Power extraction structure of fuel cell stack

Abstract

To suppress heat transfer from a fuel cell stack.SOLUTION: A power takeout structure 1 is provided for a first fuel stack 101 mounted on a vehicle and connected to an electrical unit 110. The power takeout structure 1 includes: a first conductor 11 that intermediates a power supply to the electrical unit 110 from the first fuel cell stack 101; a second conductor 12 that is arranged between the first conductor 11 and the electrical unit 110 in a power supply path to the electrical unit 110 from the first fuel cell stack 101; a relay electrode 20 that relays power supply to the second conductor 12 from the first conductor 11; and a first mount M11 that fixes the first fuel cell stack 101 to a power generation structure body case B housing the first fuel cell stack 101. The relay electrode 20 is fixed to the first mount M11.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power extraction structure of a fuel cell stack.

Background Art

[0002] Patent Document 1 discloses a solid oxide fuel cell system including a fuel cell stack, a round bar-shaped current output member having one end connected to the fuel cell stack and the other end threaded, a terminal connected to the other end, and a current cable connected to the terminal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The fuel cell stack may have a case for heat insulation or the like. However, even in this case, heat is transmitted from the conductor coupled to the fuel cell stack. As a result, there is a risk of affecting the heat resistance of an electrical load that receives power supply from the fuel cell stack. Also, in this case, there is a risk that no general electric wire can be used for the power supply from the fuel cell stack. Further, when the fuel cell stack is for in-vehicle use, the volume of the mounting space is more restricted than in the case of stationary use, and it is difficult to secure space required for cooling the conductor. For this reason, a technique for suppressing heat transfer from the fuel cell stack in the case of in-vehicle use is desired.

[0005] The present invention has been made in view of such problems, and an object thereof is to suppress heat transfer from a fuel cell stack.

Means for Solving the Problems

[0006] A power extraction structure for a fuel cell stack according to one embodiment of the present invention is mounted in a vehicle and connected to an electrical load. Solid oxide type The device includes a first conductor provided for the fuel cell stack and mediating the power supply from the fuel cell stack to the electrical load, a second conductor positioned between the first conductor and the electrical load in the power supply path from the fuel cell stack to the electrical load, a relay electrode that relays the power supply from the first conductor to the second conductor, and a fixing part that fixes the fuel cell stack to a housing that houses the fuel cell stack. The fixing portion includes a housing fixing portion that is fixed to the housing and an insulating intermediate electrode fixing portion. The intermediate electrode fixing portion is supported by the housing fixing portion. The intermediate electrode is fixed on the intermediate electrode fixing portion so as to be insulated from the housing. [Effects of the Invention]

[0007] According to this embodiment, it becomes possible to dissipate heat from the fuel cell stack to the housing via the fixed part before heat is transferred from the fuel cell stack to the second conductor. Therefore, it becomes possible to suppress heat transfer from the fuel cell stack to the second conductor and the electrical load. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an exploded perspective view of an in-vehicle fuel cell system. [Figure 2] Figure 2 shows the power extraction structure in an in-vehicle configuration. [Figure 3] Figure 3 is a perspective view of the power extraction structure. [Figure 4] Figure 4 is an exploded perspective view of the power extraction structure. [Figure 5] Figure 5 shows the relay electrode as a standalone unit. [Figure 6] Figure 6 is a first explanatory diagram of the installation structure of the first mount. [Figure 7] Figure 7 is a second explanatory diagram of the installation structure of the first mount. [Figure 8] Figure 8 shows an example of a material used for gaskets. [Figure 9] Figure 9 shows an example of metal materials focusing on hardness and thermal conductivity. [Figure 10] Figure 10 shows an example of a ceramic material that focuses on insulating properties. [Figure 11] FIG. 11 is a diagram showing an example of the material of the ceramic focusing on the thermal conductivity. [Figure 12] FIG. 12 is the first diagram of the explanatory diagram of the heat dissipation mode in the power extraction structure. [Figure 13] FIG. 13 is the second diagram of the explanatory diagram of the heat dissipation mode in the power extraction structure. [Figure 14] FIG. 14 is an explanatory diagram of the heat dissipation mode from the mounting portion. [Figure 15] FIG. 15 is the first diagram of the explanatory diagram of the heat dissipation mode according to the configuration arrangement. [Figure 16] FIG. 16 is the second diagram of the explanatory diagram of the heat dissipation mode according to the configuration arrangement. [Figure 17] FIG. 17 is a view of the power extraction structure seen from the rear of the vehicle body. [Figure 18] FIG. 18 is a diagram showing an example of the material of the metal focusing on the toughness. [Figure 19] FIG. 19 is a diagram showing an example of the material of the heat-resistant metal focusing on the thermal conductivity. [Figure 20] FIG. 20 is a partially exploded view of the power extraction structure according to the second modification example. [Figure 21] FIG. 21 is a perspective view of the power extraction structure according to the second modification example. [Figure 22] FIG. 22 is a perspective view of the power extraction structure according to the third modification example.

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 is an exploded perspective view of an in-vehicle fuel cell system (hereinafter, also referred to as "fuel cell system") 100. In the present embodiment, the fuel cell system 100 mounted on an electric vehicle driven by a drive motor will be described as an example. Further, in the present embodiment, a solid oxide type fuel cell is assumed.

[0011] The fuel cell system 100 comprises a power generation structure A and a power generation structure case B that houses the power generation structure A. There are three main reasons for housing the power generation structure A in the power generation structure case B. Firstly, to securely fix it to the vehicle body while preventing damage to the power generation structure A due to collisions or interference with other parts. Secondly, because the fuel used is mainly flammable and odorless, it is necessary to suppress leakage from fuel piping etc. to a level below the flammability limit. Thirdly, solid oxide fuel cells have a high power generation temperature (500°C or higher), and this temperature needs to be maintained during system operation. On the other hand, other auxiliary equipment and on-board components housed in the prime mover room do not have resistance to such high temperatures. Therefore, insulation is necessary to suppress temperature drops due to heat dissipation, and heat shielding is necessary to protect other auxiliary equipment etc.

[0012] The power generation structure A has an auxiliary equipment structure 103 positioned between the first fuel cell stack 101 and the second fuel cell stack 102, and is stacked in the order of second fuel cell stack 102, auxiliary equipment structure 103, and first fuel cell stack 101 from bottom to top. The auxiliary equipment structure 103 is a housing that encloses auxiliary equipment (heat exchanger, combustor, etc.) that exchanges gas with the first fuel cell stack 101 and the second fuel cell stack 102. Both the first fuel cell stack 101 and the second fuel cell stack 102 consist of single cells stacked in the vertical direction of the vehicle body.

[0013] The power generation structure case B has a split structure and includes a front member 104 located on the front side in the longitudinal direction of the vehicle body and a rear member 105 located on the rear side in the longitudinal direction of the vehicle body. The front member 104 has a box shape consisting of a front surface 104a which becomes the leading edge in the longitudinal direction of the vehicle body when mounted on the vehicle, two side surfaces 104b extending to the rear of the vehicle body from both sides of the front surface 104a in the lateral direction of the vehicle body, and an upper surface 104c and a lower surface extending to the rear of the vehicle body from both sides of the front surface 104a in the vertical direction of the vehicle body. The power generation structure A is fixed to the side surfaces 104b by bolts via first mounts M11 and M12 provided on the first fuel cell stack 101, second mounts M21 and M22 provided on the second fuel cell stack 102, and third mounts M31 and M32 provided on the auxiliary equipment structure 103. Note that the second mount M21 on the right side in the lateral direction of the vehicle body is hidden behind and is not shown.

[0014] The rear member 105 has an opening 105a through which a conductor 10 connecting the power generation structure A and the electrical unit 110 located outside the power generation structure case B passes. The electrical unit 110 includes a controller, a converter, etc. The opening 105a opens toward the rear in the longitudinal direction of the vehicle body. The opening 105a has a sealing portion surrounding the opening, which is closed when the electrical unit 110 is attached to the sealing portion. The electrical unit 110 consists of a safety device, an interrupter, a converter that adjusts the voltage fluctuations of the fuel cell stack during power generation to the voltage required by the downstream load (battery, motor, etc.). The front member 104 and the rear member 105 are integrated by connecting them at their respective mating surfaces. The connection surfaces formed by these mating surfaces are tilted backward with respect to the vertical direction of the vehicle body, and most of the power generation structure A is housed in the front member 104. The power generation structure case B corresponds to the housing.

[0015] The first fuel cell stack 101 has a case 101a. The case 101a houses the main body of the first fuel cell stack 101 and serves to prevent short circuits and damage due to contact with the main body, and to apply an appropriate load while holding the end plates at both ends of the stack. The power generation structure case B houses the first fuel cell stack 101 together with the case 101a. The first fuel cell stack 101 is provided with the power extraction structure 1 which will be described next.

[0016] Figure 2 shows the power extraction structure 1 in an in-vehicle state. Figure 3 is a perspective view of the power extraction structure 1. Figure 4 is an exploded perspective view of the power extraction structure 1. Figure 5 shows the relay electrode 20 as a single unit. The power extraction structure 1 includes a conductor 10, a relay electrode 20, and a first mount M11. The first mount M11 is a fixed part and includes a main bracket 30, a sub-bracket 31, and a mounting part 40.

[0017] The conductor 10 has a first conductor 11 and a second conductor 12. The first conductor 11 mediates the power supply from the first fuel cell stack 101 to the electrical unit 110. The first conductor 11 has one end 11a, the other end 11b, and an extension 11c, and extends toward the rear of the vehicle, i.e., toward the electrical unit 110. The one end 11a is the front end of the vehicle and is fixed to the power terminal 101b of the first fuel cell stack 101. The power terminal 101b extends a part of the end current collection plate of the first fuel cell stack 101, penetrates the end plate of the main body, and protrudes from the case 101a toward the upper part of the vehicle. The other end 11b is the rear end of the vehicle and is connected to the main bracket 30. The bolt 2 is tightened into the relay electrode 20 while passing through the other end 11b and the main bracket 30. In other words, the other end 11b is fastened together with the main bracket 30 by the bolt 2. As a result, the other end 11b is fixed to the relay electrode 20 with the main bracket 30 in between.

[0018] The extension portion 11c extends along the longitudinal direction of the vehicle body. One end 11a bends from the extension portion 11c toward the left side of the vehicle body (the other side in the left-right direction of the vehicle body), and the other end 11b bends from the extension portion 11c toward the right side of the vehicle body (one side in the left-right direction of the vehicle body). At one end 11a, the contact surface with the power terminal 101b faces downwards towards the vehicle body, and at the other end 11b, the contact surface with the main bracket 30 faces forwards towards the vehicle body. The other end 11b contacts the main bracket 30 while wrapping around to the back side of the main bracket 30 when viewed from the front of the vehicle body. For this reason, the extension portion 11c is positioned so that its position in the longitudinal direction of the vehicle body coincides with that of the main bracket 30, and the other end 11b is positioned on the electrical unit 110 side relative to the main bracket 30. The other end 11b corresponds to the fixing portion of the first conductor 11.

[0019] The second conductor 12 is positioned between the first conductor 11 and the electrical unit 110 in the power supply path from the first fuel cell stack 101 to the electrical unit 110. In other words, the second conductor 12 is positioned downstream of the first conductor 11 in the power supply path. The second conductor 12 has one end 12a at the front of the vehicle body and is connected to the main bracket 30 from the rear of the vehicle body at the end 12a. Therefore, the end 12a is positioned on the electrical unit 110 side relative to the main bracket 30. The bolt 3 is tightened into the relay electrode 20, passing through the end 12a and the main bracket 30, thereby fixing the end 12a to the relay electrode 20 with the main bracket 30 in between. The end 12a corresponds to the fixing point of the second conductor 12.

[0020] The relay electrode 20 is provided on the main bracket 30 from the front of the vehicle body. Therefore, the relay electrode 20 is positioned on the first fuel cell stack 101 side relative to the main bracket 30. The relay electrode 20 is positioned on the first fuel cell stack 101 side, with the first fuel cell stack 101 side as one side and the electrical unit 110 side as the other side. The relay electrode 20 is a busbar and has a rectangular parallelepiped shape. The relay electrode 20 is positioned with its longitudinal direction aligned with the vertical direction of the vehicle body, its width direction aligned with the left-right direction of the vehicle body, and its thickness direction aligned with the front-rear direction of the vehicle body.

[0021] The relay electrode 20 has screw holes 20a and 20b and a heat sink portion 20c. A bolt 2 is tightened into screw hole 20a, and a bolt 3 is tightened into screw hole 20b. This fixes the relay electrode 20 to the main bracket 30. The relay electrode 20 is also electrically connected to the first conductor 11 via bolt 2 and to the second conductor 12 via bolt 3. The relay electrode 20 configured in this way connects the first conductor 11 and the second conductor 12 and relays power supply between them. In the relay electrode 20, screw hole 20a is provided on one end in the longitudinal direction, and screw hole 20b is provided on the other end in the longitudinal direction. Therefore, current flows through the relay electrode 20 along the longitudinal direction, and the longitudinal direction of the relay electrode 20 constitutes the conductive direction of the relay electrode 20.

[0022] The relay electrode 20 has a cross-sectional area in the direction of conduction that corresponds to the current being conducted. The current being conducted is the current corresponding to the output of the first fuel cell stack 101. The cross-sectional area corresponding to the current being conducted is, in other words, the required cross-sectional area, and is predetermined from the viewpoint of ensuring the current being conducted. Both screw holes 20a and screw holes 20b are formed along the plate thickness direction, and the plate thickness H of the relay electrode 20 has a predetermined thickness that is necessary and sufficient for the screw holes 20a and screw holes 20b. Therefore, as the current being conducted increases, the relay electrode 20 becomes wider with the same plate thickness H in order to ensure the required cross-sectional area. As a result, a relay electrode 20 with a shape that has a larger contact area with the main bracket 30 is obtained as the current being conducted increases. The plate thickness H is the plate thickness of the relay electrode 20 in the part excluding the heat sink portion 20c. The predetermined thickness is, in other words, the necessary and sufficient thickness for fixing with bolts 2 and 3, and is determined in advance. The predetermined thickness is, for example, about 5 mm to 10 mm.

[0023] The heat sink portion 20c has a shape that increases the surface area compared to a planar shape. The heat sink portion 20c promotes heat dissipation, thereby facilitating heat transfer from other parts of the relay electrode 20. The heat sink portion 20c is provided on a portion other than the contact surface, which is the surface facing the main bracket 30. In this embodiment, the heat sink portion 20c is provided on the back surface of the contact surface, that is, the surface facing the front of the vehicle. The heat sink portion 20c may also be provided on the upper or lower surface of the vehicle body, or on the left or right surface of the vehicle body.

[0024] The heat sink portion 20c is composed of multiple fins 20ca extending along the conductive direction. Therefore, in the intermediate electrode 20, the required cross-sectional area does not change along the longitudinal direction between the screw holes 20a and 20b, making it easy to secure the required cross-sectional area and, therefore, the current supply. Furthermore, although the required cross-sectional area can be secured in parts other than the heat sink portion 20c, in this embodiment the required cross-sectional area is configured to include the heat sink portion 20c. This also prevents the intermediate electrode 20 from becoming heavier due to the heat sink portion 20c. Multiple fins 20ca can be formed by forming multiple grooves on the surface of the intermediate electrode 20.

[0025] The main bracket 30 extends in the left-right direction of the vehicle body and is cantilevered to the mounting portion 40 at one end. The relay electrode 20 is provided on the other end of the main bracket 30. The main bracket 30 corresponds to the relay electrode fixing portion. A sub-bracket 31 is further fixed to the main bracket 30. The sub-bracket 31 connects the main bracket 30 to the first fuel cell stack 101. In other words, the sub-bracket 31, together with the main bracket 30, constitutes a bracket used to fix the first fuel cell stack 101 to the front member 104. The sub-bracket 31 is fixed to the middle part of the main bracket 30 and also to the case 101a of the first fuel cell stack 101. The sub-bracket 31 is bolted to the main bracket 30 and the case 101a at, for example, two locations each.

[0026] The mount portion 40 has a main body portion 40a. The main body portion 40a supports the main bracket 30 in a displaceable manner. The main body portion 40a allows displacement of the main bracket 30 in the vertical direction of the vehicle body (the single-cell stacking direction of the first fuel cell stack 101). This is for the following reason: In the first fuel cell stack 101, the temperature changes significantly between operation and shutdown, and the dimensions in the single-cell stacking direction change accordingly. As a result, the change in the single-cell stacking direction dimensions extends to the main bracket 30 via the sub-bracket 31, and damage may occur if the change is not absorbed. Therefore, the first mount M11 fixes the first fuel cell stack 101 to the front member 104 while allowing displacement of the main bracket 30.

[0027] The mounting portion 40 further includes an installation portion. The installation portion can be configured such that the mounting portion 40 is installed on the inner wall surface of the front member 104. In this case, the entire first mount M11 is provided inside the power generation structure case B. In contrast, in this embodiment, the first mount M11 is provided as follows.

[0028] Figure 6 is a first explanatory diagram of the installation structure of the first mount M11. Figure 7 is a second explanatory diagram of the installation structure of the first mount M11. In this embodiment, the mount portion 40 has an installation portion 40b as an installation portion. The installation portion 40b is made of a flange and is provided at the portion of the main body portion 40a facing the outer wall surface of the front member 104. The installation portion 40b is integrally formed with the case member of the main body portion 40a, and the main body portion 40a and the installation portion 40b are made of metal, for example.

[0029] The front member 104 is provided with an insertion hole 104d through which the main bracket 30 is inserted. The main bracket 30 is inserted from the outside to the inside of the front member 104 through the insertion hole 104d, and the mounting portion 40 is fixed to the front member 104 from the outside. Bolts are used to fix the mounting portion 40, and the main bracket 30 is provided on the front member 104 via the mounting portion 40. As a result, some of the heat transmitted from the first fuel cell stack 101 through the first conductor 11 is dissipated to the atmosphere by the mounting portion 40 located on the outside of the front member 104 before it is transmitted to the second conductor 12, and also dissipates from the mounting portion 40 to the front member 104. As a result, heat transfer to the second conductor 12 and the electrical unit 110 is suppressed. The insertion hole 104d is set with a clearance between it and the inserted main bracket 30 that allows for vertical displacement of the main bracket 30 in accordance with temperature changes.

[0030] The mounting portion 40b has a contact surface 40ba that abuts against the front member 104. The mounting portion 40 is tightly fixed to the front member 104 at the contact surface 40ba. Tight fixing can be achieved, for example, by providing a sealant or sealing member between the contact surface 40ba and the outer wall surface of the front member 104. In this embodiment, as shown in Figure 7, the mounting portion 40 is fixed to the front member 104 via a gasket 50. By tightly fixing the mounting portion 40 to the front member 104, the temperature inside the power generation structure case B is maintained. The mounting portion 40 corresponds to the housing fixing portion. For example, the following materials can be used for the gasket including the gasket 50.

[0031] Figure 8 shows an example of materials used in a gasket, including gasket 50. In addition to metal, gaskets can be made of materials such as expanded graphite with fibers and fillers, rubber with fibers and fillers, or rubber. In contrast, gasket 50 is required to be suitable for use in high-temperature environments, as well as to be airtight to maintain a high temperature inside the power generation structure case B, and to have good thermal conductivity from the first mount M11 to the front member 104. Metals generally have a high usable temperature range, and their hardness and thermal conductivity are diverse, making it easier to ensure airtightness and thermal conductivity. For this reason, gasket 50 is made of metal. Focusing on hardness and thermal conductivity, metals include, for example, the following materials.

[0032] Figure 9 shows an example of metal materials focusing on hardness and thermal conductivity. As shown in Figure 9, aluminum and copper have lower hardness compared to other materials, exhibiting low hardness (for example, Vickers hardness of 150 HV or less). Aluminum and copper have high-class low hardness (Vickers hardness of less than 100 HV) with a Vickers hardness of two orders of magnitude or less. In terms of thermal conductivity, aluminum and copper also have higher thermal conductivity compared to other materials, exhibiting high thermal conductivity (for example, 50 W / m·K or more at 20°C). Aluminum and copper have high-class high thermal conductivity (100 W / m·K or more at 20°C) with a thermal conductivity of three orders of magnitude or more. For this reason, aluminum or copper is used for gasket 50 as a material with high thermal conductivity and low hardness.

[0033] The heat transferred to the relay electrode 20 via the first conductor 11 is dissipated through the main bracket 30, as described above. On the other hand, it is necessary to suppress discharge or leakage current from the relay electrode 20 to the main bracket 30. For this reason, in this embodiment, ceramics are used for the main bracket 30. Examples of ceramic materials include the following.

[0034] Figure 10 shows an example of a ceramic material that focuses on insulating properties. As shown in Figure 10, ceramics generally have excellent insulating properties, and insulating ceramics (for example, with a volume resistivity of 10) are used as ceramics for the main bracket 30. 8Ceramics with a volume resistivity of Ω·cm or higher are used. Since insulating ceramics have high insulating properties, they are suitable for suppressing discharge or leakage current from the intermediate electrode 20 to the main bracket 30. For example, high-class insulating ceramics (for example, those with a volume resistivity of 10) have a volume resistivity that is significantly larger than that of silicon carbide (SiC) by more than 5 orders of magnitude. 13 It is preferable that the insulating ceramic is a ceramic with a resistivity of Ω·cm or higher. Furthermore, the insulating ceramic is preferably the highest class of insulating ceramic among high-class insulating ceramics (for example, a ceramic with a volume resistivity of 10 14 It is preferable that the ceramic material is larger than Ω·cm.

[0035] The main bracket 30 also requires thermal conductivity. In contrast, ceramics containing insulating ceramics can achieve both thermal conductivity and thermal conductivity. The thermal conductivity of ceramics is as follows, for example:

[0036] Figure 11 shows an example of ceramic materials focusing on thermal conductivity. As shown in Figure 11, silicon carbide (SiC) and aluminum nitride (AlN) have higher thermal conductivity than other materials, exhibiting high thermal conductivity of three orders of magnitude or more. Furthermore, as can be seen from Figure 10, silicon carbide (SiC) and aluminum nitride (AlN) are insulating ceramics. For this reason, silicon carbide (SiC) or aluminum nitride (AlN) is used as a material with high thermal conductivity for the main bracket 30. Moreover, considering insulation and thermal conductivity comprehensively, aluminum nitride (AlN) has significantly higher insulation properties than silicon carbide (SiC). For this reason, aluminum nitride (AlN) is preferable to silicon carbide (SiC) as the material for the main bracket 30.

[0037] Next, the effects and advantages of this embodiment will be described.

[0038] The power extraction structure 1 is provided for the first fuel cell stack 101, which is mounted in the vehicle and connected to the electrical unit 110. The power extraction structure 1 includes a first conductor 11 that mediates the power supply from the first fuel cell stack 101 to the electrical unit 110, a second conductor 12 positioned between the first conductor 11 and the electrical unit 110 in the power supply path from the first fuel cell stack 101 to the electrical unit 110, a relay electrode 20 that relays the power supply from the first conductor 11 to the second conductor 12, and a first mount M11 that fixes the first fuel cell stack 101 to the power generation structure case B that houses the first fuel cell stack 101. The relay electrode 20 is fixed to the first mount M11. With this configuration, heat can be dissipated from the first fuel cell stack 101 to the power generation structure case B via the first mount M11 before heat is transferred to the second conductor 12, as will be explained below.

[0039] Figures 12 and 13 illustrate the heat dissipation mechanism in the power extraction structure 1. In this embodiment, the first conductor 11 is in contact with the main bracket 30 from the rear of the vehicle. Therefore, as shown in Figure 12, some of the heat transmitted from the first conductor 11 is directly dissipated to the main bracket 30 before being transmitted to the second conductor 12. Also, since the relay electrode 20 is in contact with the main bracket 30 from the front of the vehicle, some of the heat from the first conductor 11 is transmitted to the relay electrode 20 and then dissipated to the main bracket 30 before being transmitted to the second conductor 12, as shown in Figure 13. The heat transmitted to the main bracket 30 is then dissipated to the power generation structure case B.

[0040] Therefore, with this configuration, it becomes possible to suppress heat transfer from the first fuel cell stack 101 to the second conductor 12 and the electrical unit 110. As a result, it becomes possible to reduce costs by lowering the heat resistance of the second conductor 12, for example by using a general-purpose wire for the second conductor 12. In addition, since the amount of heat transferred to the electrical unit 110 can be reduced, it becomes possible to improve the reliability and durability of the electrical unit 110, and to reduce costs by lowering the heat resistance and cooling performance of the electrical unit 110.

[0041] The first mount M11 has a mount portion 40 fixed to the power generation structure case B and a main bracket 30 to which the relay electrode 20 is fixed. The main bracket 30 is inserted from the outside to the inside of the power generation structure case B. The mount portion 40 is tightly fixed to the power generation structure case B on the outside. With this configuration, the following effects can be obtained.

[0042] Figure 14 is an explanatory diagram of the heat dissipation manner from the mounting portion 40. According to the power extraction structure 1 with the above configuration, the mounting portion 40 is in contact with the outside air of the power generation structure case B, so it is possible to dissipate heat from the mounting portion 40 to the outside air of the power generation structure case B. In addition, since the mounting portion 40 is in close contact with the front member 104 of the power generation structure case B, it is possible to promote heat dissipation from the mounting portion 40 to the power generation structure case B. Therefore, by dissipating the heat transferred to the main bracket 30 from the mounting portion 40, it is possible to suppress heat transfer from the first fuel cell stack 101 to the second conductor 12 and the electrical unit 110.

[0043] The mounting portion 40 is fixed to the power generation structure case B via a gasket 50. With this configuration, air leakage from the power generation structure case B can be suppressed, thereby suppressing a decrease in power generation efficiency by suppressing a drop in temperature inside the power generation structure case B. In addition, the temperature rise of the surrounding components of the insertion hole 104d on the outside of the power generation structure case B can also be suppressed. Furthermore, the intrusion of foreign matter from the outside into the power generation structure case B can be suppressed, thus preventing malfunctions such as a decrease in insulation performance due to foreign matter.

[0044] Gasket 50 is a metal gasket. This configuration allows for use in high-temperature environments, thus ensuring airtightness even in high-temperature conditions.

[0045] The metal gasket is made of a material with high thermal conductivity and low hardness. This configuration promotes heat dissipation from the mounting section 40 to the power generation structure case B. In addition, the improved adhesion makes it easier to ensure heat dissipation and airtightness from the mounting section 40 to the power generation structure case B.

[0046] The intermediate electrode 20 is a busbar, having a cross-sectional area corresponding to the current flowing through it in the direction of conduction, and having screw holes 20a and 20b along the plate thickness direction. The plate thickness H of the intermediate electrode 20 is a predetermined thickness, that is, a thickness sufficient for the screw holes 20a and 20b. With this configuration, the intermediate electrode 20 can be realized in a shape that increases the contact area with the main bracket 30 as the current flowing through it increases. Therefore, heat dissipation from the intermediate electrode 20 to the main bracket 30 can be promoted. In addition, since screw holes 20a and 20b are formed in the intermediate electrode 20, nuts are not required. As a result, the overall heat capacity is reduced, improving heat dissipation, and it is also possible to reduce costs and weight and improve workability.

[0047] The intermediate electrode 20 has a heat sink portion 20c on the part other than the contact surface that faces the first mount M11. With this configuration, heat dissipation from the intermediate electrode 20 to the air layer inside the power generation structure case B can also be promoted. As a result, heat transfer to the second conductor 12 and the electrical unit 110 can be further suppressed. Furthermore, if the intermediate electrode 20 is made longer, for example, heat dissipation will increase, but the conductor resistance will also increase, so the weight will increase in order to secure the necessary cross-sectional area, making miniaturization difficult. However, with the heat sink portion 20c, heat dissipation can be improved without causing such a situation.

[0048] The heat sink portion 20c is composed of multiple fins 20ca extending along the conductive direction. With this configuration, the surface area of ​​the intermediate electrode 20 can be increased without changing the cross-sectional area in the conductive direction. For example, if grooves are provided along the width direction of the intermediate electrode 20, the required cross-sectional area will be secured at the conductive direction position where the cross-sectional area is minimized, resulting in a larger cross-sectional area at other positions and leading to an increase in weight. This situation can be avoided. Therefore, it is possible to suppress weight increase while ensuring heat dissipation.

[0049] The first mount M11 has a main bracket 30 to which the relay electrode 20 is fixed, and the main bracket 30 is made of insulating ceramics. With this configuration, insulating ceramics can be used as the material for the main bracket 30, simplifying insulation measures. As a result, it contributes to the establishment of the power extraction structure 1 with a simple structure. In this case, the number of parts can be reduced because further insulation measures are not required, so it is possible to reduce costs and weight as well as improve workability.

[0050] The insulating ceramics are defined as ceramics with high thermal conductivity. With this configuration, both insulation and heat dissipation can be achieved. Therefore, the power extraction structure 1 can be properly implemented.

[0051] The first mount M11 has a main bracket 30 to which the relay electrode 20 is fixed. The relay electrode 20 is positioned on the first fuel cell stack 101 side relative to the main bracket 30, and the other end 11b of the first conductor 11 and one end 12a of the second conductor 12 are positioned on the electrical unit 110 side relative to the main bracket 30. With this configuration, the following effects can be obtained.

[0052] Figures 15 and 16 are explanatory diagrams illustrating the heat dissipation patterns according to the configuration arrangement. Figure 17 is a view of the power extraction structure 1 from the rear of the vehicle body. With the above configuration, as shown in Figure 15, the other end 11b abuts against the main bracket 30, so that a portion of the heat from the first conductor 11 is directly dissipated to the main bracket 30, thereby reducing the amount of heat transferred to the relay electrode 20. As a result, the amount of heat transferred to the second conductor 12 and the electrical unit 110 can be reduced. In addition, as shown in Figure 16, a portion of the heat transferred to the relay electrode 20 is also dissipated to the main bracket 30, which also reduces the amount of heat transferred to the second conductor 12 and the electrical unit 110. Furthermore, as shown in Figure 17, since the other end 11b and one end 12a are positioned on the electrical unit 110 side relative to the main bracket 30, bolts 2 and 3 can be tightened from the rear of the vehicle body using a tool T, improving workability. Tool T can be inserted into the power generation structure case B through the opening 105a of the rear member 105 located at the rear of the vehicle body of the main bracket 30, and the electrical unit 110 can be attached to the opening 105a after tightening bolts 2 and 3.

[0053] (First variation) If the main bracket 30 is made of insulating ceramics, it is possible to achieve both insulation and heat dissipation. On the other hand, in this case, it becomes more brittle compared to metal, which raises concerns that the main bracket 30 may be more susceptible to damage from vibration and impact. For this reason, the main bracket 30 may be made of a heat-resistant metal such as the following.

[0054] Figure 18 shows an example of a heat-resistant metal material. For comparison, Figure 18 also shows the material of an insulating ceramic. As shown in Figure 18, heat-resistant metals have higher fracture toughness than insulating ceramics. Therefore, by constructing the main bracket 30 from a heat-resistant metal, higher toughness can be ensured compared to insulating ceramics, improving reliability and durability against vibration and shock. As a result, it contributes to the establishment of a power extraction structure 1 that is preferable from the viewpoint of vibration resistance and shock resistance. In addition, since the plate thickness H can be reduced due to the increased reliability and durability, it also contributes to weight reduction and miniaturization. Metal materials with high heat resistance tend to have high fracture toughness, and the heat-resistant metal can be, for example, a metal with fracture toughness of 10 MPa√m or more, which is higher than that of insulating ceramics. It is also preferable that the heat-resistant metal has high thermal conductivity.

[0055] Figure 19 shows an example of a heat-resistant metal material focusing on thermal conductivity. Figure 19 shows an example of a metal material used as part of an alloy in a heat-resistant metal. Although the thermal conductivity of stainless steel varies depending on the specific material (for example, SUS301 is 16.3 W / m·K and SUS405 is 27.2 W / m·K), the thermal conductivity is generally less than 30 W / m·K and does not have a high thermal conductivity of 50 W / m·K or higher. As shown in Figure 19, it can be seen that heat-resistant metals may or may not have high thermal conductivity. In contrast, if the main bracket 30 is constructed from a heat-resistant metal with high thermal conductivity, the heat dissipation of the main bracket 30 can be improved in addition to its fracture brittleness. As a result, it becomes possible to establish the power extraction structure 1 more appropriately.

[0056] (Second variation) In the first modified example, additional insulation measures will be required. Including such cases, the power extraction structure 1 may be configured as follows, for example, from the viewpoint of insulation.

[0057] Figure 20 is a partially exploded view of the power extraction structure 1A according to the second modified example. Figure 21 is a perspective view of the power extraction structure 1. In Figures 20 and 21, the main bracket 30A of the power extraction structure 1A is shown as the main part, along with the relay electrode 20, etc. The "A" added to the reference numeral, such as "1A", indicates that the configuration has been changed as follows in the second modified example.

[0058] Power extraction structure 1A is configured in the same way as power extraction structure 1, except that it is configured as follows. In this modified example, the main bracket 30A is made of a metal including the heat-resistant metal described above and has a mounting portion 30a. The mounting portion 30a is formed on the other end side (left side of the vehicle body) of the main bracket 30A and has a thickness and width set to be smaller than that of the one end side. The mounting portion 30a is formed on the main bracket 30A from the other end to the portion where the relay electrode 20 is provided, and an insulating collar 32 is attached to the mounting portion 30a. The insulating collar 32 is made of insulating ceramics and has an insertion hole for the mounting portion 30a. Insertion holes for bolts 2 and 3 are formed in the insulating collar 32, and the relay electrode 20 is fixed to the main bracket 30A with bolts 2 and 3 via the insulating collar 32 when it is attached to the mounting portion 30a.

[0059] With this configuration, although the insulation measures become more complex compared to power extraction structure 1, it is possible to ensure higher reliability and durability with the metal main bracket 30A compared to ceramics, while also providing insulation with the insulating collar 32. Therefore, these aspects contribute to the proper implementation of power extraction structure 1A. Furthermore, by constructing the insulating collar 32 from insulating ceramics, it becomes possible to use it in high-temperature environments, ensuring insulation and durability even in high-temperature environments.

[0060] The mounting portion 30a may be further formed extending from the other end to the portion where the sub-bracket 31 is provided, and the insulating collar may be further provided corresponding to the sub-bracket 31. The insulating collar 33 refers to an insulating collar provided in this manner separately from the insulating collar 32. In this case, the sub-bracket 31 is fixed to the main bracket 30A via the insulating collar 33 while it is attached to the mounting portion 30a. As a result, insulation between the first fuel cell stack 101 and the main bracket 30A can also be ensured.

[0061] (Third variation) Figure 22 is a perspective view of the power extraction structure 1B according to the third modified example. The power extraction structure 1 according to the third modified example is the same as the second modified example, except for the following differences. The "B" added to the reference numeral indicates that the configuration has been changed as follows in the third modified example.

[0062] Power extraction structure 1B is configured the same as power extraction structure 1A, except that it is configured as follows. In this modified example, the other end 11b is positioned in front of the vehicle body relative to the main bracket 30, and the intermediate electrode 20B is positioned in rear of the vehicle body relative to the main bracket 30B. In the first conductor 11B, a screw hole is formed at the other end 11b instead of a bolt insertion hole, and in the intermediate electrode 20B, a bolt insertion hole is formed instead of a screw hole 20a. The intermediate electrode 20B is fastened together with the main bracket 30B. Therefore, no screw hole 20b is formed in the intermediate electrode 20B, and no bolt insertion holes corresponding to the screw hole 20b are formed in the main bracket 30B and insulating collar 32B. Also, in the intermediate electrode 20B, the front surface of the vehicle is the surface facing the main bracket 30B, so a heat sink portion 20c is not provided. The intermediate electrode 20B may have a heat sink portion 20c on a surface other than the surface facing the main bracket 30B.

[0063] Even with this configuration, by dissipating the heat transferred from the first conductor 11B to the main bracket 30B before it is transferred to the second conductor 12, heat transfer to the electrical unit 110 and the second conductor 12 can be suppressed. Furthermore, a similar modification can be applied to the power extraction structure 1 by considering the insulating collars 32 and 33 as part of the main bracket 30B.

[0064] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0065] For example, in the embodiment described above, the case in which the first mount M11 constitutes the fixing part was explained. However, the fixing part may also be composed of the first mount M12. Furthermore, the power extraction structure 1 may be applied to the second fuel cell stack 102. In the embodiment described above, the case in which the sub-bracket 31 is arranged on one end side and the relay electrode 20 is arranged on the other end side of the main bracket 30 was explained, but for example, the relay electrode 20 may be arranged on one end side and the sub-bracket 31 on the other end side. [Explanation of Symbols]

[0066] 1, 1A, 1B: Power extraction structure 11, 11B: First conductor 11b: One end (fixed part) 12: Second conductor 12a: Other end (fixed part) 20, 20B: Intermediate electrodes 20a: Screw hole 20b: Screw hole 20c: Heatsink section 20ca: Fin 30, 30A, 30B: Main bracket (relay electrode fixing part) 31: Subbracket 32, 32B: Insulating collar 40: Mounting section (housing fixing section) 50: Gasket 101: First fuel cell stack (fuel cell stack) 110: Electrical unit (electrical load) B: Power generation structure case (enclosure) M11: First mount (fixing part) H: Thickness

Claims

1. A power extraction structure for a solid oxide fuel cell stack mounted on a vehicle and connected to an electrical load, A first conductor that mediates the supply of power from the fuel cell stack to the electrical load, In the power supply path from the fuel cell stack to the electrical load, a second conductor is disposed between the first conductor and the electrical load, A relay electrode that relays power supply from the first conductor to the second conductor, The housing housing the fuel cell stack includes a fixing part for fixing the fuel cell stack, It has, The aforementioned fixing portion includes a housing fixing portion that is fixed to the housing and an insulating relay electrode fixing portion. The relay electrode fixing portion is supported by the housing fixing portion, The relay electrode is fixed on the relay electrode fixing portion so as to be insulated from the housing. A power extraction structure for a fuel cell stack, characterized by the following features.

2. A power extraction structure for a fuel cell stack according to claim 1, The relay electrode fixing part is inserted from the outside to the inside of the housing, The housing fixing portion is fixed in close contact with the housing on the outside of the housing. A power extraction structure for a fuel cell stack, characterized by the following features.

3. A power extraction structure for a fuel cell stack according to claim 2, The housing fixing portion is fixed to the housing via a gasket. A power extraction structure for a fuel cell stack, characterized by the following features.

4. A power extraction structure for a fuel cell stack according to claim 3, The aforementioned gasket is a metal gasket. A power extraction structure for a fuel cell stack, characterized by the following features.

5. A power extraction structure for a fuel cell stack according to claim 4, The aforementioned metal gasket is made of a material with high thermal conductivity and low hardness. A power extraction structure for a fuel cell stack, characterized by the following features.

6. A power extraction structure for a fuel cell stack according to claim 1, The aforementioned relay electrode is a busbar, having a cross-sectional area corresponding to the current flowing in the direction of conduction, and having screw holes along the plate thickness direction. The thickness of the relay electrode plate is such that it is sufficient for the screw hole. A power extraction structure for a fuel cell stack, characterized by the following features.

7. A power extraction structure for a fuel cell stack according to claim 6, The relay electrode has a heat sink portion on a surface other than the surface facing the fixed portion. A power extraction structure for a fuel cell stack, characterized by the following features.

8. A power extraction structure for a fuel cell stack according to claim 7, The heat sink portion is composed of a plurality of fins extending along the conductive direction. A power extraction structure for a fuel cell stack, characterized by the following features.

9. A power extraction structure for a fuel cell stack according to claim 1, The aforementioned relay electrode fixing portion is made of insulating ceramics. A power extraction structure for a fuel cell stack, characterized by the following features.

10. A power extraction structure for a fuel cell stack according to claim 9, The insulating ceramic has high thermal conductivity. A power extraction structure for a fuel cell stack, characterized by the following features.

11. A power extraction structure for a solid oxide fuel cell stack mounted on a vehicle and connected to an electrical load, A first conductor that mediates the supply of power from the fuel cell stack to the electrical load, In the power supply path from the fuel cell stack to the electrical load, a second conductor is disposed between the first conductor and the electrical load, A relay electrode that relays power supply from the first conductor to the second conductor, The housing housing the fuel cell stack includes a fixing part for fixing the fuel cell stack, It has, The fixing portion comprises a housing fixing portion fixed to the housing, a relay electrode fixing portion to which the relay electrode is fixed, and an insulating collar attached to the relay electrode fixing portion. The relay electrode fixing portion is supported by the housing fixing portion, The relay electrode is fixed to the relay electrode fixing portion via the insulating collar so as to be insulated from the housing. A power extraction structure for a fuel cell stack, characterized by the following features.

12. A power extraction structure for a fuel cell stack according to claim 11, The insulating collar is made of insulating ceramics. A power extraction structure for a fuel cell stack, characterized by the following features.

13. A power extraction structure for a fuel cell stack according to claim 11, The aforementioned relay electrode fixing portion is made of a heat-resistant metal. A power extraction structure for a fuel cell stack, characterized by the following features.

14. A power extraction structure for a fuel cell stack according to claim 13, The heat-resistant metal has high thermal conductivity. A power extraction structure for a fuel cell stack, characterized by the following features.

15. A power extraction structure for a fuel cell stack according to claim 1, The relay electrode is positioned on the fuel cell stack side relative to the relay electrode fixing portion. The fixing portions of the first conductor and the second conductor are each positioned on the electrical load side with respect to the relay electrode fixing portion. A power extraction structure for a fuel cell stack, characterized by the following features.

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