Sensor housing, water sensor and HV battery

Abstract

Sensor housing (7) of a water sensor (4) in a battery housing (3) of an HV battery (1), with a housing base (8), a housing cover (10) and at least one side wall (11) connecting them, the interior (12) of which is connected to the interior of the battery housing (3) via at least one opening (9) and is arranged on or in a region of a base (5) of the battery housing (3), characterized in that the housing base (8) is flat in the direction of the base (5) of the battery housing (3) and convexly curved on its side facing the housing cover (10), wherein the housing base (8) tapers continuously in the direction of the at least one opening (9), wherein the housing cover (10) is concavely curved in the direction of the housing base (8), and wherein the housing cover (10) projects beyond the housing base (8) in the region of the at least one opening (9) in a direction parallel to the base (5) of the battery housing (3).

Description

[0001] The invention relates to a sensor housing for a water sensor according to the type defined in the preamble of claim 1. Furthermore, the invention relates to a water sensor in a high-voltage battery with such a sensor housing. The invention also relates to a high-voltage battery with such a water sensor.

[0002] HV batteries, also known as high-voltage batteries, are well known in the art. They are used, for example, as traction batteries in at least partially electrically powered vehicles. The term "high-voltage battery" or "HV battery" is defined accordingly in ECE 100R. In such HV batteries, water penetrating a battery housing can cause critical faults if it connects electrical potentials. It is therefore crucial that water is prevented from entering the battery housing in the first place, if possible, or, if water does enter the battery housing, for example, because cooling water has leaked out, that this water ingress is detected early so that the HV battery can be shut down or switched off, ideally before a safety-critical fault occurs.

[0003] In high-voltage batteries, the insulation resistance between the high-voltage battery's ground and the high-voltage potential is typically measured. As soon as this value falls below a specified limit, the battery is shut down for safety reasons. To measure water ingress, this means that it is sufficient to use a water sensor. This sensor consists of an electrical conductor connected to the high-voltage potential and terminated near the battery casing, which is typically grounded, preferably at the bottom, in the direction of gravity. This allows any accumulating water to electrically connect the casing to the water sensor, causing the insulation resistance to collapse and triggering the intended, well-known, safety mechanism.

[0004] In practice, however, this is not so simple. Since the water sensor must not be electrically insulated, at least at its free end, and must be guided towards the bottom of the battery housing in the confined space of the battery housing, it requires a comparatively large amount of space and a correspondingly large distance to reliably rule out faulty electrical contact with the battery housing or other components. The electrically uninsulated tip of the water sensor must therefore be a comparatively large distance from the electrically conductive bottom of the battery housing to prevent a drop in insulation resistance even without water penetration. The water level in the battery must be correspondingly high before the water sensor responds.This represents a serious disadvantage, since such a high water level as is necessary in typical structures can in itself be safety-critical.

[0005] It is therefore generally known from the prior art to surround the water sensor with an electrically insulating sensor housing, which has openings through which the water is intended to penetrate. While this achieves electrical insulation from the bottom of the battery case when dry, the response is severely impaired. Electrically insulating materials are typically hydrophobic, so water cannot penetrate through small openings in the sensor housing, or only with great difficulty, due to surface tension. Very large openings, in turn, are a disadvantage with regard to the intended insulation.

[0006] DE 10 2013 105 041 A1 describes a conductive liquid sensor for a battery pack. A wire connected to the battery potential is positioned at a location where liquid could leak.

[0007] DE 10 2018 118 467 A1 describes a humidity sensor with a transponder. Accumulating moisture creates an electrical connection, which then triggers a signal.

[0008] Furthermore, reference can be made to JP 2023 - 12 588 A. This document describes a liquid sensor in which the liquid is sucked in via capillary forces and detected in a measuring area.

[0009] The state of the art therefore includes other possibilities, for example, using foamed materials or similar materials. In this context, reference can be made to DE 10 2022 002 966 A1, for example, in which the ingress of water is absorbed via a mat element, dissolving salts contained in the mat element and thus establishing electrical contact between two sensor electrodes. This design is also comparatively complex, and it is still unclear whether the generally good functionality can be reliably maintained over a long operating period of many years.

[0010] The object of the present invention is therefore to provide an improved sensor housing for a water sensor as well as a water sensor with such a sensor housing and an HV battery with such a water sensor, which avoids the aforementioned disadvantages and ensures a good response behavior of the water sensor even at very low water levels in the battery housing with a simple and robust construction.

[0011] According to the invention, this object is achieved by a sensor housing having the features in claim 1, and in particular in the characterizing part of claim 1. Furthermore, a water sensor according to claim 8, as well as an HV battery with such a water sensor according to claim 10, solves the problem.

[0012] The sensor housing according to the invention for a water sensor in a battery housing of an HV battery comprises a housing base, a housing cover, and at least one side wall connecting them. The interior of the sensor housing is connected to the interior of the battery housing via at least one opening. The sensor housing is arranged on the base or in the region of the base of the battery housing. Water can penetrate into the sensor housing through the opening and thus reach the water sensor, causing a drop in insulation resistance to thereby trigger the known safety measures. According to the invention, the housing base is flat towards the base of the battery housing and convexly curved on its side facing the housing cover.The housing base tapers continuously toward the at least one opening, meaning that when placed on the preferably flat base of the battery housing, it smoothly transitions into it, creating no, or at least no significant, edge. The convex curvature is also designed to eliminate any edge. Both the support and the shape of the housing base itself are thus largely continuous.

[0013] The housing cover is concavely curved toward the housing base, so that the convex shape of the base toward the cover and the concave shape of the housing cover toward the housing base form a curved channel between them as the interior of the sensor housing. The housing base is smaller in the area of ​​the at least one opening perpendicular to the bottom of the battery housing, thus having a smaller extension than the housing cover. One could also say that the housing cover projects beyond the housing base in a direction parallel to the bottom of the battery housing.This special design, with the housing cover concavely curved toward the expected water level and the corresponding "hill" created by the housing base within the expected water level, ensures that the water is drawn between the housing base and the housing cover via capillary forces, thus reaching the water sensor even at very low liquid levels within the battery housing, even at a considerable distance from the bottom of the battery housing. The structure can preferably be positioned at the lowest point of the bottom of the battery housing to ensure a very rapid response of the water sensor.If this is connected via the water to the bottom of the battery housing, which is connected to ground, the insulation resistance between the ground and the HV potential of the water sensor collapses and the known safety mechanisms for switching off the HV battery before it is damaged can start prematurely.

[0014] Due to the special design and the described geometry, it does not play a significant role whether the electrically insulating material from which the sensor housing is made is hydrophobic or not, so that a common material can be used to produce the sensor housing by additive manufacturing, injection molding or the like.

[0015] According to a very advantageous development, the channel formed between the housing cover and the housing base is edgeless starting from the opening. Edgeless here means that there are no abrupt changes in cross-section, allowing the capillary effect to take effect. Accordingly, according to another very advantageous embodiment of the sensor housing according to the invention, the channel cross-section is selected such that capillarity occurs.

[0016] As already mentioned above, the housing cover and the housing base can be connected to one another via at least one side wall. According to a particularly advantageous embodiment of the sensor housing according to the invention, it is particularly preferred that the housing cover and the housing base are connected via a first side wall and a second opposite side wall, wherein two openings are provided, which are arranged opposite one another between the two side walls. The housing cover and the housing base are thus formed accordingly between two preferably parallel side walls, and the openings are arranged such that the channel runs along the same between the two side walls.

[0017] A particularly advantageous embodiment of this can also provide for the first side wall to be formed integrally with the housing cover and the second side wall to be connected to the housing base by a material bond. The housing cover can, for example, be applied to one side wall as a correspondingly shaped rib. It can be formed integrally with this or, for example, subsequently glued to it. The same applies to the housing base with the corresponding other side wall. This has the decisive advantage that by assembling the two side walls, which can, for example, be glued, screwed, clipped, latched or connected in some other way, the sensor housing can be manufactured and assembled from two parts extremely easily and efficiently.

[0018] Thanks to a very advantageous design of the sensor housing, the gap between the two openings is much larger than the gap between the two side walls. This results in a simple and correspondingly small and compact structure, which nevertheless ensures excellent functionality in "sucking in" water through capillary forces. The distance between the side walls can be a few millimeters, and that between the openings a few centimeters.

[0019] A water sensor according to the invention in a high-voltage battery with such a sensor housing comprises an electrical conductor connected to the HV potential of the HV battery, which is electrically insulated from one side of the housing cover into an interior of the sensor housing and is uninsulated in the interior of the sensor housing. This allows electrical contact to be made with water entering the sensor housing, which then establishes a potential connection to the ground of the base of the battery housing, thus triggering the safety mechanisms due to the collapse of the insulation resistance.

[0020] According to a very advantageous development of the water sensor, it can be provided that it is inserted in a region of the housing cover which, viewed perpendicular to the base of the battery housing, lies above the housing base. In the interior, the uninsulated part of the electrical conductor is therefore located above the housing base in the interior and not in the region of the housing cover which projects above the housing base in the area of ​​the openings. This reliably ensures electrical insulation by the housing base, even when arranged close to the base of the battery housing. The water sensor is preferably located centrally above the housing base with respect to its extent between the openings.

[0021] An HV battery can accordingly comprise a battery housing which has such a water sensor according to the invention with the sensor housing according to the invention.

[0022] Further advantageous embodiments of the sensor housing, the water sensor and the HV battery also emerge from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0023] Showing: Fig. 1 shows an HV battery with a water sensor in an embodiment according to the prior art; Fig. 2 a water sensor with a sensor housing in a design according to the prior art; Fig. 3 a cross section through a sensor housing according to the invention; Fig. 4 two individual parts of the sensor housing according to the invention in an exploded view; and Fig. 5 an HV battery in an embodiment according to the invention.

[0024] In the presentation of the Fig. 1 schematically shows a high-voltage battery or HV battery, designated 1. It is intended to comprise two modules of individual battery cells, each designated 2, which are installed in a common battery housing 3. In order to detect the potentially critical ingress of water into the battery housing 3, a water sensor 4 is provided, which acts as an electrical conductor and is connected to the HV potential of the HV battery 1 and projects towards a base 5 of the battery housing 3. To ensure reliable electrical insulation during normal operation, a specific distance, designated here by x, is required between the uninsulated end of the water sensor 4 and the base 5 of the battery housing 3. Accordingly, a comparatively high water level must be present in the battery housing 3 before the water connects the HV potential of the water sensor 4 to the housing 3, which is connected to ground 6.If this is the case, a drop in the insulation resistance between ground and the HV potential is detected, which then leads to an emergency shutdown of the HV battery 1 before safety-critical short circuits or the like can occur.

[0025] However, the larger the distance designated x must be selected, the later the safety mechanism will respond, and the more critical it can become with regard to short circuits, thermal runaway of the battery, or the like. For this reason, sensor housings 7 can also be arranged around the end of the water sensor 4, which allow the tip of the water sensor 4 to be brought closer to the bottom 5 of the battery housing 3. This is shown purely as an example in the illustration of the Fig. 2, which also shows a structure according to the prior art, is indicated by an enlarged view. The sensor housing 7, shown there in longitudinal section, stands with its housing base 8 directly on the base 5 of the battery housing 3. The water sensor 4 is arranged inside the sensor housing 7. Any water located on the base 5 of the battery housing 3 must then penetrate into the sensor housing 7 through the comparatively small openings 9. Since electrically insulating material is typically hydrophobic, a relatively high surface tension occurs here, so that water cannot reliably penetrate the sensor housing 7, cannot reliably wet the water sensor 4 and therefore cannot reliably trigger the desired safety mechanism.

[0026] Although larger openings 9 could remedy this problem, this would again increase the risk of an unwanted electrical arcing between the bottom 5 of the battery housing 3, i.e. the ground, and the water sensor 4 which is at HV potential, so that a larger distance in the sense of the distance x described above would have to be maintained, with the disadvantages described there.

[0027] The solution can now offer a geometrically improved sensor housing 7, which is shown in a longitudinal section in the illustration of the Fig. 3 can be seen on the bottom 5 of the battery housing 3. This sensor housing 7 comprises a housing base 8 and a housing cover 10, between which here on the right and left in the illustration of the Fig. 3, the opening 9 remains open. The housing cover 10 and the housing base 8 are connected to one another via side walls, one of which can be seen here and is provided with the reference numeral 11. A channel, designated here by 12, is thus formed between the housing base 8 and the housing cover 10 as the interior of the sensor housing 7, into which the water sensor 4, indicated here by dashed lines, protrudes.

[0028] The housing cover 10 is concavely curved, while the housing base 8 is convex. The housing base 8 thus protrudes upwards from the base 5 of the battery housing 3, and the housing cover 10 has a corresponding curvature facing the housing base 8. The channel or interior space 12 is dimensioned such that capillarity occurs. Water that collects in the area of ​​the openings 9 or one of the openings 9 is drawn into the channel 12 and thus reaches the water sensor 4 located above the housing base 8. This works simply, efficiently, reliably, and automatically.Because the special geometry of the housing cover 10 and the housing base 8 draws the water upwards via capillary force, even a very low water level is sufficient to wet the water sensor 4, which is sufficiently spaced from the base 5, and thus cause the insulation resistance to drop, which triggers the corresponding safety mechanisms. To reliably implement this effect, the housing cover 10 projects beyond the housing base 8 in the area of ​​the openings 9, meaning its extent is smaller. These areas, in which the housing cover 10 projects beyond the housing base 8, are shown in the illustration. Fig. 3 marked D.

[0029] The housing cover 10 and the housing base 8 can be positioned simply and efficiently between two plate-shaped side walls 11, which can be pushed from top to bottom into the battery housing 3 until the housing base 8 rests on the base 5 of the battery housing 3 or is at least positioned close to it. The construction becomes particularly simple and efficient when the sensor housing 7 is made of two sub-elements, as shown in the exploded view of the Fig. 4 is indicated. The side wall 11 shown on the right is formed integrally with the housing base 8 or is materially connected to it, so the housing base 8 is therefore glued to the side wall 11, for example. The other side wall 11, which is shown here on the right, is formed integrally with the housing cover 10 or is materially connected to it. It can therefore be glued to this side wall 11 accordingly. As indicated by the curved arrow shown in bold, these two side walls 11, which respectively support the housing base 8 and the housing cover 10, can now be put together. They can, for example, be glued or also latched, clipped, screwed, held against each other with clasps, or the like.In any case, it is thus possible to construct the sensor housing 7 simply and efficiently using two independent components. In particular, it can be placed around the water sensor 4 (not shown here) and brought together, for example by snapping them together. The side wall 11 shown on the right could also be manufactured from the top with the same thickness throughout, so that only the area forming the channel 12 and the area accommodating the housing base 8 are set back. Furthermore, a groove for the water sensor 4 could then run in the side wall 11 from the area of ​​the channel 12 upwards to the end of the side wall. The assembly could thus be further simplified by the two side walls 11 being in close contact with one another in their upper region.

[0030] The structure is therefore extremely simple. Finally, the illustration of the Fig. 5 again, analogous to the representation in Fig. 1, an HV battery 1 is shown, which is designed according to the invention in that the sensor housing arranged in the lower area of ​​the battery housing 3 is arranged in the sense of Fig. 3 and Fig. 4 surrounds the water sensor 4.

Claims

[1] Sensor housing (7) of a water sensor (4) in a battery housing (3) of an HV battery (1), with a housing base (8), a housing cover (10) and at least one side wall (11) connecting them, the interior (12) of which is connected to the interior of the battery housing (3) via at least one opening (9) and is arranged on or in a region of a base (5) of the battery housing (3), characterized by in that the housing base (8) is flat in the direction of the base (5) of the battery housing (3) and convexly curved on its side facing the housing cover (10), wherein the housing base (8) tapers continuously in the direction of the at least one opening (9), wherein the housing cover (10) is concavely curved in the direction of the housing base (8), and wherein the housing cover (10) projects beyond the housing base (8) in the region of the at least one opening (9) in a direction parallel to the base (5) of the battery housing (3). [2] Sensor housing (7) according to claim 1, characterized by that the housing cover (10), the housing base (8) and the at least one side wall (11) are made of an electrically insulating material. [3] Sensor housing (7) according to claim 1 or 2, characterized by that the channel (12) forming the interior space between the housing cover (10) and the housing base (8) is edgeless starting from the at least one opening (9). [4] Sensor housing (7) according to claim 3, characterized by that the cross-section of the channel (12) is selected so that capillarity occurs. [5] Sensor housing (7) according to one of claims 1 to 4, characterized by that the housing cover (10) and the housing base (8) are connected via a first side wall (11) and an opposite second side wall (11), wherein two openings (9) are provided which are arranged opposite one another between the two side walls (11). [6] Sensor housing (7) according to claim 5, characterized bythat the first side wall (11) is formed integrally with the housing cover (10) and the second side wall (11) is connected to the housing base (8) or is materially connected. [7] Sensor housing (7) according to claim 5 or 6, characterized by that the extension between the two openings (9) is greater than the extension between the two side walls (11). [8] Water sensor (4) in an HV battery (1) with a sensor housing (7) according to one of claims 1 to 7, characterized by an electrical conductor lying at the HV potential of the HV battery (1), which is introduced in an electrically insulated manner from the side of the housing cover (10) into an interior space (12) of the sensor housing (7) and is uninsulated in this interior space (12). [9] Water sensor (4) according to claim 8, characterized bythat the water sensor (4) is guided through the housing cover (10) or between the housing cover (10) and one of the side walls (11) in an area lying perpendicular to the bottom (5) of the battery housing (3) above the housing bottom (8). [10] HV battery (1) with a battery housing (3) which has a water sensor (4) according to claim 8 or 9.

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