End cell heater assembly and fuel cell stack with the same

Abstract

End cell heating arrangement (20), comprising: a housing (21) having a first surface connected to an end plate (11, 12) of a fuel cell stack (10); a planar heating element (22) mounted in a receiving recess (21g) formed in a second surface of the housing (21); a terminal plate (23) stacked and inserted between the planar heating element (22) and an end cell of the fuel cell stack (10), joined and electrically connected to the end cell, and transferring heat generated by the planar heating element (22) to the end cell; and a terminal (23a) formed integrally with the terminal plate (23) for discharging electrical energy generated by the fuel cell stack (10) and transmitted through the terminal plate (23) to the outside, wherein the planar heating element (22) performs a heating operation by being supplied with electrical energy generated by the fuel cell stack (10), wherein the electrical energy generated by the fuel cell stack (10) is supplied to the planar heating element (22) via a connector (25) installed in the housing, and wherein the connection (23a) penetrates the planar heating element (22), the housing (21) and the end plate (11, 12) and is formed integrally with the connection plate (23).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a fuel cell stack. More particularly, it relates to an end cell heater assembly and a fuel cell stack including the same, which are capable of solving a problem of deterioration in the performance of an end cell of a fuel cell at the time of a cold start. BACKGROUND

[0002] A fuel cell is an energy conversion device that converts chemical energy of fuel into electrical energy by electrochemically reacting a fuel gas and an oxidizer gas. It is used as an industrial, household, and vehicle power source, and can be used to supply electrical energy to small-sized electrical and electronic products and mobile devices.

[0003] Research has been conducted on proton exchange membrane fuel cells (polymer electrolyte membrane fuel cells - PEMFC), which have a high electrical power density, as fuel cells for current vehicles.

[0004] Fig. Figure 1 is a sectional view schematically illustrating a basic configuration of a unit cell of a polymer electrolyte membrane fuel cell.

[0005] As shown, a membrane electrode assembly (MEA) 1, which is a main constituent component, is arranged at an innermost side of each unit cell of the fuel cell.

[0006] The membrane electrode assembly 1 comprises a solid polymer electrolyte membrane capable of moving hydrogen ions, and a cathode and an anode, which are electrode layers on which catalysts are deposited on both surfaces of the electrolyte membrane so that hydrogen and oxygen can react.

[0007] Gas diffusion layers (GDL) 2 are stacked on the outer side of the membrane electrode assembly 1, that is, the outer side where the cathode and the anode are arranged, and bipolar plates 3 and 4 having flow paths through which reaction gases (hydrogen which is a fuel gas, and oxygen or air which is an oxidant gas) are supplied and a coolant flows through are arranged on the outer side of the gas diffusion layers 2.

[0008] Gaskets 8 and the like are inserted and stacked between the bipolar plates 3 and 4 for fluid sealing, and the gaskets 8 may be formed integrally with the membrane electrode assembly 1 or the bipolar plates 3 and 4.

[0009] Assuming that, based on the membrane electrode assembly 1 in Fig. 1, a left bipolar plate 3 is an anode bipolar plate and a right bipolar plate 4 is a cathode bipolar plate, channels 5 between the gas diffusion layers 2 connected to the anode of the membrane electrode assembly 1 and the anode bipolar plate 3 are anode channels through which hydrogen, which is a fuel gas, flows.

[0010] Channels 6 between the gas diffusion layers 2 connected to the cathode of the membrane electrode assembly 1 and the cathode bipolar plate 4 are cathode channels through which air (oxygen) which is an oxidizing gas passes, and spaces formed by bipolar plate web portions 3A and 4A between the adjacent anode channels 5 and between the adjacent cathode channels 6 are coolant channels 7.

[0011] This configuration / arrangement finds application as a unit cell, a plurality of cells are stacked, end plates (not shown) that support the cells are coupled to the outermost sides of the cells, and the end plates and the cells are connected to each other by a stack fixing mechanism (not shown) in a state where the cells are stacked and arranged between the end plates, thereby forming a fuel cell stack.

[0012] Each of the unit cells maintains a low voltage during operation and as a result, dozens or hundreds of cells are made in the form of a stack by stacking them in series / one after another to increase the voltage and used as an electric generator.

[0013] Fig. 2 is a sectional view schematically illustrating a fuel cell stack formed by stacking cells, and end plates are coupled to both ends of a stack 10 constituting outer sides of the cells 9 in a state where the cells 9 are stacked.

[0014] In this case, a penetrated end plate 11 having a distribution opening 11a may be coupled to one end of both ends of the stack 10, and a non-penetrated end plate 12 having no distribution opening may be coupled to the other end opposite to the one end.

[0015] In this configuration / arrangement, when hydrogen, air, and a coolant supplied through the inlet manifolds 13 of the stack 10 (the inlet manifolds for hydrogen, air, and a coolant are separate from each other) are distributed into the respective cells 9 through the flow paths of the bipolar plates, the hydrogen, air, and the coolant flow through the anode channels, the cathode channels, and the coolant channels, respectively, which are flow paths of the bipolar plates in each of the cells, and thereafter, foreign matters such as unreacted gas, nitrogen, and water and the coolant are discharged from the respective cells 9 below the stack 10 through an outlet manifold 14.

[0016] Current collector plates 15 and 16, which have terminals 15a and 16a, respectively, are provided in the end plates 11 and 12, respectively.

[0017] The current collector plates 15 and 16 are electrically connected to the bipolar plates of the end cells arranged therein and deliver an electric current generated by a fuel cell reaction in all cells 9 in the stack 10 to the outside through the terminals 15a and 16a.

[0018] In the polymer electrolyte membrane fuel cell, water (generated water) is inevitably generated at the cathode side as a result of the reaction between the fuel gas (hydrogen in the reaction gas) supplied to the anode channel and the oxidant gas (air or oxygen in the reaction gas) supplied to the cathode channel.

[0019] If the generated water remaining in the cells after stopping the operation of the fuel cell is left at a low temperature, the generated water may freeze and then block / clog pores of the gas diffusion layer (GDL) and the channels of the bipolar plate (flow paths of the reactant gas).

[0020] For this reason, the reaction gas cannot flow smoothly at the time of a cold start, and as a result, the fuel cell cannot operate normally and a start-up time may be delayed.

[0021] Accordingly, in order to ensure cold start performance and shorten start-up time, it may be necessary to melt frozen moisture / damp using electrochemical reaction heat from the fuel cell itself and to melt frozen moisture / damp using additional means, such as a separate heating source.

[0022] Fig. 3 is a view showing a temperature distribution of the cells under a normal operating condition of the fuel cell stack.

[0023] Since the fuel cell stack is formed by the plurality of unit cells, the end plates with high rigidity / strength are used to press and fix the cells with uniform pressure.

[0024] The end plate is manufactured using a material such as metal with high thermal mass to maintain high strength and as a result, as shown in Fig. 3, even in a case where the fuel cell operates normally, the operating temperature of the cell at one end of the stack, located next to the end plate, is lower than that of the cells inside the stack, thus indicating lower power generation efficiency.

[0025] In particular, at the end of starting, due to heat loss, the cells require a longer time to melt the frozen water at the time of a cold start, which causes a delay in the starting time.

[0026] It has been reported that a voltage of the cells at both ends of the stack can be significantly lower than that of the cells within the stack under cold start conditions of the fuel cell.

[0027] In this context, US 2005 / 0 058 865 A1 discloses electrical resistance heating elements that are embedded in the end plates or cell end plates of a fuel cell stack at the interfaces therebetween and that are powered by the electricity generated by the stack to heat the end cells during start-up of a frozen stack. The current flow in the heating elements is terminated when the temperature of the end cell(s) reaches a prescribed temperature above freezing. US 2003 / 0 003 330 A1 further discloses a method for operating a fuel cell system having a fuel cell stack and a plurality of fuel cells connected to the fuel cell stack. The method comprises monitoring an operating parameter associated with the fuel cell stack and adjusting a temperature of the fuel cell stack based on the operating parameter.Furthermore, US 2001 / 0 036 568 A1 discloses a fuel cell assembly comprising a fuel cell stack, a first end plate connected to the fuel cell stack, and a first heatable element configured to heat the first end plate. Finally, JP 2008 108 610 A discloses a fuel cell capable of efficiently adjusting itself so that the temperature on the anode side does not become lower than the temperature on the cathode side in an end cell, and capable of limiting a voltage drop in the end cell.

[0028] The above information disclosed in this Background section is provided only to enhance the understanding of the background of the invention and may accordingly contain information that does not constitute prior art already known to a person of ordinary skill in the art in this country. SUMMARY OF REVELATION

[0029] The present disclosure has been made in an effort to solve the above-described problems associated with the prior art and to provide an end cell heater assembly and a fuel cell stack having the same capable of solving a problem of performance deterioration of an end cell of a fuel cell at the time of a cold start.

[0030] In one aspect, the present disclosure provides an end cell heating assembly that performs a heating operation by being supplied with electric power from a power source / power stacked and interposed between end cells that are stacked to be arranged at both ends among a plurality of stacked fuel cells that generate electric power through an electrochemical reaction by being supplied with reactant gas in a fuel cell stack, and end plates at both ends of the fuel cell stack, so as to provide heat to the respective end cells at the time of the heating operation to increase a temperature of the end cell, and has a bypass flow path such that at least one of air and hydrogen supplied to the fuel cell stack as reactant gases is distributed to and flows through the bypass flow path.

[0031] In a further embodiment, the present disclosure provides an end cell heating assembly comprising: a housing having a first surface connected to an end plate of a fuel cell stack; a planar heating element mounted in a receiving recess formed in a second surface of the housing; a terminal plate stacked and interposed between the planar heating element and an end cell of the fuel cell stack, joined and electrically connected to the end cell, and transferring heat generated by the planar heating element to the end cell; and a terminal formed integrally with the terminal plate so as to transfer electrical energy generated by the fuel cell stack and transferred through the terminal plate to the outside.the outside, wherein the planar heating element performs a heating operation by being supplied with electric power generated by the fuel cell stack, wherein the electric power generated by the fuel cell stack is supplied to the planar heating element via a connector installed in the housing, and wherein the connector penetrates the planar heating element, the housing and the end plate from the connector plate and is formed integrally with the connector plate.

[0032] In another aspect, the present disclosure provides a fuel cell stack comprising: a plurality of fuel cells provided by stacking them, and generating electric power through an electrochemical reaction by supplying them with reaction gases; end plates stacked at both positions of the fuel cell stack outside the stacked fuel cells;and an end cell heater assembly that performs a heating operation by being supplied with electric power is stacked and interposed between end cells stacked so as to be arranged at both ends among the stacked fuel cells and end plates at both ends of the fuel cell stack, so as to supply heat to the respective end cells at the time of the heating operation to increase a temperature of the end cell, and has a bypass flow path such that at least one of air and hydrogen supplied to the fuel cell stack as reactant gases is distributed and flows through the bypass flow path, the end cell heater assembly comprising: a casing having a first surface connected to an end plate of a fuel cell stack; a planar heater element mounted in a receiving recess formed in a second surface of the casing;a terminal plate stacked and inserted between the planar heating element and an end cell of the fuel cell stack, joined and electrically connected to the end cell, and transmitting heat generated by the planar heating element to the end cell; and a terminal formed integrally with the terminal plate so as to output electrical energy generated by the fuel cell stack and transmitted through the terminal plate to the outside, the terminal penetrating the planar heating element, the casing, and the end plate and being formed integrally with the terminal plate. The planar heating element performs a heating operation by being supplied with electrical energy generated by the fuel cell stack, and the electrical energy generated by the fuel cell stack is supplied to the planar heating element via a connector installed in the casing.

[0033] Accordingly, the end cell heater assembly and the fuel cell stack according to the present disclosure can provide effects of increasing a temperature of the end cell arranged at both end portions of the stack under a cold start condition of the fuel cell, preventing deterioration in performance caused by heat loss of the end cell, improving distribution aids of the reaction gas at the end cell, preventing inflow of droplets (droplets flowing past, flowing in), reducing the cold start time, improving the cold start performance, and preventing voltage drop and electric power loss caused by the existing dummy cell.

[0034] Further embodiments and embodiments of the disclosure are explained below.

[0035] It is understood that the term "vehicle" or "vehicular" or other synonymous terms as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuel derived from sources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, such as both gasoline-powered and electric-powered vehicles.

[0036] The above and other features of the invention are explained below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other features of the present disclosure will now be described in detail with reference to embodiments thereof illustrated in the accompanying drawings, which are given below for illustrative purposes only and thus do not constitute a limitation of the present invention. In the figures: Fig. 1 is a sectional view showing a basic configuration of a unit cell of a polymer electrolyte membrane fuel cell; Fig. 2 is a sectional view schematically illustrating a publicly known fuel cell stack formed by stacking cells; Fig. 3 is a view illustrating a temperature distribution of cells under a normal operating condition of a fuel cell stack; Fig. 4 is a sectional view showing a fuel cell stack with dummy cells; Fig. 5 is a sectional view schematically illustrating a configuration / arrangement of a fuel cell stack according to an embodiment of the present disclosure; Fig. 6 is an assembled perspective view illustrating an end cell heater assembly according to the embodiment of the present disclosure; and Fig. 7 is an exploded perspective view of the end cell heater assembly according to the embodiment of the present disclosure.

[0038] It should be noted that the accompanying drawings are not necessarily to scale and represent a somewhat simplified representation of various features intended to illustrate the principles of the disclosure. The specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the dedicated application and the operating environment.

[0039] In the figures, reference numerals refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0040] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the disclosure will be described in connection with embodiments, it should be understood that the present description is not intended to limit the disclosure to those embodiments. On the contrary, the disclosure is intended to cover not only the embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the disclosure as defined by the appended claims.

[0041] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that a person skilled in the art to which the present disclosure belongs can easily implement the embodiments. However, the present disclosure is not limited to the embodiments described below and may be embodied in other forms.

[0042] Unless otherwise stated, the word “comprise / include” and variations such as “comprises / includes” or “comprising / having” shall be construed to mean the inclusion of the elements mentioned and not the exclusion of other elements.

[0043] For illustrative purposes, in order to better understand the present disclosure, a fuel cell stack with dummy cells will be described first before describing the embodiment.

[0044] Fig. Figure 4 shows a cross-sectional view illustrating a fuel cell stack with dummy cells.

[0045] As shown, the end plates 11 and 12 are coupled to both ends of a stack 10, which are outer sides of the cells 9, in a state in which the cells 9 are stacked.

[0046] In this case, a penetrated end plate 11 having a distribution opening 11a may be coupled to one end of the two ends of the stack 10, and a non-penetrated end plate 12 having no distribution opening may be coupled to the other end opposite to the one end.

[0047] In this configuration / arrangement, when hydrogen, air, and a coolant supplied through inlet manifolds 13 of the stack 10 (the inlet manifolds for hydrogen, air, and coolant are separated from each other) are distributed into the respective cells 9 through bipolar plates, the hydrogen, air, and coolant flow through anode channels, cathode channels, and coolant channels, respectively, which are flow paths of the bipolar plates in each of the cells 9, and thereafter, foreign matters such as unreacted gas, nitrogen, and water and the coolant are discharged from the cells 9 and the stack 10 through an outlet manifold 14.

[0048] Current collector plates 15 and 16 having terminals 15a and 16a, respectively, are provided in the end plates 11 and 12, and the current collector plates 15 and 16 are electrically connected to the bipolar plates of the dummy cells 17 arranged therein and output electric current generated by a fuel cell reaction in all of the cells 9 in the stack 10 to the outside through the terminals 15a and 16a.

[0049] A plurality of cells in the stack 10 located adjacent to the respective end plates 11 and 12 of the stack 10 are formed as the dummy cells 17 and 18 in order to improve the distribution properties of the reaction gases at end cells arranged at both ends of the stack 10 (cells arranged at ends of the stack 10 below the reaction cells, which will be described below) and to redirect and discharge droplets flowing in.

[0050] Accordingly, the cells constituting the stack 10 can be classified into the reaction cells (unit cells having a typical configuration / arrangement) 9 that generate electric energy through an electrochemical reaction by being supplied with the reaction gas, and the dummy cells 17 and 18 stacked at both end portions of the reaction cells 9.

[0051] Unlike the reaction cell 9, which has a typical configuration including the anode bipolar plate, the gas diffusion layer (GDL), the membrane electrode assembly (MEA), the gas diffusion layer, and the cathode bipolar plate, the dummy cell 17 has no membrane electrode assembly and uses a bipolar plate dedicated to the dummy cell.

[0052] Hereinafter, the reaction cell arranged at the end next to the dummy cell among the reaction cells 9 is referred to as an end cell, and the plurality of dummy cells 17 are additionally stacked between the end plates 11 and 12 outside the end cells with a typical configuration / arrangement of the unit cells, thereby forming the stack 10.

[0053] In this case, bipolar plates associated with the dummy cell, which are arranged at outermost ends under the dummy cells stacked at the end portions of the stack 10, are electrically connected to the current collector plates 15 and 16 attached to the end plates 11 and 12.

[0054] When the bipolar plate associated with the dummy cell is compared with the bipolar plate of the reaction cells 9, the bipolar plate of the reaction cells 9 has inlet and outlet manifold openings through which the respective reaction gases and the coolant flow in and out, and channels that represent flow paths of the respective reaction gases and the coolant, so that hydrogen, which is the fuel gas, air, which is the oxidant gas, and coolant can flow into, through, and be discharged from the inlet and outlet manifold openings and the channels, wherein the bipolar plate associated with the dummy cell only has inlet and outlet manifold openings and a channel for hydrogen, which is the fuel gas, or inlet and outlet manifold openings and a channel for air, which is the oxidant gas.

[0055] Accordingly, the stack 10 needs to be assembled by separately and repeatedly stacking only the plurality of gas diffusion layers and the plurality of bipolar plates associated with the dummy cells at both end portions of the stack 10 to form the dummy cell 17, and as a result, there is a disadvantage in mass production of the fuel cell stack by using an automatic stacking line.

[0056] Furthermore, since the bipolar plate associated with the dummy cell is additionally required, additional production facilities for manufacturing the associated bipolar plate are necessary, and due to the gas diffusion layer stacked between the bipolar plates associated with the dummy cell in terms of a stacking sequence, forming the plurality of dummy cells 17, a voltage drop and an electric power loss occur when electric power generated by the reaction cells 9 of the fuel cell is output to the outside through the current collector plates 15 and 16.

[0057] When the coolant flows between the dummy cells in a state where the plurality of dummy cells 17 are provided, an operating temperature of the end cells arranged at both ends of the reaction cells 9 is reduced, and in particular, the efficiency of operation may further deteriorate due to the coolant cooled under a cold start condition of the fuel cell.

[0058] Accordingly, the end cell heater assembly is disclosed which increases a temperature of the end cell disposed at the end of the reaction cell of the fuel cell stack.

[0059] The end cell heater assembly according to the present disclosure provides effects of increasing a temperature of the stack at both end portions under a cold start condition of the fuel cell, preventing deterioration in performance caused by heat loss of the end cell, improving distribution properties of the reaction gas at the end cell, preventing inflow of droplets, and preventing voltage drop and loss of electric power caused by the existing dummy cell.

[0060] Fig. 5 is a sectional view schematically illustrating a configuration / arrangement of a fuel cell stack according to an embodiment of the present disclosure;

[0061] As shown, the fuel cell stack 10 according to the embodiment of the present disclosure has a structure / arrangement in which reaction cells 9 are stacked with the membrane electrode assembly (MEA), the gas diffusion layers (GDL), the cathode bipolar plates, the anode bipolar plates, and the gaskets, and each of the reaction cells 9 generates electrical energy through an electrochemical reaction by being supplied with the reaction gas.

[0062] The membrane electrode assemblies in each of the reaction cells 9 include a solid polymer electrolyte membrane capable of moving hydrogen ions, and a cathode and an anode, which are electrode layers on which catalysts are deposited on both surfaces of the electrolyte membrane so that hydrogen and oxygen can react.

[0063] The gas diffusion layers (GDL) are stacked on the outside of the membrane electrode assembly in each of the reaction cells 9, that is, the outside where the cathode and the anode are arranged, and the bipolar plates having flow paths through which reaction gases (hydrogen, which is the fuel gas, and oxygen or air, which is the oxidant gas) are supplied and the coolant flows through, are arranged on the outside of the gas diffusion layers.

[0064] The gaskets or the like for fluid sealing are inserted and stacked between the bipolar plates, and the gaskets may be formed integrally with the membrane electrode assembly or the bipolar plate.

[0065] Channels between the gas diffusion layer connected to the anode of the membrane electrode assembly and the anode bipolar plate are anode channels through which hydrogen, which is the fuel gas, flows, and channels between the gas diffusion layer connected to the cathode of the membrane electrode assembly and the cathode bipolar plate are cathode channels through which air (oxygen), which is the oxidant gas, flows, and spaces formed by bipolar web sections between the adjacent anode channels and between the adjacent cathode channels, represent coolant channels.

[0066] In this configuration / arrangement, hydrogen, air, and a coolant supplied through the inlet manifolds 13 of the fuel cell stack 10 are distributed to the respective reaction cells 9 through the respective bipolar plates, the hydrogen, air, and coolant flow through the anode channels, the cathode channels, and the coolant channels that are flow paths of the bipolar plates in each of the reaction cells 9, and thereafter, foreign matters such as unreacted gas, nitrogen, and water and the coolant are discharged from the respective reaction cells 9 and the stack 10 through the outlet manifold 14.

[0067] The end cell heater assemblies 20 are stacked and inserted between the respective end plates 11 and 12 and the reaction cells 9 at both end portions of the fuel cell stack 10.

[0068] The end cell heater assemblies 20 attached / mounted to both end portions of the fuel cell stack 10 each have similar configurations / arrangements, and as a result, the following description will be made without distinguishing the two end cell heater assemblies.

[0069] The end cell heater assembly 20 includes a housing 21, a planar heating element 22 for heating the end cell, a current collector terminal plate 23, and a terminal 23a.

[0070] First, the casing 21 has inlet manifold openings 21a and 21b and outlet manifold openings 21c and 21d penetratingly formed at both end portions thereof, and bypass flow paths 21e and 21f formed to penetrate into the interior, so that the end cell heater assembly 20 can work / act as a dummy cell comprising a metallic bipolar plate in a publicly known fuel cell stack.

[0071] Here, the bypass flow paths 21e and 21f comprise at least one channel.

[0072] More specifically, the bypass flow paths 21e and 21f may include a single channel or a plurality of channels to allow hydrogen, which is the fuel gas, or air, which is the oxidant gas, to flow therethrough, or may include channels formed to allow the hydrogen or air to flow therethrough, respectively.

[0073] In this case, the inlet manifold openings 21a and 21b and the outlet manifold openings 21c and 21d are formed at both end portions of the housing 21 for the respective channels, and the channels are formed to connect the inlet manifold openings 21a and 21b and the outlet manifold openings 21c and 21d.

[0074] That is, the housing 21 may include at least one hydrogen channel 21e or at least one air channel 21f connecting the inlet manifold openings 21a and 21b and the outlet manifold openings 21c and 21d, or may include both the hydrogen channel 21e and the air channel 21f.

[0075] Even in a case where the housing 21 includes both the hydrogen channel 21e and the air channel 21f, a single hydrogen channel 21e or a plurality of hydrogen channels 21e may be formed, and a single air channel 21f or a plurality of air channels 21f may be formed.

[0076] In the case of the reaction cells 9 in the fuel cell stack, flow paths formed on surfaces of the bipolar plates constitute the channels for the respective reaction gases and the coolant in a state where the cells are stacked, but the bypass flow paths 21e and 21f of the casing 21, that is, the channels 21e and 21f of the casing, are inner penetrating flow paths penetrating the interior of the casing, respectively.

[0077] In the present embodiment, the casing 21 may comprise a plurality of plates which are assembled / mounted by stacking them one on top of the other, and in this case, the stacked and mounted plates may have groove-shaped flow paths formed on the surface thereof along predetermined paths / courses so as to form the channels 21e and 21f which are the inner penetrating flow paths.

[0078] In this case, flow paths for forming the channels 21e and 21f may be formed on one surface of one plate of the two plates joined and stacked to form the channels 21e and 21f, or flow paths for forming individual channels may be formed on both surfaces of the two plates joined to each other.

[0079] Groove-shaped flow paths are formed along the same paths on surfaces of the two plates that are joined together, so that when the two plates are stacked and joined, the two flow paths formed on the surfaces of the two plates that are joined together are combined to form a sealed single channel.

[0080] An example in Fig. 7 illustrates an embodiment in which two bypass flow paths 21e and 21f, that is, the hydrogen channel 21e and the air channel 21f, through which hydrogen and air can flow, respectively, are provided in the housing 21, and as an example, when the housing 21 has the hydrogen channel 21e and the air channel 21f as in Fig. 7, 3 plates may be stacked to form the housing, although this is not shown.

[0081] More specifically, groove-shaped flow paths for forming the hydrogen channel 21e having a predetermined path along the same path are formed on both surfaces of the two plates joined and stacked together among the three plates constituting the case 21, so that when the two plates are stacked and joined, the flow paths formed on the surfaces of the two plates are combined to form a sealed flow path, that is, the hydrogen channel 21e.

[0082] In this case, groove-shaped flow paths for forming the air duct 21f having a predetermined path along the same path are formed on two surfaces of the two plates joined among the three plates and stacked on each other, so that when the two plates are stacked and joined, the flow paths formed on the surfaces of the two plates are combined to form a sealed flow path, that is, the air duct 21f.

[0083] Of course, in the case of the intermediate plate among the three plates, flow paths may be formed on both surfaces of the plate, and the flow path formed on one surface of the plate having the flow paths formed on both surfaces thereof is used to form the hydrogen channel 21e, and the flow path formed on the other surface is used to form the air channel 21f.

[0084] The above example merely illustrates an example of configuring / forming the casing 21, and the number of hydrogen channels 21e and air channels 21f provided in the casing 21 as the bypass flow paths, the number of plates stacked to configure / form the casing 21, the number of flow paths formed in the respective plates and having predetermined courses / paths, and whether the flow paths are formed on one surface of the plate or both surfaces of the plate are not particularly limited, but can be variously changed and modified and then implemented and applied, and the present disclosure is not limited to the illustrated embodiment.

[0085] As shown, the inlet manifold openings 21a and 21b formed at both end portions of the housing 21 are formed as a hydrogen inlet manifold opening 21a and an air inlet manifold opening 21b, and the outlet manifold openings 21c and 21d are formed as a hydrogen outlet manifold opening 21c and an air outlet manifold opening 21d.

[0086] The inlet manifold openings 21a and 21b and the outlet manifold openings 21c and 21d of the housing 21 are connected to the inlet opening 13 and the outlet opening 14 of the reaction cells 9, respectively.

[0087] Here, the hydrogen inlet manifold opening 21a and the hydrogen outlet manifold opening 21c of the casing 21 become parts of the hydrogen inlet manifold and the hydrogen outlet manifold of the fuel cell stack 10, respectively, and communicate with the hydrogen inlet manifold 13 and the hydrogen outlet manifold 14, respectively, formed by the bipolar plates of the reaction cells 9 that are stacked.

[0088] The air inlet manifold opening 21b and air outlet manifold opening 21d of the casing 21 become parts of the air inlet manifold and the air outlet manifold of the fuel cell stack 10, respectively, and are connected to the cathode inlet manifold and the cathode outlet manifold formed by the bipolar plates of the reaction cells 9 that are stacked.

[0089] The hydrogen channels 21e of the bypass flow paths are connected to the hydrogen inlet manifold opening 21a and the outlet manifold opening 21c of the housing 21, and in this case, the respective hydrogen channels 21e are formed to penetrate the interior of the housing 21 so as to connect the hydrogen inlet manifold opening 21a and the hydrogen outlet manifold opening 21c.

[0090] The air passages 21f of the bypass flow paths are connected to the air inlet manifold opening 21b and the air outlet manifold opening 21d of the casing 21, and in this case, the respective air passages are formed to penetrate the interior of the casing 21 so as to connect the air inlet manifold opening 21b and the air outlet manifold opening 21d.

[0091] Accordingly, hydrogen, which is the fuel gas flowing in through the hydrogen inlet manifold 13 on the side of the reaction cells 9, is distributed and flows into the hydrogen channel 21e of the bypass flow paths through the hydrogen inlet manifold opening 21a of the casing 21, and the hydrogen is discharged to the hydrogen outlet manifold opening 21c of the casing 21 and then discharged to the outside of the stack 10 through the hydrogen outlet manifold 14 on the side of the reaction cells 9.

[0092] Likewise, air (oxidizer gas) flowing in through the air inlet manifold on the side of the reaction cells 9 is distributed and flows into the air channel 21f of the bypass flow paths through the air inlet manifold opening 21b of the casing 21, and the air is discharged to the air outlet manifold opening 21d of the casing 21 and then discharged to the outside of the stack through the air outlet manifold on the side of the reaction cells 9.

[0093] Since the bypass flow paths 21e and 21f are provided in the casing 21 of the above-described end cell heater assembly 20 according to the present invention, it is possible to divert droplets or the like flowing into the fuel cell stack to a gas outlet through the bypass flow paths 21e and 21f and thus improve the distribution properties of the reaction gases.

[0094] Meanwhile, as in Fig. 7, a connector / connector 25 is attached to / on the housing 21 so that electrical power can be supplied to the planar heating element 22 through the connector 25, and the connector 25 serves to accommodate the planar heating element 22 and accessories such as a current collector (a terminal plate 23 described below).

[0095] In the embodiment, the casing 21 may be formed and manufactured using a synthetic resin (plastic) material which is an electrically non-conductive material, particularly an electrically and thermally non-conductive material, in order to ensure a thermal insulation effect for the end cell, to minimize heat loss of the heater toward the end plates 11 and 12, and to ensure electrical insulation.

[0096] One surface of the housing 21 is connected to the end plates 11 and 12, and the other surface opposite to the one surface is connected to and stacked on the reaction cell 9, and a receiving recess 21g into which the planar heating element 22 and the terminal plate 23 can be inserted is formed on the surface to which the reaction cell 9 is connected.

[0097] That is, the planar heating element 22 and the terminal plate 23 are accommodated in the accommodation recess 21g of the housing 21 in a state where the planar heating element 22 and the terminal plate 23 are stacked, and the planar heating element 22 is inserted / fitted into the accommodation recess 21g of the housing 21, and then the terminal plate 23 is connected to and stacked on the planar heating element 22.

[0098] In the embodiment, a thermal insulation layer 24 may be stacked and interposed between the planar heating element 22 and an inner surface of the receiving recess 21g of the housing 21.

[0099] The planar heating element 22 is a heating means in which an outer surface of a heating element 22a is coated with a sheath (jacket) 22b made of an electrically insulating material so as to be completely and electrically insulated from the outside, and the connector 25 connected to an external power source is connected to one side of the planar heating element 22 so that the planar heating element 22 is supplied with an operating current from the external power source.

[0100] In particular, since the terminal plate 23 is bonded to and stacked on a surface of the planar heating element 22, a complete electrical insulation state of the terminal plate and the heating element 22a can be maintained by the shell 22a.

[0101] The fuel cell stack may be the external power source / energy source that supplies the planar heating element 22 with the operating current, and in this case, a power supply circuit unit (not shown) that adjusts / adjusts the generated electric power output from the fuel cell stack 10 and supplies the electric power to the connector 25 may be provided.

[0102] In a case where the fuel cell stack 10 is used as the power source for the planar heater 22, it is possible to melt the residual water generated in the cell 9 more quickly at the time of a cold start due to the heating effect by the planar heater 22 and a heating effect of the stack itself caused by an electrochemical reaction heat of the cell 9.

[0103] Of course, instead of the fuel cell stack 10, other power sources / energy sources, e.g., a battery (not shown), may be used in the vehicle, and in this case, the electrical power supply circuit unit is arranged so that the planar heating element 22 is supplied with an operating current from the battery through the connector 25.

[0104] It is advantageous if the planar heating element 22 has a thin film structure to improve the power density compared to a volume of the stack 10, and as the internal heating element 22a, a resistance heating element fabricated as a metallic thin film or fabricated by a method such as CNT (carbon nanotube) printing may be used, or a PTC (Positive Temperature Coefficient) element that can regulate a temperature and self-sufficiently prevent overheating may be used.

[0105] The heating element using the PTC element is advantageous in that the following temperature sensor and the following method for controlling, by a control unit, the heating element based on a signal from the temperature sensor are not required because the heating element becomes a heating element that self-sufficiently limits a maximum heating temperature.

[0106] A separate temperature sensor 22c may be provided on the periphery of the heating element 22, and a controller (not shown, the controller performs control of the operating power supply by the electric power supply circuit unit) that controls an operation of the planar heating element 22 receives a signal from the temperature sensor 22c, and the controller may control a heating temperature based on the signal from the temperature sensor 22c when the heating element is operating.

[0107] In this case, the temperature sensor 22c can be used to measure a temperature of the end cell at the outermost side when the heating element 22a is not operating.

[0108] The terminal 23a, which is mounted so as to sequentially penetrate the planar heating element 22, the heat insulation layer 24, the housing 21, and the end plates 11 and 12, is formed integrally with a surface of the terminal plate 23, and through holes 26a, 26b, and 26c through which the terminal 23a passes are formed in the planar heating element 22, the heat insulation layer 24, the housing 21, and the end plates 11 and 12.

[0109] The through-hole 26c of the casing 21 is penetratingly formed in a portion of the casing 21 in which the hydrogen channel 21e and the air channel 21f are not formed, and the through-hole 26a of the planar heating element 22 must be formed such that the terminal 23a passing through the through-hole 26a is not electrically connected to the internal heating element 22a.

[0110] For this purpose, a through hole larger than a cross-sectional area of ​​the terminal 23a is formed in the internal heating element 22a, and an inner peripheral portion of the through hole of the internal heating element 22a is completely coated with the shell 22b, so that a completely electrically insulated state can be maintained between the terminal 23a and the internal heating element 22a.

[0111] Alternatively, the internal heating elements 22a may be arranged around the through-hole 26a, and the heating elements 22a may be electrically connected by portions spaced from the through-hole 26a and the terminal 23a.

[0112] The terminal plate 23 may be in direct contact with the cell arranged at the outermost periphery, that is, the cell below the stacked reaction cell 9, and may also be in contact with the bipolar plate of the end cell, or may be in contact with the gas diffusion layer (GDL) of the end cell in a state where the bipolar plate is omitted.

[0113] Overall, one surface of the planar heating element 22 is in contact with the terminal plate 23, the terminal 23a is formed integrally with one surface of the terminal plate 23, one surface of the terminal plate 23 is in contact with the planar heating element 22, and the other surface of the terminal plate 23 is in direct surface contact with the reaction cell 9, that is, the end cell.

[0114] The terminal plate 23 is made using an electrically conductive and thermally conductive material, and the terminal plate 23 serves as a current collector plate that receives electrical energy generated by the reaction cell in a state where it is directly connected to the reaction cell 9 and serves to transfer the heat generated by the planar heating element 22 to the end cell.

[0115] As described above, the configuration / arrangement of the end cell heater assembly has been described in which the bypass flow paths (housing), the planar heater element for heating / warming the end cell, the current collector terminal plate and the terminal are integrally assembled / assembled.

[0116] In the fuel cell stack 10 to which the end cell heater assembly 20 having the above-mentioned configuration is applied, the electric power generated by the reaction cell 9 stacked inside the fuel cell stack can be output to the outside through the terminal plate 23 and the terminal 23a.

[0117] When the planar heater 22 performs a heating operation under a cold start condition of the fuel cell stack 10, thermal energy is directly supplied to the end cell, thereby rapidly increasing a temperature of the end cell.

[0118] When the end cell is heated by the end cell heater assembly 20, moisture (generated water) remaining frozen in the end cell can be quickly melted at the time of a cold start, and the reaction gases flow smoothly, so that voltage loss at both ends of the cell and deterioration of stack performance caused by the voltage drop can be prevented, and a start-up time can be shortened.

[0119] When the end cell heater assembly 20 is attached / installed, the occurrence of heat loss at the end plates 11 and 12 having a high heat capacity during the operation of the fuel cell can be prevented and heat loss can be compensated / balanced during the heating operation, so that the power generation efficiency can be improved and a uniform cell performance can be ensured.

[0120] The bypass flow paths 21e and 21f are provided integrally in the end cell heater assembly 20 to improve the distribution characteristics of the reaction gases and to redirect the inflowing droplets, so that the bypass flow paths 21e and 21f act as a dummy cell in a publicly known fuel cell stack, and as a result, the distribution characteristics of the reaction gases in the reaction cell 9 can be improved, inflow of droplets can be prevented, and problems in the prior art that occur when the existing dummy cell is applied can be solved.

[0121] That is, in the publicly known fuel cell stack, the current collector plate of the end plate is connected to the metallic bipolar plate of the dummy cell, and as a result, voltage loss and electrical energy loss may occur when the electrical energy generated by the reaction cell is output through the metallic bipolar plate of the dummy cell, the current collector plate, and the terminal. However, in the fuel cell stack 10 to which the end cell heater assembly 20 according to the present disclosure is applied, the electrical energy of the reaction cell 9 is output through the terminal plate 23 directly connected to the reaction cell 9 and the terminal 23a penetrating the end plates 11 and 12. As a result, it is possible to solve the problems of voltage loss and electrical energy loss that occur.when the existing dummy cell with the dedicated metallic bipolar plate and the gas diffusion layer is applied.

[0122] Moreover, when the end cell heater assembly is assembled in advance, the cells are stacked, and then stack assembly is performed, the end cell heater assembly 20 can be easily assembled by stacking and inserting / inserting the end cell heater assembly 20 between the reaction cell 9 and the end plates 11 and 12, and as a result, it is possible to omit the existing complicated process for stacking the dummy cells, and thus reduce production time, improve mass production and productivity, and prevent erroneous assembly during a stacking process.

[0123] A process for assembling the fuel cell stack according to the embodiment of the present disclosure will be described, and in a state where the end cell heater assembly 20 is assembled in advance, the end cell heater assembly 20 and the end plates 11 and 12 are temporarily assembled by inserting the terminal 23a into the through holes (reference numerals 11b and 12a in Fig. 5) the end plates 11 and 12 are inserted, or the end cell heater assembly 20 and the end plates 11 and 12 are assembled / mounted integrally using a separate fastening mechanism.

[0124] The plurality of reaction cells 9 are stacked on the terminal plate 23 of the end cell heater assembly 20, and the opposite end cell heater assembly 20 and the end plates 11 and 12, which are assembled in the same manner, are stacked on the reaction cells 9.

[0125] When the stacking process is completed as described above, the end plates 11 and 12 on both sides of the stack 10 are connected and fixed to each other by means of a publicly known stack fixing mechanism (not shown) in a state where the stack 10 is compressed, thereby forming the configuration / arrangement of the stack integrally.

[0126] In this assembly process, since the complicated process of stacking the dummy cells is omitted compared with the existing process, it is possible to prevent faulty assembly and reduce the production time to a great extent.

[0127] The disclosure has been described with reference to exemplary embodiments thereof. However, one skilled in the art will recognize that changes may be made in these embodiments without departing from the principles and teachings of the present invention, the scope of which is defined in the appended claims.

Claims

[1] End cell heating arrangement (20), comprising: a housing (21) having a first surface connected to an end plate (11, 12) of a fuel cell stack (10); a planar heating element (22) mounted in a receiving recess (21g) formed in a second surface of the housing (21); a terminal plate (23) stacked and inserted between the planar heating element (22) and an end cell of the fuel cell stack (10), joined and electrically connected to the end cell, and transferring heat generated by the planar heating element (22) to the end cell; and a terminal (23a) formed integrally with the terminal plate (23) for discharging electrical energy generated by the fuel cell stack (10) and transmitted through the terminal plate (23) to the outside, wherein the planar heating element (22) performs a heating operation by being supplied with electrical energy generated by the fuel cell stack (10), wherein the electrical energy generated by the fuel cell stack (10) is supplied to the planar heating element (22) via a connector (25) installed in the housing, and wherein the connection (23a) penetrates the planar heating element (22), the housing (21) and the end plate (11, 12) and is formed integrally with the connection plate (23). [2] The end cell heater assembly according to claim 1, wherein bypass flow paths communicating with an air inlet manifold or a hydrogen inlet manifold (13) of the fuel cell stack (10) are formed in the casing (21), and the bypass flow paths are respectively communicating with the air outlet manifold or the hydrogen outlet manifold (14) of the fuel cell stack (10) and are provided to discharge air or hydrogen flowing through the interior of the bypass flow paths to the respective outlet manifolds. [3] End cell heating arrangement according to claim 1, wherein, in the housing (21), an air inlet manifold opening (21b) communicating with an air inlet manifold of the fuel cell stack (10) or a hydrogen inlet manifold opening (21a) communicating with a hydrogen inlet manifold (13) of the fuel cell stack (10) is provided, an air outlet manifold opening (21d) communicating with an air outlet manifold of the fuel cell stack (10) or a hydrogen outlet manifold opening (21c) communicating with a hydrogen outlet manifold (14) of the fuel cell stack (10) is provided, and an air bypass flow path connecting the air inlet manifold opening (21b) and the air outlet manifold opening (21d), or a hydrogen bypass flow path connecting the hydrogen inlet manifold opening (21c) and the hydrogen outlet manifold opening (21c) is provided. [4] End cell heater assembly according to claim 1, wherein the housing (21) is made of an electrically non-conductive material. [5] The end cell heating assembly of claim 1, further comprising: a thermal insulation layer (24) stacked and inserted between the planar heating element (22) and an inner surface of the receiving recess (21g) of the housing (21). [6] The end cell heating assembly of claim 1, wherein the planar heating element (22) comprises: a heating element (22a) that performs a heating operation by being supplied with electrical energy from the fuel cell stack (10); and a cover (22b) covering the heating element (22a) to electrically insulate the heating element (22a) from the outside. [7] The end cell heating assembly of claim 1, wherein a temperature sensor is attached to the planar heating element (22) and a controller receives a signal from the temperature sensor and controls operation of the planar heating element (22). [8] The end cell heating assembly of claim 1, wherein the planar heating element (22) is a heating element (22a) using a PTC (Positive Temperature Coefficient) element. [9] Fuel cell stack (10), comprising: a plurality of fuel cells provided by stacking them, and generating electric power through an electrochemical reaction by supplying it with reaction gases; End plates stacked at both positions of the fuel cell stack (10) outside the stacked fuel cells; and an end cell heating assembly stacked and interposed between end cells arranged at both ends among the stacked fuel cells and end plates at both ends of the fuel cell stack (10) to supply heat to the respective end cells to increase a temperature of the end cells, and having a bypass flow path such that at least one of air and hydrogen supplied to the fuel cell stack (10) as reaction gases is distributed to and flows through the bypass flow path, the end cell heating assembly comprising: a housing (21) having a first surface connected to an end plate of a fuel cell stack (10); a planar heating element (22) mounted in a receiving recess (21g) formed in a second surface of the housing (21); a terminal plate (23) stacked and inserted between the planar heating element (22) and an end cell of the fuel cell stack (10), joined and electrically connected to the end cell, and transferring heat generated by the planar heating element (22) to the end cell; and a terminal (23a) formed integrally with the terminal plate (23) for discharging electrical energy generated by the fuel cell stack (10) and transmitted through the terminal plate (23) to the outside, wherein the terminal (23a) penetrates the planar heating element (22), the housing (21) and the end plate of the terminal plate (23), wherein the planar heating element (22) performs a heating operation by being supplied with electrical energy generated by the fuel cell stack (10), and wherein the electrical energy generated by the fuel cell stack (10) is supplied to the planar heating element (22) via a connector (25) installed in the housing (21). [10] The fuel cell stack according to claim 9, wherein bypass flow paths communicating with an air inlet manifold or a hydrogen inlet manifold (13) of the fuel cell stack (10) so that air or hydrogen is distributed from the air inlet manifold or the hydrogen inlet manifold (13) to and flows through the bypass flow paths are formed in the casing (21), and the respective bypass flow paths communicate with the air outlet manifold or the hydrogen outlet manifold (14) of the fuel cell stack (10) and are provided to discharge air or hydrogen flowing through the interior of the bypass flow paths to the respective outlet manifolds. [11] Fuel cell stack according to claim 9, wherein, in the housing (21), an air inlet manifold opening (21b) communicating with an air inlet manifold of the fuel cell stack (10) or a hydrogen inlet manifold opening (21a) communicating with a hydrogen inlet manifold (13) of the fuel cell stack (10) is provided, an air outlet manifold opening (21d) communicating with an air outlet manifold of the fuel cell stack (10), or a hydrogen outlet manifold opening (21c) communicating with a hydrogen outlet manifold of the fuel cell stack (10) is provided, and an air bypass flow path connecting the air inlet manifold opening (21b) and the air outlet manifold opening (21d), or a hydrogen bypass flow path connecting the hydrogen inlet manifold opening (21a) and the hydrogen outlet manifold opening (21c) is provided. [12] Fuel cell stack according to claim 9, wherein the housing (21) is made of an electrically non-conductive material. [13] Fuel cell stack according to claim 9, further comprising: a thermal insulation layer (24) stacked and inserted between the planar heating element (22) and an inner surface of the receiving recess (21g) of the housing (21). [14] A fuel cell stack according to claim 9, wherein the planar heating element (22) comprises: a heating element (22a) that performs a heating operation by being supplied with electrical energy from the fuel cell stack (10); and a cover (22b) covering the heating element (22a) to electrically insulate the heating element (22a) from the outside. [15] The fuel cell stack of claim 9, wherein a temperature sensor is attached to the planar heating element (22) and a controller receives a signal from the temperature sensor and controls operation of the planar heating element (22). [16] The fuel cell stack according to claim 9, wherein the planar heating element (22) is a heating element (22a) using a PTC (Positive Temperature Coefficient) element.

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