Patent Description:
A fuel cell is a power generation cell that combines hydrogen and oxygen to generate electricity. The fuel cell has advantages in that it is possible to continuously generate electricity as long as hydrogen and oxygen are supplied, unlike a general chemical cell, such as a dry cell or a storage cell, and in that there is no heat loss, whereby efficiency of the fuel cell is about twice as high as efficiency of an internal combustion engine.

In addition, the fuel cell directly converts chemical energy generated by combination of hydrogen and oxygen into electrical energy, whereby the amount of contaminants that are discharged is small. Consequently, the fuel cell has advantages in that the fuel cell is environmentally friendly and in that a concern about depletion of resources due to an increase in energy consumption can be reduced.

Based on the kind of an electrolyte that is used, such a fuel cell may generally be classified into a polymer electrolyte membrane fuel cell (PEMFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), and an alkaline fuel cell (AFC), and so on.

These fuel cells are operated fundamentally by the same principle, but are different from each other in terms of the kind of fuel that is used, operating temperature, catalyst, and electrolyte. Among these fuel cells, the polymer electrolyte membrane fuel cell (PEMFC) is known as being the most favorable to a transportation system as well as small-scale stationary power generation equipment, since the polymer electrolyte membrane fuel cell is operated at a lower temperature than the other fuel cells and the output density of the polymer electrolyte membrane fuel cell is high, whereby it is possible to miniaturize the polymer electrolyte membrane fuel cell.

One of the most important factors in improving the performance of the polymer electrolyte membrane fuel cell (PEMFC) is to supply a predetermined amount or more of moisture to a polymer electrolyte membrane or a proton exchange membrane (PEM) of a membrane electrode assembly (MEA) in order to retain moisture content. The reason for this is that, if the polymer electrolyte membrane or the proton exchange membrane is dried, power generation efficiency is abruptly reduced.

<NUM>) A bubbler humidification method of filling a pressure-resistant container with water and allowing a target gas to pass through a diffuser in order to supply moisture, <NUM>) a direct injection method of calculating the amount of moisture to be supplied that is necessary for fuel cell reaction and directly supplying moisture to a gas stream pipe through a solenoid valve, and <NUM>) a membrane humidification method of supplying moisture to a gas fluid bed using a polymer separation membrane are used as methods of humidifying the polymer electrolyte membrane or the proton exchange membrane.

Among these methods, the membrane humidification method, which provides water vapor to gas (i.e. air or fuel gas) that is supplied to the polymer electrolyte membrane or the proton exchange membrane using a membrane configured to selectively transmit only water vapor included in off-gas in order to humidify the polymer electrolyte membrane or the proton exchange membrane, is advantageous in that it is possible to reduce the weight and size of a humidifier.

When a module is formed, a hollow fiber membrane having large transmission area per unit volume is suitable for a permselective membrane used in the membrane humidification method. That is, when a humidifier is manufactured using a hollow fiber membrane, high integration of the hollow fiber membrane having large contact surface area is possible, whereby it is possible to sufficiently humidify the polymer electrolyte membrane or the proton exchange membrane even at a small capacity, it is possible to use a low-priced material, and it is possible to collect moisture and heat included in off-gas discharged from the fuel cell at a high temperature and to reuse the collected moisture and heat through the humidifier. Document <CIT> discloses a membrane humidifier, comprising: a housing in which a hollow fiber membrane bundle is mounted, the hollow fiber membrane bundle being formed by integrating a plurality of hollow fiber membranes; a potting portion fixing an end portion of the hollow fiber membrane bundle to the housing and coupled to an end portion of the housing so as to hermetically seal the housing; and a sealing member disposed between the housing and the potting portion and hermetically sealing the housing.

As illustrated in <FIG>, a conventional membrane humidification type humidifier <NUM> includes a humidifying module <NUM> in which moisture exchange is performed between gas supplied from the outside and off-gas discharged from a fuel cell stack (not shown), and caps <NUM> coupled respectively to opposite ends of the humidifying module <NUM>.

One of the caps <NUM> transmits gas supplied from the outside to the humidifying module <NUM>, and the other cap transmits gas humidified by the humidifying module <NUM> to the fuel cell stack.

The humidifying module <NUM> includes a mid-case <NUM> having an off-gas inlet 1110a and an off-gas outlet 1110b and a plurality of hollow fiber membranes <NUM> disposed in the mid-case <NUM>. Opposite ends of a bundle of hollow fiber membranes <NUM> are potted in fixing layers <NUM>. In general, each of the fixing layers <NUM> is formed by hardening a liquid polymer, such as liquid polyurethane resin, using a casting method (e.g. dip casting, which is also called dip potting, or centrifugal casting, which is also called centrifugal potting).

Gas supplied from the outside flows along hollow parts of the hollow fiber membranes <NUM>. Off-gas introduced into the mid-case <NUM> through the off-gas inlet 1110a comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, and is discharged from the mid-case <NUM> through the off-gas outlet 1110b. When the off-gas comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, moisture contained in the off-gas is transmitted through the hollow fiber membranes <NUM> to humidify gas flowing along the hollow parts of the hollow fiber membranes <NUM>.

Inner spaces of the caps <NUM> must fluidly communicate with only the hollow parts of the hollow fiber membranes <NUM> in a state of being completely isolated from an inner space of the mid-case <NUM>. If not, gas leakage due to pressure difference occurs, whereby power generation efficiency of a fuel cell is reduced.

In general, as illustrated in <FIG>, the fixing layers <NUM> and resin layers <NUM> provided between the fixing layers <NUM> and the mid-case <NUM> isolate the inner spaces of the caps <NUM> from the inner space of the mid-case <NUM>. Similarly to the fixing layers <NUM>, each of the resin layers <NUM> is generally formed by hardening a liquid polymer, such as liquid polyurethane resin, using a casting method (dip casting or centrifugal casting).

However, (i) the resin layer <NUM> is alternately expanded and contracted as a result of repeated operation and stop of the fuel cell, whereby the resin layer <NUM> is separated from the mid-case <NUM> due to a difference in coefficient of thermal expansion between the mid-case <NUM> and the resin layer <NUM>, and therefore a gap is generated therebetween, or (ii) there is a high probability of a gap being generated between the resin layer <NUM> and the mid-case <NUM> due to vibration and/or impact. The gap between the resin layer <NUM> and the mid-case <NUM> causes gas leakage, thereby reducing power generation efficiency of the fuel cell.

In order to prevent gas leakage due to generation of the gap between the resin layer <NUM> and the mid-case <NUM>, <CIT> discloses a method of applying a sealant (liquid sealing member) to a step formed on the side surface of the resin layer <NUM> and a groove formed in the inner surface of the mid-case <NUM>, inserting a packing member (solid sealing member) into the groove, and hardening the sealant.

However, the above method has problems of low productivity and high manufacturing cost in that (i) the sealant must be applied so as to accurately match with the groove, whereby workability is low, (ii) a considerably long time of <NUM> hours or more is required to harden the sealant, and (iii) a separate space for storing the humidifying module <NUM> is required until the sealant is hardened.

Therefore, the present disclosure relates to a humidifier for a fuel cell capable of preventing problems caused by limitations and shortcomings of the related art described above and a method of manufacturing the same.

It is an object of the present disclosure to provide a humidifier for a fuel cell capable of certainly preventing gas leakage due to repeated operation and stop of a fuel cell and being manufactured with relatively low manufacturing cost and high productivity.

It is another object of the present disclosure to provide a method of manufacturing a humidifier for a fuel cell capable of certainly preventing gas leakage due to repeated operation and stop of a fuel cell with relatively low manufacturing cost and high productivity.

In addition to the above objects, other features and advantages of the present disclosure will be described hereinafter, or will be clearly understood by those skilled in the art to which the present disclosure pertains from the following description thereof.

In accordance with an aspect of the present disclosure, there is provided a humidifier for a fuel cell, the humidifier including a humidifying module configured to humidify gas supplied from outside using moisture in off-gas discharged from a fuel cell stack and caps coupled respectively to opposite ends of the humidifying module, wherein the humidifying module includes a mid-case open at opposite ends thereof, a plurality of hollow fiber membranes disposed in the mid-case, a fixing layer in which ends of the hollow fiber membranes are potted, and a composite gasket having a groove into which the end of the mid-case is inserted, the composite gasket includes an inner body based on the groove, the inner body being located inside the mid-case, an outer body based on the groove, the outer body being located outside the mid-case, and a connecting body located between the inner body and the outer body, the connecting body being formed of a first material, and at least a portion of the inner body is adhered to the fixing layer and is formed of a second material different from the first material.

The first material may be soft rubber, and the second material may be metal, rigid plastic, hard rubber, or a different kind of soft rubber from the first material.

The first material may include soft silicone rubber or soft urethane rubber, and the second material may include polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polycarbonate (PC), acrylic resin, hard silicone, or hard urethane.

When the first material includes soft silicone rubber, the second material may include soft urethane rubber.

The inner body may include a first part directly connected to the connecting body, the first part being formed of the first material, and a second part adhered to the first part and to the fixing layer, the second part being formed of the second material.

The interface between the first and second parts may have a step.

The first part of the inner body may constitute a packing part formed of the first material together with the outer body and the connecting body, and the second part of the inner body may constitute a bracket part formed of the second material.

The packing part and the bracket part may be integrally formed through injection molding.

The composite gasket may further include a primer layer formed on at least a portion of the surface of the inner body, the primer layer including a rubber adhesive component, an acrylic adhesive component, a polyurethane adhesive component, an epoxy adhesive component, a silicone adhesive component, a polyamide-based adhesive component, a polyimide-based adhesive component, or a mixture of two or more thereof.

The fixing layer may include a first fixing layer in which the ends of the hollow fiber membranes are potted, and a second fixing layer adhered to the inner body of the composite gasket while surrounding the first fixing layer.

The first fixing layer and the second fixing layer may be formed of the same material.

Both the first fixing layer and the second fixing layer may include polyurethane (PU) resin.

The humidifying module may further include an inner case disposed in the mid-case, the inner case being open at opposite ends thereof, the hollow fiber membranes may be disposed in the inner case, and the end of the inner case may be potted in the first fixing layer.

The hollow fiber membranes may include a first group of hollow fiber membranes and a second group of hollow fiber membranes, the humidifying module may further include a first inner case in which the first group of hollow fiber membranes is disposed, and a second inner case in which the second group of hollow fiber membranes is disposed, the fixing layer may include a first fixing layer in which ends of the first group of hollow fiber membranes are potted, a second fixing layer in which ends of the second group of hollow fiber membranes are potted, and a third fixing layer adhered to the inner body of the composite gasket while surrounding the first and second fixing layers, an end of the first inner case may be potted in the first fixing layer, and an end of the second inner case may be potted in the second fixing layer.

In accordance with another aspect of the present disclosure, there is provided a method of manufacturing a humidifier for a fuel cell, the method including preparing a hollow fiber membrane cartridge having a first fixing layer in which ends of a plurality of hollow fiber membranes are potted, inserting the hollow fiber membrane cartridge into a mid-case open at opposite ends thereof, preparing a composite gasket having a groove corresponding to the end of the mid-case, mounting the composite gasket on the end of the mid-case such that the end of the mid-case is inserted into the groove, forming a second fixing layer configured to fill a gap between the mid-case and an end of the hollow fiber membrane cartridge and a gap between the composite gasket and the end of the hollow fiber membrane cartridge, simultaneously cutting the first fixing layer, the second fixing layer, and the hollow fiber membranes to open the ends of the hollow fiber membranes, and fastening a cap to the mid-case such that the composite gasket is compressed by the cap, wherein the composite gasket includes an inner body based on the groove, the inner body being located inside the mid-case based on the groove, an outer body based on the groove, the outer body being located outside the mid-case, and a connecting body located between the inner body and the outer body, the connecting body being formed of a first material, and at least a portion of the inner body is formed of a second material different from the first material.

The preparing the composite gasket may include preparing the bracket part, inserting the bracket part into a mold, injecting a melt of the first material into the mold in which the bracket part is located, and cooling the melt of the first material to obtain the packing part adhered to the bracket part.

Alternatively, the preparing the composite gasket may include performing a co-injection molding to simultaneously form the bracket part and the packing part.

The preparing the hollow fiber membrane cartridge may include inserting at least a portion of each of the hollow fiber membranes into an inner case and performing a dip casting process or a centrifugal casting process to form the first fixing layer.

An end of the inner case may also be potted in the first fixing layer together with the ends of the hollow fiber membranes when the dip casting process or the centrifugal casting process is performed.

The general description of the present disclosure given above is provided merely to illustrate or describe the present disclosure, and does not limit the scope of rights of the present disclosure.

According to the present disclosure, it is possible to effectively prevent both external leakage and internal leakage only through mechanical assembly of a composite gasket without conventional sealant application and hardening processes. According to the present disclosure, therefore, workability is improved and manufacturing time is reduced, whereby it is possible to remarkably improve productivity thereof, since the sealant application process and the sealant hardening process, which are required in the conventional art, are omitted.

In addition, a separate space for storing a half-finished product for the sealant hardening process is not required, whereby it is possible to reduce production cost of a humidifier.

The accompanying drawings, which are included to assist in understanding of the present disclosure and are incorporated in and constitute a part of the present specification, illustrate embodiments of the present disclosure and serve to explain the principle of the present disclosure together with the detailed description of the present disclosure.

However, the following embodiments are illustratively provided merely for clear understanding of the present disclosure and do not limit the scope of the present disclosure.

<FIG>, <FIG>, <FIG>, and <FIG> are sectional views showing an end of a humidifier or a half-finished product, and the other end thereof has a substantially identical (or symmetrical) section.

As illustrated in <FIG>, a humidifier <NUM> for a fuel cell according to the present disclosure includes a humidifying module <NUM> configured to humidify gas supplied from the outside using moisture in off-gas discharged from a fuel cell stack. Opposite ends of the humidifying module <NUM> are coupled to caps <NUM>, respectively.

One of the caps <NUM> receives gas from the outside through a port <NUM> and transmits the gas to the humidifying module <NUM>, and the other cap transmits gas humidified by the humidifying module <NUM> to the fuel cell stack through a port <NUM>. Each of the caps <NUM> may be formed of rigid plastic (e.g. polycarbonate, polyamide (PA), or polyphthalamide (PPA)) or metal, and may have a simple closed curve-shaped (e.g. circular or polygonal) traverse section.

The humidifying module <NUM> according to the embodiment of the present disclosure, in which moisture exchange is performed between gas supplied from the outside and off-gas supplied from the fuel cell stack, includes a mid-case <NUM> open at opposite ends thereof, a plurality of hollow fiber membranes <NUM> disposed in the mid-case <NUM>, a fixing layer <NUM> in which ends of the hollow fiber membranes <NUM> are potted, and a composite gasket <NUM> having a groove into which the end of the mid-case <NUM> is inserted.

The mid-case <NUM> has ports <NUM> for off-gas introduction/discharge (only one is shown in <FIG>). The mid-case <NUM> may be formed of rigid plastic (e.g. polycarbonate, polyamide (PA), or polyphthalamide (PPA)) or metal, and may have a simple closed curve-shaped (e.g. circular or polygonal) traverse section. According to the embodiment of the present disclosure, the mid-case <NUM> may have the same traverse section as the cap <NUM>.

Each of the hollow fiber membranes <NUM> may include a polymer membrane formed of polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride (PVDF) resin, polyacrylonitrile (PAN) resin, polyimide resin, polyamide imide resin, polyester imide resin, or a mixture of two or more thereof.

Gas supplied from the outside through one cap <NUM> is humidified while flowing along hollow parts of the hollow fiber membranes <NUM>, and is transmitted to the fuel cell stack through the other cap <NUM>.

Off-gas introduced into the mid-case <NUM> comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, and is discharged from the mid-case <NUM>. When the off-gas comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, moisture contained in the off-gas is transmitted through the hollow fiber membranes <NUM> to humidify gas flowing along the hollow parts of the hollow fiber membranes <NUM>.

The fixing layer <NUM>, which may be formed of hard or soft polyurethane resin, must isolate an inner space of the cap <NUM> from an inner space of the mid-case <NUM> such that the cap <NUM> fluidly communicates with only the hollow fiber membranes <NUM>.

As previously described, however, (i) the fixing layer <NUM> is alternately expanded and contracted as a result of repeated operation and stop of a fuel cell, whereby the fixing layer <NUM> is separated from the mid-case <NUM> due to a difference in coefficient of thermal expansion between the mid-case <NUM> and the fixing layer <NUM>, and therefore a gap is generated therebetween, or (ii) there is a high probability of a gap being generated between the fixing layer <NUM> and the mid-case <NUM> due to vibration and/or impact. The gap between the fixing layer <NUM> and the mid-case <NUM> causes gas leakage, thereby reducing power generation efficiency of the fuel cell.

Gas leakage that may be caused by generation of the gap between the fixing layer <NUM> and the mid-case <NUM> includes (i) external leakage by which off-gas in the inner space of the mid-case <NUM> sequentially passes through the gap between the fixing layer <NUM> and the mid-case <NUM> and a gap between the cap <NUM> and the mid-case <NUM> and is then discharged out of the humidifier <NUM> and (ii) internal leakage by which off-gas in the inner space of the mid-case <NUM> sequentially passes through the gap between the fixing layer <NUM> and the mid-case <NUM> and a gap between the fixing layer <NUM> and the cap <NUM> and is then introduced into the inner space of the cap <NUM>.

In order to prevent gas leakage due to generation of the gap between the fixing layer <NUM> and the mid-case <NUM>, the humidifier <NUM> for a fuel cell according to the present disclosure further includes the composite gasket <NUM>.

As illustrated in <FIG>, the composite gasket <NUM> may have a simple closed curve shape corresponding to the traverse section of the mid-case <NUM>.

As illustrated in <FIG>, which is a sectional view taken along line A-A of <FIG>, the composite gasket <NUM> may have a groove G into which the end of the mid-case <NUM> is inserted, and may include a packing part <NUM> and a bracket part <NUM>, the packing part <NUM> and the bracket part <NUM> being formed of different materials.

<FIG> are sectional views of composite gaskets <NUM> according to various embodiments of the present disclosure.

Referring to <FIG>, the composite gasket <NUM> according to the present disclosure includes an inner body 2130a based on a groove G into which the end of the mid-case <NUM> is inserted, the inner body 2130a being located inside the mid-case <NUM>, an outer body 2130b based on the groove G, the outer body 2130b being located outside the mid-case <NUM>, and a connecting body 2130c located between the inner body 2130a and the outer body 2130b, the connecting body being formed of a first material.

According to the present disclosure, at least a portion of the inner body 2130a is formed of a second material, which is different from the first material.

According to the embodiment of the present disclosure, the second material may be a material that exhibits higher adhesive force with respect to the fixing layer <NUM> than the first material, and the portion of the inner body 2130a that is formed of the second material may be strongly adhered to the fixing layer <NUM>.

For example, the connecting body 2130c of the composite gasket <NUM> is formed of a first material (e.g. soft rubber) that has a relatively low hardness of <NUM> to <NUM> Shore A, it may be more preferably of <NUM> to <NUM> Shore A, so as to be compressed by pressure applied when the cap <NUM> is fastened to the mid-case <NUM> through a bolt <NUM> and a nut <NUM>, and the portion of the inner body 2130a that comes into direct contact with the fixing layer <NUM> may be formed of a material (e.g. metal, rigid plastic, hard rubber, or soft rubber) that exhibits higher adhesive force with respect to the fixing layer <NUM> than the first material.

The first material of the connecting body 2130c may include soft silicone rubber or soft urethane rubber, and the second material of the inner body 2130a may include polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polycarbonate (PC), acrylic resin, hard silicone, or hard urethane.

In addition, when the first material of the connecting body 2130c includes soft silicone rubber, the second material of the inner body 2130a may include soft urethane rubber.

As shown respectively in <FIG>, the inner body 2130a may include (i) a first part directly connected to the connecting body 2130c, the first part being formed of the first material, and (ii) a second part adhered to the first part and to the fixing layer <NUM>, the second part being formed of the second material.

In order to increase contact area between the first and second parts, which are formed of different materials, thereby maximizing the adhesive force therebetween, the interface between the first and second parts may have a step, as illustrated in <FIG>.

Together with the outer body 2130b and the connecting body 2130c, the first part of the inner body 2130a may constitute a packing part <NUM> formed of the first material. The second part of the inner body 2130a may constitute a bracket part <NUM> formed of the second material. The packing part <NUM> and the bracket part <NUM> may be integrally formed through injection molding, a detailed description of which will follow.

When the cap <NUM> is fastened to the mid-case <NUM> through the bolt <NUM> and the nut <NUM>, the connecting body 2130c of the composite gasket <NUM> is pressurized and compressed by the end of the mid-case <NUM> and the cap <NUM>, whereby movement of gas through the interface between the composite gasket <NUM> and the mid-case <NUM> (i.e. external leakage) can be prevented, and therefore tight external sealing may be guaranteed.

In addition, since the packing part <NUM> and the bracket part <NUM> are integrally formed through injection molding, strong adhesive force therebetween may be obtained. Consequently, movement of gas through the interface between the packing part <NUM> and the bracket part <NUM> (i.e. through the interface between the first and second parts of the inner body 2130a) (i.e. internal leakage) can be prevented, and therefore excellent internal sealing may be guaranteed.

In addition, since the bracket part <NUM> (i.e. the second part of the inner body 2130a) according to the embodiment of the present disclosure has excellent adhesive force with respect to the fixing layer <NUM>, movement of gas through the interface between the bracket part <NUM> and the fixing layer <NUM> (i.e. internal leakage) can be prevented, and therefore stronger internal sealing may be provided.

Optionally, the surface of the bracket part <NUM> or the surface of the inner body 2130a may be treated with a primer, whereby the adhesive strength between the bracket part <NUM> or the inner body 2130a and the fixing layer <NUM> can be further increased, and therefore an internal sealing effect may be maximized. That is, as illustrated in <FIG>, the composite gasket <NUM> according to the present disclosure further includes a primer layer <NUM> formed on at least a portion of the surface of the inner body 2130a, whereby the composite gasket may have stronger adhesive force with respect to the fixing layer <NUM>. The primer used to increase the adhesive strength between the composite gasket <NUM> and the fixing layer <NUM> may include a rubber adhesive component, an acrylic adhesive component, a polyurethane adhesive component, an epoxy adhesive component, a silicone adhesive component, a polyamide-based adhesive component, a polyimide-based adhesive component, or a mixture of two or more thereof.

For the rubber adhesive component, natural rubber (NR) and/or synthetic rubber may be used. The synthetic rubber may be SBR, NBR, CR, BR, IIR, and/or EPDM.

For the acrylic adhesive component, acrylic emulsion, anaerobic acrylic resin, and/or acrylic resin-based adhesive tape may be used.

For the polyurethane adhesive component, solvent-type polyurethane, polyurethane hot melt, or urethane emulsion may be used.

For the polyamide-based adhesive component, polyamide hot melt may be used.

As illustrated in <FIG>, the cap <NUM> according to the embodiment of the present disclosure may have a protrusion <NUM> formed at a position corresponding to the end of the mid-case <NUM> inserted into the groove G of the composite gasket <NUM>. The protrusion <NUM> more effectively compresses the connecting body 2130c of the composite gasket <NUM> together with the end of the mid-case <NUM>, whereby tighter external sealing is achieved.

As illustrated in <FIG>, the first part of the inner body 2130a of the composite gasket <NUM> may also be adhered to the fixing layer <NUM>, in addition to the second part thereof. Liquid resin (e.g. liquid polyurethane resin) used to form the fixing layer <NUM> is hardened in a state of being in contact with both the first and second parts of the inner body 2130a of the composite gasket <NUM>, whereby the adhesive strength between the gasket <NUM> and the fixing layer <NUM> can be increased and thus internal sealing may be improved.

According to the embodiment of the present disclosure, as illustrated in <FIG>, the fixing layer <NUM> may include a first fixing layer <NUM>-<NUM> in which the ends of the hollow fiber membranes <NUM> are potted, and a second fixing layer <NUM>-<NUM> adhered to the inner body 2130a of the composite gasket <NUM> while surrounding the first fixing layer <NUM>-<NUM>.

Each of the first fixing layer <NUM>-<NUM> and the second fixing layer <NUM>-<NUM> may be formed by hardening liquid resin, such as liquid polyurethane resin, using a dip casting method or a centrifugal casting method. Although the first fixing layer <NUM>-<NUM> and the second fixing layer <NUM>-<NUM> may be formed of different materials, it may be preferable for the first fixing layer and the second fixing layer to be formed of the same material (e.g. polyurethane resin) in terms of adhesive strength therebetween.

As illustrated in <FIG>, the humidifying module <NUM> may further include an inner case <NUM> disposed in the mid-case <NUM>, the inner case being open at opposite ends thereof. In this case, the hollow fiber membranes <NUM> are disposed in the inner case <NUM>. The first fixing layer <NUM>-<NUM> in which ends of the hollow fiber membranes <NUM> are potted closes a corresponding one of the open ends of the inner case <NUM>.

According to the embodiment of the present disclosure, the inner case <NUM> has a plurality of holes H provided at positions corresponding to the ports <NUM> for off-gas introduction/discharge (only one is shown in <FIG>). Off-gas introduced into the mid-case <NUM> through the first port <NUM> passes through the first holes H and then absorbs moisture while flowing along the outer surfaces of the hollow fiber membranes <NUM>. Subsequently, the off-gas exits the inner case <NUM> through the second holes H on the opposite side and is then discharged from the mid-case <NUM> through the second port <NUM>.

The hollow fiber membranes <NUM>, the first fixing layer <NUM>-<NUM>, and the inner case <NUM> constitute a hollow fiber membrane cartridge <NUM>.

As illustrated in <FIG>, an end of the inner case <NUM> is potted in the first fixing layer <NUM>-<NUM>, whereby relative positions of the hollow fiber membranes <NUM> and the inner case <NUM> may be uniformly maintained.

Hereinafter, a humidifier <NUM> for a fuel cell according to a second embodiment of the present disclosure will be described with reference to <FIG>.

The humidifier <NUM> for a fuel cell according to the second embodiment of the present disclosure is identical to the humidifier <NUM> for a fuel cell of <FIG> except that the mid-case <NUM> has a step <NUM> formed on the inner circumferential surface thereof and the composite gasket <NUM> (more specifically, the bracket part <NUM>) is supported by the step <NUM>.

Since the bracket part <NUM> is supported by the step <NUM> of the mid-case <NUM> and has higher hardness than the packing part <NUM>, the bracket part <NUM> may effectively apply pressure to the packing part <NUM> together with the cap <NUM> when the cap <NUM> is fastened to the mid-case <NUM> through the bolt <NUM> and the nut <NUM>. Consequently, movement of gas through the interface between the packing part <NUM> and the bracket part <NUM> (i.e. through the interface between the first and second parts of the inner body 2130a) (i.e. internal leakage) can be prevented, and therefore excellent internal sealing may be guaranteed.

In addition, as illustrated in <FIG>, when at least a portion of the surface of the inner body 2130a of the composite gasket <NUM> is treated with a primer, not only the surface of the inner body to come into contact with the fixing layer <NUM> but also the surface of the inner body to be supported by the step <NUM> are treated with the primer, whereby the adhesive strength between the inner body 2130a and the fixing layer <NUM> can be further increased, and therefore an internal sealing effect may be maximized. Furthermore, the adhesive strength between the inner body 2130a and the step <NUM> can be further increased, and therefore an external sealing effect may be maximized.

Hereinafter, a humidifier <NUM> for a fuel cell according to a third embodiment of the present disclosure will be described with reference to <FIG>.

As illustrated in <FIG>, the humidifier <NUM> for a fuel cell according to the third embodiment of the present disclosure is substantially identical to the first embodiment described above except that the humidifier includes two hollow fiber membrane cartridges 2120a and 2120b.

That is, according to the third embodiment of the present disclosure, the hollow fiber membranes include a first group of hollow fiber membranes 2121a and a second group of hollow fiber membranes 2121b, the humidifying module <NUM> includes a first inner case 2123a in which the first group of hollow fiber membranes 2121a is disposed and a second inner case 2123b in which the second group of hollow fiber membranes 2121b is disposed, and the fixing layer <NUM> includes a first fixing layer <NUM>-1a in which ends of the first group of hollow fiber membranes 2121a are potted, a second fixing layer <NUM>-1b in which ends of the second group of hollow fiber membranes 2121b are potted, and a third fixing layer <NUM>-<NUM> adhered to the inner body 2130a of the composite gasket <NUM> while surrounding the first and second fixing layers <NUM>-1a and <NUM>-1b.

The first group of hollow fiber membranes 2121a, the first fixing layer <NUM>-1a, and the first inner case 2123a constitute a first hollow fiber membrane cartridge 2120a, and the second group of hollow fiber membranes 2121b, the second fixing layer <NUM>-1b, and the second inner case 2123b constitute a second hollow fiber membrane cartridge 2120b.

As illustrated in <FIG>, ends of the first and second inner cases 2123a and 2123b are potted in the first and second fixing layers <NUM>-1a and <NUM>-1b, respectively, whereby relative positions of the first group of hollow fiber membranes 2121a and the first inner case 2123a and relative positions of the second group of hollow fiber membranes 2121b and the second inner case 2123b may be uniformly maintained.

In order to increase humidification capacity, the number of hollow fiber membranes <NUM> must be increased. However, in the first and second embodiments, each of which includes only a single hollow fiber membrane cartridge <NUM>, there is a problem in that, if the number of hollow fiber membranes <NUM> is increased, it is difficult for off-gas to be transmitted to hollow fiber membranes <NUM> located at the center.

In the third embodiment of the present disclosure, by contrast, two hollow fiber membrane cartridges 2120a and 2120b are disposed spaced apart from each other, whereby, even though the number of hollow fiber membranes 2121a and 2121b is increased, off-gas may be relatively uniformly transmitted to the hollow fiber membranes 2121a and 2121b. That is, on the assumption that the number of hollow fiber membranes is uniform, the structure of the third embodiment, which includes two hollow fiber membrane cartridges 2120a and 2120b, is advantageous in terms of utilization of the hollow fiber membranes, compared to the structures of the first and second embodiments, each of which includes a single hollow fiber membrane cartridge <NUM>.

The number of hollow fiber membrane cartridge(s) mounted in the mid-case <NUM> may be determined in overall consideration of the capacity of the fuel cell (or required humidification capacity), the size of the humidifier, and the weight of the humidifier.

Hereinafter, a method of manufacturing a humidifier <NUM> for a fuel cell according to an embodiment of the present disclosure will be described in more detail with reference to <FIG>.

First, as illustrated in <FIG>, a hollow fiber membrane cartridge <NUM>' having a first fixing layer <NUM>-<NUM>' in which ends of a plurality of hollow fiber membranes <NUM>' are potted is prepared.

The hollow fiber membrane cartridge <NUM>' may be manufactured by inserting at least a portion of each of the hollow fiber membranes <NUM>' into an inner case <NUM> and performing a dip casting process or a centrifugal casting process using liquid resin, such as liquid polyurethane resin. The first fixing layer <NUM>-<NUM>' in which the ends of the hollow fiber membranes <NUM>' are potted is formed as a result of hardening of the liquid resin.

When the dip casting process or the centrifugal casting process is performed, an end of the inner case <NUM> may be potted in the first fixing layer <NUM>-<NUM>' together with the ends of the hollow fiber membranes <NUM>'.

The inner case <NUM> may have first and second groups of holes H formed in a longitudinal direction thereof so as to be located on opposite sides.

Subsequently, as illustrated in <FIG>, the hollow fiber membrane cartridge <NUM>' is inserted into a mid-case <NUM> open at opposite ends thereof.

According to the embodiment of the present disclosure, the mid-case <NUM> has a simple closed curve-shaped traverse section. The mid-case <NUM> may have a partition wall configured to divide an inner space thereof into an off-gas introduction space and an off-gas discharge space located on opposite sides in a longitudinal direction, and the hollow fiber membrane cartridge <NUM>' may be inserted through a hole formed in the partition wall so as to be supported by the partition wall. At this time, the first group of holes H of the inner case <NUM> is located in the off-gas introduction space, and the second group of holes H of the inner case <NUM> is located in the off-gas discharge space.

In this case, off-gas that has entered the off-gas introduction space is introduced into the inner case <NUM> through the first group of holes H, flows toward the second group of holes H in the inner case <NUM>, moves to the off-gas discharge space through the second group of holes H, and is discharged from the mid-case <NUM>.

Subsequently, as shown in <FIG>, a composite gasket <NUM> having a groove G corresponding to the end of the mid-case <NUM> is prepared, and the composite gasket <NUM> is mounted on the end of the mid-case <NUM> such that the end of the mid-case <NUM> is inserted into the groove G.

The composite gasket <NUM> may be obtained by (i) preparing a bracket part <NUM> formed of the second material, (ii) inserting the bracket part <NUM> into a mold, (iii) injecting a melt of the first material into the mold in which the bracket part <NUM> is located, and (iv) cooling the melt of the first material to obtain a packing part <NUM> adhered to the bracket part <NUM>. Optionally, the surface of the bracket part <NUM> may be treated with a primer and may then be inserted into the mold in order to increase the adhesive strength between the bracket part <NUM> and the packing part <NUM>.

Alternatively, a co-injection molding may be performed in order to simultaneously form the bracket part <NUM> and the packing part <NUM>.

As previously described, at least a portion of the surface of an inner body 2130a of the composite gasket <NUM> obtained through the above processes may be treated with the primer.

According to the embodiment of the present disclosure, the packing part <NUM> and the bracket part <NUM> are integrally formed through injection molding, whereby it is possible to obtain strong adhesive force therebetween even though the packing part and the bracket part are formed of different materials. Consequently, movement of gas through the interface between the packing part <NUM> and the bracket part <NUM> (i.e. internal leakage) can be prevented, and therefore excellent internal sealing may be guaranteed.

Subsequently, as shown in <FIG>, a second fixing layer <NUM>-<NUM>' configured to fill the gap between the mid-case <NUM> and the end of the hollow fiber membrane cartridge <NUM>' and the gap between the composite gasket <NUM> and the end of the hollow fiber membrane cartridge <NUM>' is formed.

The second fixing layer <NUM>-<NUM>' may be manufactured by fastening a potting cap (not shown) to the mid-case <NUM>, performing a dip casting process of injecting liquid resin, such as liquid polyurethane resin, into the potting cap and hardening the liquid resin in the state in which the potting cap is located under the mid-case <NUM>, and removing the potting cap. Alternatively, the second fixing layer <NUM>-<NUM>' may be formed through a centrifugal casting process.

Although the first and second fixing layers <NUM>-<NUM>' and <NUM>-<NUM>' may be formed of different liquid resins, it may be preferable for the first and second fixing layers to be formed of the same material (e.g. liquid polyurethane resin) in terms of adhesive strength therebetween.

According to the embodiment of the present disclosure, liquid resin (e.g. liquid polyurethane resin) used to form the second fixing layer <NUM>-<NUM>' may be hardened in while being in contact with the composite gasket <NUM> (particularly, the bracket part <NUM>), whereby the adhesive strength of the second fixing layer <NUM>-<NUM>' with respect to it can be increased and thus internal sealing may be improved.

According to the embodiment of the present disclosure, since the bracket part <NUM> is formed of a material that has excellent adhesive force with respect to the second fixing layer <NUM>-<NUM>', movement of gas through the interface therebetween (i.e. internal leakage) can be prevented, and therefore stronger internal sealing may be provided. In addition, when the surface of the bracket part <NUM> is treated with a primer, as previously described, the adhesive strength between the bracket part <NUM> and the second fixing layer <NUM>-<NUM>' can be maximized, and therefore better internal sealing may be provided.

Subsequently, the first fixing layer <NUM>-<NUM>', the second fixing layer <NUM>-<NUM>', and the hollow fiber membranes <NUM>' are simultaneously cut along a cutting line CL of <FIG>, whereby hollow fiber membranes <NUM> configured such that ends thereof potted in a first fixing layer <NUM>-<NUM> surrounded by a second fixing layer <NUM>-<NUM> are open are obtained, as illustrated in <FIG>.

Subsequently, as illustrated in <FIG>, a cap <NUM> is fastened to the mid-case <NUM>. Specifically, the cap <NUM> is fastened to the mid-case such that a connecting body 2130c of the composite gasket <NUM> is compressed by the cap <NUM>.

As illustrated in <FIG>, the cap <NUM> according to the embodiment of the present disclosure may have a protrusion <NUM> formed at a position corresponding to the end of the mid-case <NUM>. Since the end of the mid-case <NUM> is inserted into the groove G of the composite gasket <NUM>, the protrusion <NUM> more effectively compresses the connecting body 2130c of the composite gasket <NUM> together with the end of the mid-case <NUM>, whereby tighter external sealing is achieved.

Claim 1:
A humidifier (<NUM>) for a fuel cell, the humidifier comprising:
a humidifying module (<NUM>) configured to humidify gas supplied from outside using moisture in off-gas discharged from a fuel cell stack; and
caps (<NUM>) coupled respectively to opposite ends of the humidifying module (<NUM>), wherein
the humidifying module (<NUM>) comprises:
a mid-case (<NUM>) open at opposite ends thereof;
a plurality of hollow fiber membranes (<NUM>) disposed in the mid-case (<NUM>);
a fixing layer (<NUM>) in which ends of the hollow fiber membranes (<NUM>) are potted; and
a composite gasket (<NUM>) having a groove (G) into which the end of the mid-case (<NUM>) is inserted,
the composite gasket (<NUM>) comprises:
an inner body (2130a) based on the groove (G), the inner body (2130a) being located inside the mid-case (<NUM>);
an outer body (2130b) based on the groove (G), the outer body (2130b) being located outside the mid-case (<NUM>); and
a connecting body (2130c) located between the inner body (2130a) and the outer body (2130b),
the humidifier (<NUM>) characterized in that:
the connecting body (2130c) is formed of a first material having hardness of <NUM> to <NUM> Shore A, and
at least a portion of the inner body (2130a) is adhered to the fixing layer (<NUM>) and is formed of a second material different from the first material, the second material having higher adhesive force with respect to the fixing layer (<NUM>) than the first material.