A fuse cooling arrangement

Abstract

The invention concerns a method for providing a fuse cooling arrangement (1), wherein the arrangement comprises a thermal fuse (2) having a fuse body (3) and further having first and second connection tabs (4, 5) configured for connection of the thermal fuse (2) electrically to other components (6, 7), wherein the fuse cooling arrangement (1) comprises a cooling element (8) configured to cool the thermal fuse (2), the method comprising: providing a frame (9) at the cooling element (8); supplying a curable liquid or paste (10) into the frame (9) and positioning at least a part of the fuse body (3) into the frame (9) so that the curable liquid or paste (10) comes in contact with both the cooling element (8) and the fuse body (3), wherein the curable liquid or paste (10), at least when cured and solidified, forms a heat conducting material: and allowing the curable liquid or paste (10) to cure and solidify.

Description

TECHNICAL FIELD

[0001] The disclosure relates generally to cooling of a thermal fuse. In particular aspects, the disclosure relates to the provision and structure of a fuse cooling arrangement for a thermal fuse arranged in an electrical energy system of an electric vehicle. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] A battery system of an electric vehicle (EV) needs to be very powerful to provide the desired traction levels, even more outspoken in a commercial heavy-duty vehicle. Due to the high capacity of such a battery system (or, in generic terms, energy storage system, ESS) an electrical fault may lead to a release of large amounts of energy, and the system somehow needs to be structured to limit such events to avoid very costly over-dimensioning and extra insulation. To take measures with regard to electrical safety is essential in an EV.

[0003] A conventional way to implement protection against electrical faults is to use a thermal (melting) fuse. However, when operating at very high currents the lifetime of the thermal fuse may be reduced more than acceptable. The typical solution when protecting with a thermal fuse is to use a fuse current rating that is much higher than an expected maximum operational current. A problem associated with using very high ratings is that the fuse itself becomes very large and hence quite expensive, and it may also be difficult to install.

[0004] Cooling of fuses of the type of interest here has been tried but has not been fully satisfactory. For instance, one way to implement cooling of the body of the fuse is to make use of a fan but this typically leads to problems related to air cleanness and to the lifetime of the fan itself. Water cooling of the fuse tabs has also been proposed but this has often a limited effect since a lot of the heat generated inside the fuse is transferred to the fuse body.

[0005] Another possibility is to use pyro fuses, but they may be large, expensive and / or require delicate triggering circuits to be able to handle the combined current of typical battery packs.

[0006] There is thus a need for improvements in the field of electrical safety for electric vehicles.SUMMARY

[0007] According to a first aspect of the disclosure, it concerns a method for providing a fuse cooling arrangement, wherein the arrangement comprises a thermal fuse having a fuse body and further having first and second connection tabs configured for connection of the thermal fuse electrically to other components, wherein the fuse cooling arrangement comprises a cooling element configured to cool the thermal fuse, the method comprising: providing a frame at the cooling element; supplying a curable liquid or paste into the frame and positioning at least a part of the fuse body into the frame so that the curable liquid or paste comes in contact with both the cooling element and the fuse body, wherein the curable liquid or paste, at least when cured and solidified, forms a heat conducting material: and allowing the curable liquid or paste to cure and solidify.

[0008] When the liquid / paste has cured and solidified, it provides for a good heat-conducting contact between the cooling element and the fuse body, even if the fuse body (or the cooling element) has e.g. rims and recesses at its surface. That is, the liquid / paste adapts its form to that of the fuse body (and the cooling element) and is capable of filling voids that might be created at the rims and recesses if a solid heat conductor is used. This provides for an efficient cooling of the fuse, significantly better than if cooling only the connection tabs or using air cooling, and the lifetime of the fuse can thereby be kept long also when operated close to its rated current.

[0009] The liquid or paste may be a polymer-based substance and may form a so-called thermal interface material (TIM). To improve heat conduction, the curable liquid or paste may contain fillers in the form of particles of e.g. metal oxides or carbon black. The liquid or paste may, at least when cured and solidified, exhibit electrically insulating properties so as to avoid a short-circuit between the connection tabs if these are in contact with the liquid / paste. In an example, the polymeric substance is silicone- or epoxy-based and the fillers include aluminum oxide, aluminum nitride and / or boron nitride.

[0010] The frame may form some sort of vertically open wall structure so that when placed onto the cooling element, the frame forms walls and an upper surface of the cooling element forms a bottom of a mold for the curable liquid or paste. The frame may or may not be left around the cured liquid / paste depending on, for instance, its structure, how strong it is bonded to the cured liquid / paste, its cost etc. As an example, the frame may be a dismountable and thus removable and reusable wall structure made of a material that does not adhere strongly to the cured liquid / paste.

[0011] Optionally in some examples, including in at least one preferred example, the method further comprises: exposing the curable liquid or paste to heat or radiation, and / or adding a substance to the curable liquid or paste, so as to induce curing and solidification. The liquid or paste supplied to the frame may be a two-component substance, such as epoxy resin and polyamine, which is curable and curing (in a reasonably slow pace) already when supplied to the frame. Other liquids / pastes might need to be radiated by e.g. ultraviolet light to start the curing process. Still other liquids / pastes may start curing after addition of a catalyst or other additive.

[0012] Optionally in some examples, including in at least one preferred example, the method further comprises: positioning the frame at a target location of the thermal fuse and positioning the thermal fuse in its target location when positioned with the fuse body at least partly into the frame. The target location of the thermal fuse is the location where it will be positioned when the first and second connection tabs are connected to the other components, such as to first and second bus bars or cable shoes.

[0013] Optionally in some examples, including in at least one preferred example, the method further comprises: positioning the thermal fuse in its target location by connecting the first and second connection tabs to other components that are fixed in relation to the cooling element. For instance, these components, such as first and second bus bars or cable shoes, may be mounted onto the cooling element. A part of the bus bars, cable shoes or other components that is in contact with the cooling element may be made of a heat conducting and electrically insulating material, e.g. a polymer-based or ceramic-based material, so that also the connection tabs of the fuse are cooled by the cooling element.

[0014] Optionally in some examples, including in at least one preferred example, the frame comprises a wall structure and open sections directed downwards and upwards when the frame is positioned horizontally. That is, the frame may consist of a rectangular wall section that is fully open downwards and upwards when positioned horizontally. However, other shapes and structures are possible.

[0015] Optionally in some examples, including in at least one preferred example, the cooling element is a cooling plate with a substantially flat upper side.

[0016] Optionally in some examples, including in at least one preferred example, a cooling channel for a cooling medium is arranged in the cooling element. Water or other liquids may be used as cooling medium.

[0017] Optionally in some examples, including in at least one preferred example, the curable liquid or paste forms, at least when cured and solidified, an electrically insulating material. This may not be necessary if the connection tabs are not contacted with the liquid / paste, for instance if the fuse body is set in a position such that it is not fully contacted with or submersed in the liquid / paste (or if the amount of liquid / paste is limited so that it comes in contact with a portion of the fuse body but not the tabs). However, the use of an electrically insulating liquid or paste is generally recommended to avoid undesired short-circuits.

[0018] Optionally in some examples, including in at least one preferred example, a current rating of the thermal fuse is at least 20 A, or at least 40 A. That is, the maximum current that the fuse is intended to carry before it melts is at least 20 A, or at least 40 A. A typical rating range for the intended EV application may be 100-800 A, or 40-1200 A. The rated DC voltage may be around 1000 V. Such thermal fuses are relatively large, the length of the fuse body may typically be in the range 5-15 cm.

[0019] According to a second aspect of the disclosure, it concerns a fuse cooling arrangement for a thermal fuse, wherein the fuse cooling arrangement is obtained or obtainable by a method according to above. In a variant of the second aspect of the disclosure, it concerns a fuse cooling arrangement for a thermal fuse, wherein the fuse cooling arrangement is provided according to the above method.

[0020] According to a third aspect of the disclosure, it concerns a fuse cooling arrangement comprising: a thermal fuse having a fuse body and first and second connection tabs for connecting the thermal fuse electrically to other components; a cooling element; a heat conducting material arranged in contact with the fuse body and the cooling plate so as to allow the cooling element to cool the fuse body, wherein the heat conducting material is a curable, or at least partly cured and solidified, liquid or paste.

[0021] Optionally in some examples, including in at least one preferred example, a cooling channel for a cooling medium is arranged in the cooling element.

[0022] Optionally in some examples, including in at least one preferred example, the curable liquid or paste when cured and solidified forms an electrically insulating material.

[0023] Optionally in some examples, including in at least one preferred example, a current rating of the thermal fuse is at least 20 A, or at least 40 A.

[0024] According to a fourth aspect of the disclosure, it concerns an electric vehicle comprising an electrical energy system arranged for propulsion of the electric vehicle, wherein the electrical energy system comprises a fuse cooling arrangement of the above type. Typically, the thermal fuse of the cooling arrangement is arranged so as to prevent that, in case of some electrical fault, too much electrical energy is released from an energy storage system (electric battery) of the electric energy storage system.

[0025] The disclosed aspects, examples (including any preferred examples), and / or accompanying claims may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art. Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Examples are described in more detail below with reference to the appended drawings. FIG. 1 shows, in a schematic top view, an example of a fuse cooling arrangement according to the present disclosure. FIG. 2 shows, in a schematic side view, the fuse cooling arrangement according to figure 1. DETAILED DESCRIPTION

[0027] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0028] Figures 1 and 2 show top and side views, respectively, of a schematic example of a fuse cooling arrangement 1 intended to form part of an electrical energy system of an electric vehicle. The fuse cooling arrangement 1 comprises: a thermal fuse 2 having a fuse body 3 and first and second connection tabs 4, 5 connected electrically to first and second bus bars 6, 7 using screws 12, 13; and a cooling element in the form of cooling plate 8 made of aluminum with a substantially flat upper side 8a and a cooling channel 8b for a cooling medium, such as water, arranged inside the cooling plate 8.

[0029] The fuse body 3 is positioned in a frame 9 in the form of a wall structure with open upper and lower sides. Into the frame 9 has been supplied a heat conducting material in the form of a curable liquid or paste 10 that is in contact with the cooling plate 8 and, in this example, the entire body 3 of the fuse 2 so as to, at least when cured and solidified, conduct heat from the fuse body 3 to the cooling plate 8 and thereby cool the fuse body 3 when current flows through and heats the thermal fuse 2.

[0030] The curable liquid or paste 10 may be a polymer-based substance and may contain metal oxide particles or other fillers to improve heat conduction. The liquid / paste 10 exhibits electrically insulating properties so as to avoid a short-circuit between the connection tabs 4, 5 that in this case are in contact with the liquid / paste 10.

[0031] The bus bars 6, 7 are also made of a heat conducting material, and a lower portion of each bus bar 6, 7, including the portion in contact with the aluminum cooling plate 8, is made of a material that besides heat conducting is electrically insulating, e.g. a polymer-based or ceramic-based material, so also the connection tabs 4, 5 of the fuse 4 are cooled by the cooling plate 8 (via the bus bars 6, 7).

[0032] Other electrical components (not shown) may of course be connected to the bus bars 6, 7.

[0033] The current rating of the thermal fuse is in this example 100 A.

[0034] An example of a method for providing the fuse cooling arrangement 1 shown in figures 1 and 2 comprises the following steps: providing the frame 9 at the cooling element 8, which in case means placing the frame 9 horizontally onto the upper surface 8a of the cooling plate 8; positioning the frame 9 at a target location of the thermal fuse 2 and positioning the thermal fuse 2 in its target location by connecting the first and second connection tabs 4, 5 to the bus bars 6, 7, which are fixed in relation to the cooling element 8 and thereby define the target location of the fuse 2.

[0035] The dimension of the frame 9 is in this example adapted to the target location of the thermal fuse 2 in such a way that when the thermal fuse 2 is positioned in its target location and the frame 9 is properly positioned, the fuse body 3 is located in its entirety inside the frame 9, i.e. inside the mold defined by the frame 9 and the upper side 8a of the cooling plate 8.

[0036] The exemplified method further comprises: supplying the curable liquid or paste 10 into the frame 9 so that the curable liquid or paste 10 comes in contact with both the cooling element 8 and, in this case, the entire fuse body 3; and allowing the curable liquid or paste 10 to cure and solidify.

[0037] Depending on the type of liquid / paste used, the method may further comprise: exposing the curable liquid or paste 10 to heat or radiation, and / or adding a substance to the curable liquid or paste 10, so as to induce curing and solidification.

[0038] Other variants of the method is possible. For instance, the thermal fuse 2 may be fixed in its target location before positioning the frame 9 at the target location, e.g. by slightly turn the frame 9 during positioning or providing the frame 9 in two (or more) parts and assembling the frame 9 at the target position. It is also possible to supply the liquid / paste 10 into the frame 9 before fixing the fuse 2 in its target location.

[0039] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0040] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0041] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0043] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

1. A method for providing a fuse cooling arrangement (1), wherein the arrangement comprises a thermal fuse (2) having a fuse body (3) and further having first and second connection tabs (4, 5) configured for connection of the thermal fuse (2) electrically to other components (6, 7), wherein the fuse cooling arrangement (1) comprises a cooling element (8) configured to cool the thermal fuse (2), the method comprising: - providing a frame (9) at the cooling element (8); - supplying a curable liquid or paste (10) into the frame (9) and positioning at least a part of the fuse body (3) into the frame (9) so that the curable liquid or paste (10) comes in contact with both the cooling element (8) and the fuse body (3), wherein the curable liquid or paste (10), at least when cured and solidified, forms a heat conducting material: and - allowing the curable liquid or paste (10) to cure and solidify.

2. The method according to claim 1, further comprising: - exposing the curable liquid or paste (10) to heat or radiation, and / or adding a substance to the curable liquid or paste (10), so as to induce curing and solidification.

3. The method according to claim 1 or 2, further comprising: - positioning the frame (9) at a target location of the thermal fuse (2) and positioning the thermal fuse (2) in its target location when positioned with the fuse body (3) at least partly into the frame (9).

4. The method according to claim 3, further comprising: - positioning the thermal fuse (2) in its target location by connecting the first and second connection tabs (4, 5) to other components (6, 7) that are fixed in relation to the cooling element (8).

5. The method according to any of the above claims, wherein the frame (9) comprises a wall structure and open sections directed downwards and upwards when the frame (9) is positioned horizontally.

6. The method according to any of the above claims, wherein the cooling element is a cooling plate (8) with a substantially flat upper side (8a).

7. The method according to any of the above claims, wherein a cooling channel (8b) for a cooling medium is arranged in the cooling element (8).

8. The method according to any of the above claims, wherein the curable liquid or paste (10), at least when cured and solidified, forms an electrically insulating material.

9. The method according to any of the above claims, wherein a current rating of the thermal fuse is at least 20 A, or at least 40 A.

10. A fuse cooling arrangement (1) for a thermal fuse (2), wherein the fuse cooling arrangement (1) is obtained or obtainable by a method according to any of the above claims.

11. A fuse cooling arrangement (1) comprising: - a thermal fuse (2) having a fuse body (3) and first and second connection tabs (4, 5) for connecting the thermal fuse (2) electrically to other components (6, 7); - a cooling element (8); - a heat conducting material arranged in contact with the fuse body (3) and the cooling plate (8) so as to allow the cooling element (8) to cool the fuse body (3), wherein the heat conducting material is a curable, or at least partly cured and solidified, liquid or paste (10).

12. The fuse cooling arrangement (1) according to claim 11, wherein a cooling channel (8b) for a cooling medium is arranged in the cooling element (8).

13. The fuse cooling arrangement (1) according to any of claims 11-12, wherein the curable liquid or paste (10) when cured and solidified forms an electrically insulating material.

14. The fuse cooling arrangement (1) according to any of claims 11-13, wherein a current rating of the thermal fuse (2) is at least 20 A, or at least 40 A.

15. An electric vehicle comprising an electrical energy system arranged for propulsion of the electric vehicle, wherein the electrical energy system comprises a fuse cooling arrangement (1) according to any of claims 10-14.

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