Pressure relief plug and housing with such a

Abstract

One-piece molded pressure relief plug (18) for insertion into a pressure relief channel (16) of a housing (10), comprising: - a base body (26) with a lateral surface (28) extending in the direction of the longitudinal axis (L) of the pressure relief plug (18) and which has a proximal and a distal end section (30, 32); - a rubber-elastic deformable sealing lip (34) which is formed circumferentially on the distal end section (32) of the base body (26) and which extends away from the distal end section (32) in a radial direction and axially in the direction of the proximal end section (30), wherein a circumferential clearance (38) between the outer surface (28) and the sealing lip (34) is defined in the radial direction by the outer surface (28) and the sealing lip (34); and - a support area (44) formed at the distal end section (32) for axially supporting the base body (26) on a support (46) of the housing (10), wherein an axial force (F) acting on the support area (44) A ) one for axial force (F A ) proportional deformation of the distal end section (32) and consequently a force acting on the sealing lip (34) (F R ) is caused by the radially inward direction towards the longitudinal axis L.

Description

[0001] The invention relates to a housing with an overpressure protection device. Such housings are used in practice in many technical fields to protect the housing or its contents from damaging overpressure. Safety valves or so-called bursting discs are often used as overpressure protection devices. These valves respond when a maximum permissible internal housing pressure is reached or exceeded, thereby enabling atmospheric pressure equalization. Safety valves generally close automatically when the internal housing pressure drops, so that the housing can be reused without any further measures. Rupture discs, on the other hand, are irreversibly destroyed by their activation, acting as a predetermined breaking point, and must be replaced for the housing to continue to be used. Safety valves and bursting discs are complex to manufacture, assemble, and repair, and therefore represent a significant cost factor.

[0002] EP 1 001 905 B1 discloses a housing with an overpressure protection device comprising a pressure relief channel with a rubber-elastic, deformable pressure relief plug arranged in the pressure relief channel. The pressure relief plug rests with its circumferential sealing lip on the outside against a sealing surface of the housing in an axial direction and can be preloaded against the sealing surface with a defined preload via a molded-on spring element. During prolonged operation, condensation of moisture alone can lead to undesired sticking of the sealing lip to the housing. Reliable venting of the housing interior when a maximum permissible operating pressure P is reached or exceeded lim inside the housing is then no longer guaranteed.

[0003] An advanced overpressure protection device with a diaphragm sealing plug is disclosed in EP 3 292 575 B1. The diaphragm sealing plug exhibits significantly improved response to pressure increases in the housing and provides reliable pressure relief even when the sealing lip is glued to the housing. This is due to the radially sealing sealing lip, which releases when the maximum atmospheric operating pressure P prevailing inside the housing is reached or exceeded. lim The media can progressively peel or peel off the wall (=sealing surface) in an axial direction. The disadvantage is that the triggering of the overpressure seal is usually accompanied by the diaphragm sealing plug being completely moved axially out of the pressure relief channel, thus rendering the sealing function of the diaphragm sealing plug ineffective. The diaphragm sealing plug must therefore be reinstalled or even replaced after triggering.

[0004] Furthermore, US 4,086,394 A discloses a cup-shaped sealing element that is held against a support by a separate holder. The sealing element has a base to which the cup wall is integrally formed. If the base of the cup-shaped sealing element is axially compressed between the holder and support, the cup wall is not deformed and, consequently, in the installed state, the radial contact pressure of the cup wall against the wall is not affected.

[0005] JP 2003-346 764 A discloses a one-piece vent valve element with a cylindrical base body and a circumferential sealing lip. The sealing lip is molded onto the center section of the base body. By screwing the cover in further, the base body is increasingly axially compressed, but without affecting the sealing lip, so that the radial contact pressure of the sealing lip cannot be adjusted in a defined manner.

[0006] DE 10 2013 105 817 A1 also discloses a one-piece vent valve element with a cylindrical base body and a circumferential sealing lip. The sealing lip is molded onto the central section of the base body. Axial compression of the base body has no effect on the sealing lip, so the radial contact pressure of the sealing lip cannot be adjusted in a defined manner.

[0007] It is therefore the object of the invention to provide a pressure relief plug and a housing with an overpressure protection device, which can be manufactured in a simple and cost-effective manner, wherein the pressure relief plug always has a reliable response behavior and an adjustable opening pressure and is self-resetting, so that long-term use can be sufficiently covered even in critical applications, for example a battery housing for lithium batteries or lead batteries or the like.

[0008] The problem concerning the pressure relief plug is solved by a pressure relief plug according to claim 1. The housing according to the invention has the features specified in claim 10. Advantageous developments of the invention are specified in the description and the subclaims.

[0009] The pressure relief plug according to the invention is intended for insertion into a pressure relief channel of a housing and has a base body with a jacket surface and with a proximal and a distal end section. This extends in the direction of the longitudinal axis L of the pressure relief plug. A rubber-elastic, deformable sealing lip is formed (completely) circumferentially on the distal end section of the base body. The sealing lip extends in a radial outward direction and axially in the direction of the proximal end section away from the distal end section. A circumferential free space between the jacket surface and the sealing lip is delimited in the radial direction by the jacket surface of the base body and the sealing lip. The free space enables a deflection of the sealing lip radially in the direction of the jacket surface of the base body, i.e.a pressure-activated movement of the sealing lip out of its sealing seat on the wall of a pressure relief channel of the housing in which the pressure relief plug is arranged during operation.

[0010] The distal end section further comprises a support area for axially supporting the base body against an abutment of the housing. An axial force F acting on the support area a is a force to the axial force F a proportional deformation (moment) of the distal end section and thus a deflection of the sealing lip radially in the direction of the base body.

[0011] The proposed pressure relief plug is, on the one hand, simple and cost-effective to manufacture. This allows the pressure relief plug to be manufactured in one piece, for example, as an injection-molded part. The circumferential sealing lip enables radial sealing of the housing's pressure relief channel. As a result, the sealing lip can be lifted / peeled off the wall of the pressure relief channel progressively radially inwardly in axial direction as the operating pressure inside the housing increases, in order to close the pressure relief opening when the specified maximum operating pressure P is reached or exceeded. lim inside the housing. This is possible even if the sealing lip adheres to the wall of the pressure relief opening.

[0012] It should be noted that in the pressure relief plug according to the invention, in the operating state, by selecting the axial contact pressure of the support area against a suitable abutment of the housing, ie the axial force F acting on the support area a , a sensitive adjustment of the radial preload of the sealing lip against the wall of the pressure relief channel is possible. This preload of the sealing lip correlates with the maximum operating pressure P lim This correlation can be determined experimentally. Therefore, the pressure relief plug allows the maximum operating pressure P to be defined or readjusted in the assembled state. lim , in which the pressure relief plug releases the pressure relief channel. Manufacturing tolerances of the pressure relief plug or the housing can be easily compensated.

[0013] The pressure relief plug therefore enables a significantly improved response to an increase in the operating pressure P inside the housing during operation, even with a sealing lip glued to the wall, ie a more reliable venting of the housing interior when a variably preset maximum atmospheric operating pressure P is reached or exceeded. lim inside the housing.

[0014] According to the invention, the support region can extend at least partially outside the lateral surface of the base body in a radial direction. In other words, the support region can extend beyond the lateral surface of the base body in a radial direction or be arranged completely outside the lateral surface in the radial direction. This allows a change in the axial force F acting on the support region. Abe reliably converted into a moment by which the distal end section is deformed and a force F A derived and radially inward directed force component F R acts on the sealing lip. This force component F R is the intrinsic, ie the sealing lip's inherent, maximum possible contact force F Pi opposite to the sealing lip. The intrinsic contact force F Pi The sealing lip is determined in particular by the radial oversize of the pressure relief plug including the sealing lip relative to the nominal diameter of the pressure relief channel of the housing to be fitted with the pressure relief plug, and the material properties, particularly the elastic modulus, of the sealing lip. As a result, the sealing lip rests against the wall or sealing surface of the housing, resulting in a variably adjustable preload force F p sealing.

[0015] According to a particularly preferred embodiment of the invention, the support region of the distal end section of the base body can have one or more radially extending flow channels. This enables direct fluidic communication between the sealing lip and the housing interior, even when the support region of the base body is supported circumferentially on a flat (annular) abutment. The flow channels can be formed, for example, by ribs or grooves in the support region, preferably arranged in a radial direction. Alternatively, a through-bore extending through the distal end section is also conceivable. It goes without saying that the proximal opening of the through-bore must be located distal to the connection of the sealing lip to the base body.

[0016] The support area can be formed, in particular, by the end face of the distal end portion of the base body. Alternatively, an annular collar can be formed on the distal end portion, which radially surrounds the distal end portion at least partially on the outside and forms the support area.

[0017] Particularly preferably, the distal end section has a central material weakening which extends axially from the distal end face of the base body in the direction of the proximal end section. The material weakening can be formed, for example, by a soft material insert in the base body, or a central depression or cutout. The cutout / depression can in particular be hemispherical or conical. This makes it possible to achieve simplified deformability of the distal end section in the installed state of the pressure relief plug, i.e. particularly sensitive and simple adjustment of the contact pressure force of the sealing lip. The central material weakening / cutout or cutout is preferably delimited on the outside in a radial direction, preferably circumferentially, by the support surface, preferably directly.

[0018] If the material weakening of the distal end section of the pressure relief plug is designed as a conical or truncated cone-shaped recess, the wall of the recess can form the support area of ​​the base body. In this case, the abutment of the housing, in which the pressure relief plug is to be inserted, is preferably provided with a truncated cone with a more obtuse cone angle than the wall of the recess in order to adapt to the axial force F A a widening of the distal end section of the base body and a concomitant increase in the radial force F acting on the sealing lip R to enable.

[0019] From a manufacturing perspective, it has proven advantageous if the pressure relief plug is completely or partially rotationally symmetrical to the longitudinal axis L. This also simplifies installation into the housing and minimizes potential sources of error during the manufacture and assembly of the pressure relief plug.

[0020] According to the invention, the pressure relief plug is designed in one piece to enable simple production, for example as an injection-molded part.

[0021] The housing according to the invention can, in particular, be a battery housing and can also be referred to as a container. The housing has an overpressure protection device comprising a pressure relief channel and a pressure relief plug, which is arranged in the pressure relief channel in the sealing seat (which seals radially outward relative to the longitudinal axis of the pressure relief plug). The pressure relief channel extends from the housing interior to the housing exterior and is delimited by a (channel) wall. The pressure relief plug is designed as described above and rests with its circumferential sealing lip in a radial direction on the wall of the pressure relief channel with a prestressing force F PThe sealing lip can be deactivated by an increasing atmospheric pressure inside the housing and can be moved axially (outwards) progressively in a radial direction away from the wall until the pressure relief channel is opened for the purpose of pressure relief inside the housing when a maximum atmospheric pressure P lim inside the housing is released. The housing further comprises a preloading element which is arranged on the housing so as to be adjustable in an axial direction (and positionally fixable in the axial direction), and by means of which the pressure relief plug is tensioned with its support area in the axial direction against an abutment of the housing, wherein the maximum pressure P lim by axially adjusting the preload element a) is reducible in the direction of the abutment; and b) can be enlarged in a direction away from the abutment.

[0022] In other words, the maximum operating pressure P lim by a desired maximum operating pressure P lim corresponding axial force F a The pressure of the relief plug or its support area against the housing abutment is variably adjustable. This is achieved with a radially external sealing lip. The housing is suitable for use with the valve body due to the finely graduated and precisely adjustable maximum operating pressure P lim Particularly suitable for critical applications where sufficient sealing of the housing interior from the outside and, at the same time, reliable pressure limitation of the internal pressure of the housing are important.

[0023] The preloading element can particularly preferably be formed by a cap, in particular a screw cap, which is in mutual (screw) thread engagement with the housing. The cap also offers the advantage of captive securing of the pressure relief plug in the pressure relief channel and protecting the housing's overpressure relief device from mechanical damage or the ingress of coarse contaminants.

[0024] The invention is explained in more detail below using an exemplary embodiment shown in the drawing. The drawing shows: Fig. 1 shows a housing for an energy storage device with an overpressure protection device with a pressure relief channel, which is sealed fluid-tight by means of a pressure relief plug during normal operation, in a sectional view; and Fig. 2 the pressure relief plug according to Fig. 1 in a detailed section.

[0025] Fig. 1 shows a container or housing 10, which here is designed as a battery housing with a lithium-ion accumulator 12 arranged in the housing 10. It is understood that the housing 10 can also be used in other technical applications, in particular as a transport container or the like. The housing 10 has an overpressure protection device 14. The overpressure protection device 14 comprises a pressure relief channel 16 in which a pressure relief plug 18 is arranged in the sealing seat. The pressure relief plug 18 closes the pressure relief channel 16 in a fluid-tight manner in the operating state shown. The pressure relief channel 16 extends from the interior or housing interior 20 to the housing exterior 22. The pressure relief channel 16 here has a first channel segment 16a and a second channel segment 16b.The first channel segment 16a is directly fluidically connected to the housing interior 20, while the second channel segment 16b is directly fluidically connected to the housing exterior 22. The second channel segment 16b has a smaller flow cross-section than the first channel segment 16a. An outlet opening of the pressure relief channel is designated 24.

[0026] The pressure relief plug 18 is designed in such a way that when a predetermined maximum operating pressure P lim in the housing interior 20 releases the pressure relief channel 16, ie fluidically connects the interior 20 and the housing exterior 22 to enable atmospheric pressure equalization. The maximum operating pressure P lim therefore corresponds to the opening pressure of the pressure relief plug 18.

[0027] The pressure relief plug 18 is in Fig. 2 in an enlarged detail. The pressure relief plug here consists, for example, of an elastomer, i.e., entirely of a rubber-elastic, deformable material, and can in particular be designed in one piece, for example as a cost-effective injection-molded part. It is understood that the pressure relief plug can, if required, have a reinforcing insert or a coating. The pressure relief plug 18 has a base body 26 - here, for example, cylindrical - with a jacket surface 28 and a proximal and a distal end section 30, 32. The longitudinal axis of the pressure relief plug 18 is designated L. The base body 26 can also have a polygonal, in particular hexagonal or octagonal, cross-sectional shape.

[0028] A circumferential, rubber-elastic, deformable sealing lip 34 is formed on the base body 26, more precisely on its distal end section 32. The connection area between the sealing lip 34 and the base body 26 is designated 36. The sealing lip 34 extends - relative to the longitudinal axis L - from the distal end section 32 in a radial outward direction and axially in the direction of the proximal end section 30 away from the base body 26 or the distal end section 32.

[0029] The outer surface 28 and the sealing lip 34 delimit a circumferential free space 38 in the unloaded state of the pressure relief plug 18 as well as in its assembled state in the radial direction. The free space 38 allows when the maximum internal housing pressure P is reached or exceeded lim a radial deflection of the sealing lip 34 from its shown sealing position in the direction of the outer surface 28 or the longitudinal axis L for the purpose of venting the housing interior 20.

[0030] The sealing lip 34 lies on the wall 40 ( Fig. 2) of the pressure relief channel 16 sealing all around with a strictly radially aligned preload force F P The radial preload force F P is generated by the elastic recovery capacity inherent in the rubber-elastic, deformable material of the sealing lip 34. The distal end section 32 of the base body has an end face 42 that forms an axial support region 44, via which the pressure relief plug 18 is supported in an axial direction against an abutment 46. The abutment 46 can be formed, in particular, by a shoulder of the wall 40 of the pressure relief channel 16.

[0031] The distal end section 32 is according to Fig. 1 and Fig. 2, for the purpose of simplified deformability, is preferably provided with a material weakening 48, here, for example, in the form of a central recess or depression on the front side. The depression shown in the figure is essentially conical. The support region 44 surrounds the material weakening 48 in sections in a radial direction. It should be noted that the support region 44 extends in a radial direction at least in sections over the lateral surface 28 ( Fig. 1) of the base body 26.

[0032] The end face 42 also has a plurality of radially extending (flow) grooves 50 in the support area, which are fluidically connected at one end to the outer flank 52 of the sealing lip 34. If present, the grooves 50 are fluidically connected at the other end to the weakened portion of the material (recess / cutout). The grooves 50 each serve as a flow channel for the medium (e.g., atmosphere) to be evacuated from the interior 20 of the housing 10 as needed.

[0033] The proximal end section 30 ( Fig. 1) of the base body 26 serves for the axial support of a pre-tensioning element 54, by means of which the pressure relief plug 18 can be tensioned in an axial direction against the abutment 46. The pre-tensioning element 54 can be Fig. 1 may be designed in particular in the form of a screw cap or the like, which is in mutual threaded engagement 56 with the housing 10.

[0034] The sealing lip 34 is when an atmospheric maximum atmospheric internal pressure P lim in the interior 20 of the housing 10 - media-actuated - at least partially movable away from the wall 40 of the pressure relief channel 16 in a radial direction, progressively in the axial direction, in order to release the pressure relief channel 16.

[0035] P lim or the corresponding opening pressure of the pressure relief plug 18 can be adjusted by the axial preload of the pressure relief plug 18 against the housing-side abutment 46. If the axial force F acting on the pressure relief plug 18 A by supporting the pressure relief plug 18 on the abutment 46 by means of the prestressing element 54, this causes a deformation of the distal end section 32 of the base body 26 in such a way that a radially inwardly directed radial force F Ris exerted on the sealing lip 34 arranged in the sealing seat. This radial force F R is opposite to the intrinsic preload force F of the sealing lip 34 against the wall 40, which in Fig. 2 graphically displayed preload force F P is the resultant. The sealing lip 34 is subjected to the radial force F R thus relieved.

[0036] If the axial contact force F A of the pressure relief plug 18 against the housing-side abutment 46 is reduced by means of the prestressing element 54, the distal end section 32 deforms back again in a corresponding manner due to its inherent elastic restoring capacity, whereby the radial force F relieving the sealing lip 34 R is reduced. The preload force F P the sealing lip 34 and thus P lim become larger. The radial force F R or the maximum operating pressure P limare therefore antiproportional to the axial force F A .

[0037] With the radially sealing pressure relief plug 18 proposed here, the opening pressure P lim The pressure relief plug can be variably adjusted by axially preloading it against the abutment. This allows manufacturing tolerances of the components to be compensated for with respect to the maximum permissible operating pressure, allowing the pressure-protected housing to be used even in critical applications.

Claims

[1] One-piece molded pressure relief plug (18) for insertion into a pressure relief channel (16) of a housing (10), comprising: - a base body (26) with a lateral surface (28) which extends in the direction of the longitudinal axis (L) of the pressure relief plug (18) and which has a proximal and a distal end section (30, 32); - a rubber-elastically deformable sealing lip (34) which is formed circumferentially on the distal end section (32) of the base body (26) and which extends in a radial direction and axially in the direction of the proximal end section (30) away from the distal end section (32), wherein a circumferential free space (38) between the lateral surface (28) and the sealing lip (34) is delimited in the radial direction by the lateral surface (28) and the sealing lip (34); and - a support region (44) formed on the distal end section (32) for axially supporting the base body (26) on an abutment (46) of the housing (10), wherein an axial force (F A ) one to the axial force (F A ) proportional deformation of the distal end portion (32) and, consequently, a force acting on the sealing lip (34) (F R ) which is directed radially inwards towards the longitudinal axis L. [2] Pressure relief plug according to claim 1, characterized by that the support region (44) extends in a radial direction at least partially outside the lateral surface (28) of the base body (26). [3] Pressure relief plug according to claim 1 or 2, characterized by that the support area (44) is formed by an end face (42) of the distal end portion (32). [4] Pressure relief plug according to one of the preceding claims, characterized bythat the support region (44) surrounds the longitudinal axis L of the pressure relief plug (18) in an annular manner, at least in sections. [5] Pressure relief plug according to claim 4, characterized by that the support area has at least one groove in order to enable a fluid passage between the support area (44) and the abutment (46) when the support area (44) rests against the abutment (46) of the housing (10). [6] Pressure relief plug according to one of the preceding claims, characterized by in that the distal end portion (32) has a central material weakening (48), in particular in the form of a central recess, which extends from a distal end face (42) of the base body (26) axially in the direction of the proximal end portion (30). [7] Pressure relief plug according to claim 6, characterized by that the material weakening (48) is conical or truncated cone-shaped. [8] Pressure relief plug according to claim 6 or 7, characterized by that the central material weakening is limited in a radial direction on the outside, preferably circumferentially, by the support area (44). [9] Pressure relief plug according to one of the preceding claims, characterized by that the pressure relief plug (18) is rotationally symmetrical to the longitudinal axis (L). [10] Housing (10), in particular battery housing, with an overpressure protection device (14) comprising: - a pressure relief channel (16) which extends from the housing interior (20) to the housing exterior (22) and which is delimited by a wall (40); - a pressure relief plug (18) according to one of the preceding claims, which is arranged in the pressure relief channel (16) and which, with its circumferential sealing lip (34) in a radial direction, bears circumferentially and sealingly against the wall (40) with a prestressing force (F), wherein the sealing lip (34) is closed when a maximum atmospheric pressure value (P lim ) in the housing interior (20) is movable at least partially away from the wall of the pressure relief channel (16) in a radial direction in order to release the pressure relief channel (16) for the purpose of relieving pressure in the housing interior (20), and - a prestressing element (54) which is arranged on the housing (10) so as to be adjustable in a direction axial to the longitudinal axis (L) of the pressure relief plug (18) and by means of which the pressure relief plug (18) can be tensioned with its support region (44) in the axial direction against an abutment (46) of the housing (10), wherein the maximum pressure value (Plim ) by axially adjusting the preloading element (54) a) reducible in the direction of the abutment (46); and b) can be enlarged in a direction away from the abutment (46). [11] Housing according to claim 10, characterized by that the preloading element (54) is in mutual threaded engagement (56) with the housing (10). [12] Housing according to claim 10 or 11, characterized by that the abutment (46) is formed by a wall projection of the housing (10) which projects into the pressure relief channel (16). [13] Housing according to one of claims 10 to 12, characterized by that the housing (10) is a battery housing.

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