Device and method for testing airtightness of fuel cell stack

Disclosed is a device for testing airtightness of a fuel cell stack. The device for testing airtightness of a fuel cell stack including a first reaction gas inflow portion and a first reaction gas outflow portion which a first reaction gas flows in or out, respectively, and a second reaction gas inflow portion and a second reaction gas outflow portion which a second reaction gas flows in and out, respectively, includes i) a detection gas supplier supplying a detection gas to the first reaction gas inflow portion, ii) an intake installed to be movable in a sequential stacking direction of fuel cells in the second reaction gas outflow portion, iii) a detection gas concentration detector intaking a detection gas through the intake and detecting a concentration of the detection gas, and iv) a controller determining an airtightness-defective cell based on a position of the intake by analyzing the detected concentration value of the detection gas detected by the detection gas concentration detector.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean Patent Application No. 10-2016-0115743, filed in the Korean Intellectual Property Office on Sep. 8, 2016, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

An exemplary embodiment of the present disclosure relates to a device and method for testing airtightness of a fuel cell stack and, more particularly, to a device and method for testing airtightness of a fuel cell stack capable of accurately detecting an airtightness-defective cell among fuel cells.

BACKGROUND

A fuel cell stack is an electricity-generating device producing electrical energy through an electrochemical reaction between hydrogen and oxygen by fuel cells, and may be applied to fuel cell vehicles, for example.

A fuel cell stack may be configured as an electricity-generating assembly in which hundreds of units of fuel cells are successively arranged. The fuel cells each have a configuration in which separators are disposed on opposing sides with a membrane-electrode assembly interposed therebetween. Fuel cells, in a state of being pressed at a predetermined pressure, are fastened through an end plate and a fastening unit.

The MEA includes an electrolyte membrane and a cathode catalytic layer and an anode catalytic layer formed on opposing sides of the electrolyte membrane. A gas diffusion layer (GDL), a gasket, and the like, are stacked on the catalytic layers. The separators each have a flow channel allowing a reaction gas of hydrogen and air to flow to the anode catalytic layer and the cathode catalytic layer.

In the fuel cell stack, since hundreds of units of fuel cells are stacked and pressed, airtightness of the fuel cells may be defective due to various reasons. An airtightness-defective cell causes a reaction gas to flow out to degrade efficiency and performance of the fuel cell stack and causes a safety problem. Thus, testing an airtightness defect of fuel cells is essential in a process of assembling a fuel cell stack.

In the related art, airtightness testing is performed in a state in which a fuel cell stack is completely assembled. Thus, when an airtightness defect occurs, the fuel cell stack is disassembled, fuel cells are separated and airtightness testing is performed thereon to locate an airtightness-defective cell.

Thus, the related art requires a great deal of time to test airtightness of a fuel cell stack, the overall testing process is complicated, and normal cells may be damaged in the process of disassembling the fuel cell stack and separating the fuel cells.

Matters described in the background art section are provided to promote understanding of the background of the present disclosure, and may include matter that is not prior art known to those skilled in the art to which the present disclosure pertains.

SUMMARY

The present disclosure has been made in an effort to provide a device and method for testing airtightness of a fuel cell stack, having advantages of accurately detecting an airtightness-defective cell among fuel cells without disassembling a fuel cell stack.

An exemplary embodiment of the present disclosure provides a device for testing airtightness of a fuel cell stack including a first reaction gas inflow portion and a first reaction gas outflow portion through which a first reaction gas flows in and out, respectively, and a second reaction gas inflow portion and a second reaction gas outflow portion through which a second reaction gas flows in and out, respectively, including: a detection gas supplier supplying a detection gas to the first reaction gas inflow portion; an intake installed to be movable in a sequential stacking direction of fuel cells in the second reaction gas outflow portion; a detection gas concentration detector intaking the detection gas through the intake and detecting a concentration of the detection gas; and a controller determining an airtightness-defective cell based on a position of the intake by analyzing the detected concentration value of the detection gas detected by the detection gas concentration detector.

The device may further include: a jig closing the first reaction gas inflow portion, opening the second reaction gas inflow portion, and closing the first and second reaction gas outflow portions.

The intake may intake air introduced to the second reaction gas outflow portion through the second reaction gas inflow portion and a detection gas leaked to the second reaction gas outflow portion through the first reaction gas outflow portion.

The intake may intake a background source of the second reaction gas outflow portion, establish a detection background in the second reaction gas outflow portion, and intake a detection source of the second reaction gas outflow portion.

The intake may include: a background pipe intaking the background source; and a detection pipe intaking the detection source.

The intake may be provided as a dual-pipe in which the background pipe is disposed on the inner side of the detection pipe and integrally connected with the detection pipe.

Another exemplary embodiment of the present disclosure provides a device for testing airtightness of a fuel cell stack in which fuel cells are successively stacked, including: a first jig closing a first reaction gas inflow portion of the fuel cell stack and opening a second reaction gas inflow portion; a detection gas supplier connected to the first jig and supplying a detection gas to the first reaction gas inflow portion; a second jig closing first and second reaction gas outflow portions of the fuel cell stack; an intake mounted in the second jig and installed to be movable in a sequential stacking direction of the fuel cells within the second reaction gas outflow portion; a detection gas concentration detector installed to be connected to the intake, intaking a detection source on an inner side of the second reaction gas outflow portion through the intake, and detecting a concentration of the detection gas; and a controller determining an airtightness-defective cell based on a position of the intake by analyzing the detected concentration value of the detection gas detected by the detection gas concentration detector.

The detection gas supplier may include: a gas tank storing a gas lighter than air as the detection gas; and a supply hose connecting the gas tank and the first reaction gas inflow portion.

The intake may include: a background pipe intaking a background source of the second reaction gas outflow portion; and a detection pipe connected to the background pipe provided on an inner side thereof and intaking a detection source of the second reaction gas outflow portion through a portion between the detection pipe and the background pipe.

The second reaction gas outflow portion and the background pipe may be connected to an exhaust pump.

The detection pipe may be connected to the detection gas concentration detector.

A detection gas intake passage may be provided between an outer circumferential surface of the background pipe and an inner circumferential surface of the detection pipe.

The background pipe may have a flange supporting an inner wall of the second reaction gas outflow portion.

The detection pipe may be disposed to be spaced apart from the flange, and a detection source inlet passage may be provided between the detection pipe and the flange.

The device may further include: a driver installed in the second jig and linearly moving the intake by a rotational force from a servo motor.

Yet another exemplary embodiment of the present disclosure provides a method for testing airtightness of a fuel cell stack, including steps of: closing a first reaction gas inflow portion, opening a second reaction inflow portion, closing first and second reaction gas outflow portions, setting an intake in the second reaction gas outflow portion, and supplying a detection gas to the first reaction gas inflow portion; intaking a background source of the second reaction gas outflow portion through the intake and establishing a detection background; intaking a detection source of the second reaction gas outflow portion through the intake, and moving the intake in a sequential stacking direction of fuel cells through a servo motor; and detecting a concentration of the detection gas through a detection gas concentration detector and analyzing the detected concentration value to determine an airtightness-defective cell based on a position of the intake.

The intake may be in the form of a dual-pipe in which a background pipe intaking a background source may be provided on an inner side of a detection pipe intaking a detection source.

Cell numbers of fuel cells may be obtained with respect to a movement position of the intake based on an revolution per minute (RPM) of the servo motor.

A section in which the detected concentration value of the detection gas of the detection source detected by the detection gas concentration detector is uniform within a set range is set as a reference concentration.

It may be determined whether the detected concentration value of the detection gas exceeds the reference concentration.

When it is determined that the detected concentration value of the detection gas exceeds the reference concentration, the cell number of a fuel cell based on a movement position of the intake may be indicated, and the fuel cell corresponding to the cell number may be determined as an airtightness-defective cell.

According to the exemplary embodiments of the present disclosure, since an airtightness-defective cell is accurately located from among fuel cells, without assembling the fuel cell stack, a time required for testing airtightness of the fuel cell stack may be shortened and convenience of the testing process may be promoted.

In addition, in the exemplary embodiment of the present disclosure, since the detection source including a minimum amount of detection gas is intaken and a concentration of the detection gas of the detection source is detected in a state in which a detection background is established in the second reaction gas outflow portion through the intake, detection accuracy and detection regeneration capability of the detection gas concentration detector may be enhanced and performance of detecting an airtightness-defective cell may be further enhanced.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the drawings, sizes and thickness of components are arbitrarily shown for the description purposes, so the present disclosure is not limited to the illustrations of the drawings and thicknesses are exaggerated to clearly express various parts and regions.

In the following descriptions, terms such as “first” and “second,” etc., may be used only to distinguish one component from another as pertinent components are named the same, and order thereof is not limited.

The terms “unit”, “means”, “part”, “member”, and the like, described in the specification refer to units of comprehensive configuration performing at least one function or operation.

FIG. 1is a block diagram schematically illustrating a device for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure.

Referring toFIG. 1, a device100for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure may be applied to an airtightness testing process of testing airtightness of a fuel cell stack1assembled during a stack assembly process.

Here, during the stack assembly process, a plurality of fuel cells3are sequentially stacked, pressed, and fastened through end plates5to assemble the fuel cell stack1.

Hereinafter, components of the airtightness testing device100according to an exemplary embodiment of the present disclosure will be described with respect to the fuel cells3stacked in a vertical direction. Thus, a portion facing upwards may be defined as an upper portion and an upper end, and a portion facing downwards may be defined as a lower portion and a lower end.

However, the definition of directions is relative and directions may be varied according to a stacking direction of the fuel cells3, a reference position of the airtightness testing device100, and the like, and thus, the aforementioned reference direction is not limited to the reference direction of the present embodiment.

As illustrated inFIG. 2, the fuel cell stack1applied to an exemplary embodiment of the present disclosure includes a first reaction gas inflow portion1a, a first reaction gas outflow portion1b, a second reaction gas inflow portion2a, and a second reaction gas outflow portion2b, as a manifold for supplying and discharging a reaction gas (hydrogen, air).

For example, the first reaction gas inflow portion1aand the second reaction gas inflow portion2aare formed to extend downwardly from one side of an upper end plate5to a lower end plate5with respect to a vertical stacking direction of the fuel cells3. The first reaction gas outflow portion1band the second reaction gas outflow portion2bare formed to extend downwardly from another side of the upper end plate5to the lower end plate5.

The first reaction gas inflow portion1aand the first reaction gas outflow portion1bare connected through flow channels provided in separators (not shown) of the fuel cells3, and the second reaction gas inflow portion2aand the second reaction gas outflow portion2bare also connected through flow channels provided in the separators.

Here, the first and second reaction gases refer to hydrogen and air required for an electrochemical reaction of the fuel cells3. When the first reaction gas is hydrogen, the second reaction gas is air, and when the first reaction gas is air, the second reaction gas is hydrogen.

The device100for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure has a structure capable of accurately detecting an airtightness-defective cell among the fuel cells3without disassembling the fuel cell stack1, unlike the related art.

In addition, the exemplary embodiment of the present disclosure provides the device100for testing airtightness of a fuel cell stack capable of shortening time required for testing airtightness of the fuel cell stack1and promoting convenience of a testing process.

Referring toFIGS. 1 and 2, the device100for testing airtightness of a fuel cell stack according to the present exemplary embodiment includes jigs11and12, a detection gas supplier20, an intake30, a detection gas concentration detector70, and a controller90.

Various components of the airtightness testing device100described hereinafter are installed in a frame (not shown), and the frame, which supports each of the components, may be configured as a single frame or two or more divided frames. The frame may include various accessory elements such as a bracket, a bar, a rod, a plate, a housing, a case, a block, and the like, to support various components.

In an exemplary embodiment of the present disclosure, the jigs11and12, serving to install the detection gas supplier20and the intake30described hereinafter, are installed in the fuel cell stack1. The jigs11and12close the first reaction gas inflow portion1aof the fuel cell stack1, open the second reaction gas inflow portion2a, and close the first and second reaction gas outflow portions1band2b.

The jigs11and12may be provided as a single airtight jig main body, or may be provided as separate airtight jig main bodies. However, in an exemplary embodiment of the present disclosure, the jigs11and12are provided as separate airtight jig main bodies, for example, and hereinafter, the separately divided jigs11and12will be referred to as a first jig11and a second jig12.

The first jig11is connected with the detection gas supplier20(to be described hereinafter). The first jig11is mounted in an upper portion of the fuel cell stack1and closes the first reaction gas inflow portion1aand opens the second reaction gas inflow portion2a.

The second jig12is connected with the intake30(to be described hereinafter). The second jig12is mounted in an upper portion of the fuel cell stack1and closes the second reaction gas outflow portions1band2b.

In an exemplary embodiment of the present disclosure, the detection gas supplier20serves to supply a helium gas, as a detection gas, lighter than air to the first reaction gas inflow portion1of the fuel cell stack1

The detection gas supplier20is provided to be connected to the first jig11and includes a gas tank21storing a helium gas and a supply hose23connecting the gas tank21and the first reaction gas inflow portion1a.

Here, in a state in which the first reaction gas inflow portion1ais closed by the first jig11and the first and second reaction gas outflow portions1band2bare closed by the second jig1, when a detection gas is supplied to the first reaction gas inflow portion1athrough the detection gas supplier20, the detection gas may be introduced to (or may flow to) the first reaction gas outflow portion1bthrough separators of the fuel cells3.

When an airtightness-defective cell is present among the fuel cells3, the detection gas introduced to the first reaction gas outflow portion1bmay be introduced to the second reaction gas outflow portion2bthrough a leak portion of the airtightness-defective cell.

Since the second reaction gas inflow portion2ais opened through the first jig11, when a pumping pressure is applied to the second reaction gas outflow portion2bthrough a predetermined pumping unit (an exhaust pump and an intaking pump of the detection gas concentration detector as described hereinafter), air may be introduced to the second reaction gas outflow portion2bthrough the second reaction gas inflow portion2aand the separators of the fuel cells3.

FIGS. 3 and 4are views schematically illustrating an intake applied to a device for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure.

Referring toFIGS. 3 and 4, in an exemplary embodiment of the present disclosure, the intake30serves to intake air introduced to the second reaction gas outflow portion2bthrough the second reaction gas inflow portion2aand a detection gas leaked to the second reaction gas outflow portion2bthrough the first reaction gas outflow portion1b.

That is, the intake30may intake a background source of the second reaction gas outflow portion2bthrough the aforementioned pumping unit and establish a detection background in the second reaction gas outflow portion2b. Also, with the detection background established in the second reaction gas outflow portion2b, the intake30may intake a substantial detection source of the second reaction gas outflow portion2b.

Here, the background source refers to air introduced to the second reaction gas outflow portion2band a detection gas (leak gas), and the detection background refers to exhausting a detection background source from the second reaction gas outflow portion2bto the outside in order to enhance detection accuracy and detection regeneration capability of the detection gas concentration detector70(to be described hereinafter).

The detection source refers to air and a detection gas (leak gas) introduced to the second reaction gas outflow portion2bin a state in which the detection background is established in the second reaction gas outflow portion2b. Such a detection source is sucked to the detection gas concentration and may provide a minimum amount of detection gas to the detection gas concentration detector70sensitive to a flow rate of a detection gas.

The intake30is mounted in the second jig12and installed to be movable in a sequential stacking direction (vertical direction) of the fuel cells3within the second reaction gas outflow portion2b. The intake30includes a background pipe31and a detection pipe41.

The background pipe31, intaking a background source of the second reaction gas outflow portion2b, has a background source intake passage33as a hollow. The background pipe31is disposed in a vertical stacking direction of the fuel cells3in the second reaction gas outflow portion2b, and disposed such that a lower end thereof is in contact with the lower end plate5, as an initial position.

A flange35is formed in a lower end portion of the background pipe31. The flange35supports the lower end plate5and an inner wall of the second reaction gas outflow portion2b.

The detection pipe41, intaking a detection source of the second reaction gas outflow portion2b, has a hollow and is connected to the background pipe31present on an inner side of the hollow.

That is, the intake30according to an exemplary embodiment of the present invention is provided as a dual-pipe in which the background pipe31is disposed on an inner side of the detection pipe41and integrally connected with the detection pipe41.

The detection pipe41may be disposed in a vertical stacking direction of the fuel cells3in the second reaction gas outflow portion2b, and intake a detection source of the second reaction gas outflow portion2bthrough a portion between the detection pipe41and the background pipe31. Thus, a detection source intake passage43is formed between an outer circumferential surface of the background pipe31and an inner circumferential surface of the detection pipe41.

Here, the outer circumferential surface of the background pipe31and the inner circumferential surface of the detection pipe41may be integrally connected through a partition45. Thus, the detection source intake passage43at an interval set by the partition45between the outer circumferential surface of the background pipe31and the inner circumferential surface of the detection pipe41.

The detection pipe41is disposed to be spaced apart from the flange35of the background pipe31, and a detection source inlet passage47is formed between a lower end of the detection pipe41and the flange35to allow a detection source to be introduced to the detection source intake passage43.

In an exemplary embodiment of the present disclosure, as illustrated inFIGS. 1 and 3, an exhaust pump50is provided to intake a background source of the second reaction gas outflow portion2band discharge the intaken background source outwardly.

The exhaust pump50is connected to the second reaction gas outflow portion2band the background source intake passage33of the background pipe31. The exhaust pump50may be connected to an outer space of the detection pipe41and connected to the background source intake passage33of the background pipe31in the second reaction gas outflow portion2b, and intake a background source of the second reaction gas outflow portion2b.

The detection pipe41is connected to the detection gas concentration detector70(to be further described hereinafter), and intakes a detection source through the detection source intake passage43by a pumping pressure of the detection gas concentration detector70.

In an exemplary embodiment of the present disclosure, as illustrated inFIG. 1, a driver60moves the intake30in a sequential stacking direction (upward direction) of the fuel cells3from an initial position of the background pipe31.

The driver60is connected to the intake30and installed in the jig12. The driver60includes a servo motor61and may be able to move the intake30in the sequential stacking direction of the fuel cells3by a rotational force of the servo motor61.

The driver60may move the intake30in the sequential stacking direction of the fuel cells3through a guide structure63of a known art having a lead (or ball) screw and a guide rail converting a rotational force of the servo motor61into a linear movement.

Referring toFIGS. 3 and 4together withFIG. 1, in an exemplary embodiment of the present disclosure, the detection gas concentration detector70intakes a detection source of the second reaction gas outflow portion2bthrough the detection pipe41of the intake30and detects a concentration of the detection gas included in the detection source. The detection gas concentration detector70detects a concentration of a helium gas and outputs a detection value to the controller90.

The detection gas concentration detector70is installed to be connected to the detection pipe41of the intake30. The detection gas concentration detector70includes an intake pump (not shown) for intaking a detection source of the second reaction gas outflow portion2bthrough the detection pipe41. That is, the detection gas concentration detector70may intake the detection source of the second reaction gas outflow portion2bthrough the detection source intake passage43of the intake30by a pumping pressure of the intake pump.

Referring toFIG. 1, in an exemplary embodiment of the present disclosure, the controller90controls an overall operation of the airtightness testing device100. The controller90may be implemented as one or more microprocessors (control logic) operated by a program.

The controller90may apply a control signal to the detection gas supplier20, the exhaust pump50, the servo motor61, and the detection gas concentration detector70as mentioned above, and control operations thereof.

Also, the controller90may determine an airtightness-defective cell according to a position of the intake30by analyzing a concentration detection value of a detection gas detected by the detection gas concentration detector70. Control logic of the controller90for determining an airtightness-defective cell will be described in detail in a method for testing airtightness of a fuel cell stack hereinafter.

Hereinafter, a method for testing airtightness of a fuel cell stack using the device100for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure configured as described above will be described in detail with reference to the accompanying drawings.

FIG. 5is a flow chart illustrating a method for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure, andFIGS. 6 to 8are views illustrating operational states of a device for testing airtightness of a fuel cell stack to describe a method for testing airtightness of a fuel cell stack according to an exemplary embodiment of the present disclosure.

Referring toFIGS. 5 and 6, first, in an exemplary embodiment of the present disclosure, the first and second jigs11and12are mounted in the fuel cell stack1in operation S11. Here, the first jig12closes the first reaction gas inflow portion1aof the fuel cell stack1and opens the second reaction gas inflow portion2a. Also, the second jig12closes the first and second reaction gas outflow portions1band2bof the fuel cell stack1.

Here, the intake30of the second jig12is disposed in a vertical stacking direction of the fuel cells3in the second reaction gas outflow portion2b, and the background pipe31of the intake30is disposed such that a lower end thereof is in contact with the lower end plate5, as an initial position.

In this state, in an exemplary embodiment of the present disclosure, a control signal is applied to the detection gas supplier20through the controller90, and a detection gas as a helium gas lighter than air is supplied at a set pressure to the first reaction gas inflow portion1athrough the detection gas supplier20in operation S12.

Then, the detection gas is introduced to the first reaction gas outflow portion1bthrough separators of the fuel cells3. Here, since the first reaction gas inflow portion1ais closed through the first jig11and the first reaction gas outflow portion1bis closed through the second jig12, the detection gas is introduced to the first reaction gas outflow portion1bthrough the separators of the fuel cells3from the first reaction gas inflow portion1ato fill the first reaction gas outflow portion1bat a set pressure.

When it is assumed that an airtightness-defective cell is present among the fuel cells3of the fuel cell stack1, the detection gas introduced to the first reaction gas outflow portion1bis introduced to the second reaction gas outflow portion2bthrough a leak portion of the airtightness-defective cell by the set pressure.

In this state, in an exemplary embodiment of the present disclosure, a control signal is applied to the exhaust pump50through the controller90, and a pumping pressure is provided to the second reaction gas outflow portion2bthrough the exhaust pump50. Here, the exhaust pump50applies a pumping pressure to an outer space of the detection pipe41and the background source intake passage33of the background pipe31in the second reaction gas outflow portion2b.

Then, air is introduced to the second reaction gas outflow portion2bthrough the second reaction gas inflow portion2aand the separators of the fuel cells3to the second reaction gas outflow portion2bby the pumping pressure of the exhaust pump50.

The air introduced to the second reaction gas outflow portion2bis outwardly discharged by the pumping pressure of the exhaust pump50together with the detection gas introduced to the second reaction gas outflow portion2bthrough the leak portion of the airtightness-defective cell.

Thus, in an exemplary embodiment of the present disclosure, the background source (air and the detection gas) of the second reaction gas outflow portion2bis outwardly discharged by the exhaust pump50, and a detection background is established in the second reaction gas outflow portion2bin operation S13.

Here, in the second reaction gas outflow portion2b, the background source at the outer space of the detection pipe41is directly discharged to the outside by the exhaust pump50, and the other remaining background source is outwardly discharged through the background source intake passage33of the background pipe31by the exhaust pump50.

Thereafter, in an exemplary embodiment of the present disclosure, in a state in which the detection background is established in the second reaction gas outflow portion2b, a control signal is applied to an intake pump (not shown) of the detection gas concentration detector70through the controller90and a pumping pressure is applied to the detection pipe41of the intake30.

Thus, in an exemplary embodiment of the present disclosure, the background source of the second reaction gas outflow portion2bis continuously exhausted through the exhaust pump50, and in a state in which the detection background is established in the second reaction gas outflow portion2b, the detection source including the air and the detection gas (leak gas) introduced to the second reaction gas outflow portion2bis intake through the detection pipe41and discharged to the detection gas concentration detector70. The detection gas concentration detector70then detects a concentration of the detection gas included in the detection source and outputs the concentration detection value to the controller90in operation S14.

At the same time, in an exemplary embodiment of the present disclosure, as illustrated inFIGS. 5 and 7, a control signal is applied to the servo motor61of the driver60and a rotational force of the servo motor61is converted into a linear movement through the guide structure63to move the intake30in a sequential stacking direction (upward direction) of the fuel cells3in operation S15.

Here, the intake30, supporting an inner wall of the second reaction gas outflow portion2bthrough the flange35of the background pipe31, is moved in an upward direction by the driver60. The detection source of the second reaction gas outflow portion2bis intaken to the detection source intake passage43between an outer circumferential surface of the background pipe31and an inner circumferential surface of the detection pipe41through the detection source inlet passage47between a lower end of the detection pipe41and the flange35of the background pipe31, and introduced to the detection gas concentration detector70through the detection source intake passage43.

During this process, in an exemplary embodiment of the present disclosure, cell numbers of the fuel cells3are obtained with respect to a movement position of the intake30according to a revolution per minute (RPM) of the servo motor61in operation S16.

In operation S16, sequential cell numbers of the fuel cells3may be obtained through a map based on the RPM of the servo motor61, a movement position of the intake30based on the RPM, the stacking number of the fuel cells3, and the like.

Meanwhile, for example, when an airtightness defect occurs in a fuel cell3in a stacking position indicated by “A1” inFIG. 7, the detection gas introduced from the first reaction gas inflow portion1ato the first reaction gas outflow portion1bis introduced to the second reaction gas outflow portion2bthrough a leak portion of the airtightness-defective cell A1.

In this case, in an exemplary embodiment of the present disclosure, as stated above, a detection background is established in the second reaction gas outflow portion2bthrough the intake30, a detection source introduced to the second reaction gas outflow portion2bis intaken through the intake30, a concentration of the detection gas is detected through the detection gas concentration detector70, and the detection value is output to the controller90. Thereafter, in an exemplary embodiment of the present disclosure, the intake30is moved in an upward direction by the driver60.

During this process, the controller90obtains cell numbers of the fuel cells3with respect to a movement position (lifting position) of the intake30based on the RPM of the servo motor61.

Also, in an exemplary embodiment of the present disclosure, since the detection background is established in the second reaction gas outflow portion2b, the detected concentration value of the detection gas detected by the detection gas concentration detector70is maintained as a uniform concentration value within a set range in a section from a lowermost cell (cell No.1) of the fuel cells3to a previous cell of the stacking position “A1”. Thus, the controller90sets a section in which the detected concentration value of the detection gas of the detection source is uniform within a set range, to a reference concentration in operation S17.

Thereafter, the intake30is lifted, and when the detection source inlet passage47of the intake30is positioned in the fuel cell3at the stacking position “A1”, a detection gas leaked from the cell is introduced to the detection source inlet passage47together with air, intaken to the detection source intake passage43, and introduced to the detection gas concentration detector70through the detection source intake passage43. The detection gas concentration detector70then detects a concentration of the detection gas and outputs the detection value to the controller90.

The controller90then determines whether the detected concentration value of the detection gas exceeds the reference concentration in operation S18, and when it is determined that the detected concentration value of the detection gas exceeds the reference concentration, the controller90indicates the cell number of the fuel cell3based on the movement position of the intake30, and determines the fuel cell corresponding to the cell number, i.e., the cell at the stacking position “A1”, as an airtightness-defective cell in operation S19.

In an exemplary embodiment of the present disclosure, the aforementioned process is continuously performed, and here, as illustrated inFIG. 8, an airtightness defect may occur in the fuel cell3at the stacking position indicated by “A2”, for example.

In this case, since a detection background is established in the second reaction gas outflow portion2b, a detected concentration value of a detection gas of a detection source detected by the detection gas concentration detector70is maintained as a uniform concentration value within a set range in a section from a cell after the stacking position “A1” of the fuel cells3to a previous cell of the stacking position “A2”.

Here, a detection gas leaked from the airtightness-defective cell in the stacking position “A1” is outwardly discharged through the background pipe31of the intake30. Here, the leaked detection gas is blocked by the flange35of the background pipe31, is not introduced to the detection source inlet passage47of the intake30from the cells after the stacking position “A1” but outwardly discharged through the background source intake passage33of the background pipe31.

Thereafter, the intake30is lifted, and when the detection source inlet passage47of the intake30is positioned in the fuel cell3at the stacking position “A2”, a detection gas leaked from the cell is introduced to the detection source inlet passage47together with air, intaken to the detection source intake passage43, and introduced to the detection gas concentration detector70through the detection source intake passage43. The detection gas concentration detector70then detects a concentration of the detection gas and outputs the detection value to the controller90.

Then, when it is determined that the detected concentration value of the detection gas exceeds the reference concentration, the controller90indicates the cell number of the fuel cell3based on the movement position of the intake30and determines the fuel cell corresponding to the cell number, i.e., the cell at the stacking position “A2”, as an airtightness-defective cell.

Thus, in an exemplary embodiment of the present disclosure, through the sequential process as described above, an airtightness-defective cell may be accurately located from among the fuel cells3, without disassembling the fuel cell stack1. Thus, in an exemplary embodiment of the present invention, a time required for testing airtightness of the fuel cell stack1may be shortened and convenience of the testing process may be promoted.

In addition, in an exemplary embodiment of the present disclosure, since the detection source including a minimum amount of detection gas is intaken and a concentration of the detection gas of the detection source is detected in a state in which a detection background is established in the second reaction gas outflow portion2bthrough the intake30, detection accuracy and detection regeneration capability of the detection gas concentration detector70may be enhanced and performance of detecting an airtightness-defective cell may be further enhanced.

Hereinabove, exemplary embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the ideas of the present disclosure are not limited thereto and those skilled in the art who understand the ideas of the present disclosure may easily propose any other embodiments within the scope of the present disclosure through addition, change, deletion, and the like, and those embodiments will also be within the scope of the present disclosure.