Fuel cell stack housing

Abstract

Fuel cell stack housings, comprising: a lower housing (10) arranged below a fuel cell stack and comprising a base plate section (11) with a water outlet (H) therein; a sealing cap (20) that closes the water outlet (H) from an outside of the lower housing (10); a spring element (30) that resiliently biases the sealing cap (20) towards the base plate section (11) of the lower housing (10); and a drying element (40) arranged between the fuel cell stack and the base plate section (11) of the lower casing (10).

Description

[0001] The invention relates to a fuel cell stack housing, and in particular a fuel cell stack housing with a sealing structure to prevent a fuel cell stack arranged in the fuel cell stack housing from coming into contact with outside air, and a watertight structure to maintain optimal operating performance of the fuel cell stack.

[0002] A fuel cell system is a power generation system that converts the chemical energy of fuel directly into electricity. A fuel cell system comprises a fuel cell stack that generates electricity, a fuel supply unit that provides fuel (i.e., hydrogen) to the fuel cell stack, an air supply unit that provides air (i.e., oxygen) to the fuel cell stack, which acts as an oxidizer triggering an electrochemical reaction, and a heat and water treatment unit that removes heat from the fuel cell stack and controls its operating temperature. The fuel cell stack generates electricity through an electrochemical reaction between hydrogen (fuel) and oxygen (air) and also produces byproducts (heat and water) that must be removed from the fuel cell stack.

[0003] A fuel cell stack suitable for use in a fuel cell vehicle comprises many individual cells arranged in a row. Each cell has a membrane electrode assembly (MEA) located in its center. The MEA has an electrolyte membrane that allows protons to pass through it. Catalyst layers, serving as a cathode and an anode where hydrogen and oxygen react, are located on the respective surfaces of the electrolyte membrane. Gas diffusion layers (GDLs) are located on the surfaces of the catalyst layers. Separators with flow fields (channels) through which fuel and air are directed to the anode and cathode are located on the surfaces of the GDLs. End plates are located at each end of an individual cell to securely connect all the elements.

[0004] In the fuel cell stack, hydrogen and oxygen are ionized through chemical reactions via catalyst layers. An oxidation reaction then occurs to generate protons (hydrogen ions) and electrons at a fuel electrode, to which hydrogen is supplied. A reduction reaction, involving hydrogen and oxygen ions, occurs to produce water at an air electrode, to which air is supplied. A typical electrode catalyst used in a fuel cell consists of a catalyst support made of a carbon material and a catalyst such as rubble, cobalt, copper, or similar materials. Hydrogen is supplied to an anode (also called the oxidation electrode), and oxygen (air) is supplied to a cathode (also called the reduction electrode).Hydrogen supplied to the anode is converted into protons H by catalysts on electrode layers arranged on respective surfaces of the electrolyte membrane. + and electrons e - split. Of the protons and electrons, only protons can selectively pass through an electrolyte membrane, called a proton exchange membrane, and reach a cathode, while electrons move through the GDLs (conducting layers) and separators to reach the cathode.

[0005] Hydrogen ions and electrons, which reach the cathode via the electrolyte membrane and separator, combine with oxygen contained in the air supplied to the cathode via an air feed unit, thereby producing water. At this point, the movement of hydrogen ions generates an electric current that flows along an external wire. In addition to water, heat is also produced as a byproduct.

[0006] Typically, an enclosure houses and seals a high-voltage fuel cell stack to provide physical protection. In this case, condensation resulting from a temperature difference between the inside and outside of the enclosure can generate water within the enclosure. Furthermore, water generated by the fuel cell stack itself can accumulate within the enclosure. Therefore, an effective means of draining both water generated by the fuel cell stack and water produced by condensation is required.

[0007] Conventionally, a water outlet in the lower part of a housing serves as the means of water drainage. This conventional drainage method has the drawback of allowing foreign matter to enter the housing, frequently leading to malfunctions of the fuel cell stack housed within. Furthermore, the efficiency of water drainage in conventional housings depends on the position, size, and number of water outlets. In other words, increasing the number of water outlets improves water drainage but reduces the sealing performance.

[0008] DE 10 2014 005 614 A1 describes a fuel cell stack housing comprising a lower housing arranged under a fuel cell stack and having a base plate section with a water outlet therein, a sealing cap that closes the water outlet from an outside of the lower housing, and a spring element that springs the sealing cap in the direction of the base plate section of the lower housing.

[0009] Another fuel cell stack housing is known from KR 10 2012 0 116 747 A.

[0010] The invention provides a fuel cell stack housing with a sealing structure that prevents contact with outside air to prevent the ingress of foreign bodies and contaminants into a fuel cell stack, and a watertight structure to maintain optimal operating performance of a fuel cell stack arranged in the fuel cell stack housing.

[0011] According to the invention, this is achieved by a fuel cell stack housing according to the features of any one of claims 1, 6, 10 and 11. Advantageous further developments are described in the dependent claims.

[0012] According to one embodiment of the invention, a fuel cell stack housing has a lower housing arranged below a fuel cell stack and comprising a base plate section with a water outlet therein, a sealing cap that closes the water outlet from an outside of the lower housing, and a spring element that resiliently pulls the sealing cap towards the base plate section of the lower housing.

[0013] In the fuel cell stack housing, a circumferential section of a lower section of the lower housing can incline towards a lower end thereof, so that the lower housing has an inclined section that is inclined downwards from the circumferential section of the lower housing, and an end of the base plate section is connected to an end of the inclined section.

[0014] The inclined section and the base plate section can be connected in such a way as to form a storage space within it to store water that is collected in the fuel cell stack housing.

[0015] The spring element can extend in such a way that it pushes the sealing cap downwards when the weight of the water stored in the storage space reaches or exceeds a predetermined value, thus opening the sealing cap so that the stored water is discharged from the fuel cell stack housing.

[0016] The fuel cell stack housing also features a drying element located between the fuel cell stack and the base plate section of the lower housing.

[0017] According to an alternative embodiment of the invention, the fuel cell stack housing further comprises a filter element arranged between the fuel cell stack and the base plate section of the lower housing.

[0018] The fuel cell stack housing may also include a drying element located between the filter element and the base plate section of the lower housing.

[0019] The filter element can be a porous layer, non-woven fabric (e.g., nonwoven fabric) or paper.

[0020] The water outlet can have a cylindrical shape and extend from a lower surface of the base plate section of the lower housing.

[0021] According to a further alternative embodiment of the invention, the sealing cap has a flat section which has a larger dimension than the water outlet and a projection which extends from the flat section to an inside of the water outlet, such that a side surface of the projection faces an inside surface of the water outlet.

[0022] According to another alternative embodiment of the invention, a fuel cell stack housing comprises a lower housing arranged below a fuel cell stack and having a base plate section provided with a water outlet formed therein, a sealing cap that closes the water outlet from an outside of the lower housing, a spring element that springily (or elastically) biases (e.g. pulls) the sealing cap towards the base plate section of the lower housing, a filter element arranged between the fuel cell stack and the base plate section of the lower housing, and a drying element arranged between the filter element and the base plate section of the lower housing.The spring element extends in such a way that it pushes the sealing cap downwards through water, so that the water is drained from the fuel cell stack housing when a weight of water stored in the lower housing reaches or exceeds a reference value.

[0023] The fuel cell stack housing according to the invention can drain water without using electricity or an external driving force, resulting in a simplified fuel cell system. Furthermore, since water drainage can be performed even when a vehicle is parked, water-related problems can be drastically reduced.

[0024] Furthermore, since a predetermined degree of dryness is maintained in various operating states of a fuel cell stack due to the presence of a drying element located in a fuel cell stack housing, and since a sealing condition of a fuel cell stack housing is maintained by a sealing cap, the fuel cell stack housing, in a normal state in which no water is present in the fuel cell stack housing, can protect a fuel cell stack from external contaminants or foreign bodies.

[0025] The invention is explained in more detail with reference to the drawing. The drawing shows: Fig. 1 a perspective sectional view of a lower housing of a fuel cell stack housing according to an embodiment of the invention; Fig. 2 an enlarged view of a water outlet formed on the lower housing of the fuel cell stack housing according to the embodiment of the invention; Fig. 3 a sectional view of the fuel cell stack housing according to the embodiment of the invention; and Fig. 4 a sectional view of the fuel cell stack housing according to the embodiment of the invention in a state in which water is drained from it.

[0026] The following describes, with reference to the drawing, a fuel cell stack housing according to one embodiment of the invention.

[0027] With regard to the Fig. 1, Fig. 2 to Fig. 3 A fuel cell stack housing according to an embodiment of the invention comprises a lower housing 10, a sealing cap 20 and a spring element 30.

[0028] The lower housing 10 is a lower part of the fuel cell stack housing. The lower housing 10 is connected to a side housing and an upper housing to form a sealed space for housing a fuel cell stack. A fuel cell stack is arranged within the lower housing 10.

[0029] According to one embodiment of the invention, a lower section of the lower housing 10 has a flat section 11 (hereinafter referred to as the base plate section) arranged in the center and an inclined section 12 arranged on the circumferential section of the lower housing 10. The base plate section 11 is provided with a water outlet H. Water generated in the fuel cell stack housing is stored on an upper surface of the base plate section 11, i.e., in a space formed between the fuel cell stack and the base plate section 11, and is then discharged from the fuel cell stack housing via the water outlet H when a certain condition is met. The water discharge process is described later.

[0030] The circumferential section of the lower part of the lower housing 10 is chamfered at one end. That is, the lower housing 10 has the chamfered section 12, which is inclined downwards from the circumferential section of the lower housing 10. One end of the chamfered section 12 is connected to one end of the base plate section 11. The chamfered section 12 and the base plate section 11 form a storage space S to store the water generated in the fuel cell stack housing. As a result of the chamfered section 12, the water can easily flow downwards along the inclined inner surface of the fuel cell stack housing to the water outlet H and thus be easily discharged through the water outlet H. That is, the chamfered section 12 of the lower housing 10 facilitates the discharge of water.

[0031] The sealing cap 20 is arranged to close the water outlet H from the outside of the lower housing 10. The sealing cap 20 can be made of elastic rubber or silicone to ensure a secure seal on the inside of the fuel cell stack housing by closing the water outlet H when no water is present in the fuel cell stack housing. Furthermore, to achieve a secure seal, the sealing cap 20 has a flat section 21 that is larger than the water outlet H and a projection 22 that extends from an upper surface of the flat section 21 and has a side surface facing an inner surface of the water outlet H when the projection 22 is inserted into the water outlet H.

[0032] To increase the sealing effect of the sealing cap 20, the water outlet H can have a cylindrical shape extending downwards from the bottom surface of the base plate section 11, and the sealing cap 20 can be arranged on an end section of a cylinder that serves as the water outlet H.

[0033] A first end of the spring element 30 is coupled to a lower section of the base plate section 11, and a second end (remaining end) of the spring element 30 is coupled to the sealing cap 20 to hold the sealing cap 20 resiliently. According to the invention, the fuel cell stack housing must maintain a sealed state except during periods when water is being drained from the fuel cell stack housing. Therefore, the spring element 30 resiliently pulls the sealing cap 20 towards the base plate section 11 of the lower housing 10 of the fuel cell stack housing.

[0034] The spring element 30 can be a coil spring. If the water outlet H has a cylindrical shape extending downwards from the bottom surface of the base plate section 11 of the lower housing 10, the coil spring is arranged such that it surrounds the cylindrical water outlet H.

[0035] With reference to Fig. 4. When water is generated in the fuel cell stack housing, it can collect by gravity on the upper surface of the base plate section 11 of the lower housing 10. When the weight of the collected water reaches or exceeds a predetermined value, determined by the spring constant of a helical spring serving as the spring element 30, the spring element 30 extends downwards to press down the sealing cap 20, thus opening the water outlet H. The collected water H2 can then be discharged from the fuel cell stack housing. After the water has been completely discharged, the sealing cap 20 is reset by the spring-like restoring force of the spring element 30 to close the water outlet H.

[0036] According to the invention, the fuel cell stack housing can further comprise a drying element 40 and a filter element 50. As in the Fig. 1, Fig. 2 to Fig. As shown in Figure 3, the fuel cell stack housing has both the drying element 40 and the filter element 50. However, alternatively, a fuel cell stack housing according to the invention can have only one of the drying element 40 and the filter element 50.

[0037] The drying element 40 and / or the filter element 50 can be arranged between a fuel cell stack and the base plate section 11 of the lower housing 10. If the fuel cell stack housing includes both the drying element 40 and the filter element 50, the filter element 50 can be arranged between the fuel cell stack and the drying element 40.

[0038] The drying element 40 absorbs water or moisture generated in the fuel cell stack housing, thereby drying the interior of the fuel cell stack housing. The drying element 40 can have a composition comprising bentonite, calcium chloride (CaCl₂), or sodium chloride (NaOH), all of which are deliquescent substances. The fuel cell stack housing according to the invention can include a desiccant support plate 60, which is a porous plate and supports the drying element 40.

[0039] The drying element 40 absorbs moisture or water generated in the fuel cell stack housing. However, if the amount of moisture or water generated in the fuel cell stack housing exceeds the water absorption capacity of the drying element 40, or if the drying element 40 excessively absorbs the amount of water exceeding its absorption capacity, the absorbed water can form a pool on the upper surface of the base plate section 11 of the lower housing 10 and is thus stored in the fuel cell stack housing. When the amount of water stored on the base plate section 11 of the lower housing 10 reaches or exceeds a predetermined amount, the spring element 30 (spring) extends as described above, and the sealing cap 20 moves downward to open the water outlet H. As a result, the stored water can be discharged from the fuel cell stack housing.

[0040] The filter element 50 functions in such a way that it prevents the water contained in the drying element 40 below or stored on the base plate section 11 from moistening a fuel cell stack arranged on it.

[0041] The filter element 50 can be made from a porous layer, non-woven fabric (e.g. nonwoven fabric) or paper, all of which are made from polytetrafluoroethylene (PTFE).

[0042] The PTFE-based porous layer has micro-sized pores to allow air and / or vapor to pass through, but not liquid water or dust. When a fuel cell stack is operating, i.e., when the humidity in the fuel cell stack housing increases, moisture H1 in a gaseous phase passes through the PTFE-based porous layer and is then absorbed by the drying element 40.

[0043] The nonwoven fabric (e.g., nonwoven cloth) or paper has micro-sized pores similar to the PTFE-based porous layer. The nonwoven fabric (e.g., nonwoven cloth) or porous paper allows air or vapor to pass through, but does not allow dust to pass through. The nonwoven fabric (e.g., nonwoven cloth) or paper has the ability to absorb moisture or liquid phase water. The nonwoven fabric (e.g., nonwoven cloth) or porous paper has almost the same effect as the PTFE-based porous layer in that it allows air or vapor to pass through. In addition, if moisture or liquid phase water accumulates on the upper surface of the nonwoven fabric (e.g., nonwoven cloth) or porous paper, it allows the water itself to pass through in the direction of gravity. Moisture or liquid phase water passing through the filter element 50, which consists of nonwoven fabric (e.g., nonwoven cloth) or porous paper, is then filtered out.The material, which is made of nonwoven fabric) or porous paper, encounters the drying element 40 and is then collected in the water outlet H.

[0044] If moisture or vapor phase water increases in the fuel cell stack housing, whether the fuel cell stack is operating or not, the humidity in the fuel cell stack housing is managed by the filter element 50, which is made of a PTFE-based porous layer. Conversely, if moisture or liquid phase water increases in the fuel cell stack housing, the humidity in the fuel cell stack housing is managed by absorbing the moisture or water through the filter element 50, which is made of non-woven fabric (e.g., non-woven fabric) or paper, and ultimately collecting it in the water outlet H.

[0045] As described above, the fuel cell stack housing according to the invention can drain water without the use of electricity or drive power, resulting in a simplified system. Furthermore, since water drainage occurs even when a vehicle is parked, water-related problems are drastically reduced.

[0046] Specifically, according to the invention, the fuel cell stack housing can maintain a predetermined degree of dryness in various operating states of a fuel cell stack by using the drying element. Furthermore, since the sealing condition of the fuel cell stack housing is maintained by the sealing cap in a normal state in which no water is present in the fuel cell stack housing, it is possible to effectively protect a fuel cell stack from impurities or foreign bodies.

Images