Rupture disk
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- UMWELTTECHN GEORG FRITZMEIER
- Filing Date
- 2026-01-21
- Publication Date
- 2026-07-30
Smart Images
Figure EP2026051403_30072026_PF_FP_ABST
Abstract
Description
[0001] Burst disc
[0002] Description
[0003] Technical field
[0004] The disclosure relates to a rupture disc, preferably for use on a housing of a (gas-carrying) underride guard (UGS) or a (vehicle) battery. The disclosure further relates to a housing of a (gas-carrying) underride guard (UGS) or a (vehicle) battery with a rupture disc.
[0005] Finally, the disclosure relates to the use of a burst disc on a housing of an underride guard or a (vehicle) battery of an electric vehicle.
[0006] Background of the Revelation
[0007] In the field of electromobility, gas- and watertight battery housings are known. Furthermore, it is known that electric vehicles are fitted with underride protection, also known as underbody protection, to protect against impacts from below, such as water, uneven surfaces, or stone chips.
[0008] The housings of such batteries can, in principle, have an integrated underride guard. Alternatively, a separately manufactured and mounted underride guard housing can be provided. For example, an underride guard housing mounted on a battery housing can be provided.
[0009] With current high-performance electric vehicle batteries, which are normally enclosed in a waterproof (battery) casing, it is important that these casings release a degassing vent in the event of a fault, even at relatively low pressures, to dissipate hot, flammable gases into the environment. This is intended to prevent, in particular, a thermal chain reaction, the so-called thermal runaway of the battery. FR2695P-WG-0005
[0010] 2 / 28
[0011] State of the art
[0012] In electromobility, battery housings with rupture discs are known, which release an opening by breaking a membrane at a predetermined low burst pressure.
[0013] A rupture disc of this type for an electric vehicle battery housing is disclosed at the internet address https: / / git-sicherheit.de / de / produkte / neue-berstscheiben-fuer-die-elektromobilitaet. In addition to its primary function of bursting at a predetermined internal pressure of the battery housing, the rupture disc features an integrated pressure equalization function. It incorporates a graphite membrane designed to burst. The pressure equalization function is performed by an additional waterproof PTFE membrane. This allows for limited compensation of pressure fluctuations occurring between the housing interior and the environment, as well as in the range below the burst pressure, without the rupture disc opening completely.
[0014] A multi-part rupture disc with pressure equalization function for battery housings of electric vehicles is also revealed at the internet address https: / / www.donaldson.com / en-jp / venting / products / battery / .
[0015] A comparatively complex modular ventilation system with emergency degassing function and pressure equalization function for battery housings of electric vehicles is disclosed at the internet address https: / / oem.mann-hummel.com / de / oem-produkte / filterloesungen-elektrische-antriebe / batteriesysteme / druckausgleichselement.html.
[0016] A disadvantage of all the aforementioned rupture discs, and particularly of the last-mentioned ventilation system, is the complex design resulting from their multi-part construction. The membranes designed to burst require a surrounding frame-like or ring-shaped support structure with appropriate seals. Furthermore, the aforementioned prior art rupture discs require an internal grid-like support structure for the flat membrane during normal operation or when closed. This grid structure is necessary to protect the fragile membrane during handling and to support it when submerged.
[0017] Furthermore, simpler adhesive film rupture discs made of PET and aluminum foil with a circumferential predetermined breaking point are known from the prior art. However, microchannels can form during operation, which is detrimental and compromises the sealing of the interior of the affected housing. Disadvantages of these adhesive discs include their vulnerability to mechanical damage from small stones, high-pressure cleaners, etc., due to the thinness of the component, and the difficulty in ensuring a reliable bond throughout its service life under varying external conditions. In particular, consistent properties cannot be guaranteed across the entire relevant temperature range between -40°C and +80°C.
[0018] Brief description of the Revelation
[0019] The purpose of this disclosure is to provide a rupture disc that, with minimal technical effort and high reliability, releases an opening at a predetermined opening pressure and reliably withstands positive opening pressures until the predetermined opening pressure is reached. Furthermore, the rupture disc should also reliably withstand negative opening pressures. In other words, the rupture disc should also reliably withstand negative pressures on the affected container or housing.
[0020] This problem is solved by a rupture disc according to claim 1, preferably for use on a housing of a (gas-carrying) underride guard or a (vehicle) battery. Furthermore, the problem is solved by a housing of a (gas-carrying) underride guard or a (vehicle) battery with a rupture disc according to claim 12. Finally, the problem is solved by using a rupture disc on a housing of an underride guard or a (vehicle) battery of an electric vehicle according to claim 15. The rupture disc according to the disclosure is designed and configured to close an opening, preferably a vent opening, of a container or housing, preferably a battery housing or an underride guard housing, and to release the opening at a predetermined opening pressure.The rupture disc has a disc-like bistable activation surface surrounded by a contact edge to which a circumferential seal of the rupture disc is arranged, attached, or formed. The seal can be a foam seal, an injection-molded seal made of a soft component, or an injection-molded, integrated elastomer part. The activation surface can be moved from a curved closed position (normal state) through a dead center to a curved open position (similar to a snap-action mechanism) by the predetermined opening pressure. A side facing the housing to be sealed is provided on the activation surface and on the entire rupture disc; this side is referred to as the sealing side because the seal is arranged, attached, or formed there. On this sealing side, at least two, e.g., two, three, four, or more, in particular n, snap hooks are formed on the activation surface adjacent to the seal.In the case of only two snap hooks, these are arranged opposite each other with respect to a perpendicular center line of the activation surface. In the case of more than two snap hooks, these are preferably distributed evenly around the circumference of the activation surface. The seal runs around the outside of the snap hooks. The snap hooks each have projections designed to engage behind an edge surrounding the opening. These projections clamp the edge of the opening together with the seal when the activation surface, and thus the snap hooks, are in the closed position. In the closed position of the activation surface and the snap hooks, the projections are closer to the seal than in the open position of the activation surface and the snap hooks. The rupture disc according to the disclosure releases the affected opening into which it was inserted non-destructively at the predetermined opening pressure.Therefore, according to the disclosure, the rupture disc can also be described as a sealing closure element that detaches from the edge (in a defined, pressure-dependent manner). This creates a rupture disc that, with minimal tooling effort and high reliability, can withstand positive opening pressures up to the predetermined value FR2695P-WÖ-0005.
[0021] 5 / 28
[0022] withstands the opening pressure in a sealing manner and releases the opening with high reliability at the predetermined opening pressure.
[0023] Furthermore, the rupture disc also reliably withstands negative opening pressures. In other words, it also withstands negative pressures on the affected container or housing, as in this case the seal is stretched over the contact edge against the edge of the opening and pressed with increasing negative opening pressure. For this purpose, the seal is preferably a foam seal attached to the contact edge.
[0024] Functionally and from a device engineering perspective, it is simple if the snap hooks are in their respective outer positions when closed, and if they are retracted and / or pivoted to their respective inner positions when open. The terms "outer" and "inner" refer to the vertical center line of the rupture disc. Therefore, the inner positions of the snap hooks are closer to the vertical center line of the activation surface than the outer positions.
[0025] In a particularly simple embodiment of the rupture disc from a device engineering perspective, the activation surface, the contact edge and the snap hooks are a single-piece injection-molded plastic part.
[0026] Particularly reliable switching of the activation surface from the closed position to the open position at the predetermined opening pressure is achieved when the activation surface is divided into several planar segments (e.g., triangular or quadrilateral, approximately trapezoidal) which are connected to each other via integrally formed film hinges (e.g., arranged in a cross, X, or star pattern), and especially preferably to the mounting edge via circumferential film hinges. In one embodiment, the film hinges can have a thickness of 0.4 to 0.5 mm.
[0027] Between the flat segments and the snap hooks extending from them at approximately right angles (away from them), one or two support sections can be formed on the sealing side. FR2695P-WÖ-0005
[0028] 6 / 28
[0029] In a particularly preferred further development of the rupture disc, a pressure equalization element is inserted into one of the segments.
[0030] When using a rupture disc on a battery housing or underride guard, the pressure equalization element is preferred so that, when a transport aircraft carrying the affected housing or container without pressure equalization takes off, the rupture disc does not pop out and release the opening, but remains in its sealing function.
[0031] In one specific design of the pressure equalization element, a small opening is provided in the affected segment. This opening is closed by an adhesively or welded-on air-permeable membrane and protected by a cap on the side opposite the sealing surface. In operation, the side opposite the sealing surface is the outer side in relation to the housing or container and therefore must be protected from external influences.
[0032] When using the burst disc with pressure equalization element on a battery housing or underride protection, the cap is also preferred to withstand, for example, a steam jet cleaner.
[0033] In another specific embodiment of the pressure equalization element, the activation surface, in particular a segment, is perforated. On the sealing side, a waterproof but air-permeable membrane is welded onto the perforation holes.
[0034] During a leak test of the affected container or housing, particularly the housing of the underride guard, the perforated holes should be kept sealed. This can be achieved by pressing a rubber pad against the side opposite the sealing surface. Alternatively, the holes can be sealed with an adhesive pad attached to the side opposite the sealing surface, which is then removed after the leak test. In both configurations of the pressure equalization element, the membrane is preferably a PTFE membrane.
[0035] In preferred embodiments of the rupture disc, the activation surface, the contact edge, and the seal essentially form an n-gon. Accordingly, n segments and n snap hooks are provided. Mounting the rupture disc in the opening of the affected housing or container is particularly simple if the n-gon is uniform and if the segments are of equal size, since in this case, the correct rotational position does not need to be considered. Preferably, the snap hooks are also of equal size.
[0036] In particularly preferred embodiments, the activation surface, the contact edge, and the seal form a rectangle. Four segments, each with four snap hooks, are provided. Preferably, the segments and snap hooks are of equal size in pairs. A central fifth segment may also be provided.
[0037] In a preferred rectangular embodiment, the four snap hooks are each formed integrally on a segment.
[0038] In another rectangular embodiment, two opposing snap hooks are formed on each segment, and two (further) opposing snap hooks are formed on the contact edge. To achieve synchronous movement of the two snap hooks formed on the contact edge with the activation surface, a leaf spring is clamped between the two snap hooks formed on the contact edge. This leaf spring can be attached to the central fifth segment of the activation surface on the sealing side. The leaf spring, together with the activation surface, can be moved from a curved closed position (normal state) through a dead center to a curved open position by the predetermined opening pressure (similar to a snap-action mechanism).
[0039] Two opposing snap hooks can be so long that their length is essentially or approximately the same as that of a respective edge of the FR2695P-WÖ-0005
[0040] 8 / 28
[0041] The affected opening corresponds to this. Each of these two snap hooks can be fitted with two positioning aids, which are inserted into the four corners of the affected opening.
[0042] In a particularly preferred embodiment, the predetermined opening pressure is between 175 mbar and 225 mbar, e.g., 200 mbar. This makes the rupture disc particularly suitable for a watertight battery housing or a gas-carrying underride guard, because below 180 mbar, e.g., at only 140 mbar, the rupture disc should not yet burst open and release the degassing vent, but should remain in its sealing function, as it could be a case of air transport of the affected housing without a pressure chamber.
[0043] In a particularly preferred embodiment, the contact edge and the seal are designed to be stable and sealing for an opening pressure of at least -180 mbar. This makes the rupture disc particularly suitable for the gas- and watertight housing of the battery or the gas-carrying underride guard, because in this application scenario, such a negative opening pressure (negative pressure in the housing or water pressure from outside on the housing) could occur due to thermal shock immersion of the housing or a steam jet, at which the rupture disc should not leak.
[0044] The plastic from which the film hinges are preferably injection-molded in one piece with the segments, the mounting edge, and the snap hooks, preferably has a modulus of elasticity of less than 3000 MPa, particularly preferably less than 2500 MPa. This ensures that the film hinges offer the desired low resistance when switching between the closed and open positions, and thus reliable response at the predetermined low opening pressure.
[0045] The plastic from which the film hinges are preferably injection-molded in one piece with the segments, the mounting edge, and the snap hooks, particularly preferably has a glass transition temperature of over 100°C, and more preferably over 110°C. This ensures that the film hinges offer the desired independence from the temperature of the (determined by the thickness of the film hinges FR2695P-WG-0005
[0046] 9 / 28
[0047] (adjusted) low resistance when switching between the closed position and the open position, thus ensuring reliable response at the predetermined low opening pressure.
[0048] High-temperature-resistant thermoplastics based on polyethersulfone or polyphenylsulfone can be used. The glass transition temperature of these plastics is significantly higher than the operating temperature in the case of the battery and / or underbody protection. The modulus of elasticity as a function of temperature remains relatively constant (e.g., + / - 15% from -40 to +80°C). Alternative preferred materials include polycarbonate (PC) and blends such as ASA+PC, and a transparent and amorphous polyamide (PA), for example, Grilamid® TR 90 or Grilamid® TR ICR 12 LS.
[0049] To enable the use of more cost-effective plastics for the rupture disc and especially for the activation surface, whose modulus of elasticity (e.g., over an operating range of -40°C to 80°C) depends significantly on the temperature, a leaf spring (mentioned above) can be clamped between two opposing snap hooks to assist the switching of the contact surface from the closed to the open position. This effect is more pronounced at lower temperatures.
[0050] A suitable leaf spring is a thermobimetallic spring shaped and designed accordingly, which is composed of two flat layers of different metals, or a leaf spring, tension spring or compression spring made of a shape memory alloy (SMA).
[0051] The size of the vent opening in the wall, the spacing of the snap hooks, and the dead center of the activation surface are preferably designed, dimensioned, and coordinated such that the snap hooks still engage behind the edge of the vent opening when the activation surface is at its dead center. Thus, the dead center is designed so that the snap hooks still have a hold in the vent opening. This ensures that the rupture disc cannot gape open (on one side) at a pressure just below the opening pressure, become stuck, or snap open or closed uncontrollably.
[0052] Also disclosed is a battery with a gas- and watertight housing, in the wall of which a degassing opening is provided, into which a rupture disc according to the disclosure is inserted. The wall can have a thickness which, in the closed position of the activation surface and the snap hooks, corresponds to a distance between the seal and the respective receptacles of the snap hooks. A housing for a battery is also disclosed, in the wall of which a degassing opening is provided, into which a rupture disc according to the disclosure is inserted.
[0053] Also disclosed is an assembly with a battery that has an internal vent opening to the gas- and watertight housing of the gas-carrying underride guard. A vent opening to the environment is provided in the wall of the underride guard housing, into which a rupture disc as disclosed is inserted. The wall thickness can be such that, in the closed position of the activation surface and the snap hooks, it corresponds to the distance between the seal and the respective snap hook surfaces. In a critical situation, the gas to be vented then has the opportunity to cool below its auto-ignition temperature within the underride guard.
[0054] The task is also solved by using a aforementioned or disclosed bursting disc on a aforementioned or disclosed housing of an underride guard or a battery.
[0055] Of course, an electric vehicle with a aforementioned or disclosed battery and / or with a aforementioned or disclosed gas-carrying underride guard is also disclosed.
[0056] All the opening pressures mentioned, i.e. the positive pressures acting in the opening direction of the rupture disc and the negative pressures (or vacuums) that press the rupture disc and thus the seal against the wall of the affected housing, are to be understood as pressure differences between an internal housing pressure and an ambient pressure.
[0057] The aforementioned rupture disc, as disclosed, is preferably not limited to use on the housing of a (gas-carrying) underride guard or a (vehicle) battery. Applications of the aforementioned rupture disc, as disclosed, outside of electromobility are also conceivable, for example, in plant engineering as explosion protection, in aerospace due to its low weight, in the packaging industry, etc.
[0058] Brief description of the characters
[0059] Figure 1 shows an electric vehicle with an underride guard with a burst disc according to the present disclosure;
[0060] Figure 2 shows an electric vehicle with a battery having a rupture disc according to the present disclosure;
[0061] Figure 3 shows the battery and underride guard from Figures 1 and 2 in a perspective view from below;
[0062] Figure 4 shows the battery with the underride guard from Figure 3 in a perspective view, each with a burst disc;
[0063] Figure 5 shows a first embodiment of the rupture disc according to the disclosure for use in the battery or the underride guard from the preceding figures in one view;
[0064] Figure 6 shows the rupture disc from Figure 5 in a view of the sealing side;
[0065] Figure 7 shows a section of the rupture disc from Figures 5 and 6 in a degassing opening with a superimposed representation of the opening position on one side and the closing position on the other; Figure 8a shows a first variant of a further embodiment of the rupture disc according to the disclosure in a section of the degassing opening;
[0066] Figure 8b shows a second variant of the bursting disc from Figure 8a in a longitudinal section;
[0067] Figure 8c shows a leaf spring from Figures 8a and 8b at a high temperature;
[0068] Figure 8d shows the leaf spring from Figures 8a to 8c at a medium temperature;
[0069] Figure 8e shows the leaf spring from Figures 8a to 8d at a low temperature;
[0070] Figure 9a shows a first variant of a further embodiment of the rupture disc according to the disclosure in a view of the sealing side;
[0071] Figure 9b shows the rupture disc from Figure 9a in a further view;
[0072] Figure 10a shows a second variant of the burst disc from Figures 9a and 9b in a view of the sealing side;
[0073] Figure 10b shows the bursting disc from Figure 10a in a further view;
[0074] Figure 11 shows a section of a casting tool with an outer mold part and with an inner core and with a section of the bursting disc from Figures 5 to 7 with a superimposed representation of the opening position and the closing position;
[0075] Figure 12 shows another representation of the outer part of the casting tool with the bursting disc from Figure 10 in the open position;
[0076] Figure 13 shows a further embodiment of the rupture disc according to the disclosure in a view of the sealing side; Figure 14 shows a further embodiment of the rupture disc according to the disclosure in a view of the sealing side; and
[0077] Figure 15 shows a further embodiment of the rupture disc according to the disclosure in a view of the sealing side.
[0078] Description of the implementation examples
[0079] Below, various embodiments of the present disclosure are described on the basis of the accompanying figures.
[0080] Figure 1 shows an electric vehicle in a translucent view, revealing a battery 2 and a gas-conducting underride guard 3 located beneath it. The underride guard 3 is essentially formed by a housing comprising a base, a cover, and a gas-conducting gap between them. The underride guard 3, or rather its housing, is attached to the housing of the battery 2 above it, the battery 2 housing having its own sealed compartment with a (not shown) outgassing opening to the gas-conducting gap of the underride guard 3.
[0081] Under normal operating conditions, water must not penetrate the underride guard 3 (e.g., during fording of water up to 1 m deep by the electric vehicle). Furthermore, the underride guard 3 can withstand internal pressures up to approximately 150 mbar without damage. At higher internal pressures (approximately 300 mbar), a battery 2 failure is assumed, and the underride guard 3 can still safely vent the gas from the battery 2. For this purpose, a rupture disc 1; 101; 201, as described in the present disclosure, is provided on the underride guard 3 according to a primary application scenario.
[0082] The burst disc 1; 101; 201 is inserted into a rectangular outgassing opening in a wall of the gas-carrying underride guard 3 in a watertight and airtight manner, thus sealing the gas-carrying gap of the underride guard 3 in a watertight and airtight manner. The underride guard 3 is constructed to be airtight and watertight and must be in normal operation FR2695P-WG-0005
[0083] 14 / 28
[0084] Negative pressures from -180mbar (temperature shock diving) to positive pressures approx.
[0085] Tolerates +140mbar (air transport without a pressurized cabin).
[0086] A malfunction of battery 2 (thermal runaway) occurs at a critical pressure of 200 mbar. In this case, the underride guard 3 can capture the gases from battery 2 and release them in a controlled manner into the environment via the vent. The rupture disc 1; 101; 201 automatically opens the vent at a defined opening pressure. Highly flammable and / or hot gases thus pass from the sealed housing of battery 2 into the sealed space of the underride guard 3. The underride guard 3 collects the hot gas in its gas guide gap and directs it away. The aim is to prevent flames outside the vehicle. To achieve this, the gas should cool down (below its auto-ignition temperature upon reaction with oxygen outside the sealed space), and glowing particles should be filtered out before the gas is released through the open vent.
[0087] The underride guard 3 may also have a (not shown) separate ventilation valve for pressure equalization (e.g. with a PTFE membrane).
[0088] Figure 2 shows an electric vehicle in which the burst disc 1; 101; 201 is installed directly on a wall of the housing of the battery 2 according to an alternative application scenario.
[0089] Figure 3 shows the battery 2 and the underride guard 3 from Figures 1 and 2 in a perspective view from below onto the flat base 3a of the underride guard 3.
[0090] Figure 4 shows the battery 2 with the underride guard 3 from Figure 3 in a perspective view from above. It can be seen that the cover 3b of the underride guard 3 rests against the battery 2 over a large area. In a superimposed representation of the two application scenarios according to Figures 1 and 2, a rupture disc 1; 101; 201 is shown for each of the two components that could be directly or indirectly affected by a thermal runaway. However, according to the present disclosure, it is preferred to provide either a rupture disc 1; 101; 201 on the battery or a rupture disc 1; 101; 201 on the underride guard 3.
[0091] Figure 5 shows a first embodiment of the rupture disc 1 according to the disclosure for use in the housing of the battery 2 or the underride guard 3 from the preceding figures in a view of an outer surface. Figure 6 shows the rupture disc 1 from Figure 5 in a view of the opposite sealing side. A central, approximately rectangular activation surface 4 is provided, which is composed of two trapezoidal segments 6 and two triangular segments 6. The four segments 6 are connected to each other via film hinges 8 and to a contact edge 10 via circumferential film hinges 9, wherein the film hinges 8 between the segments 6 are strip-like and wider than the film hinges 9 between the segments 6 and the contact edge 10.
[0092] The activation surface 4 formed by the segments 6 and the film hinges 8, 9 is clamped into the mounting edge 10. A snap hook 12 extends from the sealing side shown in Figure 6 on each segment 6 adjacent to the mounting edge 10. The snap hooks 12 are attached to the respective segment 6 as stably and without bending as possible. For this purpose, webs or support sections 6a are provided.
[0093] Snap hooks 12 are provided on each side of the rectangular rupture disc to ensure the necessary sealing pressure of a foam seal 16 that surrounds the contact edge 4 (water and airtightness plus tolerance compensation). The film hinges 8, 9 are designed to be as thin as possible, with a thickness of 0.4 mm. Alternatively, according to the present disclosure, it is also possible to provide snap hooks 12 only on two opposite sides, e.g., on the two longitudinal sides. In particular, it has been found that the necessary sealing pressure for small or very elongated rupture discs 1 can also be ensured by snap hooks 12 on only two opposite sides.
[0094] In Figures 5 and 6, the activation surface 4 is curved towards the sealing side (i.e., downwards in Figure 5 and upwards in Figure 6). This results in the FR2695P-WÖ-0005
[0095] 16 / 28
[0096] Activation surface 4 a closed position in which the snap hooks 12 are also in their closed position with reference to the center vertical 14 radially outside.
[0097] The bursting disc 1 functions like a bistable snap-action device, in which the activation surface 4 can be clicked from the closed position shown, via a defined dead point along the central vertical 14, to an open position. In this open position, the snap hooks 12 are also in an open position radially inwards with respect to the central vertical 14.
[0098] Figure 7 shows a section of the rupture disc 1 from Figures 5 and 6 in a degassing opening 18 with a superimposed representation of the activation surface 4 in its (in Figure 7 upper) opening position and in its (in Figure 7 lower) closed position.
[0099] The snap hooks 12 are coupled to each other via the film hinges 8, 9 and the segments 6 and can only be moved simultaneously. Each snap hook has a device 12a.
[0100] In the closed position of the activation surface 4, the snap hooks 12 are in the closed position (left in Figure 7), in which the respective components 12a can engage behind an edge 18a of the degassing opening 18 and thereby positively lock the rupture disc 1 to the edge 18a. The foam seal 16 is thus fully and tightly stretched against the outer surface of the housing wall (upper in Figure 7). This also results in easier and automated installation of the rupture disc 1.
[0101] When, starting from this closed position, the opening pressure of 200 mbar (from below in Figure 7) acts on the central activation surface 4, the activation surface 4 transitions from the closed to the open state. The snap hooks 12 move inwards (to the right in Figure 7), the rupture disc 1 springs out of the venting opening 18, and the built-up pressure can dissipate to prevent or appropriately manage thermal runaway of the battery 2 (see Figure 1 or 2). FR2695P-WÖ-0005
[0102] 17 / 28
[0103] The dead center point (central in Figure 7) for the snap hook 12 shown in the cutaway view is designed such that the snap hooks 12 still have a hold in the degassing opening 18. This ensures that the degassing opening 18 or the burst disc 1 cannot open, "stick", or snap open or closed uncontrollably at a pressure just below the opening pressure (on one side).
[0104] When installed, the rupture disc 1 cannot be removed from the outside without causing damage. The retention by the snap hooks 12 is independent of the set opening pressure due to the positive locking mechanism. There are no angled locking surfaces as with releasable hooks. Attempting to pry off the rupture disc 1 would require significantly more force, as the snap hooks 12 would have to shear off.
[0105] The following requirements for the rupture disc 1 in the closed position should preferably be met: tightness; suitability for air transport (overpressure or positive opening pressure max. 140 mbar during air transport); temperature shock immersion (underpressure or negative opening pressure max. 180 mbar); protection against water jets, immersion, and high-pressure or steam jet cleaning; suitable corrosion resistance; suitable resistance to outdoor weathering;
[0106] Continuous temperature resistance (from 80°C to -40°C).
[0107] Regarding the material of the rupture disc 1, which is injection-molded in one piece (apart from the sound-perforating seal 16), FEM calculations have shown that the opening pressure is directly dependent on the Young's modulus of the plastic. At the same time, the Young's modulus should be low (up to 2500 MPa) to allow for low opening pressures. If the opening pressure is to remain stable over the given temperature range, the remaining range of injection-moldable materials is rather small. Particularly suitable are high-temperature-resistant thermoplastics or thermoplastics such as polycarbonate (PC) and a transparent and amorphous polyamide (PA), for example, known as Grilamid® TR. The glass transition temperature of these plastics is significantly higher than the operating temperature. The Young's modulus remains relatively constant over the temperature range of -40 to +80°C. FR2695P-WG-0005
[0108] 18 / 28
[0109] Since such plastics with high gas transition temperatures and low modulus of elasticity are expensive and difficult to process in the area of thin foil hinges, a solution with more affordable materials, such as PP (polypropylene) or PA (polyamide), can also be considered. Either one accepts the opening pressures that depend on the ambient temperature, or one controls them, for example, via an integrated temperature-dependent leaf spring. In other words, the temperature dependence of the more affordable material is at least partially compensated for by the temperature-dependent leaf spring.
[0110] Figure 8a shows a first variant of a further rectangular embodiment of the rupture disc 101 according to the disclosure in a translucent view. The rupture disc 101 is inserted in a section of the outgassing opening 18 and is shown in an internal view of the housing to be protected, with the foam seal omitted.
[0111] Following the principle of the previous embodiment, two opposing snap hooks 12 are each formed on a segment 6 (top and bottom in Figure 8a). Two further opposing snap hooks 12 (left and right in Figure 8a) are formed on the contact edge 10.
[0112] To achieve synchronous movement of the two snap hooks 12 formed at the edge 10 of the mounting surface with the activation surface, a leaf spring 104 is clamped between the two snap hooks 12 formed at the edge 10 of the mounting surface. This leaf spring is attached to a fifth central segment on the sealing side of the activation surface 4 (visible in Figure 8a). The leaf spring 104, together with the activation surface 4, can be moved from a curved closed position, via a dead center, to a curved open position by the predetermined opening pressure.
[0113] Figure 8b shows a second variant of the rupture disc 101 with the leaf spring 104 in a longitudinal section. The differences from the previous variant (from Figure 8a) are that the activation surface 4 does not have a fifth central segment, but corresponds to the activation surface 4 from Figures 5 to 7. In particular, the connection of the leaf spring 104 to the activation surface 4 has been omitted. Furthermore, all four snap hooks 12 (according to Figures 5 to 7) are attached to a respective segment 6.
[0114] In the second variant according to Figure 8b, the leaf spring 104 extends between the two snap hooks 12 shown in section in Figure 8b on the two shorter sides of the bursting disc 101. For this purpose, the two affected snap hooks 12 (radially inwards) each have a retaining lug 12b.
[0115] The two variants of the embodiment of the rupture disc 101 shown in Figures 8a and 8b each have the strip-like, rectangular metallic leaf spring 104. In both variants, the leaf spring 104 extends between the two snap hooks 12 on the short sides of the rectangular rupture disc 101. The activation surface 4, injection-molded from a more cost-effective plastic, is rather stiff at lower temperatures, e.g., -40°C, and would therefore inherently require a correspondingly high opening pressure or a high opening force F. To compensate for this undesirable behavior, the leaf spring 104 is a specially shaped and designed thermobimetallic spring, and its assistance in switching from the closed to the open position increases with decreasing temperature. This, for example,In the specific embodiment shown, the temperature-dependent behavior of the activation surface 4 of both variants is compensated over the intended temperature range of -40°C to 80°C.
[0116] In the second variant according to Figure 8b, it is important that the construction is designed in such a way that the leaf spring 104 does not impede the movement of the activation surface 4 and thus of the four snap hooks 12 from the dead point into the open state, i.e. that the leaf spring 104 does not come free or become loose or even fall off.
[0117] Figure 8c shows the leaf spring 104 of the two variants from Figures 8a and 8b at the maximum intended temperature of, for example, 80°C. The plastic of the activation surface 4 (see Figures 8a and 8b) is soft enough to maintain the intended low opening pressure of 200 bar. Accordingly, the leaf spring 104 does not provide any additional opening force F. FR2695P-WÖ-0005
[0118] 20 / 28
[0119] Figure 8d shows the leaf spring 104 of the two variants from Figures 8a and 8b at a mean temperature of, for example, 20°C. The plastic of the activation surface 4 (see Figures 8a and 8b) is moderately hard or firm, so that the intended low opening pressure of 200 bar is only maintained if the leaf spring 104 provides a (comparatively) small additional opening force F.
[0120] Figure 8e shows the leaf spring 104 of the two variants from Figures 8a and 8b at a minimum intended temperature of, for example, -40°C. The plastic of the activation surface 4 (see Figures 8a and 8b) is so hard or rigid that the intended low opening pressure of 200 bar is only maintained if the leaf spring 104 provides a (comparatively) large additional opening force F.
[0121] Therefore, alternative thermoplastics could also be used in this embodiment, since the leaf spring 104 compensates for the elasticity of the activation surface 4 and thus homogenizes the opening pressure of the entire burst disc 101 over the predetermined temperature range.
[0122] Under normal operating conditions, differential pressures to the surrounding environment also occur in the sealed compartment of battery 2 and in the gas flow gap of the underride guard 3. These pressures can be constantly equalized via a pressure equalization valve (e.g., during air transport). Moisture is also discharged via these valves. These valves have, for example, air-permeable PTFE membranes as a water barrier (the sealed compartment and gas flow gap should remain watertight).
[0123] A pressure equalization element can also be integrated into the rupture disc 201. Figure 9a shows a first variant of an embodiment of the rupture disc 201 according to the disclosure in a view of the sealing side. Figure 9b shows the rupture disc 201 from Figure 9a in a view of the side opposite the sealing side. The basic structure of the rupture disc 201 corresponds to the first embodiment from Figures 5 to 7, with the difference that a pressure equalization element 205 is inserted into one of the segments 6. FR2695P-WG-0005
[0124] 21 / 28
[0125] For this purpose, a small opening is provided in segment 6, which is closed by an adhesively or welded-on PTFE membrane 205a and protected by an outer cap 205b. This design combines the rupture disc 201 with a pressure equalization function.
[0126] Figure 10a shows a second variant of the rupture disc 201 from Figures 9a and 9b in a view of the sealing side, with the seal omitted. Figure 10b shows the rupture disc 201 from Figure 10a in a view of the side opposite the sealing side.
[0127] A segment of the activation surface 4 is perforated. On the sealing side, a waterproof but air-permeable PTFE membrane 205a is welded onto the holes of the perforation.
[0128] If the second variant according to Figures 10a and 10b is inserted into a vent opening of an underride guard according to the primary application scenario, and if this underride guard needs to be tested for leaks, the membrane 205a would cause a leakage reading. To avoid this, the perforation holes are preferably kept sealed during the test. For this purpose, the perforation holes are sealed with an adhesive pad 205c, which is adhered to the perforation on the side opposite the sealing side and is removed after the test.
[0129] Figures 11 and 12 show isometric views illustrating the injection molding process of the burst disc 1.
[0130] Figure 11 shows a section of a casting mold with an outer mold part 20 and an inner core 22, and a section of the rupture disc 1 from Figures 5 to 7. In a superimposed view, the activation surface 4 and two snap hooks 12 are shown in their closed and open positions, although the latter position cannot be reached with the inner core 22 of the casting mold still in place. FR2695P-WÖ-0005
[0131] 22 / 28
[0132] The rupture disc 1 is cast in its closed position, with the activation surface 4 in Figure 11 facing downwards and the snap hooks 12 on the outside. The snap hooks 12 are cast between the outer mold part 20 and the inner core 22.
[0133] Figure 12 shows another view of the outer mold part 20 of the injection mold with the rupture disc 1 from Figure 11. After the rupture disc 1 has hardened, the inner core 22 is moved away via a two-stage ejector, so that the activation surface 4 can now be pressed into the (upper in Figure 12) open position, in which the snap hooks 12 are on the inside. This also causes the supports 12a to retract radially, and the rupture disc 1 can be easily demolded. No slides are required in the injection mold to create the undercuts.
[0134] Ideally, the rupture disc 1 only needs to be moved once during demolding, from the closed position to the open position, and once again during installation, from the open position back to the closed position. Once installed, the rupture disc 1 is then largely stress-free and does not move further. Creep effects and fatigue therefore play a minor role.
[0135] Figure 13 shows another uniform triangular embodiment of the rupture disc 301 according to the disclosure in a view of the sealing side, with the seal omitted.
[0136] Figure 14 shows another rectangular embodiment of the rupture disc 401 according to the disclosure in a view of the sealing side, wherein the seal has been omitted.
[0137] Figure 15 shows another uniform nine-sided embodiment of the rupture disc 501 according to the disclosure in a view of the sealing side, with the seal omitted.
[0138] Figures 13 to 15 thus show different conceivable geometries of the revelation-based bursting disk 301; 401; 501. Geometrically, the FR2695P-WG-0005
[0139] 23 / 28
[0140] Rupture discs 301; 401; 501 have a large degree of freedom. Snap hooks 12 arranged parallel to the edge are preferred to press the foam seal (not shown in Figures 13 to 15) circumferentially. The rupture disc 301; 401; 501 can have a substantially triangular, a substantially quadrilateral, or any n-sided geometry. List of reference symbols:
[0141] 1; 101; 201; 301; 401 ; 501 rupture disk
[0142] 2 batteries
[0143] 3 Underride protection
[0144] 3a Floor
[0145] 3b Lid
[0146] 4 activation area
[0147] 6 segments
[0148] 6a Support section
[0149] 8 Film hinge (narrow)
[0150] 9 film hinges (wide)
[0151] 10. Investment edge
[0152] 12 snap hooks
[0153] Annex 12a
[0154] 12b Retaining nose
[0155] 14 perpendicular bisectors
[0156] 16 Seal / Foam seal 18 Opening / Degassing opening 18a Edge
[0157] 20 outer molded part
[0158] 22 inner core
[0159] 104 leaf spring
[0160] 205 Pressure equalization element 205a PTFE membrane
[0161] 205b cap
[0162] 205c adhesive pad
[0163] F additional opening force W wall thickness
Claims
FR2695P-WÖ-0005 25 / 28 Claims 1. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) which is designed and configured to close an opening (18) and to release the opening (18) at a predetermined opening pressure, wherein the rupture disc (1 ;101 ; 201; 301; 401;501) has a disc-like bistable activation surface (4) surrounded by a contact edge (10) on which a circumferential seal (16) is arranged, provided, or formed, wherein the activation surface (4) can be moved from a curved closed position to a curved open position via a dead center by the predetermined opening pressure, and wherein at least two snap hooks (12) with respective attachments (12a) are formed on the activation surface (4) adjacent to the seal (16) on the seal side, opposite each other with respect to a perpendicular center (14) of the activation surface (4), wherein the attachments (12a) are closer to the seal (16) in the closed position of the activation surface (4) than in the open position of the activation surface (4).; 2. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to claim 1 , wherein the snap hooks (12) are in a respective outer position in the closed position of the activation surface (4) with respect to the perpendicular center (14) of the activation surface (4), and wherein the snap hooks (12) are retracted and / or pivoted into a respective inner position in the open position of the activation surface (4).
3. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to any of the preceding claims, wherein the activation surface (4) and the contact edge (10) and the snap hooks (12) are injection molded as a one-piece plastic part.
4. Burst disc (1; 101; 201; 301; 401; 501) according to claim 3, wherein the activation surface (4) is divided into several segments (6) which are connected to each other and to the mounting edge (10) via integrally formed film hinges (8, 9). FR2695P-WG-0005 26 / 28 5. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to claim 4, wherein the segments (6) are triangular or trapezoidal.
6. Burst disc (201) according to claim 4 or 5, wherein a pressure equalization element (205) is inserted into one of the segments (6).
7. Burst disc (301 ; 501 ) according to one of claims 4 to 6, wherein the activation surface (4) and the contact edge (10) form a uniform n-gon, and wherein n segments (6) and n snap hooks (12) are provided.
8. Burst disc (1 ; 101 ; 201 ; 401 ) according to one of claims 4 to 6, wherein the activation surface (4) and the contact edge (10) and the seal form a rectangle, and wherein four snap hooks (12) and at least four segments (6) are provided, wherein preferably the segments (6) and the snap hooks (12) are of equal size in pairs.
9. Burst disc (1 ; 201 ; 401 ) according to claim 8, wherein the four snap hooks (12) are each formed integrally on a segment (6).
10. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to any of the preceding claims, wherein the predetermined opening pressure is between 175 mbar and 225 mbar.
11. Burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to one of the preceding claims, which is designed to seal for an opening pressure of -180 mbar.
12. Housing of a battery (2) or of a gas-carrying underride guard (3), in the wall of which a degassing opening (18) is provided, into which a burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) is inserted according to one of the preceding claims.
13. Housing according to claim 12, wherein the wall has a wall thickness (W) which is substantially a distance of the seal (16) to the respective systems (12a)FR2695P-WG-0005 27 / 28 the snap hook (12) in the closed position corresponds to the activation surface (4).
14. Housing according to claim 12 or 13, wherein the size of the outgassing opening (18) and the distance of the snap hooks (12) to the perpendicular center (14) and the dead center are designed and dimensioned such that the devices (12a) engage behind the edge (18a) of the outgassing opening (18) when the activation surface (4) is at the dead center.
15. Use of a burst disc (1 ; 101 ; 201 ; 301 ; 401 ; 501 ) according to one of claims 1 to 11 on a housing of a battery (2) or a gas-carrying underride guard (3), in particular according to one of claims 12 to 14.