PRESSURE EQUALIZATION DEVICE, METHOD FOR PRESSURE EQUALIZATION AND HOUSING

Abstract

A pressure equalization device for a housing has a base body and a closure element with a flow path between them being open in a normal operating state of the pressure equalization device. A flow opening in the flow path is spanned by a membrane. An emergency venting spike projects from the closure element toward the membrane. The pressure equalization device transitions after emergency venting into an emergency operating state in which the closure element gas-tightly closes the base body. A housing with such a pressure equalization device is provided. In a method for pressure equalization with such a pressure equalization device between a housing interior and an environment, gas exchange between interior and environment is performed through the membrane and the flow path between closure element and base body. During emergency venting, the membrane is destroyed by the emergency venting spike. The closure element then closes the base body.

Claims

1. A pressure equalization device for a housing, the pressure equalization device comprising: a base body configured to be flowed through; a closure element arranged at the base body; a flow path provided between the base body and the closure element, wherein the flow path is open in a normal operating state of the pressure equalization device; a flow opening positioned in the flow path in the base body; and a membrane arranged in the base body and spanning the flow opening, wherein the pressure equalization device is configured to transition after an emergency venting event into an emergency operating state of the pressure equalization device, and wherein the closure element gas-tightly closes the base body in the emergency operating state of the pressure equalization device.

2. The pressure equalization device according to claim 1, wherein the closure element is pretensioned against the base body.

3. The pressure equalization device according to claim 2, further comprising a spring element pretensioning the closure element against the base body, wherein the spring element is supported at a cover of the pressure equalization device.

4. The pressure equalization device according to claim 1, further comprising projections, wherein, in the normal operating state of the pressure equalization device, the closure element rests on the projections and the flow path extends between the projections.

5. The pressure equalization device according to claim 4, wherein the projections are arranged at the base body and extend with at least one axial component away from a side of the base body facing the closure element.

6. The pressure equalization device according to claim 1, further comprising at least one spacer, wherein, in the normal operating state of the pressure equalization device, the closure element is spaced apart from the base body at least regionally by the at least one spacer.

7. The pressure equalization device according to claim 6, wherein the at least one spacer comprises a first end and a second end, wherein the first end is held at a cover of the pressure equalization device, and wherein the second end is held at the closure element.

8. The pressure equalization device according to claim 7, wherein a connection of the at least one spacer to the closure element is configured to be destroyed above a predetermined limit temperature.

9. The pressure equalization device according to claim 7, wherein the at least one spacer comprises a force transmitting structure extending between the second end arranged proximal to the closure element and the first end arranged proximal to the cover of the pressure equalization device, and wherein the force transmitting structure comprises one or more rated break points configured to fail at a predetermined pressure load.

10. The pressure equalization device according to claim 9, wherein the force transmitting structure comprises at least one radial protrusion formed as an axial stop, and wherein the axial stop contacts an inner surface of the cover of the pressure equalization device in the emergency operating state.

11. The pressure equalization device according to claim 9, wherein the at least one spacer has a sleeve shape, and wherein the rated break points are distributed about a circumference thereof.

12. The pressure equalization device according to claim 6, wherein the at least one spacer is axially displaced together with the closure element when the pressure equalization device transitions into the emergency operating state.

13. The pressure equalization device according to claim 6, wherein the at least one spacer comprises a material configured to lose a shape stability at a temperature of at most 250° C.

14. The pressure equalization device according to claim 1, wherein the closure element comprises a bistable spring body.

15. The pressure equalization device according to claim 14, wherein the closure element is curved toward the flow opening in a normal operating configuration of the closure element in the normal operating state of the pressure equalization device, and wherein the closure element is curved away from the flow opening in an emergency operating configuration of the closure element in the emergency operating state of the pressure equalization device.

16. The pressure equalization device according to claim 1, wherein, in the emergency operating state of the pressure equalization device, the closure element contacts continuously circumferentially the base body.

17. The pressure equalization device according to claim 16, wherein the base body comprises a seal element, and wherein the closure element contacts continuously circumferentially the seal element of the base body.

18. A housing comprising the pressure equalization device according to claim 1.

19. A method for pressure equalization between an interior of a housing comprising a pressure equalization and an environment, the method comprising: performing a gas exchange between the interior of the housing and the environment through a membrane of the pressure equalization device and through a flow path of the pressure equalization device between a closure element and a base body; and closing the base body by the closure element.

20. The method according to claim 19, further comprising: lifting the closure element off the base body in an emergency venting process; destroying during the emergency venting process a spacer of the pressure equalization device, the spacer spacing apart the closure element from the base body at least regionally in a normal operating state of the pressure equalization device; transferring the closure element, embodied as a bistable spring body, from a normal operating configuration into an emergency operating configuration during the emergency venting process; providing the spacer, held with a first end thereof at a cover of the pressure equalization device and held with a second end thereof at the closure element; and destroying a connection of the spacer to the closure element above a predetermined limit temperature during the emergency venting process.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] Further features and advantages of the invention result from the following detailed description of embodiments of the invention, from the claims as well as with the aid of the Figures of the drawing which show details according to the invention. The aforementioned and still to be described features can be realized individually by themselves or several combined in arbitrary expedient combinations in variants of the invention. The features illustrated in the drawing are illustrated such that the particularities according to the invention can be made clearly visible.

[0049] FIG. 1a shows, in a schematic section view, a pressure equalization device according to the invention with a base body which can be flowed through and against which a closure element is pretensioned, wherein a spacer keeps open a flow path between the base body and the closure element in a normal operating state.

[0050] FIG. 1b shows the pressure equalization device of FIG. 1a in an enlarged detail section view.

[0051] FIG. 2 shows, in a schematic section view, the pressure equalization device of FIG. 1a during an emergency venting process in which outflowing gas lifts the closure element against the action of a spring element farther off the base body and has removed the spacer.

[0052] FIG. 3a shows, in a schematic section view, the pressure equalization device of FIG. 1a after completion of the emergency venting process in an emergency operating state, wherein the closure element is pushed by the spring element against the base body so that it closes the latter seal-tightly.

[0053] FIG. 3b shows the pressure equalization device of FIG. 3a in an enlarged detail section view.

[0054] FIG. 4 shows a schematic flowchart of a method according to the invention for pressure equalization by use of the pressure equalization device of FIG. 1a.

[0055] FIG. 5a shows, in a schematic section view, a further pressure equalization device according to the invention with a base body that can be flowed through and against which a bistable closure element is pretensioned, wherein a flow path between the base body and the closure element is open in a normal operating configuration of the closure element.

[0056] FIG. 5b shows the pressure equalization device of FIG. 5a in an enlarged detail section view.

[0057] FIG. 6 shows, in a schematic section view, the pressure equalization device of FIG. 5a during an emergency venting process in which outflowing gas lifts the closure element against the action of a spring element off the base body and has inverted the closure element into an emergency operating configuration.

[0058] FIG. 7a shows, in a schematic section view, the pressure equalization device of FIG. 5a after completion of the emergency venting process in an emergency operating state, wherein the closure element, which is in the emergency operating configuration, is pressed by the spring element against the base body so that it closes the latter seal-tightly.

[0059] FIG. 7b shows the pressure equalization device of FIG. 7a in an enlarged detail section view.

[0060] FIG. 8 shows a schematic flowchart of a method according to the invention for pressure equalization by using the pressure equalization device of FIG. 5a.

[0061] FIG. 9 shows, in a greatly simplified section view, a housing according to the invention with a pressure equalization device according to the invention, wherein in the housing a plurality of battery cells are arranged.

[0062] FIG. 10 shows, in a schematic section view, a further pressure equalization device according to the invention with a base body which can be flowed through and against which a closure element is pretensioned, wherein a flow path between the base body and the closure element is open in a normal operating configuration of the closure element.

[0063] FIG. 11a shows a detail view of the pressure equalization device of FIG. 10 in the normal operating state.

[0064] FIG. 11b shows a detail view of the pressure equalization device of FIG. 10 in the emergency venting state.

[0065] FIG. 12 shows, in a schematic section view, a still further pressure equalization device according to the invention with a base body which can be flowed through and against which a closure element is pretensioned, wherein a flow path between the base body and the closure element is open in a normal operating configuration of the closure element.

[0066] FIG. 13a shows a detail view of the pressure equalization device of FIG. 12 in the normal operating state.

[0067] FIG. 13b shows a detail view of the pressure equalization device of FIG. 12 in the emergency venting state.

[0068] FIG. 13c shows a detail view of the pressure equalization device of FIG. 12 after an emergency venting event.

DETAILED DESCRIPTION

[0069] FIG. 1a shows a pressure equalization device 10. In FIG. 1b, an enlarged detail of the pressure equalization device 10 is illustrated. The pressure equalization device 10 comprises a base body 12. Here, the base body 12 is of a one-part configuration. The pressure equalization device 10 serves for pressure equalization between an interior 14 and an environment 16 of a housing 18, compare FIG. 9. The base body 10 for this purpose can be inserted into a housing wall 20 of the housing 18. A seal 22 ensures that the gas exchange for pressure equalization occurs through the pressure equalization device 10 and not past it.

[0070] The base body 12 comprises a flow opening 24. The flow opening 24 is spanned by a selectively permeable membrane 26. The membrane 26 is permeable for gases. Liquids and solids are retained by the membrane 26. The flow opening 24 can be divided like a grid into several partial openings. The membrane 26 can rest on webs between the partial openings.

[0071] A cover 28 is held at the base body 10. The cover 28 comprises at least one venting opening 30, here a plurality of venting openings 30. The venting openings 30 can be distributed about a circumference of the cover 28.

[0072] The pressure equalization device 10 comprises a closure element 32. The closure element 32 is pretensioned by a spring element 34, here a coil spring, against the base body 12. The spring element 34 can be supported at the cover 28 for this purpose.

[0073] In FIGS. 1a and 1b, the pressure equalization device 10 is in a normal operating state. In the normal operating state, a flow path 36 is open between the closure element 32 and the base body 12. For a pressure equalization, air can flow along the flow path 36 through the flow opening 24 or the membrane 26, through between the closure element 32 and the base body 12, and through the venting openings 30 in the cover 28. In this manner, a gas exchange out of the housing 18 as well as out of the environment 16 into the housing 18 is possible.

[0074] In order to be able to hold the closure element 32 in the normal operating state spaced apart from the base body 12, a spacer 38 is provided. The spacer 38 is presently arranged at the base body 12. The spacer 38 comprises a plurality of projections 40. In the normal operating state, the closure element 32 contacts the projections 40. Recesses 42 are formed between the projections 40. The flow path 36 extends through the recesses 42.

[0075] FIG. 2 shows the pressure equalization device 10 during an emergency venting process. In the emergency venting process, hot gas flows under high pressure and with a large volume flow out of the housing 18. The closure element 32 is lifted in this way against the effect of the spring element 34 farther away from the base body 12. In this way, a large cross section which can be flowed through is released. This reduces the flow resistance of the pressure equalization device 10. The emergency venting process can therefore occur very quickly.

[0076] At the beginning of the emergency venting process, the membrane 26 (compare FIG. 1a) was deflected by the increasing pressure in the interior 14 of the housing 18 and pressed against an emergency venting spike 44. In this way, the membrane 26 was destroyed. This further reduces the flow resistance of the pressure equalization device 10. The emergency venting spike 44 projects here from the closure element 32 toward the membrane 26.

[0077] In the emergency venting process, the spacer 38 (compare FIGS. 1a and 1b) is destroyed. Here, the spacer 38 is comprised of a material, for example, a plastic material, which has a melting point of less than 200° C. Due to the hot gas flowing out from the housing 18, the spacer 38 is melted in the emergency venting process and removed from the base body 12.

[0078] FIGS. 3a and 3b show the pressure equalization device 10 after completion of the emergency venting process. The pressure equalization device 10 is now in an emergency operating state. After relief of the excess pressure in the interior 14 of the housing 18, the spring element 34 forces the closure element 32 against the base body 12. The closure element 32 closes seal-tightly the base body 12. For this purpose, the closure element 32 can contact continuously circumferentially a seal element 46 of the base body 12. An inflow of substances, in particular liquids or gases, from the environment 16 into the interior 14 of the housing 18 through the pressure equalization device 10 is no longer possible now. Also, outflow of gas from the interior 14 into the environment 16 is not possible as long as the pressure in the interior 14 is insufficient in order to lift the closure element 32 off the base body 12 against the force of the spring element 34. When the pressure in the interior 14 becomes large enough, a pressure equalization to the exterior is also possible in the emergency operating state in that the closure element 32 temporarily is lifted off the seal element 46.

[0079] FIG. 4 shows a flowchart of the pressure equalization between the interior 14 of the housing 18 and the environment 16 by use of the afore described pressure equalization device 10.

[0080] In a step 102, a gas exchange between the interior 14 and the environment 16 occurs in a normal operating state, wherein gas flows through the flow opening 24 or the membrane 26, through the recesses 42 between the closure element 32 and the base body 12, and through the venting openings 30 in the cover 28 along the flow path 36, compare FIGS. 1a and 1b. In this manner, the pressure in the interior 14 of the housing 18 is equalized to the pressure of the environment 16. In this context, the flow can be oriented temporarily into the housing 18 and out of the housing 18, respectively.

[0081] In a step 104, an emergency venting process is performed. Due to a sudden pressure increase in the interior 14, the membrane 26 is deflected toward the closure element 32 and is destroyed by the emergency venting spike 44. Due to the hot gas which is flowing at high pressure out from the interior 14, the closure element 32 is lifted off the base body 12, compare FIG. 2. Moreover, the outflowing hot gas destroys the spacer 38 by melting it.

[0082] After relief of the excess pressure in the interior 14, the closure element 32 is pushed by the spring element 34 against the base body 12. The pressure equalization device 10 or its base body 12 is seal-tightly closed thereby in a step 106, compare FIGS. 3a and 3b, so that the emergency operating state is established. The flow path 36 (compare FIGS. 1a and 1b) is now blocked.

[0083] FIGS. 5a and 5b show a further pressure equalization device 50 in the normal operating state. The pressure equalization device 50 is of a similar configuration as the above-described pressure equalization device 10 and serves the same purpose. In particular, the pressure equalization device 50 can be arranged in place of the pressure equalization device 10 at the housing 18 of FIG. 9. In the following, primarily the differences of the pressure equalization devices 50 in relation to the pressure equalization device 10 will be described; in other respects, reference is being had to the preceding description.

[0084] In the pressure equalization device 50, the closure element 32 is configured as a bistable spring body. For the normal operating state, the closure element 32 is in a normal operating configuration. The closure element 32 can be plate-shaped. Presently, the closure element 32 in the normal operating configuration is curved toward the flow opening 24 with the membrane 26.

[0085] The base body 12 of the pressure equalization device 50 is of a multi-part configuration. Presently, the base body 12 comprises an inner part 52, an outer part 54, and a holder part 56. It is understood that the pressure equalization device 50 could also be provided with a one-part base body 12; a multi-part base body 12 could also be provided in the pressure equalization device 10.

[0086] Projections 40 on which the closure element 32 is resting in the normal operating state are formed in the pressure equalization device 50 at the base body 12, here at its inner part 52. The flow path 36 along which the pressure equalization device 50 can be flowed through in the normal operating state extends through recesses 42 between the projections 40.

[0087] FIG. 6 shows the pressure equalization device 50 during an emergency venting process. Due to the hot gas which is flowing at high pressure and with a large volume flow out of the interior 14 of the housing 18, the closure element 32 has been moved against the effect of the spring element 34 away from the base body 12. In addition, the gas pressure has transferred the closure element 32 into an emergency operating configuration. In the emergency operating configuration, the closure element 32 is curved away from the flow opening 24. In other words, in the illustrated embodiment the closure element 32 can be transferred from the normal operating configuration into the emergency operating configuration by inversion. The closure element 32 can be referred to as a metal snap dome.

[0088] FIGS. 7a and 7b show the pressure equalization device 50 in the emergency operating state after completion of the emergency venting process. Since the closure element 32 is curved away from the flow opening 24 in the emergency operating configuration, the projections 40 are no longer in contact with the closure element 32. Instead, a radially outer rim of the closure element 32 is pressed continuously circumferentially against the base body 12 by the spring element 34. The base body 12 can comprise a seal element 46 for seal-tight contact of the closure element 32. In the emergency operating state, the closure element 32 closes the base body 12 and thus the pressure equalization device 50.

[0089] FIG. 8 shows a flowchart of the pressure equalization between the interior 14 and the environment 16 by use of the pressure equalization device 50.

[0090] In a step 102, a gas exchange between the interior 14 and the environment 16 takes place in a normal operating state, wherein the gas flows through the flow opening 24 or the membrane 26, through the recesses 42 between the closure element 32 and the base body 12, and through the venting openings 30 in the cover 28 along the flow path 36, compare FIGS. 5a and 5b. In this way, the pressure in the interior 14 of the housing 18 is equalized to the pressure of the environment 16. In this context, the flow can occur temporarily into the housing 18 and out of the housing 18, respectively.

[0091] In a step 104b, an emergency venting process is performed. Due to the sudden pressure increase in the interior 14, the membrane 26 is deflected toward the closure element 32 and destroyed by the emergency venting spike 44. Due to the hot gas flowing under high pressure out of the interior 14, the closure element 32 is lifted off the base body 12, compare FIG. 6. Furthermore, the outflowing hot gas transfers the closure element 32 into the emergency operating configuration in that it inverts the closure element 32.

[0092] After relief of the excess pressure in the interior 14, the closure element 32 is forced by the spring element 34 against the base body 12. The pressure equalization device 50 or its base body 12 is therefore seal-tightly closed in a step 106, compare FIGS. 7a and 7b, so that the emergency operating state is established. The flow path 36 (compare FIGS. 5a and 5b) is now blocked.

[0093] In FIG. 9, the arrangement of the pressure equalization device 10 or 50 in the housing wall 20 of the housing 18 is schematically illustrated. The housing wall 20 comprises a through passage 58 for receiving the pressure equalization device 10 or 50. In the housing 18, electrochemical energy storage cells 60, here lithium-ion cells, are arranged. The overall arrangement of FIG. 9 can therefore also be referred to as a battery 62.

[0094] In FIG. 10, a still further embodiment of the pressure equalization device 10 according to the invention is illustrated. It differs from the embodiment according to FIG. 1 to FIG. 3b by the different configuration of the spacer 38. The spacer 38 is here provided between the closure element 32 and the cover 28 and is formed as a sleeve-shaped body. The spacer 38 is connected with its closure element end 384 proximal to the closure element 32 to the latter and connected with its end proximal to the cover 28 to the cover 28. The pressure force which is exerted by the spring element 34 on the closure element 32 thus passes through the spacer 38, which is tensile-loaded, into the cover 28. In particular, the spacer 38 comprises, or is comprised of, a plastic material while the closure element 32 is comprised in particular of a metal material. The spacer 38 however can also be comprised of a metal material. The spacer 38 can be connected to the closure element 32, for example, by material fusion or by form fit. Here, particularly gluing, welding under plasma treatment, injection molding as well as screws and/or rivets are conceivable.

[0095] At its side which is facing the cover 28, the spacer 38 is connected to the cover 28 by snap hooks 382 which engage in corresponding snap openings of the cover 28. In other embodiments, not illustrated, the spacer however can also be connected to the cover 28 by other connections appearing suitable to a person in the art.

[0096] As has already been explained in the context of the first two embodiments, in the normal operating state which is illustrated in FIG. 10, a flow path 36 is released that enables an air exchange through the membrane 26.

[0097] When now an emergency venting event occurs, the closure element 32 is suddenly displaced against the spring force so that the maximum possible passage cross section can be made available. Due to the hereby occurring axial pressure forces which act on the spacer 38, the latter is axially entrained also and initially contacts the inner surface of the cover 28 with its radially protruding axial stops 383. As a result, the spacer 38 is structurally destroyed at its appropriately dimensioned rated break points 381, which are present distributed about the circumference, and breaks apart into two pieces, a bottom part facing the closure element 32 and a top part which is facing the cover 28. This process is illustrated in FIGS. 11a and 11b.

[0098] After the emergency venting event has passed, the pressure on the closure element 32 decreases again and the closure element 32, driven by the spring force of the spring element 34, is axially moved back so that it contacts the seal element 46 with its circumferentially extending rim and prevents a further gas flow through the flow opening 24.

[0099] This embodiment has the advantage that the spacer 38 is present outside of the closure element 32 and thus outside of the flow path 36 so that individual components of the spacer 38 which are produced by the irreversible destruction thereof cannot reach the interior of a housing, in particular battery housing, at which the pressure equalization device is mounted, which interior is freely accessible after the emergency venting event due to the destruction of the membrane 26.

[0100] Furthermore, there is the advantage that it is visible from the exterior whether an emergency opening has taken place because, thereafter, the snap hooks 382 of the spacer 38 are no longer present in their original form due to the irreversible destruction.

[0101] In FIGS. 12, 13a-c, a further embodiment of the pressure equalization device 10 according to the invention is illustrated which shares structural similarities with the embodiment of FIGS. 10, 11a, 11b, for which reason only the differences will be explained.

[0102] The spacer 38 has a sleeve shape and is connected at its closure element end 384 to the closure element 32 and with the other end is held at the cover 28 by the axial stop 383 formed as a pin, wherein the spacer 38 is tensile-loaded in the normal operating state. The axial stop can also be formed in any other way appearing suitable to a person of skill in the art. The connection of the spacer 38 to the closure element 32 at its closure element end 384 is thermally destructible above a predetermined limit temperature, in particular above 200° C., so that it is destroyed in case of an emergency venting event. The connection can be in particular an adhesive connection or other material fusion connection, for example, injection molding of the spacer 38 onto the closure element 28.

[0103] When an emergency venting event occurs and the pressure equalization device 10 is transferred into the emergency venting state, the closure element 32 is displaced axially and together with it the spacer 38, wherein also the axial stop 383 is lifted off the cover 28. This is illustrated in FIGS. 13a and 13b. Due to the temperatures which are present during the emergency venting process, the connection of the spacer 38 to the closure element 32 at its closure element end 384 is destroyed so that the closure element 32 is axially moved back, driven by the spring force of the spring 34, after completion of the emergency venting process and contacts the circumferentially extending seal 46 of the base body 12.