Connector for monitoring the voltage of a fuel cell stack

A cell monitor connector is provided that can prevent detachment of the cell monitor connector from a fuel cell device with a simple configuration. A connector 4 for measuring voltage has a housing 41 with a plurality of slits 45 formed therein and an end of a separator 21 of a plurality of fuel cells 2 can be inserted into the slits 45. The housing 41 has a rib 46R at at least one end in the stacking direction of the fuel cells 2 such that the rib 46R projects in a direction perpendicular to the stacking direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of International Application No. PCT/JP2014/071298, filed Aug. 12, 2014, and claims the priority of Japanese Application No. 2013-225504, filed Oct. 30, 2013, the content of both of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a cell monitor connector to be connected to an end of a fuel cell device formed of a plurality of fuel cells stacked in a predetermined stacking direction, so as to monitor the state of the fuel cells by way of voltage measurement.

BACKGROUND ART

In a fuel cell device comprised of a plurality of stacked fuel cells, it is common practice to measure (monitor) the voltage of the fuel cell device and to use the obtained measurement value as an index for control. More specifically, a measured voltage is used as an index for controlling the supply of a fuel gas and an oxidizing gas to the fuel cells, or as an index for diagnosing failure, etc., of the fuel cells. In order to measure the voltage of the fuel cell device, a connector for measuring voltage is electrically connected to a part of the fuel cell device.

Meanwhile, in order to obtain a fuel cell device smaller in size, a reduction in thickness of each fuel cell is now being attempted. When making the fuel cell thinner, maintaining its structural strength is an issue. If a connector is connected to the fuel cell as described above, the possibility of breakage of the fuel cell may increase due to an external force applied by the connector. In particular, when the fuel cell device is installed on a vehicle, unavoidable external forces, such as vibrations during driving, are continuously applied via the connector, which causes a great concern of breakage. Moreover, there is a concern of complicated assembly if a connector is connected to each of the cells.

In light of the above, Patent Document 1, indicated below, discloses a configuration in which one connector is electrically connected to several separators of the fuel cells. As a result, external force will be distributed and a load applied to each separator can be made relatively small so that breakage of the separators can be suppressed and ease of assembly can be improved.

PRIOR ART REFERENCE

Patent Document

Patent Document 1: JP2013-118047 A

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, due to the structure of the fuel cell device having a plurality of stacked fuel cells, a connector to be connected to such fuel cell device has a problem of being prone to backlash. More specifically, since the fuel cell device is likely to have a dimensional error in its stacking direction, the part of the connector to be connected to several fuel cells needs to have a large dimensional tolerance. For this reason, connection between the fuel cell device and the connector will be loose, causing problems of backlash or detachment (the connector and the fuel cell device will be electrically disconnected) of the connector

The present invention has been made in view of the above-described problems. An object of the present invention is to provide a cell monitor connector which can prevent detachment of the cell monitor connector from the fuel cell device, with a simple configuration.

Means for Solving the Problem

In order to solve the above-described problems, a cell monitor connector according to the present invention is a cell monitor connector to be connected to an end of a fuel cell device formed of a plurality of fuel cells stacked in a predetermined stacking direction, so as to measure voltage, the cell monitor connector comprising: a housing having a plurality of slits formed therein, wherein an end of a separator of the plurality of fuel cells can be inserted into the slits; a plurality of terminals provided inside the housing and electrically connectable to the end of the separator when the separator is inserted into the slit; and wires connected to the terminals, wherein the housing has a rib at at least one end in the stacking direction, such that the rib projects in a direction perpendicular to the stacking direction.

In the cell monitor connector according to the present invention, since the housing has a projecting rib, a rotation of the cell monitor connector can be suppressed by restricting the rotation of the rib. Accordingly, even if the cell monitor connector is set so as to have a large dimensional tolerance in order to accept dimensional errors that may occur in the fuel cell device configured by stacking a plurality of fuel cells, it is still possible to prevent detachment of the cell monitor connector from the fuel cell device.

In the cell monitor connector according to the present invention, it is preferable for the rib to be formed at a position facing a gasket of the fuel cell.

In the case where a projecting rib is formed in the housing, the rib may interfere with a constituent element of the fuel cell upon rotation of the cell monitor connector and such element and the rib may even be broken. In the preferable mode described above, the rib is formed at a position facing the gasket of the fuel cell so that the rib will first interfere with the gasket upon rotation of the cell monitor connector, thereby suppressing breakage as described above. The “gasket” referred to herein is a seal member for separating a fluid flow path formed in the fuel cell. Such gasket has elasticity, and thus deforms and absorbs impact when it interferes with the rib. Consequently, breakage can be prevented.

Further, in the cell monitor connector according to the present invention, it is preferable for the rib to be formed at a position in which the rib will interfere with the gasket of the fuel cell so as to restrict rotation of the cell monitor connector around an axis parallel to the stacking direction when the cell monitor connector is connected to the end of the fuel cell device.

In the above-described preferable mode, when the housing of the cell monitor connector rotates around an axis parallel to the stacking direction of the fuel cell device, the rib and the gasket of the fuel cell interfere with each other so that breakage of the rib can be prevented while suppressing rotation of the housing. As a result, even if the cell monitor connector is set so as to have a large dimensional tolerance in order to accept dimensional errors that may occur in the fuel cell device configured by stacking a plurality of fuel cells, it is still possible to prevent detachment of the cell monitor connector from the fuel cell device.

Further, in the cell monitor connector according to the present invention, it is also preferable for the plurality of terminals to be composed of a first terminal group including a first number of the terminals arranged with spaces therebetween on a first line extending in the stacking direction and a second terminal group including a second number of the terminals arranged with spaces therebetween on a second line which is substantially parallel to the first line, the second number being smaller than the first number by one, wherein the terminals arranged at both ends of the second group are closer to the center part of the housing in the stacking direction than the terminals arranged at both ends of the first group.

When the plurality of terminals is composed of a first group and a second group which are arranged substantially parallel to each other, and if the first terminal group and the second terminal group have the same number of terminals, the housing containing such terminals will have projecting parts on both ends thereof. Accordingly, if such cell monitor connectors are aligned along the fuel cell stacking direction, and if one cell monitor connector rotates due to an external force, the projecting part of the cell monitor connector may interfere with the projecting part of the adjacent cell monitor connector, which could lead to breakage.

In the preferable mode described above, the number of terminals aligned in the second group is smaller by one than the number of terminals aligned in the first group and the terminals at both ends of the second terminal group are closer to the center part of the housing than the terminals at both ends of the first terminal group. As a result, the formation of projection parts at both ends of the housing can be suppressed and interference and breakage of the adjacent cell monitor connectors can also, accordingly, be suppressed.

It is also preferable for the cell monitor connector according to the present invention to have a retainer which is inserted into the housing and holds the wires, wherein the housing has a recessed part on an outer surface thereof at a portion corresponding to the second terminal group, so that the retainer is fixed to the housing when a lock formed at both ends of the retainer is engaged with the recessed part.

In the above-described preferable mode, the housing has a recessed part on its outer surface at a portion corresponding to both ends of the second through-hole group in which the number of terminals to be arranged is relatively small, and the retainer is fixed by engaging the lock formed at both ends of the retainer with the recessed part. By engaging the lock with the recessed part of the housing, projection of the retainer from the housing can be suppressed and, as a result, checking the connection state between the cell monitor connector and the fuel cell device will be easy and connection can be further ensured.

Effect of the Invention

The present invention can provide a cell monitor connector which can prevent detachment of the cell monitor connector from the fuel cell device, with a simple configuration.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. In the drawings, for ease of understanding, the same elements will be given the same reference numerals wherever possible, and any repetitive descriptions will be omitted.

First, a fuel cell device according to an embodiment of the present invention will be described with reference toFIGS. 1 and 2.FIG. 1is a front view of a fuel cell device1according to an embodiment of the present invention andFIG. 2is a schematic view of such fuel cell device1according to an embodiment of the present invention.

As shown inFIG. 1, the fuel cell device1which is formed of a plurality of fuel cells2has a substantially square outer shape when seen in a front view. A connector4for measuring the voltage of the fuel cells2is electrically connected to an end of the fuel cell device1and such end corresponds to a corner of the square.

As shown inFIG. 2, the fuel cell device1is formed by continuously connecting a plurality of fuel cell stacks11in the Z-direction (stacking direction). Each fuel cell stack11is formed by stacking twelve fuel cells2, each having the same form, in the Z-direction (stacking direction) (the fuel cells2in the middle part of the fuel cell stack are not shown inFIG. 2). Each fuel cell2is formed of, for example, an electrolyte, for example, a membrane-electrode assembly (hereinafter referred to as an “MEA”)30, and a pair of separators21(one separator is denoted by21L and the other by21R inFIG. 2) that sandwich the MEA30. The MEA and the separators21L and21R are each formed in an approximately rectangular planar shape. The MEA30is formed such that the outer shape thereof is smaller than the outer shape of the separators21L and21R.

The MEA30is comprised of a polymer electrolyte membrane (hereinafter also simply referred to as an electrolyte membrane)31which is made of a polymer material ion-exchange membrane, and a pair of electrodes (diffusion electrodes on the anode and the cathode) which sandwich the electrolyte membrane31. The electrolyte membrane31is formed so as to be larger in size than each of the electrodes. Each electrode is bonded to the electrolyte membrane31in accordance with, for example, hot pressing, while leaving the peripheral portion of the electrolyte membrane31.

Each electrode that constitutes the MEA30is formed of, for example, a porous carbon material (diffusion layer) having a catalyst of, for example, platinum attached to the surface thereof. Hydrogen gas serving as a fuel gas (reactant gas) is supplied to one of the electrodes (anode), while an oxidizing gas (reactant gas) such as air or an oxidant is supplied to the other electrode (cathode), and these two reactant gases cause an electrochemical reaction within the MEA30so that electromotive force can be obtained from the fuel cells2.

The separator21is formed of a gas-impermeable conductive material. Examples of the conductive material include carbon, conductive hard resins and metals such as aluminum and stainless steel. The base material of the separator21in the present embodiment is a metal plate, and a film with excellent corrosion resistance (e.g., metal-plated coating) is formed on a surface of the base material facing the electrode.

A groove-like flow path formed of a plurality of recessed parts is provided on both sides of the separator21. Such flow path can be made, for example, by way of pressing if the base material of the separator is a metal plate as in the separator21of the present embodiment. The groove-like flow path formed in this manner provides an oxidizing gas flow path34, a hydrogen gas flow path35and a cooling water flow path36. More specifically, a plurality of hydrogen gas flow paths35is provided on the inner side, i.e., the electrode side of the separator21R, while a plurality of cooling water flow paths36is provided on the back side (outer side). Similarly, a plurality of oxidizing gas flow paths34is provided on the inner side, i.e., the electrode side of the separator21L, while a plurality of cooling water flow paths36is provided on the back side (outer side). The present embodiment is configured such that, when the outer surface of the separator21L of one of the two adjacent cells2,2comes into contact with the outer surface of the separator21R of the other (adjacent) cell2, the cooling water flow paths36of the two cells together form flow paths having a rectangular cross-section.

A first gasket231and a second gasket232are provided between the separators21L and21R which constitute the fuel cell2, so as to separate the flow paths formed in the fuel cell2. Further, a third gasket233formed of a plurality of members (e.g., four rectangular small frames and one big frame for creating a fluid flow path) is provided between the respective separators21L and21R of the adjacent fuel cells2,2. This third gasket233is provided so as to be placed in a space between the periphery of the cooling water flow paths36in the separator21L and the periphery of the cooling water flow paths36in the separator21R and serves as a member for sealing the space.

An end21aof the separator21L in the Y-direction is formed so as to project in the Y direction relative to an end of the separator21R. The above-described connector4for measuring the voltage of the fuel cells2is electrically connected to the end21a. More specifically, the connector4has a housing41made of resin, and twelve slits45are formed at an end portion of the housing41at substantially the same pitch as the pitch of the fuel cells2in the stacking direction. The end21aof each separator21L is configured so as to be able to be inserted into each slit45. Further, eleven metal terminals6are provided inside the housing41. The respective terminals6are arranged in eleven of the twelve slits45formed in the housing41so as to be exposed from inside the housing41. When the end21aof the separator21L is inserted into each slit45, the end21ais held by the terminal6, thereby establishing an electric connection between the connector4and the fuel cell device1. A wire51or wire52, being an electric cable extending to another electrical part, is connected to each terminal. The voltage of the fuel cell2is measured using such electrical part.

Next, the details of the connector4and the connected state of the connector4with the fuel cell device1will be described with reference toFIGS. 3 and 4.FIG. 3is a perspective view of the A-part inFIG. 1andFIG. 4is a perspective view of the connector4according to an embodiment of the present invention.

The details of the connector4will be described first. As shown inFIG. 3, the housing41of the connector4is comprised of: a body42; a fixation part43provided at one end of the body42; and a connection part44provided at the other end of the body42, and these parts are integrally formed of a resin material. The outer shape of the housing41is approximately U-shaped when seen in a front view.

Provided inside the body42of the housing41are eleven terminals6which are made of metal (for simplicity, the terminals6are just briefly shown inFIG. 4). The eleven terminals6are composed of a first terminal group61and a second terminal group62. The first terminal group61is a group of six terminals6arranged on a first line L1extending in the stacking direction (the Z-direction) of the fuel cells2with spaces therebetween, while the second terminal group62is a group of five terminals6arranged on a second line L2which is substantially parallel to the first line L1, with spaces therebetween. In other words, the eleven terminals6are arranged in two lines and the number of terminals6in the second terminal group62, positioned on the upper side inFIG. 3, is smaller by one than the number of terminals6in the first terminal group61. It should be noted that a retainer7is arranged inside the body42as a separate member from the body42, and an engagement hole42a2(recessed part) is formed on the front-side wall of the body42. The detailed configuration of such retainer and engagement hole will be described later.

At one end in the Y-direction of the body42, eleven wires51,52are inserted and electrically connected to the respective terminals6inside the body42. More specifically, six wires51to be connected to the first terminal group61are aligned at positions corresponding to the terminals6in the first terminal group61, while five wires52to be connected to the second terminal group62are aligned at positions corresponding to the terminals6in the second terminal group62. With this arrangement, the eleven wires51,52also form a first group510of wires arranged in a line and a second group520of wires arranged substantially parallel to the first wire group510. The terminals6connected to the wires52L and52R located at both ends of the second wire group520are positioned closer to the center part of the housing41in the Z direction than the terminals6connected to the wires51L and51R located at both ends of the first wire group510.

The fixation part43is formed below the wires51and52of the body42. Furthermore, as shown inFIG. 4, a fixation hook48is provided on an outer surface of the body42close to the fixation part43, such that it projects toward the fixation part43. The fixation hook48is configured such that, due to the elasticity of the resin material forming the housing41, the fixation hook48can be displaced within a predetermined range in the X direction, upon application of external force. As explained later, the fixation hook48and the fixation part43contribute to preventing detachment of the connector4from the fuel cell device1.

As shown inFIGS. 3 and 4, the connection part44is formed at the opposite end of the body42from the fixation part43. Twelve slits45are formed in the connection part44with substantially the same pitch as the pitch of the fuel cells2in the stacking direction (the Z-direction). The end21aof the separator21L constituting the fuel cell2can be inserted into each slit45(for simplicity, only a single fuel cell2is shown inFIG. 3). A pair of ribs46L and46R is formed at both ends of the connection part44in the Z-direction so as to project in a direction perpendicular to the Z-direction (i.e., projecting in a direction perpendicular to the stacking direction of the fuel cells2).

Next, the state in which the connector4has been connected to the fuel cell device1will be described in detail. The connector4is connected by way of the process of pressing the connector4in the Y-direction into an end of the fuel cell device1. More specifically, as shown inFIG. 3, the connector4is pressed into the fuel cell device1so that the ends231aof the twelve first gaskets231of the fuel cells2are inserted respectively into the twelve slits45of the housing41. As a result, each of the paired ribs46L and46R of the housing41is positioned so as to project toward the end231aof the first gasket231of the fuel cell2, the end231abeing formed by extending a part of an end of the first gasket231.

Furthermore, the body42and the fixation part43of the housing41are arranged so that a projecting piece22which is formed at an end of the fuel cell2can be placed between the body42and the fixation part43. A groove22ais formed on the upper part of the projecting piece22so as to be recessed downward. When the connector4is pressed into the fuel cell device1in the Y direction for connection, the fixation hook48provided in the body42interferes with the tip of the projecting piece22, is displaced in the X direction, and then returns to the original position so as to enter the groove22a. In other words, the fixation part48and the groove22aserve as a snap-fit structure and their engagement can provide a simple structure for preventing detachment of the connector4.

Next, the situation in which an external force is applied to rotate the connector4will be described with reference toFIG. 5.FIG. 5is a front view of the A-part shown inFIG. 1where the connector4is rotated.

As described above, under the situation in which the connector4is connected to the fuel cells2, the end21aof each separator21is inserted into each slit45of the connector4. Accordingly, if an external force is applied to the connector4, movement of the connector4in the Z-direction will be restricted by the end21a, but the connector4can move in the X-direction and the Y-direction along the end21a. Furthermore, the connector4can rotate in the direction shown by the arrow R along the end21awith the tip of the projecting piece22as a pivoting point (i.e., the connector4can rotate about an axis parallel to the Z-direction).

If such rotation of the connector4in the direction shown by the arrow R is not restricted in any manner, the rotation will cause the fixation hook48to go out of the groove22aof the projecting piece22, engagement between the fixation hook48and the groove22awill be released, and the connector4will be detached from the fuel cell device1.

In view of the above, the connector4is configured such that, when it rotates in the direction shown by the arrow R, the connection part44of the connector4moves outward of the fuel cells2and the rib46R provided in the connection part44interferes with the end231aof the first gasket231(see the B-part). As a result, the rotation of the connector4can be suppressed and the fixation hook48and the groove22aof the projecting piece22can be kept engaged with each other so that detachment of the connector4can be prevented.

In addition, as described above by referring toFIG. 3, the eleven terminals6provided inside the housing41of the connector4are arranged in two lines, namely, a line of the first terminal group61and a line of the second terminal group62, and the number of terminals6in the second terminal group62, located on the upper side, is smaller by one than the number of terminals6in the first terminal group61. Moreover, the terminals6connected to the wires52L and52R located at both ends of the second wire group520are arranged closer to the center part of the housing41in the Z-direction than the terminals6connected to the wires51L and51R located at both ends of the first wire group510. Accordingly, compared to the case in which the first and second terminal groups61and61have the same number of terminals, projection of the body42of the housing41in the Z-direction can be reduced or eliminated. As a result, in the case where several connectors4are aligned in the stacking direction of the fuel cells2as shown inFIG. 3, if a connector4rotates in the direction shown by the arrow R inFIG. 5due to application of an external force, interference with the adjacent connector4and possible breakage attributable to such interference can be suppressed.

Next, a connector according to another embodiment of the present invention will be described with reference toFIGS. 6 and 7.FIG. 6is a perspective view of a connector4aaccording to another embodiment of the present invention andFIG. 7is a cross-sectional view along the line C-C inFIG. 6. It should be noted that such connector4aaccording to another embodiment of the present invention is a modification of the above-described connector4in which the configuration of the body42of the housing41has been changed. Accordingly, the connector4awill be described below with regard to such difference, and other explanations will be omitted.

As shown inFIG. 6, the connector4ahas a retainer7which is to be arranged inside the body42a, as a separate member from the body42a.

The retainer7is a member formed of resin with a plate-like outer shape, and has six through-holes71and five through-holes72extending therethrough in its thickness direction (the Y-direction). The six through-holes71are aligned in the Z-direction, with a through-hole71L at one end and a through-hole71R at the other end. The five through-holes72are positioned above the six through-holes71and aligned in the Z-direction, with a through-hole72L at one end and a through-hole72R at the other end. The through-holes72L and72R located at both ends of the five through-holes72are positioned closer to the center part of the retainer7in the Z-direction than the through-holes71L and71R located at both ends of the six through-holes71.

Plate-like arms73L and73R are provided at both ends in the Z-direction of the retainer7and extend obliquely downward from the upper end of the retainer7. At the lower end of each arm73L,73R, an engagement hook (lock)74L,74R is formed so as to project upward. The arms73L and73R each have a thickness which allows the arm to bend in the Z-direction due to its elasticity, and upon bending of the arms73L and73R, the engagement hooks74L and74R can be displaced in the Z-direction.

Meanwhile, a slit-like insertion hole42a1is formed at the upper end of the body42asuch that the longitudinal side of the hole extends in the Z-direction. On both end surfaces in the Z-direction of the body42a, engagement holes (recessed parts)42a2,42a2are formed at the positions corresponding to the position of the second terminal group62(not shown inFIG. 6) in the X-direction (InFIG. 6, the engagement hole42a2formed on the end surface at the back side in the drawing is not shown). Moreover, a slit-like insertion hole42a3for the first wire group and a slit-like insertion hole42a4for the second wire group are formed at one end in the Y-direction of the body42asuch that the longitudinal side of each hole extends in the Z-direction. The insertion hole42a1, engagement holes42a2,42a2, first wire group insertion hole42a3and second wire group insertion hole42a4are all in communication with the interior of the body42a.

When pressing the retainer7into the insertion hole42a1so as to place the retainer7inside the body42a, the engagement hooks74L and74R are first brought into contact with an end of the insertion hole42a1so that the arms73L and73R bend in the Z-direction. Due to this the engagement hooks74L and74R are displaced in the Z-direction toward the center part of the retainer7and, as a result, the outer dimension of the retainer7in the Z-direction is reduced so as to thereby allow the insertion of the retainer7.

As shown inFIG. 7, when the retainer7has been inserted so that the lower end thereof reaches the inner surface of the body42a, the engagement hooks74L and74R fit into the engagement holes42a2,42a2. As a result, the bended arms73L and73R move outward of the body42aand return to the original position, thereby achieving the engagement between the engagement hooks74L and74R and the engagement holes42a2,42a2.

When the retainer7is placed inside the body42a, the first wire group insertion hole42a3of the body42ais in communication with the six through-holes71of the retainer7and the second wire group insertion hole42a4of the body42ais in communication with the five through-holes72of the retainer7. Here, the first wire group insertion hole42a3is in communication with the through-holes71so as to be slightly offset in the X-direction and the second wire group insertion hole42a4is in communication with the through-holes72so as to be slightly offset in the X-direction. Accordingly, six wires51of the first wire group510which are inserted through the first wire group insertion hole42a3and the insertion holes71are sandwiched by the respective inner surfaces of the first wire group insertion hole42a3and the insertion holes71, and are held so that the wires do not drop off the body42a. Similarly, five wires52of the second wire group520which are inserted through the second wire group insertion hole42a4and the insertion holes72are also sandwiched by the respective inner surfaces of the second wire group insertion hole42a4and the insertion holes72, and are held so that the wires do not drop off the body42a.

By engaging the engagement hooks (locks)74L and74R with the engagement holes (recessed parts)42a2,42a2of the housing41ain this manner, projection of the retainer7from the housing41acan be suppressed. As a result, checking the connection state between the connector4aand the fuel cell device1will be easy and connection can be further ensured.

Embodiments of the present invention have been described above by referring to specific examples. However, the present invention is not limited to those specific examples. In other words, modifications of those examples, which will be made by a person skilled in the art as appropriate, are also included in the scope of the present invention as long as they have the features of the present invention. For example, each element in the above-described specific examples and the arrangement, materials, conditions, shapes, dimensions, etc., of such element are not limited to those described above and may be modified as appropriate. In addition, each element included in each of the above-described embodiments may be combined as long as such combination is technically possible and such combination is also included in the scope of the present invention as long as it has the features of the present invention.

DESCRIPTION OF REFERENCE NUMERALS