Note: Descriptions are shown in the official language in which they were submitted.
CA 02564237 2007-05-17
79225-7(D)
RESILIENT SEALS BETWEEN SEPARATOR PLATES IN A FUEL CELL STACK
This is a divisional of Canadian paterit
application 2,369,182 filed January 25, 2002.
EACK_ GI~OUND C) F' THE I1~'\iE1q TICiI~
Fjelcl of tlie Inr,eiition
Tlie present iMiention relates to a solid polymer electrolyte niembrane type
fuel
cell, and a fuel cell stack constituted by stac:hulg a plurality of said fuel
cell units, and
m.ore specifically relates to a techuique effective in absorbiiig increase and
decl-ease in
the stacking direction of separators.
Description of the Related Art
Fuel cells include a solid polymer electrolyte membrane type fuel cell
constituted by providi.ng a pair of electrodes on opposite sides of the solid
polymer
electrolyte inembrane and sandwiching the oiitside thereof by a pair of
separators.
In this fuel cell, a charuael for a fuel gas (for example hydroger,.) is
prm,ided on
the -whole surface of a separator provi.ded facing one electrode, a channel
for an oxidant
gas.(for example air including oxygtm) is provided on the u,hole surface of a
separator
pro~~ided faci]:zg the otlier electrode, and a claanziel for a coolizig
znedium is provided on
either one of the surface of separators opposite to a surface facii-ig the
electrode.--.
-W11en the fuel gas is supplied to the reaction surfacc of one elcctrode,
l~ydrogel~
i: i.oni~ed, and inoves to the oth.er eJectrode ~,ia tl~e solid polym.er
electrol~~e niemlkanP.
F1CClrORS nPl1 rated durimg the , eaction proCP;S 3re'~al:_e)1 OUl to aD
e);tPllia; c1Tcult, arid
a]-e us ~ as dire currel,t elsctric ener~~,
riT~~ O :ia11f ~2s ls {
~. ! 7
'0 r i0=1 l!1
CA 02564237 2006-11-06
2
electrons and the oxygen react with each other to thereby generate water.
The surface on the opposite side of the electrode reaction plane of the
separator
is cooled by the cooling medium flowing between the separators.
Since these reactant gas and cooling medium should flow in respectively
independent channels, a sealing technique, which separates each channel, is
important.
The portions to be sealed include; the peripheries of communication holes
formed penetrating through the separator so as to distribute and supply the
reactant gas
and the cooling medium to each fuel cell unit in the fuel cell stack, the
outer peripheries
of membrane electrode assembly formed of the solid polymer electrolyte
membrane and
a pair of electrodes arranged on opposite sides thereof, the outer peripheries
of a coolant
passage plane of the separator, and the outer peripheries of front and back
faces of the
separator. As the sealing material, a elastic and, adequately resilient
material, for
example, an organic rubber, is adopted.
In the case where the fuel cells are stacked in a plurality of numbers to
construct the fuel cell stack, and this fuel cell stack is mounted in a
vehicle, there may be
a case where drops of water splash and the fuel cell becomes wet, depending on
the
installed position, or dust enters into the gap between separators.
However, the sealing material can prevent such water and dust from entering
into the reactant gas channel or into the cooling medium channel.
At the time of stacking the separators, if there is a difference in thickness
between the membrane electrode assembly, or if there is bending or distortion
in the
separator (particularly, in a thin separator made of metal), or if the
compressive load
applied from the opposite ends of the fuel cell stack is non-uniform, the
separators are
not stacked parallel with each other, and inclination or warp occurs. Hence,
the
compression amount of each sealing material becomes unequal, and as a result,
CA 02564237 2006-11-06
3
sealability deteriorates in sealing material having a small amount of
compression.
At the time of stacking the separators, it is also difficult to stack these
separators accurately without shifting their relative positions along the
electrode reactioii
plane.
As measures against the above problems, there can be considered a method in
which foreign substance is prevented from entering into the gap between the
separators,
and the separators are stacked parallel with each other, by providing, for
example, a
picture frame-shaped member made of resin, at the outer edge of the separator.
Techniques similar to this are disclosed in, for example, Japanese Unexamined
Patent Application, First Publication Nos. Hei 10-74530, Hei 7-249417 and Sho
61-279069.
However, if the sealing material or the membrane electrode assembly shrinks in
the stacking direction of the separators due to deterioration with the lapse
of time, or the
fuel cell expands or contracts due to the influence of heat or the like, the
following
problems will occur.
For example, when the protruding height of the sealing material from the
separator becomes lower than the protruding height of the picture franle-
shaped member,
shrinkage of the space between separators is restricted by the picture frame-
shaped
member. Hence, a gap may be caused between the separator and the sealing
material or
the membrane electrode assembly, thereby causing a decrease in the power
generation
performance, and consequently causing a situation where power generation is
not
possible.
On the other hand, if the space between separators expands due to the
influence
of heat or the like, a sealing material such as a rubber will be resiliently
restored and
extend in the stacking direction of the separators, and hence, this sealing
material can
CA 02564237 2006-11-06
4
follow the expansion of the space between separators without separating from
the
separator, to some extent. A picture frame-shaped member made of resin or the
like,
however, since this does not expand in the stacking direction of the
separators, this
cannot accommodate the expansion of the space between separators.
Therefore, a gap occurs between the picture frame-shaped members, and
foreign substance may enter there.
Moreover, it is desired to prevent a liquid connection by the cooling medium,
which causes an electric current flowing through the cooling medium, and it is
also
necessary to prevent adjacent separators in the reactant gas channel from
being
electrically short circuited.
Particularly, in the case of a fuel cell using thin metal separators, since
the space
between separators is small, it is particularly desired to specially take
measures to
prevent electrical short circuited from occurring between adjacent separators,
taking into
account that foreign substance such as dust and carbon particles become mixed
in the
reactant gas.
SUMMARY OF THE INVENTION
In order solve above-described problems, the fuel cell of the present
invention
is constituted as follows.
According to the first aspect of the present invention, a fuel cell comprising
a
pair of separators which clamp outsides of a pair of electrodes (for example,
electrodes 9
in the embodiment) provided on both sides of a solid polymer electrolyte
membrane
[film] (for example, the solid polymer electrolyte membrane [film] 7 in the
embodiment),
wherein the fuel cell further comprises a nonconductive picture frame-shaped
member
(for example, picture frame-shaped members 61, 81, 91, 101, 121, 131, 141, 251
and
CA 02564237 2006-11-06
79225-7
261 in the embodiments) which allows increasing and decreasing of a space
between
separators, while sealing the gap between separators, is provided at the outer
edge of
said separator, the picture frame-shaped member being made of an elastic
material and the
picture fraine-shaped member being disposed on both sides of each of the
separators.
According to this construction, with respect to a movement increasing the
space
between separators, a gap is not produced between the separator and the
picture
frame-shaped member, and furthermore, with respect to a movement narrowing the
space between separators, this movement is not restricted by the picture frame-
shaped
member.
According to the second aspect of the present invention, in a fuel cell
according
to the first aspect, said picture frame-shaped members (for example, picture
frame-shaped members 101, 111, 121, 131 in the embodiments) are constituted so
as to
be able to slide relative to each other.
According to the above construction, the width of the space between separators
can be mechanically adjusted by relative sliding movement of the picture frame-
shaped
members.
Accordii7g to the third aspect of the present invention, in the fuel cell
according
to the first aspect, said separator is made of a metal, and said picture frame-
shaped
member (for example, picture frame-shaped members 61, 81, 91, 261 in the
embodiments) is formed of a hard material (for example, main body portions 61
a, 81 a,
91 a, and 261a in the embodiment) and a elastic material (increase and
decrease
absorbing portions 61 b, 81 b, 91 b, and 261. b in the embodiment).
According to the above construction, since the elastic material is capable of
elastically contracting in the stacking direction of the fuel cell, separators
are not limited
in access to each other.
The expansion of spaces between separators in proximity can be accommodated
CA 02564237 2006-11-06
6
by the elastic material due to resilient contraction thereof in the stacking
direction.
According to the fourth aspect of the present invention, in the fuel cell
according to the first aspect, said picture frame-shaped member comprises a
separator
positioning device (for example, a combination of a concave portion 123 and a
convex
portion 125, a combination of an end surface 131 A and an end surface 131 B,
and a
combination of a grooved portion with a triangular cross-section 143 and a
protruded
portion 145 with a triangular cross-section 145 in the embodiments).
According to the above construction, it is possible to prevent relative
misalignment between separators that may occur when the separators are
stacked.
According to the fifth aspect of the present invention, in the fuel cell
according
to the first aspect, the outer peripheries of the separators are covered with
the picture
frame-shaped members (for example, picture frame-shaped members 61, 81, 91,
101,
111, 121, 131, 141, 251, and 261 in the embodiments).
According to the above structure, it is possible to prevent adjacent
separators
from being short circuited.
According to the sixth aspect of the present invention, in the fuel cell
according
to the fifth aspect, an reaction surface peripheral sealing member (for
example, the
peripheral sealing member 52 in the embodiment) is provided for covering the
reaction
surfaces of separators and the outside portion of the reaction surface
peripheral sealing
member is totally covered by an insulating outer edge member (for example, an
increase
and decrease absorbing portion 261 b in the embodiment) is provided around a
communication hole formed in the separator.
According to the above structure, since the exposed metal surface outside of
the
reaction surface peripheral sealing member of the separators is totally
covered by the
insulating outer surface member, the corrosion resistance of the separators is
improved
CA 02564237 2006-11-06
/9225-7
7
and the electrical short circuiting between separators can be effectively
prevented.
According to the seventh aspect of the present invention, in the fuel cell
according to the sixth aspect, the outermost portion of the separator
is totally covered by an insulating outer peripheral member
(for example, increase and decrease absorbing member 261b),
which is integrally constructed with the reaction surface peripheral
sealing member.
According to the above construction, since the exposed metal surfaces at the
outer area of both surfaces at the peripheral area of the reaction surface
peripheral
sealing member exposed outside of the reaction outer surface sealing member
are totally
covered by the insulating outer surface member, it is possible for separators
to be more
resistant to corrosion, and to short circuiting between adjacent separators.
According to the eighth aspect of the present invention, in the fuel cell
according to the seventh aspect, one of the reaction surface peripheral
sealing member of
adjacent separators is formed in a flat shape, and the other reaction surface
peripheral
sealing member which faces to the flat reaction surface peripheral sealing
member is
formed so as to protrude.
According to the above construction, since outer surfaces of the reaction
surface
peripheral sealing members are formed in combination of flat and protruded
areas, so
that the relative misalignment of the flat surface of an reaction surface
peripheral sealing
member can be absorbed by the protruded surface of the other reaction surface
peripheral sealing member.
According to the ninth aspect of the present invention, in the fuel cell stack
according to the eighth aspect, which is constituted by a plurality of stacked
[stackd] fuel
cell units, the picture frame-shaped members allow expansion or contraction of
spaces
CA 02564237 2007-07-31
79225-7D
8
between separators, while sealing the space between
respective separators.
According to the above construction, for not only
a single fuel cell but also for a plurality of adjacent fuel
cells, it is possible to prohibit generating a space between
a separator and the picture frame-shape member, and
contraction of the space between separators is not
prohibited by the picture frame-shape member.
According to the tenth aspect of the present
invention, a fuel cell comprising: a pair of separators
sandwiching a pair of electrodes formed on both surfaces of
a solid polymer electrolyte membrane; and insulating members
around communication holes formed in said separators, so as
to form a space between the insulating members on adjacent
separators each insulating member covering an inner
peripheral surface and inner peripheral end surface of the
communication holes.
According to the above construction, it is
possible to prevent liquid connection by the cooling medium
and to prevent short circuiting between adjacent separators
in the reactant gas channel.
According to the eleventh aspect of the present
invention, in the fuel cell according to the tenth aspect,
respective spaces (for example, the space 203 in the
embodiment) are provided between each two insulating members
of the adjacent separators (for example, insulating
member 201 in the embodiment) in the stacking direction of
the separators.
CA 02564237 2007-07-31
79225-7D
8a
According to the above construction, the increase
and decrease of the separator spaces can be absorbed by the
gap in the stacking direction of separators.
CA 02564237 2006-11-06
9
According to the twelfth aspect of the present invention, in the fuel cell
according to the tenth aspect, each insulating member (for example, the
insulating
member 201 in the embodiment) of respective adjacent separators is formed such
that
adjacent separators are capable of relatively sliding to allow increase and
decrease of the
space between separators while the insulating members are sealing the spaces
between
separators.
According to the above construction, increase and decrease of the separator
spaces can be mechanically absorbed by relative sliding of respective
insulating
members.
According to the thirteenth aspect of the present invention, in the fuel cell
according to the tenth aspect, the insulating members (for example, the
insulating
member 231 and 241 in the embodiments) are made of elastic material.
According to the above construction, contraction of the separator spaces are
not
regulated because the soft material is capable of resiliently contracting in
the stacking
direction of the fuel cells, and expansion of the separator space can be
followed by the
resilient restoration of the elastic material due to resilient elongation of
the elastic
material.
According to the fourteenth aspect of the present invention, in the fuel cell
according to the tenth aspect, the inner peripheral surfaces of the
communication holes
are covered by the insulating member (for example, the insulating members 201,
211,
221, 231, 241, and 271 in the embodiments).
According to the above construction, it is possible to prevent short
circuiting
between inner peripheral end faces of the communication holes in the adjacent
separators.
According to the fifteenth aspect of the present invention, in the fuel cell
CA 02564237 2006-11-06
according to the tenth aspect, one of the insulating members of one of the
adjacent
separators (for example, a flat portion 271 b of the insulating member in the
embodiments) is formed in a flat shape, and the insulating member (for
example, a
protruded portion 271a of the insulating member in the embodiments) of one of
insulating members of another separator facing to the former flat insulating
member is
formed so as to protrude.
According to the above construction, provision of a combination of the
insulating members of a separator into flat and protruded areas makes it
possible to
absorb the relative misalignment of the protruded insulating member with
respect to the
flat insulating member.
According to the sixteenth aspect of the present invention, in the fuel cell
according to the fifteenth aspect, provided with a reaction surface peripheral
sealing
member (for example, the peripheral sealing material 52), one of the reaction
surface
peripheral sealing members of adjacent separators (for example, the flat
portion of the
peripheral sealing material 52b in the embodiments) is formed in a flat shape,
and the
other one of the reaction surface peripheral sealing members of the opposing
adjacent
separators is formed so as to protrude.
According to the above construction, since the reaction surface peripheral
sealing members are formed in a combination of flat and protruded areas, the
relative
misalignment of the protruded reaction surface peripheral sealing member
corresponding
to the flat outer reaction surface member cab be absorbed.
According to the seventeenth aspect of the present invention, in the fuel cell
according to the sixteenth aspect, the outside portion of the reaction surface
peripheral
sealing members (the outer peripheral sealing material 52 in the embodiments)
is totally
covered by the insulating member (for example, the insulating member 271 in
the
CA 02564237 2006-11-06
il
embodiment).
According to the above construction, since the exposed metal portion of the
separators at the outside portion of the reaction surface peripheral sealing
member are
totally covered by the insulators, it is possible to improve the corrosion
resistance of the
separators and it is possible to prevent adjacent separators from being
electrically short
circuited.
According to the eighteenth aspect of the present invention, in the fuel cell
according to the seventeenth aspect, the reaction surface peripheral sealing
member (for
example, the peripheral sealing member 52 in the embodiments) and the
insulating
member (for example, the insulating member 271 in the embodiment) are
integrally
constituted.
According the above construction, it is possible to form the reaction surface
peripheral sealing member and the insulating member can be integrally formed
therewith.
According to the nineteenth aspect of the present invention, in the fuel cell
according to the sixteenth aspect, both outside surfaces of the reaction
surface peripheral
sealing member (for example, the outer surface sealing member 52 in the
embodiments)
are covered by the insulating outer peripheral member (for example, the
insulating
member 271 in the embodiments) constituted integrally with the reaction
surface
peripheral sealing member.
According to the above construction, since both surfaces of the exposed metal
surfaces at the outside portion of the reaction surface peripheral sealing
member are
covered by the insulating members, the corrosion resistance of separators is
improved
and the electrical short circuiting between adjacent separators can be
avoided.
CA 02564237 2006-11-06
79225-7 (D)
lla
In a broad aspect, the invention provides a fuel
cell comprising a pair of separators sandwiching a pair of
electrodes formed on both surfaces of a solid polymer
electrolyte membrane, insulating members are provided around
communication holes formed in said separators, so as to form
each space between each two insulating members.
CA 02564237 2006-11-06
12
BRIEF DESCRIPTION OF THE DRAWINGS
Fig.. 1 is a plan view showing a separator of a solid polymer electrolyte
membrane [film] type fuel cell according to a first embodiment of the present
invention.
Fig. 2 is a cross-section obtained by sectioning a fuel cell stack formed by
stacking a plurality of solid polymer electrolyte membrane [film] fuel cells
comprising
the separators in Fig. 1, at a position corresponding to line A-A in Fig. 1.
Fig. 3A is a cross-section showing the main parts of a modification example of
the first embodiment, and Fig. 3B is a cross-section along line B-B in Fig.
3A.
Fig. 4 is a cross-section showing the main parts of another modification
example in the first embodiment.
Fig. 5 is a cross-section showing the main parts of a second embodiment of the
present invention.
Fig. 6 is a cross-section showing the main parts of a modification example of
the second embodiment.
Fig. 7 is a cross-section showing the main parts of another modification
example in the second embodiment.
Fig. 8 is a cross-section showing the main parts of a third embodiment of the
present invention.
Fig. 9 is a cross-section showing the main parts of a modification example of
the third embodiment.
Fig. 10 is a cross-section showing the main parts of another modification
example in the third embodiment.
Fig. 11 is a cross-section showing the main parts of a fourth embodiment of
the
present invention.
Fig. 12 is a cross-section showing the main parts of a modification example of
CA 02564237 2006-11-06
13
the fourth embodiment.
Fig. 13 is a cross-section showing the main parts of another modification
example in the fourth embodiment.
Fig. 14 is a cross-section showing the main parts of a fifth embodiment of the
present invention.
Fig. 15 is a cross-section showing the main parts of a modification example of
the fifth embodiment.
Fig. 16 is a cross-section showing the main parts of a sixth embodiment of the
present invention.
Fig. 17 is a cross-section showing the main parts of a modification example of
the sixth embodiment.
Fig. 18A is a diagram showing main portions of the other modification example
of the first embodiment, and 18B shows a enlarged diagram of the protruded
portion 52a
of the peripheral sealing material.
Fig. 19A is a diagram showing the main portion of the fifth embodiment, and
19B is an enlarged diagram of the protruded portion of the peripheral sealing
material.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with
reference to the attached drawings.
Fig. 1 is a plan view showing a separator 3 constituting a solid polymer
electrolyte membrane [film] type fuel cell I according to a first embodiment.
The fuel cell 1 is constructed by alternately stacking the separators 3 and an
membrane electrode assembly 5 formed by sandwiching [clamping] a solid polymer
electrolyte membrane [film] 7 by a pair of electrodes 9, as shown in Fig. 2,
and a fuel
CA 02564237 2006-11-06
14
cell stack is formed by stacking a plurality of unit fuel cells 1.
As shown in Fig. 1, the separator 3 comprises a corrugated sheet portion 33 in
which a plurality of concave portions 31 having a certain height are formed at
a certain
pitch by press molding a stainless steel plate material having a plate
thickness of from
0.2 to 0.5 mm, and a plane portion 35 for mutually contacting edge portions
located
outside of each corrugated sheet portion 33 through a sealing material.
This separator 3 is provided with an inlet side oxidant gas communication hole
41 a for passing an oxidant gas therethrough and an inlet side fuel gas
communication
hole 42a for passing a fuel gas therethrough, on the upper side at opposite
ends in the
horizontal direction located at the outer peripheral portion in that plane.
The separator
3 is further provided, at the center at opposite ends in the horizontal
direction, with an
inlet side cooling medium communication hole 43a for passing a cooling medium
therethrough, and an outlet side cooling medium communication hole 43b for
passing
the used cooling medium therethrough.
There are also provided in the separator 3 an outlet side oxidant gas
communication hole 41b for passing the oxidant gas therethrough and an outlet
side fuel
gas communication hole 42b for passing the fuel gas therethrough, on the lower
side at
opposite ends in the horizontal direction located at the outer peripheral
portion in that
plane, so that these are at diagonally opposite positions with respect to the
inlet side
oxidant gas communication hole 41 a and the inlet side fuel gas communication
hole 42a,
respectively.
In the separator 3 on a cathode side shown in Fig. 1, the oxidant gas flows in
from the inlet side oxidant gas communication hole 41 a, and then flows into
each
concave portion 31 in the corrugated sheet portion 33, to be directed from one
short edge
side of the separator towards the other short edge side thereof, and flows out
from the
CA 02564237 2006-11-06
outlet side oxidant gas communication hole 41 b.
Similarly, in the separator 3 on an anode side (the plan view is not shown),
the
fuel gas flows in from the inlet side fuel gas communication hole 42a, and
then flows
into each concave portion 31 in the corrugated sheet portion 33, to be
directed from one
short edge side of the separator towards the other short edge side thereof,
and flows out
from the outlet side fuel gas communication hole 42b.
The above described inlet side oxidant gas communication hole 41 a, inlet side
fuel gas communication hole 42a, inlet side cooling medium communication hole
43a,
outlet side oxidant gas communication hole 41b, outlet side fuel gas
communication hole
42b and outlet side cooling medium communication hole 43b respectively
correspond to
communication holes according to the present invention.
On the front face and the back face of the separator 3, there are arranged a
first
sealing material 51 surrounding the outside of the corrugated sheet portion
33, the inlet
side oxidant gas communication hole 41 a, the outlet side oxidant gas
communication
hole 41 b, the inlet side fuel gas communication hole 42a, and the outlet side
fuel gas
communication hole 42b, and a second sealing material 53 surrounding the
outside of
the inlet side cooling medium communication hole 43a and the outlet side
cooling
medium communication hole 43b.
Here, the corrugated portion 33 is a portion corresponding to the reaction
surface of the separator, and, among sealing materials, the outer peripheral
sealing
material 52 surrounding the portion corresponding to the outer periphery of
the
corrugated portion 33 corresponds to the reaction surface peripheral sealing
member.
Note that the sealing material is removed in order to inflow or outflow the
oxidizing gas at portions adjacent to the inlet side oxidant gas communication
hole 41 a
and the outlet side oxidant gas communication hole 41b. Similarly, in the
anode side of
CA 02564237 2006-11-06
16
the separator (iiot shown in the plan view), the sealing material is also
removed at
portions adjacent to the inlet side fuel gas communication hole 42a and the
outlet side
fuel gas communication hole 42b.
Moreover, a nonconductive picture frame-shaped member 61 covering the outer
periphery and the outer end face of the whole periphery is arranged at the
outer edge
por-tion of the separator 3.
This picture frame-shaped member 61, as shown in Fig. 2, is constituted by a
body portion 61 a having a rectangular section comprising a hard resin
material, such as
polyamide or PTFE, and a increase and decrease absorbing portion 61 b
(hereinafter
referred to as a flexible absorbing portion) having a trapezoidal section
comprising a
material softer than the body portion 61a and having resilience, for example,
a foam
material such as rubber.
A border plane 61 A between the body portion 61 a and the flexible absorbing
portion 61 b, and an upper end face 61 bA of the flexible absorbing portion 61
b are set at
a lower position than upper end faces 51 A and 53A of the first and second
sealing
materials 51 and 53, and the difference of elevation between the upper end
face 61 bA
and the upper end faces 51A and 53A is set less than a compression margin of
the first
and second sealing materials 51 and 53.
The compression margin means a crushing margin at the time of crushing the
first and second sealing materials 51 and 53 when stacking the separators, so
that a
predetermined seal surface pressure acts on the separator 3.
When a concave portion 31 in a separator 3 constituting one fuel cell 1 and an
other concave portion 31 in a separator 3 constituting an other fuel cell 1
are put together
sequentially, a space having a trapezoidal section shown in the figure formed
between
the concave portion 3 1 of the separator 3 and the electrode 9 becomes an
oxidant gas
CA 02564237 2006-11-06
17
channel 71 for circulating the oxidant gas and a fuel gas channel 73 for
circulating the
fuel gas. The space having a hexagonal section shown in the figure formed
surrounded
by the separators 3 becomes a cooling medium channel 75 for circulating the
cooling
medium.
At the time of stacking the separators, the first and second sealing materials
51
and 53 are crushed by the compression margin, so as to reliably seal the
periphery of
each of the communication holes 41a, 42a, 43a, 41b, 42b, and 43b with a
predetermined
seal surface pressure acting on the separator 3.
At this time, the flexible absorbing portion 61b of the picture frame-shaped
member 61 arranged at the outer edge portion of each separator 3 is also
pressed by the
separator 3 and compressed by a predetermined dimension, more specifically, by
a
difference obtained by subtracting the height difference between the upper end
face
6lbA and the upper end faces 51A and 53A from the compression margin of the
first
and second sealing materials 51 and 53.
Therefore, even if the space between separators expands due to the influence
of
heat or the like, the flexible absorbing portion 61 b of the picture frame-
shaped member
61 is resiliently restored and extends in the stacking direction of the
separators, and
follows the body portion 61a of other picture frame-shaped members 61, which
are apt
to separate from the flexible absorbing portion 61 b.
Hence, even if the space between separators is enlarged, the picture
frame-shaped members 61 being in contact with each other are not separated. As
a
result, foreign substance can be effectively prevented from entering from
outside, and
the durability of the first and second sealing materials 51 and 53 is also
improved.
Since the flexible absorbing portion 61 b is resiliently contractible in the
stacking direction of the separators, relative approach of the separators 3 is
not restricted,
CA 02564237 2006-11-06
18
so long as this is within a resiliently contractible range.
Therefore, even if the first and second sealing materials 51 and 53, or the
membrane electrode assembly 5 deteriorates with the lapse of time and the
height
becomes low, the flexible absorbing portion 61b can contract in the stacking
direction of
the separators to thereby decrease the space between separators. As a result,
the close
contact state of these sealing materials 51, 53 and the membrane electrode
assembly 3
[5] with the separator 3 can be maintained, preventing a decrease in the power
generation performance and a situation that power generation is not possible
Since the picture frame-shaped member 61 is formed of an insulating material,
there is the effect that a short circuiting does not occur, even if the
surface of the fuel cell
stack becomes wet due to water or condensation, and the effect that a short
circuiting
does not occur due to a contact of adjacent separators. Furthermore, since the
outer
peripheral faces of the separator 3 is covered by the insulating material, it
is also
possible to prevent adjacent separators from being short circuited.
Further, the picture frame-shaped member 61 arranged around the whole
periphery of the outer edge portion of the separator 3, particularly the body
portion 61 a
consisting of a hard resin material, functions as a rib for reinforcement.
Hence,
deformation of a thin metal separator 3 can be effectively prevented.
In the case where a thick separator which does not require the reinforcing
function is used instead of this thin metal separator 3, the whole picture
frame-shaped
member 61 may be constituted of a elastic material.
Fig. 3A is a cross-section showing a modification example of the first
embodiment, and Fig. 3B is a cross-section along a line B-B in Fig. 3A.
In the description for this modification example, the same constituents as
those
of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description thereof
CA 02564237 2006-11-06
19
is omitted.
A picture frame-shaped member 81 in this modification example is constructed
such that a flexible absorbing portion 81 b covers a body portion 81 a, and a
drain hole 83
is formed in at least one of the flexible absorbing portions 81 b 1 extending
parallel with
the separator 3.
The body portion 81a and the flexible absorbing portion 81b are constituted
of,
for example, the same material as that of the body portion 61 a and the
flexible absorbing
portion 61 b in Fig. 1.
The drain hole 83 is for discharging excess gas or produced dew condensation
water between separators 3, and is formed curved in an approximate Z-shape as
shown
in Fig. 3B, so as to prevent foreign substance from entering from outside, by
shifting the
position of openings 83a and 83b in the direction of the separator width (in
the vertical
direction in Fig. 3B).
Also with this modification example, since the picture frame-shaped member
81 comprises the flexible absorbing portion 81 b, foreign substance can be
prevented
from entering from outside at the time of enlargement of the space between
separators,
and a deterioration of sealability with deterioration of the sealing material
with the lapse
of time can be prevented, as in the first embodiment.
The picture frame-shaped member 81 may be connected to a second sealing
material 53, as with one arranged on the separator 3 located at the lowest
stage in Fig.
3A.
Fig. 18A is a diagram showing the other modification example of the first
embodiment, and 18B shows a enlarged diagram of the protruded portion 52a of
the
outer peripheral sealing material.
In the explanation of this modification example of the first embodiment, the
CA 02564237 2006-11-06
same constituents as those of Fig. 2 are denoted by the reference symbols and
their
explanations are omitted.
In the picture frame-shaped member 261 according to this modification
example, the flexible absorbing portion 261 b(the insulating outer peripheral
member)
covers the main body portion 261 a, and the both surfaces of the outside
portion of the
outer peripheral sealing material 52 of the separator 3, that is, the front
and rear surfaces
of the outside portion is covered by the flexible absorbing portion 261 b.
Since the
outer peripheral end surface of the separator 3 and the inner edge surface of
respective
communication holes 41a,42a,43a, 41b, 42b, and 43b are covered by the picture
frame-shaped member 261 and the flexible absorbing portion 261b, and the inner
end
surface of respective communication holes 41 a, 42a, 43a, 41 b, 42b, and 43b
are covered
by the flexible absorbing portion 261 b.
These main body portion 261 a and the flexible absorbing portion 261 b are
constituted by the same material as those of the main body portion 61a and the
flexible
absorbing portion 61 b shown in Fig. 2.
In addition, the flexible absorbing portion 261 b is integrally constituted
with the
first sealing material including the peripheral sealing material 52, and also
integrally
constituted with the second sealing material 53.
The peripheral sealing material flat portion 52b of one of adjacent separators
3
is formed in a flat shape, and the peripheral sealing material 52a is formed
in a protruded
shape. Furthermore, the top portion of the protruded peripheral sealing
material is
configured to form an R-shape in cross-section.
According to the construction of this modification example, the flexible
absorbing portion 261 b is capable of elastically contracting in the stacking
direction of
the separators, it is possible, as described in the first embodiment, to
prevent
CA 02564237 2006-11-06
21
containination when the separator space is expanded, and also to prevent
sealing
property of the sealing material due to passage of time.
Sine the outer end surface of the separator 3 and the inner end surfaces of
respective communication holes 41 a, 42a, 43a, 41b, 42b and 43b are covered by
the
picture frame-shaped member, it is possible to prevent the electrical short
circuiting at
the outer end surface of the separator 3 and the inner end surfaces of the
communication
holes 41 a, 42a, 43 a, 41 b, 41 b, and 43 b.
In addition, since the exposed metal surface of the separator 3 at the outside
portion of the peripheral sealing material 52 is totally covered by the
flexible absorbing
portion 261b, it is possible to prevent adjacent separators to be electrically
short
circuited while improving the corrosion resistance.
Furthermore, since the flexible absorbing portion 261b is integrally
constructed
with the first sealing material 51 as well as the second sealing material 53,
it is possible
to form these materials at the same time, which results in reducing the
manufacturing
cost of these components.
In addition, since the peripheral sealing materials 52 are formed in a
combination of a flat shape and a protruded shape, misalignment of the
protruded
portion 52a of the peripheral sealing material 52a with respect to the flat
portion 52b of
the peripheral sealing material 52a can be absorbed, which makes it
unnecessary to
aligning operation of the sealing positions, and which results in increasing
the
productivity.
At the time of stacking separators, the R-shape cross section of the top
portion
of the protruded portion of the peripheral sealing material of one separator
is pressed on
the flat portion of the sealing material of another separator, the sealing is
improved.
Fig. 4 is a cross-section showing another modification example of the first
CA 02564237 2006-11-06
22
embodiment.
In the description of this modification example, the same constituents as
those
of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description thereof
is omitted.
The picture frame-shaped member 91 according to this modification example is
constructed such that a covering margin L 1 of a body portion 91 a which
covers the
reaction plane 3A side of the separator 3 is set to substantially the half of
a covering
margin L2 which covers the cooling plane 3B side, and a flexible absorbing
portion 91 b
is integrated with only the inside edge portion on the cooling plane side of
the body
portion 91 a.
The body portion 91 a and the flexible absorbing portion 91 b are constituted
of,
for example, the same material as that of the body portion 61 a and the
flexible absorbing
portion 61 b in Fig. 1.
Also with this modification example, since the picture frame-shaped member
91 comprises the flexible absorbing portion 91 b, foreign substance can be
prevented
from entering from outside at the time of enlargement of the space between
separators,
and a deterioration of sealing capability with deterioration of the sealing
material with
the lapse of time can be prevented, as in the first embodiment.
Further, the flexible absorbing portion 91 b of the picture frame-shaped
member
91 according to this embodiment has a higher protrusion height from the
separator 3 than
that of the flexible absorbing portion 61 b in the first embodiment. As a
result, an even
greater increase and decrease margin can be acquired, and hence this has
excellent
following ability at the time of enlargement of the space between separators.
A fuel cell according to a second embodiment of the present invention will now
be described.
CA 02564237 2006-11-06
23
Fig. 5 is a cross-section showing the main parts of the fuel cell.
The same constituents as those of Fig. 1 are denoted by the same reference
symbols as in Fig. 1, and description thereof is omitted.
A picture frame-shaped member 101 according to this embodiment has a
different basic construction from that of the first embodiment and the
modification
examples thereof which use elastic deformation to absorb increase and
decrease, in that
increase and decrease in the stacking direction of the separators is absorbed
mechanically.
This picture frame-shaped member 101 has a convex shape in section with a
protruding portion 10 1 a protruding from a base portion 101 b, and the
protruding portion
101 a is arranged so as to face the inside of the fuel cell stack (the right
side in Fig. 5)
and the outside thereof (the left side in Fig. 5) alternately along the
stacking direction of
the separators.
The adjacent two picture frame-shaped members 101 are normally not brought
into contact with each other on a plane 101 B parallel with the separator 3,
but are
brought into contact with each other on a plane 101 A parallel with the
stacking direction
of the separators.
That is to say, a space between separators is provided by the protruding
height
of first and second sealing materials 51 and 53 (in Fig. 5, only the second
sealing
material 53 is shown) from the separator 3. This protruding height is set
larger than the
sum of the protruding height of the protruding portion 101 a and the
protruding height of
the base portion 101 b from the separator 3.
As a result, a gap 103 is formed between the base portion 101 b of one of the
two adjacent picture frame-shaped members 101 and the protruding portion 101 a
of the
other picture frame-shaped member 101.
CA 02564237 2006-11-06
24
According to this construction, the movement of expanding or contracting the
space between separators is absorbed only by enlarging or narrowing the gap
103
between the picture frame-shaped members 101, while the plane 101A of one of
the two
adjacent picture frame-shaped members 101 and the plane 101 A of the other
picture
frame-shaped member 101 slides relative to each other, without separating from
each
other.
Therefore, as in the first embodiment, foreign substance can be prevented from
entering from outside at the time of enlargement of the space between
separators, and a
deterioration of sealability with deterioration of the sealing material with
the lapse of
time can be prevented.
In this embodiment, if taking notice of the adjacent two picture frame-shaped
members 101, since the planes 101B parallel with the separator 3 do not come
in contact
with each other, any load along the stacking direction of the separators does
not occur
between these two picture frame-shaped members 101.
Therefore, the compression load acting on the first and second sealing
materials
51 and 53 does not disperse into the picture frame-shaped member 101, thereby
enabling
effective prevention of a reduction of a seal surface pressure.
Fig. 6 is a cross-section showing a modification example of the second
embodiment.
In the description of this modification example below, the same constituents
as
those of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description
thereof is omitted.
According to a picture frame-shaped member 111 of this modification example,
as in the construction in Fig. 5, a surface I 11A of one of the adjacent
picture
frame-shaped members 111 and a surface 111 A of the other picture frame-shaped
CA 02564237 2006-11-06
members 111 slide relative to each other without separating from each other,
to thereby
enlarge or narrow a gap 113 between picture frame-shaped members 111. As a
result,
as in the second embodiment, intrusion of foreign substance at the time of
enlargement
of the space between separators, a deterioration of sealability with
deterioration of the
sealing material with the lapse of time, and a decrease in the seal surface
pressure can be
prevented.
In this embodiment, from the point that picture frame-shaped members 111
having the same cross-section are arranged at the outer edge portion of each
separator 3
in the same form, the construction is different in to that of the second
embodiment in
which picture frame-shaped members 101 having the same cross-section are
arranged at
the outer edge portion of each separator 3 in a different form, that is, with
the protruding
direction of the protruding portions 101 a alternately changed in the stacking
direction of
the separators.
Hence, in the case where the picture frame-shaped member 111 is integrally
formed at the outer edge portion of the separator 3 by injection molding,
molding is
possible with only one kind of mold, thereby enabling a reduction in
production cost.
Fig. 7 is a cross-section showing another modification example of the second
embodiment.
In the description of this modification example below, the same constituents
as
those of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description
thereof is omitted.
In a picture frame-shaped member 121 according to this modification example,
a concave portion 123 is formed in the end face on the cooling plane 3B side
of the
separator 3, and a convex pot-tion 125 having a shape capable of being fitted
to the
concave portion 123 is protrudingly formed on the end face on the reaction
plane 3A
CA 02564237 2006-11-06
26
side of the separator 3.
According to this construction, increase and decrease can be absorbed by
enlarging or narrowing the gap between the picture frame-shaped members 121,
while
the inner face 123A of the concave portion and the external face 125B of the
convex
portion slide relative to each other parallel with the stacking direction of
the separators,
without separating from each other. Further, since the picture frame-shaped
members
121 having the same cross-section are arranged at the outer edge portion of
each
separator 3 in the same form, intrusion of foreign substance at the time of
enlargement of
the space between separators, a deterioration of sealability with
deterioration of the
sealing material with the lapse of time, and a decrease in the seal surface
pressure can be
prevented, and a reduction in production cost can be realized, as with the
modification
example of Fig. 6.
Moreover, according to the picture frame-shaped member 121 in this
modification example, if the convex portion 125 of the picture frame-shaped
member
121 arranged in one of the adjacent separators 3 is fitted into the concave
portion 123 of
the picture frame-shaped member 121 arranged in the other separator 3, the
relative
position of the separators 3 can be automatically adjusted, thereby enabling
an
improvement of workability at the time of assembly and maintenance.
That is to say, in this modification example, a separator positioning device
according to the present invention is constituted by the concave portion 123
and the
convex portion 125.
A fuel cell according to a third embodiment of the present invention will now
be described.
Fig. 8 is a cross-section showing the main parts of the fuel cell.
The same constituents as those of Fig. 2 are denoted by the same reference
CA 02564237 2006-11-06
27
symbols as in Fig. 2, and description thereof is omitted.
A picture frame-shaped member 131 according to this embodiment has a
bowl-like inclined face with an end face 131A on the cooling plane 3B side of
the
separator 3 and an end face 131B on the reaction plane 3A side of the
separator 3
inclined with respect to the cooling plane 3B and the reaction plane 3A, with
the inner
side down (in the cross-section showing the main part in Fig. 8, the right
side down).
In this embodiment, the separator positioning device is constituted by these
end
faces 131 A and 131 B.
According to this construction, increase and decrease of the space between
separators can be absorbed by relative sliding movement of the end face 131A
of one of
the adjacent picture frame-shaped members 131 and the end face 131 B of the
other
picture frame-shaped member 131, without separating from each other. Moreover,
since picture frame-shaped members 131 with the same cross-section and with
the same
shape are disposed around the outer periphery of the separator 3, the relative
position of
the separators 3 is automatically adjusted. Since the picture frame-shaped
members
131 having the same cross-section are arranged at the outer edge portion of
each
separator 3 in the same form, intrusion of foreign substance at the time of
enlargement of
the space between separators, a deterioration of sealability with
deterioration of the
sealing material with the lapse of time, and a decrease in the seal surface
pressure can be
prevented, and a reduction in production cost and an improvement of
workability at the
time of assembly and maintenance can be realized, as in the modification
example of Fig.
6.
A fuel cell according to a fourth embodiment of the present invention will now
be described.
Fig. 9 is a cross-section showing the main parts of the fuel cell.
CA 02564237 2006-11-06
28
The same constituents as those of Fig. 2 are denoted by the same reference
symbols as in Fig. 2, and description thereof is omitted.
A picture frame-shaped member 141 according to this embodiment is formed of
the same elastic material as that of, for example, the flexible absorbing
member 61 b in
Fig. 1, in the form of feathers of an arrow in cross-section.
In this picture frame-shaped member 141, the separator positioning device is
constituted by a triangular groove 143 in section formed on the end face of
the cooling
plane 3B side and a triangular protruding portion 145 in section formed on the
end face
of the reaction plane 3A side.
According to this construction, the increase and decrease of the space between
separators is absorbed by elastic increase and decrease of the picture frame-
shaped
member 141. Also, if the triangular protruding portion 145 of the picture
frame-shaped
member 141 arranged on one of the adjacent separators 3 in section is fitted
into the
triangular groove 143 in section of the other picture frame-shaped member 141
arranged
in the other separator 3, the relative position of the separators 3 can be
automatically
adjusted, and further, the picture frame-shaped members having the same cross-
section
are arranged at the outer edge portion of each separator 3 in the same form.
As a result,
intrusion of foreign substance at the time of enlargement of the space between
separators,
a deterioration of sealability with deterioration of the sealing material with
the lapse of
time, and a decrease in the seal surface pressure can be prevented, and a
reduction in
production cost and an improvement of workability at the time of assembly and
maintenance can be realized, as in the construction of Fig. 8.
In the above described constructions in which the picture frame-shaped
members 61, 81, 91, 101, 111, 121, 131, and 141 are arranged at the outer edge
portion
of the separator, the outer edge of the separator 3 may be folded to form bent
portions 3a,
CA 02564237 2006-11-06
29
3b and 3c, as shown in Fig. 10.
According to this construction, the bent portions 3a, 3b and 3c function as a
reinforcement rib and a member of preventing disconnection of the picture
frame-shaped
members 61, 81,91,101,111, 121, 131, and 141. As a result, deformation of the
thin
metal separator 3 and disconnection of the picture frame-shaped member 61, 81,
91, 101,
111,121, 131, and 141 can be effectively prevented.
A fuel cell according to a fifth embodiment of the present invention will now
be
described.
Fig. 11 is a cross-section showing the main parts of the fuel cell.
The same constituents as those of Fig. 2 are denoted by the same reference
symbols as in Fig. 2, and description thereof is omitted.
In this fuel cell, an annular insulating material 201 comprising a resin,
rubber or
the like, which cover the inner peripheral surfaces and the inner peripheral
end surfaces,
is arranged around the inlet side oxidant gas communication hole 41 a, the
inlet side fuel
gas communication hole 42a, the inlet side cooling medium communication hole
43a,
the outlet side oxidant gas communication hole 41b, the outlet side fuel gas
communication hole 42b and the outlet side cooling medium communication hole
43b,
formed in the separator 3.
In Fig. 11, only the outlet side fuel gas communication hole 42b is shown.
According to this construction, a liquid connection by the cooling medium
and an electrical short circuiting between adjacent separators in the reactant
gas channel
can be prevented.
Particularly, since a fuel cell according to the present embodiment uses metal
and thin separators, the space between the separators are small, and hence
this has a
disadvantageous structure in preventing an electrical short circuiting between
separators.
CA 02564237 2006-11-06
Therefore, the effect according to this construction is substantial.
Moreover, at the periphery of the communication hole in this thin metal
separator 3, the insulating member 201 functions as a reinforcement rib, and
hence the
deformation thereof can also be effectively prevented.
Furthermore, since the protruding height of the insulating member from the
front and back faces of the separator is set such that the insulating member
201 arranged
on one of the adjacent two separators 3 does not come in contact with the
insulating
member 201 on the other separator 3, that is, a gap 203 is formed between the
insulating
members 201, increase and decrease of the space between separators can be
absorbed by
enlarging or narrowing this gap 203.
Therefore, intrusion of foreign substance at the time of enlargement of the
space
between separators, a deterioration of sealability with deterioration of the
sealing
material with the lapse of time, and a decrease in the seal surface pressure
can be
prevented.
Moreover, insulating members 201 having the same cross-section are arranged
around the communication holes of each separator 3 in the same form.
Therefore,
when the insulating member 201 is integrally formed with the separator 3 by
injection
moldiiig, molding is possible with only one kind of mold, thereby enabling a
reduction
in production cost. -
Fig. 12 and Fig. 13 are cross-sections showing modification examples of the
fifth embodiment.
In the description of this modification example below, the same constituents
as
those of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description
thereof is omitted.
In the modification example of Fig. 12, an annular insulating member 211
CA 02564237 2006-11-06
31
comprising the same material and having the same sectional shape, for example,
as that
of the picture frame-shaped member 101 in Fig. 5, is arranged around each
communication hole 41a, 42a, 43a, 41b, 42b, and 43b. In the modification
example of
Fig. 13, an annular insulating member 221 comprising the same material and
having the
same sectional shape, for example, as that of the picture frame-shaped member
111 in
Fig. 6, is arranged around each communication hole 41a, 42a, 43a, 41b, 42b,
and 43b.
According to these constructions, as with the construction in Fig. 11, a
liquid
connection by the cooling medium and an electrical short circuiting between
adjacent
separators in the reactant gas channel, intrusion of foreign substance at the
time of
enlargement of the space between separators, a deterioration of sealability
with
deterioration of the sealing material with the lapse of time, and a decrease
in the seal
surface pressure can be prevented.
Particularly, in the modification example in Fig. 13, all the insulating
members
221 arranged around the respective communication holes 41a, 42a, 43a, 41b,
42b, and
43b have the same sectional shape. Therefore, when the insulating member 221
is
integrally formed with the separator 3 by injection molding, molding is
possible with
only one kind of mold, thereby enabling a reduction is production cost.
Fig. 14 and Fig. 15 are cross-sections showing other modification examples of
the fifth embodiment.
In the description of this modification example below, the same constituents
as
those of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description
thereof is omitted.
In the modification example of Fig. 14, an annular insulating member 231
comprising the same material and having the same sectional shape, for example,
as that
of the picture frame-shaped member 61 in Fig. 2, is arranged around each
CA 02564237 2006-11-06
32
communication hole 41a, 42a, 43a, 41b, 42b, and 43b. In the modification
example of
Fig. 15, an annular insulating member 241 comprising the same material, for
example,
as that of the flexible absorbing 61 b in Fig. 2, and having a guard portion
241 a at one of
the open ends is arranged around each communication hole 41 a, 42a, 43a, 41 b,
42b, and
43b.
Also according to these construction, as with the construction in Fig. 11, a
liquid connection by the cooling medium and an electrical short circuiting
between
adjacent separators in the reactant gas channel, intrusion of foreign
substance at the time
of enlargement of the space between separators, a deterioration of sealability
with
deterioration of the sealing material with the lapse of time, and a decrease
in the seal
surface pressure can be prevented. Further, the production cost at the time of
integrally
forming the insulating members 231 and 241 with the separator 3 by injection
molding
can be reduced.
A fuel cell according to a sixth embodiment of the present invention will now
be described.
Fig. 19A is a cross-section showing the main parts of the fuel cell, and Fig.
19B
is a enlarged diagram of a protruding portion of the peripheral sealing
material 52a.
In this embodiment, the same constituents as those of Fig. 2 are denoted by
the
same reference symbols as in Fig. 2, and description thereof is omitted.
In this fuel cell, both surfaces of the outside portion of the peripheral
sealing
material 52, that is the front and rear surfaces of the outside portion is
totally covered by
the insulating material 271. In addition, the outer peripheral end surface of
the
separator 3 and the inner peripheral end surfaces of respective communication
holes 41 a,
42a, 43a, 41b, 42b, and 43a are also covered by the insulating member 271.
This insulating member 271 is made of elastic and elastic foam material such
as
CA 02564237 2006-11-06
33
rubber and the like, similar to the flexible absorbing portion 61 b.
Furthermore, the insulating member 271 is integrally constructed with the
first
sealing material 51 including peripheral sealing material 52 and is also
integrally
constructed with the second sealing material 53.
The flat portion 52b (the flat portion of the insulating member 271 b) of the
peripheral sealing material at one side of the adjacent separator 3 is formed
in flat, and
the protruded portion 52a 8the protruded portion of the insulating member 271
a) of the
peripheral sealing material at another side of the adjacent separator is
formed in
protruded. Furthermore, the top portion of the protruded portion of the
peripheral
sealing material is configured to be semicircular section.
The peripheral portion of the separator 3 and the inner peripheral portion of
respective communication holes 41a, 42a, 43a, 41b, 42b, and 43b comprise step
portions
3d, respectively. The peripheral portions 3a of the separator 3 and the inner
peripheral
portions of respective communication holes 41a, 42a, 43a, 41b, 42b, and 43b
are
converted to be the reaction surface 3A by these step portions 3d. A space 273
is
provided between the reaction surfaces 3A of the separator 3.
According to this construction, it is possible to effectively avoided the
electrical
short circuiting between peripheral end portions of the separator 3 and
between the inner
peripheral end surfaces of respective communication holes 41 a, 42a, 43 a,
41b, 42b, and
43a.
In addition, since both surfaces of the exposed metal surface of the separator
3
at the peripheral sealing material 52 are totally covered by the insulating
member 271, it
is possible to improve the corrosion resistance of the separators and to
prevent the
electrical short circuiting between separators 3.
Furthermore, since the insulating member 271 is integrally constructed with
the
CA 02564237 2006-11-06
34
first sealing material 51 and the second sealing material 53, these insulating
materials
can be formed simultaneously, and thereby the production cost can be reduced.
Since the peripheral sealing materials 52 are formed in combination of a flat
shape and a protruded shape, it is possible to absorb the relative
misalignment of the
protruded peripheral material with respect to the flat peripheral material,
which thereby
makes it unnecessary to conduct an alignment operation for peripheral sealing
materials
52.
In addition, at the time of stacking the separators, the flat portion 52b of
the
peripheral sealing material is pressed by the semicircular top portion of the
protruded
peripheral sealing material 52a, it is possible to enhance the sealing between
these
peripheral portions.
In addition, since step portions 3d provided at the outer edge portions 3d of
the
separators 3 made of thin metal plates and provided around the communication
holes
function as a reinforcing rib, deformation of the separators 3 can be
effectively
prevented.
Since the protruded height of the step portion from front and rear surfaces of
the
adjacent separators 3 are set so as not to close the passage to the reaction
surfaces 3A,
that is, so as to form a space 273, the increase and decrease between adjacent
separators
3 can be absorbed by the increase and decrease of the space 273.
Accordingly, it is possible to prevent extraneous materials from entering into
the space when it is expanded, deterioration of the sealing material due to
elapse of time,
and reduction of the sealing surface pressure.
Fig. 16 is a cross-section showing a sixth embodiment.
In the description of this modification example below, the same constituents
as
those of Fig. 2 are denoted by the same reference symbols as in Fig. 2, and
description
CA 02564237 2006-11-06
thereof is omitted.
A picture frame-shaped member 251 according to this embodiment is
constructed such that the outer periphery of a body portion 251 a arranged at
the outer
peripheral portion of the separator 3 is covered with a flexible absorbing
portion 251 b
comprising a vibration isolating material such as rubber, so that the flexible
absorbing
portion 251 b has also a function as a mounting portion to a vehicle body.
Also according to this construction, as with the construction in Fig. 1,
intrusion
of foreign substance at the time of enlargement of the space between
separators and a
deterioration of sealability with deterioration of the sealing material with
the lapse of
time can be prevented.
Moreover, in the case where the fuel cells I are stacked [stackd] in the
lateral
direction (in the horizontal direction) and mounted on a clanlp face 300, the
flexible
absorbing portion 251 b of the picture frame-shaped member 251 comes in
contact with
the clamp face 300 of the fuel cell 1, to also have a vibration isolating
function. Hence,
it is not necessary to mount the vibration isolating part to the fuel cell
stack as a separate
body, thereby enabling a cost reduction.
The flexible absorbing portion 251 b comprising the vibration isolating
material
may be provided for each fuel cell or for a plurality of fuel cells as a unit.
A modification example shown in Fig. 17 shows a fuel cell stack in -vvhich one
flexible absorbing portion 251b comprising the vibration isolating material is
provided
for each fuel cell. In this fuel cell stack, the flexible absorbing portion
251b
comprising the vibration isolating material and a flexible absorbing portion
251 c
comprising the same material as that of the flexible absorbing portion 61 b in
Fig. 2 are
alternately arranged for every other separator 3.
In the above described embodiments and modification examples, the separator
CA 02564237 2006-11-06
36
3 is formed of a stainless steel, but it may be formed of an other metal
material such as
titanium or a carbonaceous material.
As will be apparent from the above description, according to the present
invention, the following effects can be obtained.
(1) According to the first aspect of the present invention, with respect to a
movement
enlarging the space between separators, a gap is not formed between the
separator and
the picture frame-shaped member, and further, with respect to a movement
narrowing
the space between separators, this movement is not restricted by the picture
frame-shaped member. As a result, intrusion of foreign substance at the time
of
enlargement of the space between separators and insufficient sealing with
deterioration
of the sealing material with the lapse of time can be effectively prevented,
and excellent
power generation performance can be maintained.
(2) According to the second aspect of the present invention, the wideness or
narrowness
of the space between separators can be mechanically absorbed by relative
sliding
movement of the picture frame-shaped members. As a result, intrusion of
foreign
substance at the time of enlargement of the space between separators and
insufficient
sealing with deterioration of the sealing material with the lapse of time can
also be
effectively prevented, and excellent power generation performance can be
maintained.
(3) According to the third aspect of the present invention, since the elastic
member is
capable of resiliently contracting in the stacking direction of the
separators, relative
approach of the separators is not restricted. With respect to an enlargement
of the space
between separators, the elastic member is resiliently restored and extends in
the stacking
direction of the separators, and follows the separator. As a result, intrusion
of foreign
substance at the time of enlargement of the space between separators and
insufficient
sealing with deterioration of the sealing material with the lapse of time can
also be
CA 02564237 2006-11-06
37
effectively prevented, and excellent power generation performance can be
maintained.
(4) According to the fourth aspect of the present invention, registration of
separators is
automatically performed at the time of stacking the separators, and hence
workability at
the time of assembly and maintenance can be improved.
(5) According to the invention of claim 5, it is possible to prevent an
electrical short
circuiting between adjacent separators, and thereby good power generation
performance
of the fuel cell stack can be maintained
(6) According to the sixth aspect of the present invention, it is possible to
improve the
corrosion resistance of separators and to prevent the electric short
circuiting between
adjacent separators, and thereby make it possible to maintain the good power
generation
performance.
(7) According to the seventh aspect of the present invention, it is possible
to improve the
corrosion resistance of separators and to prevent the electric short
circuiting between
separators, and thereby make it possible to maintain the good power generation
performance.
(8) According to the eighth aspect of the present invention, since it is
possible to absorb
the misalignment of the protruded reaction surface peripheral sealing member
with
respect to the flat reaction surface peripheral sealing member, the
productivity of the fuel
cell stack can be improved.
(9) According to the ninth aspect of the present invention, not only in a
single fuel cell,
but also between the adjacent fuel cells, increase and decrease of the space
between
separators can be followed. As a result, intrusion of foreign substance at the
time of
enlargement of the space between separators and insufficient sealing with
deterioration
of the sealing material with the lapse of time can also be effectively
prevented, and
excellent power generation performance can be maintained.
CA 02564237 2006-11-06
38
(10) According to the tenth aspect of the present invention, since it is
possible to
effectively prevent the liquid connection by the cooling medium and an
electrical short
circuiting between adjacent separators, and hence excellent power generation
can be
maintained more reliably.
(11) According to the eleventh aspect of the present invention, it is possible
to absorb
increase and decrease of the spaces between separators, it is possible to
effectively
prevent intrusion of foreign substance at the time of enlargement of the space
between
separators, insufficient sealing with deterioration of the sealing material
with the lapse of
time, and reduction of sealing surface pressure.
(12) According to the twelfth aspect of the present invention, since the
increase and
decrease of the spaces between separators can be mechanically absorbed, it is
possible to
effectively prevent intrusion of foreign substance at the time of enlargement
of the space
between separators, insufficient sealing with deterioration of the sealing
material with
the lapse of time, and reduction of sealing surface pressure.
(13) According to the thirteenth aspect of the present invention, contraction
of the spaces
between separators can be followed because the elastic material can be
contracted
elastically in the stacking direction of the capacitors. The expansion of the
spaces
between separators, since the elastic material can elongate by elastic
restoration, it is
possible to effectively prevent intrusion of foreign substance at the time of
enlargement
of the space between separators, insufficient sealing with deterioration of
the sealing
material with the lapse of time, and reduction of sealing surface pressure.
(14) According to the fourteenth aspect of the present invention, it is
possible to
effectively prevent the electrical short circuiting at the inner peripheral
surfaces of
respective communication holes of adjacent separators, and thereby the fuel
cell is
capable of good power generating performance.
CA 02564237 2006-11-06
.
39
(15) According to the fifteenth aspect of the present invention, it is
possible to absorb the
relative misalignment of one insulating members to the other insulating member
by
combining a flat member and a protruded menlber, and thereby increase the
productivity
of the fuel cell.
(16) According to the sixteenth aspect of the present invention, it is
possible to absorb
the relative misalignment of one insulating members to the other insulating
member by
combining a flat member and a protruded member, and thereby increase the
productivity
of the fuel cell.
(17) According to the seventeenth aspect of the present invention, since it is
possible to
improve the short circuiting between adjacent separators, the good power
generation
performance is maintained.
(18) According to the seventeenth aspect of the present invention, since it is
possible to
integrally construct the reaction surface peripheral sealing member and the
insulating
member at the same time, and thereby the production cost can be reduced
(19) According to the nineteenth aspect of the present invention, it is
possible to improve
the corrosion resistance of separators, and it is also possible to effectively
prevent short
circuiting between adjacent separators. Thus, it is possible to maintain the
good
generating performance.
