PRESSURE EQUALIZATION DEVICE AND TESTING PROCEDURES

Abstract

The application discloses a pressure equalization device (100, 400) for a battery box (202). The pressure equalization device comprises: a cage (102, 402) for attachment to a valve opening (210) in the battery box, the cage defining a fluid passage (104, 404) for moving gas between an interior and exterior of the battery box; a valve element (106, 406) covering the fluid passage; and a spring (108) arranged to press the valve element against the cage to close the fluid passage, allowing the valve element to move into an open position when the internal pressure inside the battery box exceeds a threshold pressure. The valve element has a breathing orifice (138, 438) and a breathable membrane (112, 412) covering the breathing orifice. A test method and a test apparatus are also presented.

Description

TECHNICAL AREA

[0001] The invention described herein relates to a pressure equalization device for a battery box, in particular a battery box of an electric or hybrid vehicle. The pressure equalization device comprises a breathable membrane for gas exchange under normal operating conditions of the battery box and a vent that opens when the internal pressure of the battery box exceeds a threshold pressure. A test method and a test apparatus are also disclosed. BACKGROUND

[0002] Batteries in electric vehicles must be adequately protected against impact damage and environmental influences. However, this must be balanced against the risk of battery degradation and / or failure. Failed and / or deteriorating batteries can release fluids (including gases) that must escape from both the battery and its protective enclosure. Therefore, there is a tension between providing adequate protection and allowing for fluid exchange. SUMMARY

[0003] The invention corresponds to the appended claims. According to the disclosure, a pressure equalization device for a battery box is provided, the pressure equalization device comprising: a cage for attachment to a valve opening in the battery box, wherein the cage defines a fluid passage for moving gas between an interior and an exterior of the battery box, a valve element covering the fluid passage, and a spring arranged to press the valve element against the cage to close the fluid passage and such that the valve element is movable into an open position when an internal pressure within the battery box exceeds a threshold pressure, wherein the valve element has a breathing orifice and a breathable membrane covering the breathing orifice.In this way, the pressure equalization device can prevent the ingress of environmental influences, but allow fluids accumulated in the battery box to escape.

[0004] Advantageously, the cage has a flange against which the valve element rests in a closed configuration. The flange can be configured to rest against an outer surface of the battery box, and the cage can have one or more clamps extending through the valve opening into the battery box and engaging an inner surface of the battery box to secure the pressure equalization device to the battery box. In this way, the pressure equalization device can be easily installed on a battery box. Preferably, the clamp(s) can extend over the flange, and / or the flange can have a mounting plate for mounting to the battery box. Appropriately, the cage can have a hub section and one or more arms that secure the hub section to the flange.Optionally, the hub section has a tubular body with an opening for receiving a shaft of the valve element, with the spring being arranged inside the tubular body.

[0005] The flange preferably has a gasket, and optionally the gasket can be positioned between the flange and the outer surface of the battery box to provide a seal against environmental influences during use. The gasket can be located on the flange and provide a sealing surface for the valve element.

[0006] Preferably, the breathing opening and the breathable membrane extend over less than 20% of the area of ​​the valve element.

[0007] Appropriately, the valve element is circular, and the breathing opening and the breathable membrane are arc-shaped, for example as a segment of a ring.

[0008] Alternatively, the valve element is circular, and the breathable membrane is circular and aligned centrally with the valve element.

[0009] A cover can be suitably attached to the valve element, extending over the breathing orifice and the breathable membrane, the cover defining a membrane fluid passage for fluid communication between the external environment and an outer surface of the breathable membrane. Optionally, the cover extends only over the breathable membrane.

[0010] In a further section of the disclosure, a method for testing whether a battery box is liquid-tight is provided. The battery box has a pressure equalization device as described above. The method comprises: grasping a valve element of the pressure equalization device, opening the valve opening by deactivating a spring of the pressure equalization device, and checking for a liquid leak.

[0011] In a further section of the disclosure, a leak detection device suitable for carrying out the aforementioned method is provided. The leak detection device comprises: a test body dimensioned to form a fluid-tight seal around a pressure equalization device, a test seal arranged on the test body to form a fluid-tight seal to a pressure equalization device, a gripper arranged to grasp a valve element of a pressure equalization device, and optionally, wherein the gripper has a piston and / or the test body is dimensioned to form a fluid-tight seal on the pressure equalization device, or the test body is dimensioned to form a fluid-tight seal over the pressure equalization device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments of the invention are described only as examples with reference to the accompanying drawings. Fig. Figure 1 represents a first example of a pressure equalization device. Fig. 2A represents a cross-section of the pressure equalization device of Fig. 1 with the valve element in a closed position. Fig. 2B represents a cross-section of the pressure equalization device of Fig. 1 with the valve element in an open position. Fig. 3A shows a perspective cross-section of the pressure equalization device of Fig. 1 with the valve element in an open position. Fig. 3B shows a perspective cross-section of the pressure equalization device of Fig. 1 with the valve element in an open position. Fig. Figure 4A shows a second example of a pressure equalization device from a first perspective view. Fig. Figure 4B shows a second example of a pressure equalization device from a second perspective view. Fig. Figure 5 shows a cross-section of the pressure equalization device of Fig. 4A and Fig. 4B. Fig. Figure 6 represents an exemplary pressure equalization assembly with two pressure equalization devices, wherein the pressure equalization assembly is shown in an exploded view of the assembly. Fig. 7A represents an outer surface of the pressure equalization assembly of Fig. 6 dar. Fig. 7B represents an inner side of the pressure equalization assembly of Fig. 6 dar. Fig. Figure 8 illustrates a leak detection device. DETAILED DESCRIPTION

[0013] Fig. Figure 1 represents a pressure equalization device 100 for a battery box. The battery box can be the battery box of an electric or hybrid vehicle. The battery box contains a plurality of battery cells. The battery box provides a substantially sealed container in which the battery cells and other components are housed. As described below, the pressure equalization device 100 is provided in a wall of the battery box and, under normal operating conditions, provides gas exchange between the interior and exterior of the battery box to allow for ventilation and pressure equalization. In the event of a battery malfunction, such as thermal runaway in one or more battery cells, the pressure equalization device 100 forms a vent for the release of gases from the interior of the battery box to the outside.

[0014] In particular, the pressure equalization device 100 is configured to allow pressure equalization between the inside and outside of the battery box in two modes: In a first mode, a breathable membrane 112 allows gas exchange during normal operation, and in a second mode, the pressure equalization device 100 opens another fluid passage that allows gas exchange at a higher rate in order to vent gases at higher pressure from inside the battery box.

[0015] As in Fig. As shown in Figure 1, the pressure equalization device 100 has a cage 102 for attachment to a valve opening of the battery box (illustrated in Figure 1). Fig. 2A to Fig. 3B). The cage 102 defines a fluid passage 104 for the movement of gas between an interior of the battery box and an exterior of the battery box.

[0016] The pressure equalization device 100 comprises a valve element 106 that covers the fluid passage 104. A spring 108 is arranged to press the valve element 106 against the cage 102 to close the fluid passage 104. The valve element 106 can be moved into an open position against the force of the spring 108 when the internal pressure inside the battery box exceeds a threshold pressure, in order to vent the internal pressure. When the valve element 106 is in the open position, it forms a vent to allow gases to escape from inside the battery box to the outside.

[0017] The valve element 106 also has an opening 110 and a breathable membrane 112 that covers the opening 110. An inner surface of the breathable membrane 112 is connected to the fluid passage 104, so that the breathable membrane 112 defines a boundary between the inside and outside of the battery box. The breathable membrane 112 is configured to equalize the internal pressure inside the battery box with the ambient pressure outside the battery box during operation.

[0018] Fig. 2A, Fig. 2B, Fig. 3A and Fig. Figure 3B represents the pressure equalization device 100 mounted on the battery box 202. In particular, the pressure equalization device 100 is mounted in a valve opening 210, which is formed in a wall 204 of the battery box 202. The wall 204 comprises an inner surface 206 and an outer surface 208.

[0019] Fig. 2A and Fig. 3A represents the pressure equalization device 100 in its normal, closed configuration. Fig. 2B and Fig. Figure 3B depicts the pressure equalization device 100 in an open configuration. The pressure equalization device 100 moves into the open configuration in response to the fact that the internal pressure of the battery box 202 exceeds a threshold pressure. With reference to Fig. 1 to Fig. 3B The cage 102 comprises a flange 114 which, when in use, rests against the outer surface 208 of the wall 204 of the battery box 202 around the valve opening 210. The cage 102 also comprises a hub section 118, which is centrally located with respect to the flange 114 and extends into the battery box 202. The hub section 118 is connected to the flange 114 via arms 120. The arms 120 are spaced apart such that a fluid passage 104 is defined for the flow of gases through the cage 102.

[0020] The clamp 102 includes clamps 116 that extend through the valve opening 210. The clamps 116 engage the inner surface 206 of the wall 204 to firmly connect the cage 102 (and the pressure equalization device 100) to the battery box 202 within the valve opening 210. In this example, the clamps 116 extend from the flange 114, but in other examples, the clamps 116 may extend from the arms 120 of the cage 102. In this example, the pressure equalization device 100 has an outer circular shape, the flange 114 is circular, and the hub section 118 is centered with respect to the flange 114. In other examples, however, the shape may not be circular, such as oval, square, or triangular, and the hub section 118 may not be centered.

[0021] The valve element 106 comprises a sealing plate 136 and a shaft 126 extending from the sealing plate 136. The valve element 106 also comprises a tubular extension 140 that extends around the shaft 126.

[0022] The hub section 118 of the cage 102 comprises a tubular body 122 with an opening 124 at the end facing the outside of the battery box 202 to accommodate the shaft 126 of the valve element 106. The tubular body 122 is contained within the tubular extension 140 that extends from the valve element 106. The tubular body 122 and the tubular extension 140 can assist in guiding or restricting movement of the valve element 106 relative to the cage 102. An end stop 134 is provided at an inner end of the shaft 126, and a spring 108 is arranged within the tubular body 122. The spring 108 is a compression spring. The spring 108 is held between the end stop 134 and the end of the tubular body 122 around the opening 124.

[0023] In this way, the spring 108 pushes the valve element 106 into a closed position, as shown in Fig. 2A and Fig. Figure 3A illustrates this. In the closed position, the valve element 106, in particular the sealing plate 136, is pressed against the flange 114, and especially against a seal 128 provided in the flange 114. Specifically, the valve element 106 is pressed against the flange 114 on the outside of the battery box 202. The valve element 106 is pressed against the wall 204 of the battery box 202 so that it rests against an outer surface of the flange 114. In this position, the valve element 106 closes the fluid passage 104.

[0024] As illustrated, the seal 128 can additionally act between the flange 114 and the outer surface 208 of the wall 204, or separate seals can be provided.

[0025] The valve element 106 is a rigid structure, made, for example, of a polymer. The cage 102 is also a rigid structure, made, for example, of a polymer or a metal.

[0026] As illustrated, the valve element 106 further comprises an opening 110 that extends through the sealing plate 136. The opening 110 is covered with a breathable membrane 112. The breathable membrane 112 can be bonded or welded to the sealing plate 136 or be formed with the sealing plate 136.

[0027] Under normal operating conditions, the breathable membrane 112 allows gas exchange through the sealing plate 136 to provide a breathing function for the battery box 202. The breathable membrane 112 is preferably permeable to gas, particularly air, and impermeable to fluids such as water and particles such as dirt. In this way, the breathable membrane 112 allows the battery box 202 to "breathe" in order to maintain ambient pressure, while simultaneously preventing the ingress of fluid and dirt into the battery box 202.

[0028] A cover 130 is provided on the valve element 106, extending over the opening 110 and the breathable membrane 112. The cover 130 is located on an outer surface of the valve element 106. The cover 130 is attached to the valve element 106, in particular to the cover plate 136. The cover 130 can be glued or welded to the valve element 106, or clamped into the valve element 106. The valve element 106 can include a fastening structure, for example, a clamping structure, to which the cover 130 is attached. The fastening structure can also provide a surface or recess for mounting the breathable membrane 112. The cover 130 is fixedly attached to the valve element 106 and is not movable relative to the valve element 106.The cover 130 includes a membrane fluid passage 132 extending from the outside of the breathable membrane 112 to a breathing opening 138 that opens to the external environment. As in . Fig. As shown in Figure 1, the cover 130 can have two breathing openings 138. The cover 130 thus protects the breathable membrane 112 and simultaneously allows gas exchange between the inside and outside of the battery box 202.

[0029] During normal operation of the battery box 202, the breathable membrane 112 allows gas exchange between the inside of the battery box 202 and the external environment to equalize pressure.

[0030] When the internal pressure of the battery box 202 exceeds a threshold pressure sufficient to compress the spring 108, the valve element 106 is moved into an open position, as shown in Fig. 2B and Fig. Figure 3B shows the arrangement. In this position, the sealing plate 136 is spaced from the flange 114 to form a vent opening through which fluid (gases) from the battery box 202 can be vented via the fluid passage 104. In this configuration, the gases can escape at high velocity due to the vent opening formed by moving the sealing plate 136. The spring force of the spring 108 can be selected such that the valve element 106 moves into the open position at a predetermined internal pressure of the battery box 202, which may be based on modeling the thermal runaway of the battery cells or other safety factors.

[0031] When the valve element 106 moves into the open configuration, the breathable membrane 112 and the cover 130 move with the valve element 106.

[0032] When the internal pressure of the battery box 202 drops below the threshold pressure, the spring 108 moves the valve element 106 back into a sealing position and closes the vent opening.

[0033] As in Fig. 1, Fig. 3A and Fig. As shown particularly clearly in Figure 3B, the opening 110, the breathable membrane 112, and the cover 130 extend only over a portion of the valve element 106. In particular, the opening 110, the breathable membrane 112, and the cover 130 extend only over a portion of the sealing plate 136. In examples, the opening 110, the breathable membrane 112, and the cover 130 extend over less than approximately 50% of the surface area of ​​the sealing plate 136, preferably less than approximately 40%, or less than approximately 30%, or less than approximately 20%.

[0034] In examples such as those shown, the opening 110, the breathable membrane 112, and the cover 130 can have an arcuate shape. The arcuate shape can have a diameter corresponding to the diameter of the circular sealing plate 136. The opening 110, the tubular body 122, and the cover 130 can form a segment of a ring on the sealing plate 136. The cover 130 extends only over a portion of the valve element 106 (sealing plate 136); in particular, the cover 130 extends only over the portion of the valve element 106 in which the breathable membrane 112 is provided.

[0035] Fig. 4A to Fig. Figure 5 illustrates another exemplary pressure equalization device 400. The pressure equalization device 400 in this example is similar to that of Fig. 1 to Fig. 3B. In particular, the pressure equalization device 400, as illustrated, comprises, as in the pressure equalization device 100 described above, a cage 402 and a valve element 406 movably mounted on the cage 402, as well as a spring 408 that presses the valve element 406 against a flange 414 of the cage 402, which includes a seal 428b against which the valve element 406 forms a seal to close the fluid passage 404. The flange 414 also includes a seal 428a arranged to seal against a housing on which the pressure equalization device 400 is mounted. The valve element 406 includes arms 420 connecting the flange 414 to a hub section 418, and clamps 416 for mounting the pressure equalization device 400 in an opening of a housing.

[0036] The hub section 418 defines a tubular body 422 and an opening 424 in which the valve element 406 is slidably received. The valve element 406 comprises a sealing plate 436 that engages in the flange 414, and a shaft 426 that extends from the sealing plate 436 through the opening 424 into the tubular body 422. The valve element 406 includes an end stop 434 at one end opposite the sealing plate 436, and the spring 408 acts between the end stop 434 and a portion of the tubular body 422.

[0037] The valve element 406 also has a breathable membrane 412 mounted on the sealing plate 436, and a membrane fluid passage 432 is defined by the shaft 426 of the valve element 406, which allows breathing through the breathable membrane 412.

[0038] In this example, the breathable membrane 412 is used in contrast to the example of Fig. 1 to Fig. 3B is arranged centrally on the valve element 406. As shown, the sealing plate 436 is circular, and the breathable membrane 412 is circular and aligned with the center of the sealing plate 436. A cover 430 is provided and is also arranged centrally on the valve element 406 to cover the breathable membrane 412. The cover 430 is circular. The cover 430 includes one or more breathing openings 438. As shown in Fig. As shown in Figure 5, the valve element 406 and the cover 430 are connected by a snap connection 440.

[0039] The gasket of the flange 414 in this example has two parts: a first gasket 428a, which projects on an outer surface of the flange 414 to form a lip seal into which the sealing plate 436 engages, and a second gasket 428b, which projects on an inner surface of the flange 414 to engage with the housing on which the pressure equalization device 400 is mounted. The gaskets 428a and 428b are preferably formed by two-component injection molding (2K injection molding) of a softer polymer with the stiffer polymer of the cage body 402. Mold channels can connect the gaskets 428a and 428b through a portion of the flange 414.

[0040] Fig. 6 to Fig. Figure 7B illustrates a pressure equalization assembly 600 comprising two pressure equalization devices - a first pressure equalization device 602a and a second pressure equalization device 602b.

[0041] In various examples, the first pressure equalization device 602a and the second pressure equalization device 602b can both be the pressure equalization device 100 described above or the pressure equalization device 400, or the first pressure equalization device 602a can be the pressure equalization device 100 and the second pressure equalization device 602b can be the pressure equalization device 400, or vice versa. In these examples, the pressure equalization assembly 600 advantageously provides a higher degassing rate than a single pressure equalization device and a higher breathing rate. This can be useful for larger battery assemblies. The arrangement of two pressure equalization devices can form a narrower external shape than a single, larger pressure equalization device, which can be advantageous for mounting the pressure equalization assembly 600 to a battery assembly.

[0042] In another example, as illustrated, the first pressure equalization device 602a has the pressure equalization device 400 described above, and the second pressure equalization device 602b has a pressure equalization device similar to the one described in Fig. 4A to Fig. The first pressure equalization device 602a is described in Figure 5, but without a breathable membrane. Instead, a sealing plate is provided in place of the breathable membrane, and no cover is provided. In this example, the first pressure equalization device 602a provides a breathing function, and both the first pressure equalization device 602a and the second pressure equalization device 602b are intended for degassing at higher pressure situations. In the examples, both the first pressure equalization device 602a and the second pressure equalization device 602b have the same opening pressure (e.g., the same valve element area and the same spring). Therefore, both the first pressure equalization device 602a and the second pressure equalization device 602b would open at the same pressure to provide degassing.

[0043] In other examples, the first pressure equalization device 602a may have a different opening pressure than the second pressure equalization device 602b, for example, because it has a different size and / or spring. This may provide for a first degassing rate at a first pressure where only the first pressure equalization device 602a is open, and a second degassing rate at a higher pressure where both the first pressure equalization device 602a and the second pressure equalization device 602b are open.

[0044] As illustrated, the first pressure equalization device 602a and the second pressure equalization device 602b are mounted on a mounting plate 606. The flanges 604 and gaskets 608 of the first pressure equalization device 602a and the second pressure equalization device 602b are integrated into the mounting plate 606. The cages are also formed integrally with the mounting plate 606. As shown in Fig. As most clearly shown in Figure 7B, the seal 608 can be formed with the mounting plate 606 by two-component injection molding, with parts of the seal 608 extending between the two flanges 604 to enable or simplify the two-component injection molding. The valve elements and springs of the first pressure equalization device 602a and the second pressure equalization device 602b are attached to the cages as described above with reference to previous examples.

[0045] The mounting plate 606 includes mounting openings 610 for attaching the mounting plate 606 to the housing (e.g., battery box). The clamps 116, 416 from the previous examples may be omitted, as they are not required for attaching the pressure equalization assembly 600 to the housing (battery box). Stiffening ribs may be added to the valve element to ensure that the valve makes a sealing contact. Additionally, an ingress protection cover may be provided to protect the pressure equalization device from being directly sprayed with water, e.g., in an automated car wash.

[0046] Fig. Figure 8 represents a pressure equalization device 100, 400, which is arranged on a battery box 202 and engages with a leak detection device 802. The leak detection device 802 is arranged to open the pressure equalization device and to check the fluid tightness of the battery box 202 (e.g., to check whether water can penetrate or whether the battery box 202 is otherwise compromised and there is a risk of ingress of contaminants from the environment). Fig. Figure 8 identifies the pressure equalization device using numbers from the 100 series; however, any pressure equalization device disclosed in this application can be replaced by another, or the teachings of this disclosure can be applied to any suitable pressure equalization device. The use of numbers from the 100 series is not intended as a restriction, but rather to improve the clarity of the figure by omitting other reference numbers that might otherwise obscure it.

[0047] The leak detection device 802 is intended to form part of a production line and to test the battery box 202 as described above. The procedure for testing whether a battery box 202 is liquid-tight is described.

[0048] The method involves grasping a valve element 106, 406 of a pressure equalization device, opening the valve opening 210 by releasing a preload arranged to bring the valve element into a closed position (e.g. a spring 108, 408, as a non-limiting example), and subsequently checking for a fluid leak (e.g. by applying a vacuum or otherwise looking for a pressure difference).

[0049] The method may further include forming a test seal on or around a pressure equalization device. It is understood that each arrangement tests different parts, such as including or excluding the seal between the pressure equalization device and the battery box.

[0050] The method may include mounting the leak detection device 802 onto the pressure equalization device, for example, at a suitable stage of production. The method may facilitate the gripping of a valve element by a piston 804, which is arranged to move between positions near and far from the pressure equalization device. Likewise, the method may also include releasing a grip from a valve element, for example, once the test is complete (although releasing at other times may also be part of the method). In the event of release, the method may include closing the valve opening so that the pressure equalization device is returned to an "in use" state.

[0051] The procedure may involve disassembling the leak detection device from the pressure equalization device so that, for example, a manufacturing process can continue.

[0052] As discussed above, testing for a fluid leak may involve measuring a pressure differential. While the term "fluid" typically refers to water, the fluid being tested for could be any suitable liquid (such as oil). It is clear that the test results and acceptable parameters may vary depending on the fluid.

[0053] According to the above, Fig.Figure 8 represents a leak detection device 802 suitable for carrying out the method described above. The leak detection device includes a test body 806 suitable for forming a fluid-tight seal to the battery box 202 / to the pressure equalization device. The test body 806 is therefore dimensioned to form a fluid-tight seal around a pressure equalization device. A test seal 808 is provided and arranged on the test body to form a fluid-tight seal to a pressure equalization device.

[0054] A gripper 810 is arranged to grasp a valve element 106 of a pressure equalization device 100. The gripper may be arbitrarily suitable for forming a reversible grip on the valve element 106 and enabling the valve to be placed in an open position so that the preceding procedure can be carried out. Exemplary grippers may include bayonet fittings, profile bars / openings, snap-in fasteners, elastic lips, and / or clamps. It may be preferred that the gripper 810 grasps the valve element 106 simply by pressing against it (i.e., without rotating the gripper). The gripper may have a piston to allow the gripper to be placed near and / or rest on the valve element 106.

[0055] The test specimen 806 can be dimensioned to form a fluid-tight seal on the pressure equalization device, or the test specimen can be dimensioned to form a fluid-tight seal over the pressure equalization device (i.e. to the battery box 202 and not to the pressure equalization device).

[0056] It is evident that a pressure equalization device may be suitable for use with the preceding method and / or leak detection device if the pressure equalization device has a valve element having a gripping feature 812 arranged to be gripped by a gripper. The gripping feature 812 may be any suitable feature to be gripped by the grippers 810 (i.e., it need not be complementary but merely compatible). Therefore, as a non-limiting example, the gripping feature 812 may be any suitable rib, groove, elastic lip, elastic clamp, threaded rod or opening, or bayonet fitting.

[0057] Further embodiments of the disclosure are set out in the following sentences, which are not to be confused with the claims: Pressure equalization device for a battery box, comprising the pressure equalization device: a cage for attachment to a valve opening in the battery box, wherein the cage defines a fluid passage for moving gas between an interior of the battery box and an exterior of the battery box; a valve element covering the fluid passage, and a spring arranged to press the valve element against the cage to close the fluid passage and such that the valve element is movable into an open configuration when an internal pressure within the battery box exceeds a threshold pressure, wherein the valve element has a breathing orifice and a breathable membrane covering the breathing orifice.

[0058] Pressure equalization device according to sentence 1, wherein the cage has a flange against which the valve element rests in a closed configuration.

[0059] Pressure equalization device according to sentence 2, wherein the flange is configured to rest against an outer surface of the battery box, and the cage has one or more clamps extending through the valve opening into the battery box and engaging an inner surface of the battery box to secure the pressure equalization device to the battery box. Pressure equalization device according to sentence 2, wherein the one or more clamps extend from the flange.

[0060] Pressure equalization device according to sentence 2, wherein the flange has a mounting plate for mounting on the battery box.

[0061] Pressure equalization device according to any preceding sentence 2, wherein the cage has a hub section and one or more arms that attach the hub section to the flange.

[0062] Pressure equalization device according to sentence 6, wherein the hub section has a tubular body with an opening for receiving a shaft of the valve element and wherein the spring is arranged inside the tubular body.

[0063] Pressure equalization device according to any one of sentences 2 to 7, wherein the flange has a seal. Pressure equalization device according to sentence 6, wherein the seal is arranged in use between the flange and the outer surface of the battery box, and / or wherein the seal is arranged on the flange and provides a sealing surface for the valve element.

[0064] Pressure equalization device according to any one of sentences 1 to 9, wherein the breathing opening and the breathable membrane extend over less than 20% of the area of ​​the valve element. Pressure equalization device according to any one of sentences 1 to 10, wherein the valve element is circular and the breathing opening and the breathable membrane are arc-shaped, for example as a segment of a ring.

[0065] Pressure equalization device according to any one of sentences 1 to 10, wherein the valve element is circular and the breathable membrane is circular and aligned centrally with the valve element. Pressure equalization device according to any one of sentences 1 to 12, further comprising a cover attached to the valve element and extending over the breathing opening and the breathable membrane, wherein the cover defines a membrane fluid passage for fluid communication between the external environment and an outer surface of the breathable membrane. Pressure equalization device according to sentence 2, wherein the cover extends only over the breathable membrane.

[0066] Pressure equalization device according to any one of sentences 1 to 14, wherein the cage and / or the valve element comprises a rigid material, for example a polymer or metal. Pressure equalization assembly comprising a mounting plate, a first pressure equalization device and a second pressure equalization device, wherein the first and second pressure equalization devices are arranged on the mounting plate.

[0067] Pressure equalization assembly according to sentence 2, wherein the mounting plate has a seal and wherein the seal is formed integrally with the mounting plate, for example by two-component injection molding.

[0068] Method for testing whether a battery box (202) with a pressure equalization device (100, 400) is liquid-tight, comprising the method of: grasping a valve element (106, 406) of a pressure equalization device, opening the valve opening (210) by overriding a spring (108, 408) of the pressure equalization device, and checking for a liquid leak.

[0069] Method according to sentence 18, further comprising forming a test seal on or around a pressure equalization device; and / or mounting a leak detection device (802) on a pressure equalization device; and / or wherein a valve element is gripped via a piston (804); and / or releasing a handle from a valve element; and / or closing the valve opening; and / or dismantling a leak detection device from a pressure equalization device; and / or wherein testing for a fluid leak comprises measuring a pressure differential.

[0070] Leak detection device suitable for carrying out the method according to sentence 18 or sentence 19, the leak detection device comprising: a test body (806) dimensioned to form a fluid-tight seal around a pressure equalization device, a test seal (808) arranged on the test body to form a fluid-tight seal to a pressure equalization device, a gripper (810) arranged to grasp a valve element of a pressure equalization device, and optionally, wherein the gripper has a piston and / or the test body is dimensioned to form a fluid-tight seal on the pressure equalization device, or the test body is dimensioned to form a fluid-tight seal over the pressure equalization device.

[0071] Pressure equalization device suitable for use with the method according to one of sentences 18 or 19 or the leak detection device according to sentence 20, wherein the pressure equalization device has a valve element, the valve element having a gripping feature arranged to be gripped by a gripper.

[0072] Unlike other pressure equalization devices, the pressure equalization devices 100, 400 and the pressure equalization assembly 600 described above have a low profile extending outwards from the battery box 202. The limited size of the cover 130, 430, which is provided only over the breathable membrane 112, 412, reduces the height and width of the cover 130, 430 and thus the profile of the pressure equalization device 100, 400, 600 extending outwards over the battery box 202. This allows the pressure equalization device 100, 400 to be installed in tighter spaces around the battery box 202.

[0073] Furthermore, the attachment of the pressure equalization device 100, 400 to the battery box 202 via the clamps 116, 416 provides for easy mounting of the pressure equalization device 100, 400 to the battery box 202.

Claims

[1] Pressure equalization device (100, 400) for a battery box (202), the pressure equalization device comprising: a cage (102, 402) for attachment to a valve opening (210) in the battery box, the cage defining a fluid passage (104, 404) for moving gas between an interior of the battery box and an exterior of the battery box; a valve element (106, 406) covering the fluid passage, and a spring (108) arranged to press the valve element against the cage to close the fluid passage and to allow the valve element to move into an open position when an internal pressure inside the battery box exceeds a threshold pressure, the valve element having a breathing orifice (138, 438) and a breathable membrane (112, 412) covering the breathing orifice. [2] Pressure equalization device according to claim 1, wherein the cage has a flange against which the valve element rests in a closed configuration, and optionally, wherein: (a) the flange is configured to rest against an outer surface of the battery box, and the cage has one or more clamps extending through the valve opening into the battery box and engaging an inner surface of the battery box to secure the pressure equalization device to the battery box, and / or (b) the one or more clamps extend from the flange, and / or (c) the flange has a mounting plate for mounting to the battery box. [3] Pressure equalization device according to claim 2, wherein the cage has a hub section and one or more arms that attach the hub section to the flange, and optionally, wherein the hub section has a tubular body with an opening for receiving a shaft of the valve element and wherein the spring is arranged inside the tubular body. [4] Pressure equalization device according to claim 2, wherein the flange has a seal, and optionally, wherein the seal is positioned between the flange and the outer surface of the battery box, and / or The seal is located on the flange and provides a sealing surface for the valve element. [5] Pressure equalization device according to one of claims 1 to 4, wherein the breathing opening and the breathable membrane extend over less than 20% of the area of ​​the valve element. [6] Pressure equalization device according to one of claims 1 to 5, wherein the valve element is circular and the breathing opening and the breathable membrane are arc-shaped, for example as a segment of a ring. [7] Pressure equalization device according to one of claims 1 to 5, wherein the valve element is circular and the breathable membrane is circular and is aligned centrally with the valve element. [8] Pressure equalization device according to any one of claims 1 to 7, further comprising a cover attached to the valve element and extending over the breathing opening and the breathable membrane, wherein the cover defines a membrane fluid passage for the fluid connection between the external environment and an outer surface of the breathable membrane, and optionally, wherein the cover extends only over the breathable membrane. [9] Method for testing whether a battery box (202) is liquid-tight, wherein the battery box has a pressure equalization device (100, 400) according to one of the preceding claims, comprising the method: grasping a valve element (106, 406) of the pressure equalization device, opening the valve opening (210) by overriding a spring (108, 408) of the pressure equalization device, and checking for a liquid leak. [10] Leak detection device suitable for carrying out the method according to claim 9, the leak detection device comprising: a test body (806) dimensioned to form a fluid-tight seal around a pressure equalization device, a test seal (808) arranged on the test body to form a fluid-tight seal to a pressure equalization device, a gripper (810) arranged to grasp a valve element of a pressure equalization device, and optionally, wherein the gripper has a piston and / or the test body is dimensioned to form a fluid-tight seal on the pressure equalization device, or the test body is dimensioned to form a fluid-tight seal over the pressure equalization device.

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