U.S. patent application number 13/564459 was filed with the patent office on 2013-02-07 for pressure compensation device for a housing of an electrochemical device.
This patent application is currently assigned to ElringKlinger AG. The applicant listed for this patent is Jan Groshert, Frank Heim, Thomas STRAU L. Invention is credited to Jan Groshert, Frank Heim, Thomas STRAU L.
Application Number | 20130032219 13/564459 |
Document ID | / |
Family ID | 46466332 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130032219 |
Kind Code |
A1 |
Heim; Frank ; et
al. |
February 7, 2013 |
PRESSURE COMPENSATION DEVICE FOR A HOUSING OF AN ELECTROCHEMICAL
DEVICE
Abstract
A pressure compensation device for compensating an internal
pressure in a housing of an electrochemical device is provided,
including at least one gas through-opening and at least one
membrane element with a gas-permeable membrane, which is deformable
depending on a change in the internal pressure and by which the gas
through-opening is blocked, and a protective degassing element,
which is configured and arranged in such a way that when a critical
deformation of the membrane is reached, it damages the membrane in
such a way that the membrane at least partially opens the gas
through-opening for protective degassing of the housing. The
pressure compensation device allows both reliable pressure
compensation between the interior of the housing and the exterior
of the housing of an electrochemical device during normal operation
of the electrochemical device and also ensures reliable bursting
protection in the event of excess internal pressure in the
housing.
Inventors: |
Heim; Frank;
(Walddorfhaslach, DE) ; Groshert; Jan; (Dettingen,
DE) ; STRAU L; Thomas; (Krumbach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Heim; Frank
Groshert; Jan
STRAU L; Thomas |
Walddorfhaslach
Dettingen
Krumbach |
|
DE
DE
DE |
|
|
Assignee: |
ElringKlinger AG
|
Family ID: |
46466332 |
Appl. No.: |
13/564459 |
Filed: |
August 1, 2012 |
Current U.S.
Class: |
137/14 ;
137/197 |
Current CPC
Class: |
H01M 2/1264 20130101;
F16K 17/16 20130101; H01M 2/1241 20130101; Y10T 137/3084 20150401;
Y02E 60/10 20130101; Y10T 137/0396 20150401 |
Class at
Publication: |
137/14 ;
137/197 |
International
Class: |
F24D 19/08 20060101
F24D019/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2011 |
DE |
10 2011 080 325.4 |
Claims
1. A pressure compensation device for compensating an internal
pressure in a housing of an electrochemical device, comprising at
least one gas through-opening and at least one membrane element
with a gas-permeable membrane, which is deformable depending on a
change in the internal pressure and by which the gas
through-opening is blocked, the pressure compensation device
comprising a protective degassing element, which is configured and
arranged in such a way that when a critical deformation of the
membrane is reached, it damages the membrane in such a way that the
membrane at least partially opens the gas through-opening for a
protective degassing of the housing.
2. The pressure compensation device according to claim 1, wherein
the membrane comprises a porous plastics material.
3. The pressure compensation device according to claim 1, wherein
the membrane comprises a fluoropolymer material.
4. The pressure compensation device according to claim 1, wherein
the pressure compensation device comprises a carrier element and a
clamping element, the membrane element being held by clamping
between the carrier element and the clamping element.
5. The pressure compensation device according to claim 4, wherein
the carrier element and the clamping element are integrally
connected to one another.
6. The pressure compensation device according to claim 5, wherein
the carrier element and the clamping element are latched to one
another.
7. The pressure compensation device according to claim 1, wherein
the pressure compensation device comprises a carrier element, in
the material of which the membrane element is at least partially
embedded.
8. The pressure compensation device according to claim 1, wherein
the pressure compensation device is fixable by means of at least
one fastening device on the housing of the electrochemical
device.
9. The pressure compensation device according to claim 8, wherein
the pressure compensation device has at least one fastening flange
with at least one fastening device receiver for a fastening
device.
10. The pressure compensation device according to claim 1, wherein
the pressure compensation device comprises at least one sealing
element for sealing between the pressure compensation device and
the housing of the electrochemical device.
11. The pressure compensation device according to claim 1, wherein
the pressure compensation device comprises at least one protection
element, by which an outside of the membrane is protected from
mechanical damage from outside the pressure compensation
device.
12. The pressure compensation device according to claim 11, wherein
the protection element has at least one gas through-opening.
13. The pressure compensation device according to claim 1, wherein
the pressure compensation device comprises at least one mechanism
for changing the relative position between the protective degassing
element and the membrane.
14. The pressure compensation device according to claim 13, wherein
the mechanism for changing the relative position comprises an
adjusting thread provided on the protective degassing element.
15. Use of a pressure compensation device for compensating an
internal pressure in a housing of an electrochemical device,
wherein the pressure compensation device comprises at least one gas
through-opening, at least one membrane element with a gas-permeable
membrane, which is deformable depending on a change in the internal
pressure and by which the gas through-opening is blocked, and a
protective degassing element, which is configured and arranged in
such a way that when a critical deformation of the membrane is
reached, it damages the membrane in such a way that the membrane at
least partially opens the gas through-opening for a protective
degassing of the housing, in an electrochemical device, which
comprises a housing and a plurality of electrochemical cells
arranged in the housing, the pressure compensation device being
arranged on the housing.
16. An electrochemical device, comprising a housing, one or more
electrochemical cells arranged in the housing and at least one
pressure compensation device arranged on the housing for
compensating an internal pressure in the housing of the
electrochemical device, wherein the pressure compensation device
comprises at least one gas through-opening, at least one membrane
element with a gas-permeable membrane, which is deformable
depending on a change in the internal pressure and by which the gas
through-opening is blocked, and a protective degassing element,
which is configured and arranged in such a way that when a critical
deformation of the membrane is reached, it damages the membrane in
such a way that the membrane at least partially opens the gas
through-opening for a protective degassing of the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from, and the benefit under
35 U.S.C. .sctn.119, of German Patent Application No. 10 2011 080
325.4, filed Aug. 3, 2011, which is incorporated herein by
reference in its entirety and for all purposes.
FIELD OF DISCLOSURE
[0002] The present invention relates to a compensation device for
compensating an internal pressure in a housing of an
electrochemical device, the pressure compensation comprising at
least one gas through-opening and at least one membrane element
with a gas-permeable membrane, which is deformable depending on a
change in the internal pressure and by which the gas
through-opening is blocked.
BACKGROUND OF THE INVENTION
[0003] Closed containers with a large internal volume and a thin
wall cannot be completely hermetically sealed relative to the
external wall. In order to prevent the housing of the container
bursting or bulging, a continuous air exchange with the environment
is necessary. Nevertheless, the interior of the housing is to be
protected from penetrating dirt and water.
[0004] Pressure compensation devices for such housings of the type
mentioned at the outset are therefore known, which comprise
membranes or films having a certain gas permeability, in particular
air permeability, but also a seal against water.
[0005] If an excess pressure occurs within the housing within a
short time, for example upon the failure of a battery cell within
an energy store housing, this critical pressure has to be able to
be rapidly reduced to prevent damage to the housing.
[0006] In order to realize protection of this type for the housing
against bursting, it is known to insert bursting discs, in
particular made of a metallic sheet material, or safety flaps or
valves into the housing wall.
SUMMARY OF THE INVENTION
[0007] The present invention is based on the object of providing a
pressure compensation device of the type mentioned at the outset,
which allows both reliable pressure compensation between the
interior of the housing and the exterior of the housing of an
electrochemical device during normal operation of the
electrochemical device and also ensures reliable bursting
protection in the event of excess internal pressure in the housing,
the pressure compensation device being simply constructed and
easily producible.
[0008] This object is achieved according to the invention in a
pressure compensation device having the features of the preamble of
claim 1 in that the pressure compensation device comprises a
protective degassing element, which is configured and arranged in
such a way that when a critical deformation of the membrane is
reached, it damages the membrane in such a way that the membrane at
least partially opens the gas through-opening for a protective
degassing of the housing.
[0009] The solution according to the invention is therefore based
on the idea of combining the functions of pressure compensation and
protective degassing for the housing of the electrochemical device,
with simultaneously high resistance relative to a high water
pressure exterior to the housing, in one and the same
component.
[0010] The use of a stable, but porous and therefore gas-permeable
membrane fulfils the pressure compensation function and the
protection of the interior of the housing from penetrating water
and dirt during normal operation of the electrochemical device.
[0011] The use of a protective degassing element, for example in
the form of a protective degassing spike, which adds a
predetermined rupture point to the porous membrane, leading to the
desired failure of the membrane in the event of a pressure increase
up to a critical pressure, ensures the required bursting protection
for the housing.
[0012] In contrast to this, in known devices, two different
components are always necessary, namely a first for the pressure
compensation during environmentally caused pressure fluctuations
during normal operation of the electrochemical device and a second
element for the rapid reduction of pressure in the event of an
explosion-like increase in the internal pressure in the housing of
the electrochemical device. In this case, the first element has to
have a certain gas permeability and water pressure resistance for
the pressure compensation, and the second element, in the event of
a critical pressure increase, has to allow rapid pressure
compensation by opening an adequately large gas passage
cross-section.
[0013] If the element for the pressure compensation is formed as a
membrane, which is designed to be so thin that it tears on its own
at critical pressure, there is always the danger that a failure of
the membrane of this type will not only occur due to loading with a
critical internal pressure, but also unintentionally due to water
pressure loading from the exterior of the housing.
[0014] On the other hand, in the pressure compensation device
according to the invention, a membrane with porous properties is
used, which has a certain gas permeability to ensure the pressure
compensation between the interior and the exterior of the housing,
but is designed such that it has an adequate water pressure
resistance for protection of the interior of the housing from
penetrating dust and water.
[0015] The membrane of the pressure compensation device according
to the invention does not tear on its own in the event of a
critical pressure increase in the interior of the housing, but only
when the membrane is damaged by the action of the protective
degassing element on the membrane in such a way that the membrane
fails within a very short time (within a few milliseconds)
following this damage and opens an adequately large cross-section
for the protective degassing of the housing.
[0016] The protective degassing element may, in particular, be
configured as a protective degassing spike, which is preferably
stationary or fixed. Owing to loading with an increased internal
pressure in the housing of the electromechanical device, the
membrane opens toward the protective degassing spike. At a critical
excess pressure in the interior of the housing, the membrane
impinges on the protective degassing spike, with the protective
degassing spike inflicting preliminary damage on the membrane,
which leads to the ultimate failure of the membrane within a few
milliseconds, so the membrane opens an adequately large
cross-section for protective degassing and no longer blocks the gas
through-opening of the pressure compensation device.
[0017] By adjusting the spacing between the protective degassing
element, in particular the protective degassing spike, and the
membrane (without a bulge in the rest state of the membrane, in
other words when the internal pressure in the housing of the
electrochemical device corresponds to the external pressure in the
exterior of the housing), the bursting pressure leading to damage
of the membrane can be adjusted individually and precisely.
[0018] In a preferred configuration of the invention, the membrane
comprises a porous plastics material and is preferably
substantially completely formed from a porous plastics material of
this type.
[0019] In particular, it may be provided that the membrane
comprises a fluoropolymer material and is preferably substantially
completely formed from a fluoropolymer material.
[0020] It is particularly favorable if the membrane comprises a
polytetrafluoroethylene material and/or a polytetrafluoroethylene
compound and is preferably formed substantially completely of one
of the materials mentioned.
[0021] A polytetrafluoroethylene compound is to be taken to mean
here a mixture of a polytetrafluoroethylene material and one or
more fillers.
[0022] The term polytetrafluoroethylene (PTFE), in this case, also
indicates in this description and in the accompanying claims
modified polytetrafluoroethylene materials, in which some of the
fluorine atoms of the polytetrafluoroethylene are replaced by
substituents.
[0023] A porous, gas-permeable and water pressure-resistant
membrane made of a PTFE material or a PTFE compound may, in
particular, be produced in that a granulate of a PTFE material or a
PTFE compound is pressed and sintered in a cylindrical or hollow
cylindrical mould. A peeled foil is produced from the sintered
cylinder or hollow cylinder thus obtained, in that the cylinder or
the hollow cylinder is made to carry out a rotary movement and a
peeling knife is fed against the lateral surface of the cylinder or
hollow cylinder. The membrane can be separated out, in particular
cut-out or stamped out, from the peeled film thus obtained.
[0024] There are various possibilities for fastening the membrane
to the remaining components of the pressure compensation
device.
[0025] Thus, it may be provided, for example, that the pressure
compensation device comprises a carrier element and a clamping
element, the membrane element being held by clamping between the
carrier element and the clamping element.
[0026] In this case, the carrier element and the clamping element
are produced separately from one another and preferably releaseably
or non-releaseably connected to one another after the arrangement
of the membrane element between the carrier element and the
clamping element.
[0027] For example, it may be provided that the carrier element and
the clamping element are integrally connected to one another.
[0028] An integral connection of this type may be produced, in
particular by welding, in particular laser welding or ultrasonic
welding.
[0029] Alternatively or in addition to this, it may also be
provided that the carrier element and the clamping element are
latched to one another.
[0030] As an alternative, it may also be provided that the pressure
compensation device comprises a carrier element, in the material of
which the membrane element is at least partially embedded, in
particular at the outer edge of the membrane element.
[0031] It may, in particular, be provided that the membrane element
has the material of the carrier element injected around it,
preferably after being placed in the injection molding tool.
[0032] The membrane element may substantially completely consist of
the membrane.
[0033] The pressure compensation device according to the invention
is fixable, preferably releaseably, preferably by means of at least
one fastening device, for example by means of at least one
fastening screw, to the housing of the electrochemical device.
[0034] It may, in particular, be provided for this, that the
pressure compensation device has at least one fastening flange with
at least one fastening device receiver for a fastening device.
[0035] In order to prevent an uncontrolled gas exchange between the
interior and the exterior of the housing, past the pressure
compensation device, it is advantageous if the pressure
compensation device comprises at least one sealing element for the,
preferably substantially gas tight, sealing between the pressure
compensation device and the housing of the electrochemical
device.
[0036] A sealing element of this type may, in particular, comprise
an elastomer material and preferably be formed substantially
completely from an elastomer material.
[0037] In particular, the sealing element may comprise an
O-ring.
[0038] Furthermore, it is favorable if the pressure compensation
device comprises at least one protection element, by means of which
an outside of the membrane is protected from mechanical damage from
outside the pressure compensation device.
[0039] A protection element of this type may be, in particular, in
the form of a lid or cap.
[0040] In order to not impede gas passing through the pressure
compensation device, it is favorable if the protection element has
at least one gas through-opening, preferably a plurality of gas
through-openings.
[0041] In order to particularly easily be able to adjust and/or
vary the critical bursting pressure, at which the membrane is to
fail and open the gas through-opening of the pressure compensation
device for a protective degassing of the housing, it is favorable
if the pressure compensation device comprises a mechanism for
changing the relative position between the protective degassing
element and the membrane (in the rest state of the membrane).
[0042] A mechanism of this type for changing the relative position
may, in particular, comprise an adjusting thread provided on the
protective degassing element.
[0043] An adjusting thread of this type may, in particular,
cooperate with a thread that is complementary thereto on another
component of the pressure compensation device, for example on a
protection element of the pressure compensation device.
[0044] In this case, the adjusting thread of the protective
degassing element may be configured as an external thread or an
internal thread and the thread that is complementary thereto may be
configured accordingly as an internal thread or an external
thread.
[0045] The pressure compensation device according to the invention
is suitable, in particular, for use in an electrochemical device,
which comprises a housing, one or more electrochemical cells
arranged in the housing and at least one pressure compensation
device according to the invention arranged on the housing.
[0046] The electrochemical device may, in particular, be configured
as a battery, for example as a lithium-ion battery.
[0047] If the electrochemical device according to the invention is
configured as a battery, it is suitable, in particular, to be a
highly loadable energy source, for example to drive motor
vehicles.
[0048] Further features and advantages of the invention are the
subject of the following description and the graphical view of
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 shows a plan view of a pressure compensation device
for compensating the internal pressure in a housing of an
electrochemical device;
[0050] FIG. 2 shows a schematic longitudinal section through the
pressure compensation device from FIG. 1, along the line 2-2 in
FIG. 1;
[0051] FIG. 3 shows a schematic cross-section through the pressure
compensation device from FIG. 1, along the line 3-3 in FIG. 1;
[0052] FIG. 4 shows a schematic perspective view of the pressure
compensation device from FIGS. 1 to 3;
[0053] FIG. 5 shows a schematic side view of the pressure
compensation device from FIGS. 1 to 4, with the viewing direction
in the direction of the arrow 5 in FIG. 1;
[0054] FIG. 6 shows a further schematic side view of the pressure
compensation device from FIGS. 1 to 5, with the viewing direction
in the direction of the arrow 6 in FIG. 1;
[0055] FIG. 7 shows a schematic plan view from below of the
pressure compensation device from FIGS. 1 to 6; and
[0056] FIG. 8 shows an enlarged view of the region I from FIG. 2 in
a second embodiment of the pressure compensation device, which
comprises a mechanism for changing the relative position between a
protective degassing element of the pressure compensation device
and a membrane of the pressure compensation device.
[0057] The same or functionally equivalent elements are designated
by the same reference numerals in all the figures.
DETAILED DESCRIPTION OF THE INVENTION
[0058] An electrochemical device, designated as a whole by 100 and
shown schematically as a whole in FIGS. 1 to 7 and, in particular,
in FIG. 6 comprises a closed housing 102, in the interior 104 of
which a plurality of electrochemical cells 106 are arranged, which
may be electrically connected, for example, in series or in
parallel.
[0059] The housing 102 comprises a housing wall 108, with a, for
example, substantially circular, recess 110, which is closed by a
pressure compensation device designated as a whole by 112.
[0060] As can be seen in particular from the sectional views of
FIGS. 2 and 3, the pressure compensation device 112 comprises a
carrier element 114, with which the pressure compensation device
112 abuts in the assembled state on the housing wall 108; a
membrane element 116, which rests on a membrane element seat 118 of
the carrier element 114; a clamping element 120, which is connected
to the carrier element 114 and abuts with a clamping region 122 on
the side of the membrane element 116 remote from the carrier
element 114, so the membrane element 116 is held by clamping
between the carrier element 114 and the clamping element 120; and a
protection element 124, which is connected to the carrier element
114 and covers the membrane element 116 and the clamping element
120 toward an exterior 126 of the housing 102, so a mechanical
influence from outside the housing 102 on the membrane element 116
is prevented by the protection element 124.
[0061] As can best be seen from FIGS. 2 and 3, the carrier element
114 comprises a, for example, substantially hollow cylindrical, gas
through-channel 128, which, when the pressure compensation device
112 is in the assembled state, preferably extends at least
partially into the interior 104 of the housing 102.
[0062] The gas through-channel 128 surrounds a, for example
substantially circular, gas through-opening 130, through which the
interior 104 of the housing 102 of the electrochemical device 100
has a fluid connection to an interior 132 of the pressure
compensation device 112.
[0063] A reinforcement structure 131, which may, in particular,
comprise a central ring 133, which is held by a plurality of, for
example, four, struts 135 on a casing wall of the gas
through-channel 128, may be arranged in the gas through-channel
128.
[0064] The gas through-opening 130 is covered by the membrane
element 116.
[0065] The membrane element 116 comprises a, for example,
substantially circular, membrane 134, which is gas-permeable and is
deformable depending on a change of the internal pressure in the
interior 104 of the housing 102.
[0066] The membrane 134, may, in particular, comprise a porous
plastics material and is preferably substantially completely formed
from a porous plastics material of this type.
[0067] The plastics material may, for example, comprise a
fluoropolymer material, and in particular consist substantially
completely of a fluoropolymer material.
[0068] It is particularly favorable if the membrane comprises a
polytetrafluoroethylene material and/or a polytetrafluoroethylene
compound and is preferably substantially completely formed from one
of the materials mentioned.
[0069] A polytetrafluoroethylene compound is to be taken to mean a
mixture here of a polytetrafluoroethylene material and one or more
fillers.
[0070] The term polytetrafluoroethylene (PTFE) in this description
and the accompanying claims also designates, in this case, modified
polytetrafluoroethylene materials, in which some of the fluorine
atoms of the polytetrafluoroethylene are replaced by
substituents.
[0071] A porous gas-permeable and water pressure-resistant membrane
134 made of a PTFE material or a PTFE compound may be produced in
particular, by a granulate of PTFE material or a PTFE compound
being pressed and sintered in a cylindrical mould. A peeled film is
produced from the sintered cylinder thus obtained, in that the
cylinder is made to carry out a rotary movement and a peeling knife
is fed against the outer surface of the cylinder. The membrane 134
can be separated, in particular cut out or stamped out, from the
peeled film thus obtained.
[0072] The membrane element seat 118 of the carrier element 114, on
which the membrane element 116 rests (preferably substantially
flat), is surrounded by an annular ring protrusion 136 projecting
toward the clamping element 120.
[0073] The ring protrusion 136 of the carrier element 114 engages
in an annular groove 140, which is preferably configured in a
substantially complementary manner to the ring protrusion 136, on
the side of the clamping element 120 facing the carrier element
114.
[0074] The clamping element 102, which is, in particular, formed as
a clamping ring 142, furthermore comprises a preferably
substantially hollow-cylindrical gas through-channel 144, which is
formed and arranged substantially coaxially with respect to the
centre axis 138 of the pressure compensation device 112 and
substantially coaxially to the gas-through opening 130 and the gas
through-channel 128 of the carrier element 114 and substantially
coaxially to the membrane 134 of the membrane element 116.
[0075] The clamping element 120 and/or the carrier element 114 is
preferably formed from a plastics material, in particular as a
plastics material injection-molded part.
[0076] The clamping element 120 and/or the carrier element 114,
may, in particular, be formed from a thermoplastics material or a
thermosetting plastics material.
[0077] In particular, the clamping element 120 and/or the carrier
element 114 may comprise a polypropylene material, a polyethylene
material, and/or a polyamide material.
[0078] The clamping element 120 and the carrier element 114 may
basically be fixed to one another in any manner in order to clamp
the membrane element 116 between them.
[0079] The clamping element 120 and the carrier element 114 may be
releaseably or non-releaseably connected to one another.
[0080] For example, it may be provided that the clamping element
120 and the carrier element 114 are integrally connected to one
another, in particular by adhesion and/or by welding.
[0081] The clamping element 120 and the carrier element 114, may,
in particular, be connected to one another by ultrasonic welding or
by laser welding.
[0082] Alternatively or in addition to this, it may be provided
that the clamping element 120 and the carrier element 114 are
connected to one another by clipping or latching or screwing.
[0083] At the side of the carrier element 114, which is remote from
the clamping element 120 and with which the carrier element 114,
when the pressure compensation device 112 is in the assembled
state, abuts on the outside of the housing wall 108 of the housing
102, the carrier element 114 is provided with an annular sealing
element 146, which annularly surrounds the gas through-channel 128
of the carrier element 114.
[0084] The sealing element 146, may, in particular, be configured
as an O-ring, which is at least partially arranged in an annular
groove 150 provided on the carrier element 114.
[0085] The sealing element 146 is preferably formed from an
elastomer material, in particular from an elastomeric plastics
material.
[0086] As is, furthermore, best to be seen from FIGS. 1 and 2, the
carrier element 114 is provided, preferably radially outside the
sealing element 146, with one or more fastening flanges 152, of
which each has at least one fastening device receiver 154. Each of
the fastening element receivers 154 is used to receive a respective
fastening device (not shown), for example a fastening screw, by
means of which the pressure compensation device 112 is fastenable,
preferably releaseably, to the housing 102 of the electrochemical
device 100.
[0087] On its side remote from the housing wall 108 when the
pressure compensation device 112 is in the assembled state, the
carrier element 114 is furthermore provided with an annular holding
projection 156, which projects along the direction of the centre
axis 138 and cooperates with an also annular holding portion 158 of
the protection element 124 in order to hold the protection element
124 on the carrier element 114.
[0088] In this case, the protection element 124 and the carrier
element 114 may be releaseably or non-releaseably connected to one
another.
[0089] The protection element 124 preferably comprises a plastics
material and may, in particular, be formed as a plastics material
injection-molded part.
[0090] The protection element 124 preferably comprises a
thermoplastics material and/or a thermosetting plastics
material.
[0091] In particular, the protection element 124 may comprise a
polypropylene material, a polyethylene material and/or a polyamide
material.
[0092] The protection element 124 may, for example, be integrally
connected to the carrier element 114, in particular by adhesion
and/or by welding.
[0093] In particular, the protection element 124 may be connected
by ultrasonic welding and/or laser welding to the carrier element
114.
[0094] Alternatively or in addition to this, it may also be
provided that the protection element 124 is connected to the
carrier element 114 by clipping, latching and/or screwing.
[0095] The protection element 124 may in particular, be configured
as a lid or a cap and may have a substantially dome-shaped form.
The protection element 124 extends starting from the holding
portion 158, on which the protection element 124 is connected to
the carrier element 114, across the central region of the carrier
element 114, the clamping element 120 and the membrane element 116,
so these components of the pressure compensation device 112 are
protected by the protection element 124 from a mechanical influence
from the exterior 126 of the housing 102 of the electrochemical
device 100.
[0096] In order to allow a passage of gas from the interior 132 of
the pressure compensation device 112 into the exterior 126, the
wall of the protection element 124 is provided with one or more,
for example ten, gas through-openings 160, as can best be seen from
FIG. 1.
[0097] If a plurality of gas through-openings 160 are provided on
the protection element 124, these are preferably distributed
substantially equidistantly along the periphery of the protection
element 124.
[0098] A protective degassing element 164 projects into the
interior 132 of the pressure compensation device 112 from a central
region 162 of the protection element 124, which is intersected by
the centre axis 138 of the pressure compensation device 112.
[0099] The protective degassing element 164, may, in particular, be
configured as a protective degassing spike 166, which ends at a tip
168.
[0100] The tip 168 of the protective degassing element 164 opposes
the membrane 134 at a predetermined spacing d (when the membrane
134 is in the rest state).
[0101] The protective degassing element 164 preferably extends
along the centre axis 138 of the pressure compensation device 112.
The tip 168 of the protective degassing element 164 preferably lies
on the centre axis 138 of the pressure compensation device 112.
[0102] Depending on the size of the desired spacing d between the
tip 168 of the protective degassing element 164 and the membrane
134, the central region 162 of the protection element 124, on which
the protective degassing element 164 is arranged, is formed as a
recess (as in the embodiment shown) or as a land (not shown) in the
lid-shaped or cap-shaped protection element 124.
[0103] To prevent direct access from the gas through-openings 160
of the protection element 124 to the membrane 134, it may be
provided that an annular projection 170, which extends from the
protection element 124 into the interior 132 of the pressure
compensation device 112, is provided on the protection element 124
radially inwardly from the gas through-openings 160.
[0104] The annular projection 170 preferably extends in the
direction of the centre axis 138 to the axial position of the edge
172 of the gas through-openings 160 of the protection element 124
located closest to the carrier element 114.
[0105] It is furthermore preferably provided that the annular
projection 170 on the protection element 124 and the gas
through-channel 144 of the clamping element 120 overlap one another
in the direction of the centre axis 138 so gas from the region of
the membrane 134 has to flow in a zigzag course predetermined by
the gas through-channel 144 and the annular projection 170 through
the interior 132 of the pressure compensation device 112 to the gas
through-openings 160 in order to arrive from the pressure
compensation device into the exterior 126.
[0106] The pressure compensation device 112 described above
functions as follows:
[0107] During normal operation of the electrochemical device 100,
the pressure compensation device 112 allows a pressure compensation
between the interior 104 of the housing 102 of the electrochemical
device 100, on the one hand, and the exterior 126 of the housing
102, on the other hand.
[0108] For this purpose, gas, in particular air, can arrive from
the interior 104 of the housing 102 through the gas through-channel
128 of the carrier element 114 with the gas through-opening 130,
through the porous, gas-permeable membrane 134, through the part of
the interior 132 of the pressure compensation device 112 located on
the side of the membrane 134 remote from the carrier element 114
and through the gas through-openings 160 in the protection element
124 into the exterior 126 or, in the reverse direction, from the
exterior 126 into the interior 104 of the housing 102.
[0109] This makes reliable pressure compensation through the
pressure compensation device 112 possible during pressure
fluctuations caused by the environment.
[0110] The membrane 134 has adequate gas permeability and water
pressure resistance for the pressure compensation and protects the
interior 104 of the housing 102 from the penetration of dust and
water.
[0111] The membrane 134 is constructed adequately strongly to avoid
an unintended failure of the membrane 134 by water pressure loading
from the outside.
[0112] If, on the contrary, in a malfunction, for example in the
event of failure of one of the electrochemical cells 106 in the
interior 104 of the housing 102, a high excess pressure is produced
in the interior 104 of the housing 102 (for example by the escape
of electrolyte gases, such as HF or H.sub.2, from one of the
electrochemical cells 106), the membrane 134 bulges owing to this
pressure loading in the direction of the protective degassing
element 164 and impinges on the tip 168 of the protective degassing
element 164.
[0113] The tip 168 of the protective degassing element 164 inflicts
preliminary damage on the membrane 134 which, within a very short
time (within a few milliseconds) leads to the failure and to the
destruction of the membrane 134, so an adequately large
cross-section of the gas through-opening 134 is no longer blocked
by the membrane 134, but is opened for protective degassing.
[0114] The bursting pressure, at which the membrane 134 is damaged
by the protective degassing element 164, can be adjusted
individually and within narrow limits by a suitable selection of
the spacing d between the protective degassing element 164 and the
membrane 134 when the membrane 134 is in the rest state.
[0115] A second embodiment of a pressure compensation device 112
shown partially in FIG. 8 differs from the first embodiment shown
in FIGS. 1 to 7 in that the protective degassing element 164 is not
fixed at an invariably predetermined spacing from the membrane 134
on the protection element 124, but the protective degassing element
164 is instead provided with an adjusting thread 172, which
cooperates with a thread 174 that is complementary thereto on the
protection element 124 in such a way that the position of the
protective degassing element 164 relative to the protection element
124 (and therefore also relative to the membrane 134 in the rest
state) can be changed in the direction of the central axis 138 in
that the adjusting thread 172 of the protective degassing element
164 is screwed to a greater or less extent into the thread 174 of
the protection element 124.
[0116] It may, in particular, be provided, in this case, that the
adjusting thread 172 is configured as an external thread and the
thread 174 is configured as an internal thread that is
complementary thereto.
[0117] Consequently, the spacing d between the tip 168 of the
protective degassing element 164 and the membrane 134, and
therefore the bursting pressure, at which the membrane 134 bulging
forward owing to a pressure increase in the interior 104 of the
housing 102 to the protective degassing element 164 comes into
contact with the tip 168 of the protective degassing element 164
and is damaged thereby, can be easily set or adjusted.
[0118] The second embodiment of the pressure compensation device
112 shown in FIG. 8 therefore comprises a mechanism 176 to change
the relative position between the protective degassing element 164
and the membrane 134 when the membrane 134 is in the rest
state.
[0119] While in the first embodiment shown in FIGS. 1 to 7, the
protective degassing element 164 is preferably formed in one piece
with the protection element 124 and is preferably formed from a
plastics material, in the second embodiment, the protective
degassing element 164 may be formed from a material that is
different from the material of the protection element 124.
[0120] It may thus be provided, for example, that the protective
degassing element 164 in the second embodiment comprises a metallic
material and, is preferably formed substantially completely from a
metallic material.
[0121] Otherwise, the second embodiment shown in FIG. 8 of the
pressure compensation device 112 coincides with respect to
structure, mode of functioning and mode of production with the
first embodiment shown in FIGS. 1 to 7, to the above description of
which reference is to this extent made.
[0122] Both in the first embodiment shown in FIGS. 1 to 7 and in
the second embodiment shown in FIG. 8 of the pressure compensation
device 112, it may alternatively be provided that the membrane
element 116 is not fastened by clamping between the carrier element
14 and the clamping element 120 in the pressure compensation device
112, but, instead, the carrier element 114 and the clamping element
120 are formed in one piece with one another and the membrane
element 116 has the material of the carrier element 114 injected
around it on its periphery, so that the membrane element 116 and
the carrier element 114 are integrally connected to one
another.
[0123] This can be effected, in particular, in that the membrane
element 116 is placed in an injection-molding tool and has the
material of the carrier element 114 injected around it.
* * * * *