Patent Publication Number: US-2023145296-A1

Title: Fuel Cell Vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2021-0151448, filed on Nov. 5, 2021, which application is hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     Embodiments relate to a fuel cell vehicle. 
     BACKGROUND 
     A fuel cell included in a fuel cell vehicle is a power generation device in which hundreds of stacked unit cells generate electricity. The generated electricity is collected in current collectors disposed at respective end portions of a cell stack, and is transferred to a junction box disposed at the upper end of the cell stack. To this end, the fuel cell vehicle includes a bus bar and a terminal block in order to transfer the electricity collected in the current collectors to the junction box. 
     The bus bar is a conductor that serves as an electrical path connecting the current collectors to the terminal block, and the terminal block is a component for transferring the electricity received from the current collectors through the bus bar to the junction box. 
     When the high voltage generated in the fuel cell is transmitted through the bus bar at a high current density, the bus bar generates heat. A method of increasing the cross-sectional area of the bus bar in order to respond to the amount of heat generated in the bus bar may be proposed. In this case, however, when the distance between coolant and an end of the bus bar is long, the heat caused by the resistance of the bus bar, which is a conductor, is not uniformly distributed, which entails a problem in which the cross-sectional area of the bus bar needs to be designed in consideration of the point in the bus bar at which the temperature of the bus bar due to the heat generated therein is the highest. 
     Further, the increase in the cross-sectional area of the bus bar may increase the size, manufacturing cost, and weight of the bus bar, and may be disadvantageous from the aspect of packaging. Accordingly, there are limitations on the extent to which the output of a fuel cell vehicle equipped with a fuel cell can be increased and the extent to which the size thereof can be reduced. 
     SUMMARY 
     Embodiments provide a system or a fuel cell vehicle. Various embodiments provide a system or a fuel cell vehicle that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     Embodiments provide a fuel cell vehicle including a bus bar having a small cross-sectional area. 
     A fuel cell vehicle according to an embodiment may include a fuel cell, a bus bar, which has one end portion electrically connected to the fuel cell and which is electrically conductive, a terminal block electrically connected to the opposite end portion of the bus bar, a junction box including a chamber storing therein coolant and a tube forming a path to allow the coolant to flow therethrough from the chamber to a cover of the terminal block, and an insulation protection unit, which is disposed so as to surround at least a portion of the bus bar to electrically insulate the bus bar from the fuel cell and which has a flow path to allow the coolant supplied from the cover to flow therethrough. 
     For example, the insulation protection unit may expose the one end portion and the opposite end portion of the bus bar, and may surround at least a portion of the upper portion, the lower portion, or the side portion of the bus bar. 
     For example, the cover of the terminal block may include a coolant connection portion connected to the tube to receive the coolant introduced thereinto, a through-hole connected to the coolant connection portion and penetrating the cover, and an adapter connecting the through-hole to the flow path in the insulation protection unit. 
     For example, the coolant connection portion may have the shape of a nipple that protrudes toward the tube to be coupled to the tube. 
     For example, the coolant connection portion may have the shape of an opening that is coupled to the tube. 
     For example, the insulation protection unit may include one end portion, which is disposed at the starting point of the flow path and is an inlet coupled to an end portion of the adapter to receive the coolant introduced thereinto. 
     For example, the insulation protection unit may include an opposite end portion located opposite the one end portion. The ending point of the flow path may be spaced a predetermined distance apart from the opposite end portion of the insulation protection unit, and the flow path may be blocked at the ending point. 
     For example, one of the one end portion of the insulation protection unit and the end portion of the adapter may have a protrusion, and the other one of the one end portion of the insulation protection unit and the end portion of the adapter may have a recessed portion formed therein to allow the protrusion to be fitted thereinto. 
     For example, the fuel cell vehicle may further include a sealing gasket sealing the coupled portion between the protrusion and the recessed portion. 
     For example, the one end portion of the insulation protection unit and the end portion of the adapter may be integrated. 
     For example, the insulation protection unit may include a first plate, which is disposed so as to expose the one end portion and the opposite end portion of the bus bar and to surround a portion of each of the lower portion and the side portion of the bus bar, and a second plate, which is coupled to the first plate so as to cover at least a portion of the upper portion of the bus bar and which has formed therein the flow path. 
     For example, the bus bar may include a first portion vertically overlapping the cover and a second portion extending from the first portion toward an end portion of the fuel cell. 
     For example, the flow path in the second plate may cover the upper portion of the first portion. 
     For example, the flow path in the second plate may cover the upper portion of at least a portion of the second portion. 
     For example, the bus bar may include a first bus bar disposed between one of the two opposite end portions of the fuel cell and the terminal block and a second bus bar disposed between the other one of the two opposite end portions of the fuel cell and the terminal block. The insulation protection unit may include a first insulation protection unit, which surrounds at least a portion of the first bus bar and has a first flow path to allow the coolant to flow therethrough, and a second insulation protection unit, which surrounds at least a portion of the second bus bar and has a second flow path to allow the coolant to flow therethrough. 
     For example, the first bus bar and the second bus bar may have cross-sectional shapes that are symmetrical with each other with respect to the terminal block, and the first insulation protection unit and the second insulation protection unit may have cross-sectional shapes that are symmetrical with each other with respect to the terminal block. 
     For example, the fuel cell may include a cell stack including a plurality of unit cells stacked in a first direction, end plates respectively disposed at the two opposite end portions of the cell stack, and current collectors disposed between the two opposite end portions of the cell stack and the end plates. The current collectors may collect power generated in the cell stack, and may be electrically connected to the one end portion of the bus bar. The flow path may extend in the first direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIG.  1 A  is an assembled cross-sectional view of a fuel cell vehicle according to an embodiment; 
         FIG.  1 B  is an assembled cross-sectional view of the fuel cell vehicle shown in  FIG.  1 A , from which a junction box is removed; 
         FIG.  1 C  is an exploded cross-sectional view of the fuel cell vehicle shown in  FIG.  1 B ; 
         FIG.  2    is a plan view of a junction box according to an embodiment; 
         FIGS.  3 A and  3 B  are perspective views of a cover of a terminal block according to an embodiment; 
         FIGS.  4 A to  4 C  are, respectively, an exploded perspective view, an assembled cross-sectional view, and a plan view of a first bus bar and a first insulation protection unit according to an embodiment; 
         FIG.  5    is a perspective view of the terminal block, the bus bars, and the insulation protection units; 
         FIG.  6    is a cross-sectional view taken along line I-I′ in  FIG.  5   ; and 
         FIGS.  7 A and  7 B  are exploded cross-sectional views of embodiments of an adapter and the insulation protection unit. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. The examples, however, may be embodied in many different forms, and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will more fully convey the scope of the disclosure to those skilled in the art. 
     It will be understood that when an element is referred to as being “on” or “under” another element, it may be directly on/under the element, or one or more intervening elements may also be present. 
     When an element is referred to as being “on” or “under”, “under the element” as well as “on the element” may be included based on the element. 
     In addition, relational terms, such as “first”, “second”, “on/upper part/above” and “under/lower part/below”, are used only to distinguish between one subject or element and another subject or element, without necessarily requiring or involving any physical or logical relationship or sequence between the subjects or elements. 
     Hereinafter, a fuel cell vehicle according to an embodiment will be described with reference to the accompanying drawings. The fuel cell vehicle will be described using the Cartesian coordinate system (x-axis, y-axis, z-axis) for convenience of description, but may also be described using other coordinate systems. In the Cartesian coordinate system, the x-axis, the y-axis, and the z-axis are perpendicular to each other, but the embodiments are not limited thereto. That is, the x-axis, the y-axis, and the z-axis may intersect each other obliquely. For convenience of description, the x-axis direction will be referred to as a “first direction”, the y-axis direction will be referred to as a “second direction”, and the z-axis direction will be referred to as a “third direction”. 
       FIG.  1 A  is an assembled cross-sectional view of a fuel cell vehicle according to an embodiment,  FIG.  1 B  is an assembled cross-sectional view of the fuel cell vehicle shown in  FIG.  1 A , from which a junction box (or a high-voltage junction box) 300  is removed, and  FIG.  1 C  is an exploded cross-sectional view of the fuel cell vehicle shown in  FIG.  1 B .  FIG.  2    is a plan view of the junction box  300  according to an embodiment.  FIGS.  3 A and  3 B  are perspective views of a cover  304  of a terminal block TB according to an embodiment.  FIGS.  4 A to  4 C  are, respectively, an exploded perspective view, an assembled cross-sectional view, and a plan view of a first bus bar  212  and a first insulation protection unit  220  according to an embodiment.  FIG.  5    is a perspective view of the terminal block TB, the bus bars  212  and  214 , and the insulation protection units  220  and  222 .  FIG.  6    is a cross-sectional view taken along line I-I′ in  FIG.  5   .  FIGS.  7 A and  7 B  are exploded cross-sectional views of embodiments of an adapter  308  and the insulation protection unit  222 . 
     A fuel cell vehicle according to an embodiment may include a fuel cell  100 , bus bars  212  and  214 , insulation protection units  220  and  222 , a terminal block TB, and a junction box  300 . 
     Hereinafter, an example of the fuel cell  100  included in the fuel cell vehicle according to the embodiment will be described with reference to  FIG.  1 C . However, the fuel cell vehicle according to the embodiment may include a fuel cell that is configured differently from the fuel cell shown in  FIG.  1 C . 
     The fuel cell  100  may be, for example, a polymer electrolyte membrane fuel cell (or a proton exchange membrane fuel cell) (PEMFC), which has been studied most extensively as a power source for driving vehicles. 
     The fuel cell  100  may include first and second end plates (or pressing plates or compression plates)  110 A and  110 B, insulation plates  114 A and  114 B, current collectors  116 A and  116 B, and a cell stack  112 . 
     The cell stack  112  may include a plurality of unit cells  112 - 1  to  112 -N, which are stacked in the first direction. Here, “N” is a positive integer of 1 or greater, and may range from several tens to several hundreds. The embodiments are not limited to any specific value of “N”. 
     Each unit cell  122 - n  may generate 0.6 volts to 1.0 volt of electricity. Here, 1≤n≤N. Thus, “N” may be determined in accordance with the intensity of the power supplied from the fuel cell  100  to a load. Here, “load” may refer to a part of the fuel cell vehicle that requires power from the fuel cell. 
     The fuel cell vehicle according to the embodiment may be a vehicle that requires a great amount of power, such as, for example, a bus, a truck, a large sport utility vehicle (SUV), or a pickup truck (hereinafter referred to as a “commercial vehicle”). In the case of a vehicle that requires a great amount of driving power, a plurality of fuel cells may be provided. 
     Each unit cell  112 - n  may include a membrane electrode assembly (MEA)  10 , gas diffusion layers (GDLs)  22  and  24 , gaskets  32 ,  34 , and  36 , and separators (or bipolar plates) 42  and  44 . 
     The membrane electrode assembly  10  has a structure in which catalyst electrode layers, in which an electrochemical reaction occurs, are attached to both sides of an electrolyte membrane through which hydrogen ions move. Specifically, the membrane electrode assembly  10  may include a polymer electrolyte membrane (or a proton exchange membrane)  12 , a fuel electrode (or a hydrogen electrode or an anode)  14 , and an air electrode (or an oxygen electrode or a cathode)  16 . 
     The polymer electrolyte membrane  12  is disposed between the fuel electrode  14  and the air electrode  16 . 
     Hydrogen, which is the fuel in the fuel cell, may be supplied to the fuel electrode  14  through the first separator  42 , and air containing oxygen as an oxidizer may be supplied to the air electrode  16  through the second separator  44 . 
     The hydrogen supplied to the fuel electrode  14  is decomposed into hydrogen ions (protons) (H+) and electrons (e−) by the catalyst. The hydrogen ions alone may be selectively transferred to the air electrode  16  through the polymer electrolyte membrane  12 , and at the same time, the electrons may be transferred to the air electrode  16  through the gas diffusion layers  22  and  24  and the first and second separators  42  and  44 , which are conductors. In order to realize the above operation, a catalyst layer may be applied to each of the fuel electrode  14  and the air electrode  16 . The movement of the electrons described above causes the electrons to flow through an external conductive wire, thus generating current. That is, the fuel cell generates electric power due to the electrochemical reaction between hydrogen, which is the fuel, and oxygen contained in the air. 
     In the air electrode  16 , the hydrogen ions supplied through the polymer electrolyte membrane  12  and the electrons transferred through the first and second separators  42  and  44  meet the oxygen in the air supplied to the air electrode  16 , thus causing a reaction that generates water. The water generated in the air electrode  16  may permeate the polymer electrolyte membrane  12 , and may be transferred to the fuel electrode  14 . 
     The first and second gas diffusion layers  22  and  24  serve to uniformly distribute hydrogen and oxygen, which are reactant gases, and to transfer the generated electrical energy. To this end, the first and second gas diffusion layers  22  and  24  may be disposed on respective sides of the membrane electrode assembly  10 . The first gas diffusion layer  22  may serve to diffuse and uniformly distribute hydrogen supplied as a reactant gas through the first separator  42 , and may be electrically conductive. The second gas diffusion layer  24  may serve to diffuse and uniformly distribute air supplied as a reactant gas through the second separator  44 , and may be electrically conductive. 
     The gaskets  32 ,  34 , and  36  may serve to maintain the airtightness and clamping pressure of the cell stack at an appropriate level with respect to the reactant gases and the coolant, to disperse the stress when the first and second separators  42  and  44  are stacked, and to independently seal the flow paths. As such, since airtightness and watertightness are maintained by the gaskets  32 ,  34 , and  36 , the flatness of the surfaces that are adjacent to the cell stack  112 , which generates electric power, may be secured, and thus surface pressure may be uniformly distributed over the reaction surfaces of the cell stack  112 . 
     The first and second separators  42  and  44  may serve to move the reactant gases and the cooling medium and to separate each of the unit cells from the other unit cells. In addition, the first and second separators  42  and  44  may serve to structurally support the membrane electrode assembly  10  and the gas diffusion layers  22  and  24  and to collect the generated current and transfer the collected current to the current collectors  116 A and  116 B. 
     The first and second separators  42  and  44  may be spaced apart from each other in the first direction, and may be respectively disposed outside the first and second gas diffusion layers  22  and  24 . That is, the first separator  42  may be disposed on the left side of the first gas diffusion layer  22 , and the second separator  44  may be disposed on the right side of the second gas diffusion layer  24 . 
     The first separator  42  serves to supply hydrogen as a reactant gas to the fuel electrode  14  through the first gas diffusion layer  22 . The second separator  44  serves to supply air as a reactant gas to the air electrode  16  through the second gas diffusion layer  24 . In addition, each of the first and second separators  42  and  44  may form a channel through which the cooling medium (e.g. coolant) may flow. 
     The first and second end plates  110 A and  110 B may be disposed at respective side ends of the cell stack  112 , and may support and fix the plurality of unit cells. That is, the first end plate  110 A may be disposed at one side end of the cell stack  112 , and the second end plate  110 B may be disposed at the opposite side end of the cell stack  112 . 
     The insulation plates  114 A and  114 B may be disposed between the cell stack  112  and the inner surfaces  110 AI and  110 BI of the first and second end plates  110 A and  110 B that face the cell stack  112 . 
     The current collectors  116 A and  116 B may be disposed between the cell stack  112  and the inner surfaces  114 AI and  114 BI of the first and second insulation plates  114 A and  114 B that face the cell stack  112 . In some cases, the insulation plates  114 A and  114 B may be omitted. In this case, the current collectors  116 A and  116 B may be disposed between the cell stack  112  and the inner surfaces  110 AI and  110 BI of the first and second end plates  110 A and  110 B that face the cell stack  112 . 
     The current collectors  116 A and  116 B serve to collect the electrical energy generated by the flow of electrons in the cell stack  112  and to supply the electrical energy to a load of the fuel cell vehicle. That is, the current collectors  116 A and  116 B may collect the electric power generated in the cell stack  112 . To this end, as shown in  FIGS.  1 B and  1 C , one end portion of each of the current collectors  116 A and  116 B may be bent in the first direction so as to be located above the cell stack  112 , and may thus be electrically connected to a corresponding one of end portions E 11  and E 21  of the bus bars  212  and  214 , which will be described later. 
     Although not illustrated, the fuel cell  100  may further include an enclosure. 
     Referring again to  FIG.  1 B , the bus bars  212  and  214  serve to electrically connect the current collectors  116 A and  116 B of the fuel cell  100  to the terminal block TB, and are conductors that are electrically conductive. That is, the bus bars  212  and  214  serve to transfer the electrical energy generated in the fuel cell wo to the terminal block TB. 
     To this end, the bus bar  212  includes an end portion E 11  electrically connected to the fuel cell  100  and an opposite end portion E 12  electrically connected to the terminal block TB, and the bus bar  214  includes an end portion E 21  electrically connected to the fuel cell  100  and an opposite end portion E 22  electrically connected to the terminal block TB. 
     The bus bars may include first and second bus bars  212  and  214 . The first bus bar  212  is disposed between one end portion of the fuel cell wo and the terminal block TB to electrically connect the first current collector  116 A to the terminal block TB. The second bus bar  214  is disposed between the opposite end portion of the fuel cell  100  and the terminal block TB to electrically connect the second current collector  116 B to the terminal block TB. 
     The first bus bar  212  and the second bus bar  214  may have cross-sectional shapes that are symmetrical with each other in the first direction with respect to the terminal block TB. In this case, the description of the first bus bar  212  may apply to the second bus bar  214 , and the description of the second bus bar  214  may apply to the first bus bar  212 . Therefore, with regard to any aspect of any one of the first and second bus bars  212  and  214  that is not described in detail, reference may be made to the description of the other one of the first and second bus bars  212  and  214 . 
     Referring to  FIG.  6   , the first bus bar  212  may include a first portion  212 P 1  and a second portion  212 P 2 , and the second bus bar  214  may include a first portion  214 P 1  and a second portion  214 P 2 . 
     The first portions  212 P 1  and  214 P 1  may be portions that vertically overlap the cover  304  of the terminal block TB, which will be described later. Alternatively, the first portions  212 P 1  and  214 P 1  may be portions that are adjacent to the opposite end portions E 12  and E 22  of the bus bars  212  and  214  that are connected to the terminal block TB. 
     The second portions  212 P 2  and  214 P 2  may be portions that extend from the first portions  212 P 1  and  214 P 1  toward the end portions of the fuel cell  100 , i.e. the current collectors  116 A and  116 B. 
     The insulation protection units  220  and  222  are disposed so as to surround at least a portion of the bus bars  212  and  214 , and serve to electrically insulate the bus bars  212  and  214  from the fuel cell  100 . As shown in  FIG.  1 B , the bus bars  212  and  214 , which are electrically conductive, are disposed above the cell stack  112  of the fuel cell  100 . Accordingly, when the insulation protection units  220  and  222  are not present, the bus bars  212  and  214  may not be electrically insulated from the cell stack  112 , and thus the cell stack  112  may not operate normally. In order to prevent this, the insulation protection units  220  and  222  may be disposed so as to surround at least a portion of the bus bars  212  and  214  to electrically insulate the bus bars  212  and  214  from the cell stack  112 . For example, the insulation protection units  220  and  222  may be made of an electrically insulative material. 
     In addition, according to the embodiment, each of the insulation protection units  220  and  222  has formed therein a flow path through which the coolant supplied from the cover  304  of the terminal block TB flows. 
     The insulation protection units may include first and second insulation protection units  220  and  222 . The first insulation protection unit  220  surrounds at least a portion of the first bus bar  212 , and has formed therein a flow path P 1  (hereinafter referred to as a “first flow path”) through which the coolant flows. The second insulation protection unit  222  surrounds at least a portion of the second bus bar  214 , and has formed therein a flow path P 2  (hereinafter referred to as a “second flow path”) through which the coolant flows. 
     Also, the first insulation protection unit  220  and the second insulation protection unit  222  may have cross-sectional shapes that are symmetrical with each other in the first direction with respect to the terminal block TB. In this case, the description of the first insulation protection unit  220  may apply to the second insulation protection unit  222 , and the description of the second insulation protection unit  222  may apply to the first insulation protection unit  220 . Therefore, with regard to any aspect of any one of the first and second insulation protection units  220  and  222  that is not described in detail, reference may be made to the description of the other one of the first and second insulation protection units  220  and  222 . 
     The insulation protection units  220  and  222  may be disposed so as to expose the end portions E 11  and E 21  and the opposite end portions E 12  and E 22  of the bus bars  212  and  214  and to surround at least a portion of the upper portions, the lower portions, or the side portions of the bus bars  212  and  214 . 
     Referring to  FIGS.  4 A to  4 C , the first insulation protection unit  220  may include first and second plates  220 L and  220 U. The first plate  220 L may be disposed so as to expose the end portion E 11  and the opposite end portion E 12  of the first bus bar  212  and to surround at least a portion of each of the lower portion  212 L and the side portion  2125  of the first bus bar  212 . The second plate  220 U may be coupled to the first plate  220 L so as to expose the end portion E 11  and the opposite end portion E 12  of the first bus bar  212  and to cover at least a portion of the upper portion  212 U of the first bus bar  212 . The second plate  220 U has formed therein the first flow path P 1 . The description of the configuration of the first insulation protection unit  220  may also apply to the configuration of the second insulation protection unit  222 , which is not illustrated in the drawings. That is, the second insulation protection unit  222  may include first and second plates  222 U and  222 L, like the first insulation protection unit  220  shown in  FIGS.  4 A to  4 C . 
     According to an embodiment, the first flow path P 1  in the second plate  220 U may cover only the upper side of the first portion  212 P 1  of the first bus bar  212 . 
     When the bus bars  212  and  214  transfer power from the fuel cell  100  to the terminal block TB, the first portions  212 P 1  and  214 P 1  of the bus bars  212  and  214  generate a larger amount of heat than the second portions  212 P 2  and  214 P 2 . The first flow path P 1  may cover the first portion  212 P 1 , and the second flow path P 2  may cover the first portion  214 P 1 . 
     According to another embodiment, as shown in  FIG.  6   , the first flow path P 1  in the second plate  220 U may cover not only the upper side of the first portion  212 P 1  of the first bus bar  212  but also the upper side of at least a portion of the second portion  212 P 2 . 
     Also, referring to  FIG.  4 C , the edge P 1 EL of the first flow path P 1  formed in the second plate  220 U may be located so as to be spaced a predetermined distance D apart from the edge EL of the second plate  220 U in the second direction. 
     The junction box  300  serves to distribute the power generated in the cell stack  112  of the fuel cell  100 . That is, the junction box  300  serves to control the output of the electrical energy generated in the fuel cell  100  and to transfer the electrical energy. To this end, the junction box  300  may be electrically connected to the fuel cell  100  via the terminal block TB, and may include fuses and relays to control components of peripheral auxiliary devices (balance-of-plant (BOP)) assisting in the operation of the fuel cell  100 . For example, as shown in  FIG.  1 A , the junction box  300  may be disposed above the fuel cell  100 , but the fuel cell vehicle according to the embodiment is not limited to any specific position of the junction box  300 . In this case, the terminal block TB and the insulation protection units  220  and  222  may be disposed below the junction box  300 , and only the end portions E 11  and E 21  of the bus bars  212  and  214  may be exposed to the outside of the junction box  300 , but the embodiments are not limited thereto. 
     The terminal block TB serves to transfer the electrical energy, received from the current collectors  116 A and  116 B through the bus bars  212  and  214 , to the junction box  300 . To this end, the terminal block TB may be electrically connected to the opposite end portions E 12  and E 22  of the bus bars  212  and  214 . 
     The configuration of the terminal block TB will now be described briefly with reference to  FIGS.  5  and  6   . However, the fuel cell vehicle according to the embodiment is not limited as to the specific configuration of the terminal block TB to be described below. 
     The terminal block TB may include a body BO, a partition wall PW, a positive bus terminal BTP, a negative bus terminal BTN, a positive heater terminal HTP, and a negative heater terminal HTN. 
     Each of the body BO and the partition wall PW may be made of an insulative material. At least a portion of each of the positive bus terminal BTP, the negative bus terminal BTN, the positive heater terminal HTP, and the negative heater terminal HTN may be embedded in the body BO, or may be disposed on the body BO, as illustrated in  FIG.  6   . 
     The partition wall PW is disposed on the body BO in order to electrically isolate the positive bus terminal BTP, the negative bus terminal BTN, the positive heater terminal HTP, and the negative heater terminal HTN from each other. 
     One of the first and second bus bars  212  and  214  is a positive bus bar, and the other one thereof is a negative bus bar. For convenience of description, it is assumed that a coolant manifold is disposed in the first end plate  110 A and that a hydrogen manifold and an air manifold are disposed in the second end plate  110 B. Hereinafter, the first bus bar  212  will be referred to as a positive bus bar, and the second bus bar  214  will be referred to as a negative bus bar. In this case, the length of the first positive bus bar  212  in the first direction may be shorter than the length of the second negative bus bar  214  in the first direction, but the embodiments are not limited thereto. 
     The positive bus terminal BTP may be connected to the first positive bus bar BP ( 212 ), the negative bus terminal BTN may be connected to the second negative bus bar BN ( 214 ), the positive heater terminal HTP may be connected to a positive wire WP (not shown), and the negative heater terminal HTN may be connected to a negative wire WN (not shown). To this end, conductive wires may be disposed in the terminal block TB. 
     Although not illustrated, these components (BTP and BP), (BTN and BN), (HTP and WP), and (HTN and WN) may be connected to each other by means of electrically conductive bolts or the like, but the embodiments are not limited to any specific connection structure between the components (BTP and BP), (BTN and BN), (HTP and WP), and (HTN and WN). Each of the terminals BTP, BTN, HTP, and HTN of the terminal block TB may be connected to the fuel cell  100  via the bus bars BP and BN and the wires WP and WN. 
     As shown in  FIG.  5   , the positive bus terminal BTP and the negative bus terminal BTN may be arranged so as to be aligned with each other in the first direction, and the positive heater terminal HTP and the negative heater terminal HTN may be arranged so as to be aligned with each other in a direction parallel to the first direction. Alternatively, unlike what is illustrated in  FIG.  5   , one of the positive bus terminal BTP and the negative bus terminal BTN and one of the positive heater terminal HTP and the negative heater terminal HTN may be arranged so as to be aligned with each other in the first direction, and the other one of the positive bus terminal BTP and the negative bus terminal BTN and the other one of the positive heater terminal HTP and the negative heater terminal HTN may be arranged so as to be aligned with each other in a direction parallel to the first direction. 
     Although not illustrated, heaters H 1  and H 2  may be disposed at respective ends of the cell stack  112 . The first heater H 1  may be connected to one of the positive wire WP and the negative wire WN, and the second heater H 2  may be connected to the other one of the positive wire WP and the negative wire WN. 
     The heaters and the current collectors  116 A and  116 B of the fuel cell  100  may be connected to the junction box  300  via the terminal block TB. To this end, the first positive bus bar BP ( 212 ) and the second negative bus bar BN ( 214 ) may electrically connect the current collectors  116 A and  116 B to the terminal block TB, and the positive wire WP and the negative wire WN may electrically connect the heaters H 1  and H 2  to the terminal block TB. 
     Although not illustrated, the positive bus terminal BTP, the negative bus terminal BTN, the positive heater terminal HTP, and the negative heater terminal HTN of the terminal block TB may be connected to the fuses and the relays of the junction box  300 . Since the electrical connection between the terminal block TB and the junction box  300  is well-known technology, a detailed description thereof will be omitted. An example of the connection between each of the terminals BTP, BTN, HTP, and HTN of the terminal block and the fuses and the relays of the junction box  300  is disclosed in Korean Patent Application No. 10-2020-0118363, which was filed by the present applicant. 
     In addition, the terminal block TB may further include a cover  304 . The cover  304  serves to support the weight of the bus bars  212  and  214 , to electrically insulate the same, and to make the same watertight. 
     The cover  304  of the terminal block TB may include a coolant connection portion  306 , a through-hole TH, and an adapter  308 . 
     The coolant connection portion  306  is a portion that is connected to a tube  310 , which will be described later, and functions as an inlet through which the coolant flows into the cover  304  of the terminal block TB. 
     According to an embodiment, as illustrated in  FIG.  3 A , the coolant connection portion  306 A may have the shape of a nipple that protrudes toward a tube  310 A to be coupled to the tube  310 A. 
     According to another embodiment, as illustrated in  FIG.  3 B , the coolant connection portion  306 B may have the shape of an opening that is coupled to a tube  310 B. Here, the opening may have a circular planar shape, but the embodiments are not limited to any specific planar shape of the opening. 
     In addition, referring to  FIGS.  3 A and  3 B , the through-hole TH may be connected to the coolant connection portion  306  ( 306 A or  306 B), and may penetrate the cover  304  ( 304 A or  304 B) in the third direction. 
     The adapter  308  serves to connect the through-hole TH to the flow paths P 1  and P 2  in the insulation protection units  220  and  222 . To this end, as shown in  FIGS.  3 A and  3 B , the adapter  308  may include an end portion  308 E 1 , which is connected to the through-hole TH, and an opposite end portion  308 E 2 , which is connected to the insulation protection units  220  and  222 . The adapter  308  may have a cross-sectional shape that extends from the end portion  308 E 1  in the third direction and is then bent and extends in the first direction. The adapter  308  may include a fluid passage CP to provide the coolant, introduced through the coolant connection portion  306  and the through-hole TH, to the flow paths P 1  and P 2  in the insulation protection units  220  and  222 . 
     The coolant connection portion  306  ( 306 A or  306 B) and the adapter  308  may be formed integrally with the cover  304  ( 304 A or  304 B). 
     According to the embodiment, one of the coolant connection portion  306  and the adapter  308  may be formed at the upper side of the cover  304 , and the other one thereof may be formed at the lower side of the cover  304 . For example, as shown in  FIGS.  3 A and  3 B , the coolant connection portion  306 A or  306 B may be formed at the upper side of the cover  304 A or  304 B, and the adapter  308  may be formed at the lower side of the cover  304 A or  304 B. 
     The first diameter Φ1 of the through-hole TH, the second diameter Φ2 of the fluid passage CP in the adapter  308 , and the third diameter Φ31 and Φ32 of the flow paths P 1  and P 2  in the insulation protection units  220  and  222  may be equal to each other, but the embodiments are not limited thereto. 
     The through-hole TH may have a first diameter Φ1 that is uniform from the inlet to the outlet thereof in the third direction, the fluid passage CP in the adapter  308  may have a second diameter Φ2 that is uniform from a starting portion  308 E 1  to an ending portion  308 E 2  thereof, and the flow paths P 1  and P 2  in the insulation protection units  220  and  222  may have a third diameter Φ31 and Φ32 that is uniform from starting points PS 1  and PS 2  to ending points PE 1  and PE 2  thereof. However, the embodiments are not limited thereto. 
     The insulation protection units  220  and  222  may include end portions, which are located at the starting points of the flow paths P 1  and P 2  and which function as inlets that are coupled to the opposite end portion  308 E 2  of the adapter  308  to receive the coolant introduced thereinto. In addition, the insulation protection units  220  and  222  may include opposite end portions, which are located opposite the end portions functioning as the inlets. In this case, the ending points of the flow paths P 1  and P 2  may be spaced a predetermined distance apart from the opposite end portions of the insulation protection units  220  and  222 , and the flow paths P 1  and P 2  may have shapes that are blocked at the ending points thereof. 
     For example, referring to  FIGS.  4 B and  6   , the first insulation protection unit  220  may include an end portion  220 E 1 , which is located at the starting point PS 1  of the first flow path P 1  and which functions as an inlet that is coupled to the opposite end portion  308 E 2  of the adapter  308  to receive the coolant introduced thereinto, and an opposite end portion  220 E 2 , which is located opposite the end portion  220 E 1 . In this case, the ending point PE 1  of the first flow path P 1  may be spaced a predetermined distance d 1  apart from the opposite end portion  220 E 2  of the first insulation protection unit  220 , and the first flow path P 1  may have a shape that is blocked at the ending point PE 1  thereof. 
     For example, referring to  FIG.  6   , the second insulation protection unit  222  may include an end portion  222 E 1 , which is located at the starting point PS 2  of the second flow path P 2  and which functions as an inlet that is coupled to the opposite end portion  308 E 2  of the adapter  308  to receive the coolant introduced thereinto, and an opposite end portion  222 E 2 , which is located opposite the end portion  222 E 1 . In this case, the ending point PE 2  of the second flow path P 2  may be spaced a predetermined distance d 2  apart from the opposite end portion  222 E 2  of the second insulation protection unit  222 , and the second flow path P 2  may have a shape that is closed at the ending point PE 2  thereof. 
     In addition, one of the end portion  220 E 1  or  222 E 1  of the insulation protection unit  220  or  222  and the opposite end portion  308 E 2  of the adapter  308  may have a protrusion, and the other one thereof may have a recessed portion into which the protrusion is fitted. 
     For example, as shown in  FIG.  7 A , the end portion  222 E 1  of the second insulation protection unit  222  may have a protrusion, and the opposite end portion  308 E 2  of the adapter  308  may have a recessed portion into which the protrusion is fitted. Alternatively, as shown in  FIG.  7 B , the opposite end portion  308 E 2  of the adapter  308  may have a protrusion, and the end portion  222 E 1  of the second insulation protection unit  222  may have a recessed portion into which the protrusion is fitted. 
     As described above, when the adapter  308  and the insulation protection units  220  and  222  are coupled to each other using the protrusion and the recessed portion, the coolant may leak through the coupled portion between the protrusion and the recessed portion. In order to prevent this, the fuel cell vehicle may further include a sealing gasket  510  for sealing the coupled portion between the protrusion and the recessed portion, as shown in  FIGS.  7 A and  7 B . 
     According to another embodiment, the end portions  220 E 1  and  222 E 1  of the insulation protection units  220  and  222  and the opposite end portion  308 E 2  of the adapter  308  may be integrated. In this case, the sealing gasket  510  shown in  FIGS.  7 A and  7 B  is not required. 
     As illustrated in  FIG.  2   , the junction box  300  may include a chamber  302  and a tube  310 . 
     The chamber  302  serves to store therein the coolant necessary to cool the bus bars  212  and  214 . 
     The tube  310  may form a path through which the coolant flows from the chamber  302  to the cover  304  ( 304 A or  304 B) of the terminal block TB, and may be implemented as a flexible vent hose. In this case, the end portion of the tube  310  ( 310 A) may be connected to the cover  304  ( 304 A or  304 B) of the terminal block TB using a clamp so as to form a seal in order to prevent leakage of the coolant. 
     The flow of the coolant in the fuel cell vehicle configured as described above will be described below. 
     First, the coolant stored in the chamber  302  shown in  FIG.  2    is supplied to the coolant connection portion  306  ( 306 A or  306 B) formed at the cover  304  ( 304 A or  304 B) of the terminal block TB through the tube  310  ( 310 A or  310 B) in the direction of the arrow shown in  FIG.  6   . Thereafter, the coolant introduced through the coolant connection portion  306  ( 306 A or  306 B) is supplied to the flow paths P 1  and P 2  in the insulation protection units  220  and  222  through the through-hole TH and the fluid passage CP in the adapter  310 . Accordingly, the coolant flows from the starting points PS 1  and PS 2  to the ending points PE 1  and PE 2  of the flow paths P 1  and P 2 , which extend from the insulation protection units  220  and  222  in the first direction, thereby cooling the bus bars  212  and  214 . 
     The bus bars  212  and  214  are cooled by controlling the flow rate of the coolant according to the operation region and the output of the junction box  300 , whereby the temperature of the bus bars  212  and  214  may be maintained constant. 
     For example, when the bus bars  212  and  214  are not cooled, energy transfer loss at the bus bars  212  and  214  may increase due to heat generated in the bus bars  212  and  214 . The reason for this is that the energy transferred through the bus bars  212  and  214  is lost as heat. In consideration of this, a method of increasing the cross-sectional areas of the bus bars  212  and  214  may be proposed. However, the increase in the cross-sectional areas of the bus bars  212  and  214  may increase the weight, size, and manufacturing cost of the bus bars  212  and  214 , and may be disadvantageous from the aspect of packaging. In particular, the first portions  212 P 1  and  214 P 1  of the bus bars  212  and  214 , which are in contact with the terminal block TB, generate the largest amount of heat, and thus a fire may occur at the first portions  212 P 1  and  214 P 1 . 
     In contrast, according to the embodiment, the coolant is supplied through the flow paths P 1  and P 2 , which are formed along the route along which the bus bars  212  and  214  are formed, and the temperature of the coolant is adjusted to cool the bus bars  212  and  214 , thereby making it possible to reduce energy transfer loss at the bus bars  212  and  214 . Accordingly, compared to the configuration in which the bus bars  212  and  214  are not cooled, the cross-sectional areas of the bus bars  212  and  214  may be reduced, which makes it possible to reduce the size, weight, and manufacturing cost of the bus bars  212  and  214  and which may be advantageous from the aspect of packaging due to the resultant increase in space for packaging. As a result, it is possible to manufacture a fuel cell vehicle having a compact size while meeting requirements for high output. 
     In addition, since the first portions  212 P 1  and  214 P 1  of the bus bars  212  and  214 , which are in contact with the terminal block TB, are cooled by the coolant, it is possible to prevent the occurrence of a fire at the first portions  212 P 1  and  214 P 1  and thus to improve the electrical stability of the fuel cell vehicle. 
     As is apparent from the above description, according to the fuel cell vehicle of the embodiment, it is possible to reduce the size, weight, and manufacturing cost of the bus bar, and thus the bus bar according to the embodiment may be advantageous from the aspect of packaging by increasing the amount of space for packaging. Further, it is possible to manufacture a fuel cell vehicle that has a compact size and meets requirements for high output. Furthermore, since the first portion of the bus bar, which is in contact with the terminal block, is cooled by coolant, it is possible to prevent the occurrence of a fire at the first portion and thus to improve the electrical stability of the fuel cell vehicle. 
     However, the effects achievable through the disclosure are not limited to the above-mentioned effects, and other effects not mentioned herein will be clearly understood by those skilled in the art from the above description. 
     The above-described various embodiments may be combined with each other without departing from the objects of the present disclosure unless they are incompatible with each other. 
     In addition, for any element that is not described in detail in any of the various embodiments, reference may be made to the description of an element having the same reference numeral in another embodiment. 
     While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, these embodiments are only proposed for illustrative purposes and do not restrict the present disclosure, and it will be apparent to those skilled in the art that various changes in form and detail may be made without departing from the essential characteristics of the embodiments set forth herein. For example, respective configurations set forth in the embodiments may be modified and applied. Further, differences in such modifications and applications should be construed as falling within the scope of the present disclosure as defined by the appended claims.