with parts such as the end unit.

[0075] The present invention has been described above with reference to preferred embodiments. However, it should be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the claims.

Claims

1. A fuel cell stack, characterized in that: have: A battery stack (101) is formed by stacking a plurality of power generation cells (1) each having a membrane electrode structure (2) and a separator (3) in a predetermined direction; a first end unit (102) and a second end unit (102) arranged at one end and the other end of the battery stack (101) in the specified direction; a cooling medium discharge flow channel (PA2) provided to penetrate the battery stack (101) in the prescribed direction to discharge the cooling medium introduced into the plurality of power generation cells (1); and The tube body (7) is substantially cylindrical and is disposed in the cooling medium discharge flow channel (PA2). A first opening (71a) and a second opening (72a) are provided at one end and the other end, respectively, for communicating with the upstream side and the downstream side of the cooling medium discharge flow channel (PA2). The second end unit (102) has one end surface (511) facing the cooling medium discharge flow channel (PA2) and another end surface (513) on the opposite side of the one end surface (511). A through hole (102g) is provided in the second end unit (102), the through hole being in communication with the second opening (72a) of the tube body (7) and penetrating the second end unit (102). The first end unit (102) and the second end unit (102) respectively have a first supporting portion (201) and a second supporting portion (202) for supporting the peripheral portion of the one end and the peripheral portion of the other end of the tube body (7). The second supporting portion (202) has a tapered portion (521) on the circumference of the through hole (102g), and the tapered portion (521) has a tapered surface (521b) formed so as to be tapered toward the other end surface (513) of the second end unit (102) with an axis (CL1) extending substantially parallel to the prescribed direction as the center.

2. The fuel cell stack according to claim 1, wherein: The tapered portion (521) has grooves (525-527) that are recessed from the tapered surface (521b) and extend approximately horizontally with the axis (CL1) beyond a contact position (Pa) for the top end of the tube (7) to contact.

3. The fuel cell stack according to claim 2, characterized in that The tube (7) extends in a substantially horizontal direction. The grooves (525, 527) are provided on the upper portion of the tapered portion (521).

4. The fuel cell stack according to any one of claims 1 to 3, characterized in that The second end unit (102) includes a current collector (41) disposed adjacent to the battery stack (101), an insulating plate (51) disposed adjacent to the current collector (41), and an end plate (61) disposed adjacent to the insulating plate (51). The tapered portion (521) is provided on the insulating plate (51).

5. The fuel cell stack according to any one of claims 1 to 3, characterized in that The through hole (102g) is a first through hole, In the second end unit (102), a second through hole (102b) is opened below the first through hole (102g) to form the cooling medium discharge flow channel (PA2).

6. The fuel cell stack according to claim 5, characterized in that The first through hole (102g) is smaller than the second through hole (102b), and branches off from the cooling medium discharge flow channel (PA2) to open.

7. The fuel cell stack according to claim 6, characterized in that The second end unit (102) has a reduced diameter portion (511) provided in such a manner that the flow channel area of ​​the cooling medium discharge flow channel (PA2) in the second through hole (102b) gradually decreases. The first through hole (102g) passes through the upper end portion of the reduced diameter portion (511) and opens.

8. The fuel cell stack according to claim 4, wherein: The insulating plate (51) has a protrusion (510) protruding toward the end plate (61). The protrusion (510) is engaged with the through hole (61a) of the end plate (61).

Images