Search

EP-4321391-B1 - JUNCTION BOX

EP4321391B1EP 4321391 B1EP4321391 B1EP 4321391B1EP-4321391-B1

Inventors

  • PLANAS GIRONA, ALBERT
  • ROVIRA MASIP, Guillem
  • PRAT TERRADES, JAUME

Dates

Publication Date
20260506
Application Date
20220811

Claims (12)

  1. A junction box for a vehicle comprising: a plurality of busbars (12, 14, 16, 32, 34; 130), and a housing (100) to substantially enclose the plurality of busbars, wherein the housing (100) comprises a base (110), a cover and one or more sidewalls (105) connecting the base (110) with the cover, and wherein the base (110) is made of an electrically insulating material and comprises an inner side facing an inside of the junction box, and an outer side facing an outside of the junction box, wherein a portion of at least one of the plurality of busbars is embedded within the base, wherein the base (110) includes one or more grooves (111) at the outer side, wherein a portion of at least one of the busbars that is embedded within the base extends over one or more of the grooves (111), and wherein the junction box further comprises a support frame (120) to support the base (110), wherein the support frame (120) is partially arranged in one or more grooves (111) of the base (110).
  2. The junction box according to claim 1, wherein the base (110) substantially extends along a base plane, and wherein the portion of the busbar (130) extending over one or more of the grooves (111) comprises a first segment (131) extending substantially parallel to the base plane on a first side of the groove; a second segment (135) extending substantially parallel to the base plane on a second side of the groove; and one or more further segments (132, 134) between the first (131) and second (135) segments which are not parallel to the base plane.
  3. The junction box according to claim 2, wherein at least one of the further segments (132, 134) is arranged at or near the groove (111).
  4. The junction box according to any of claims 1 - 3, wherein the outer side of the base (110) is configured to be cooled.
  5. The junction box according to any of claims 1 - 4, wherein a thickness of the base between the outer side and the portion of the busbars embedded within the base is at least 1 mm, and specifically between 1 and 2.5 mm.
  6. The junction box according to any of claims 1 - 5, wherein the support frame further includes a perimetral flange (122) surrounding at least a part of a perimeter of the base (110), and one or more braces (124, 126, 128) to connect parts of the perimetral flange (122).
  7. The junction box according to any of claims 1 - 6, wherein the plurality of busbars includes: (i) a main busbar group including a first main busbar (12) connected to a first electrode of the main battery of the vehicle, and a second main busbar (16) connected to a second electrode of the main battery of the vehicles; and (ii) a rear drive busbar group for connecting to a rear inverter for driving a rear motor of the vehicle; and/or a front drive busbar group for connecting to a front inverter for driving a front motor of the vehicle.
  8. The junction box according to claim 7, wherein the first (12) and/or the second (16) main busbar is at least partially embedded in the base (110), and wherein the rear drive busbar group and/or the front drive busbar group are not embedded in the base (110).
  9. The junction box according to claim 7 or 8, further comprising a common mode filter, wherein the common mode filter comprises a ferrite core, and wherein the ferrite core is arranged around one or more portions of the rear and/or front drive busbar group, and optionally wherein the ferrite core is a one-piece ferrite core.
  10. The junction box according to claim 9, wherein the main busbar group is electrically connected to a fuse and/or a relay (50, 52), and wherein the rear drive busbar group and/or the front drive busbar group are electrically connected to the fuse and/or relay that are electrically connected to the main busbar group.
  11. A system comprising the junction box according to any of claims 1 - 10, and a cooling system comprising a cooling surface, and wherein the cooling surface is attached to the outer side of the junction box.
  12. A method for manufacturing a junction box for a vehicle according to any of claims 1 - 11, the method comprising: positioning a first group of busbars (12, 14, 16, 32, 34) in a mold; injection molding of a base (110) of the junction box, such that at least a portion of each of the busbars (12, 14, 16, 32, 34) of the first group is embedded in the base (110); providing a second busbar (22, 24); arranging a ferrite core (62) around the second busbar (22, 24); and mounting the second busbar (22, 24) with the ferrite core (62) to the base (110), and further comprising joining a support frame (120) to the base (110) of the junction box, including fitting part of the support frame (120) in grooves in the base (110).

Description

TECHNICAL FIELD The present disclosure relates to junction boxes for electrical or hybrid vehicles, and to methods for manufacturing such junction boxes. BACKGROUND The battery of an electric or hybrid vehicle can function as an energy storage element for powering an electrical motor and thus enabling the vehicle to move. The battery may be part of the floor structure of the vehicle. A battery may include several cells, e.g. lithium-ion cells grouped into modules. In order to drive the vehicle, the battery may be connected to one or more electrical motors. The electrical motor or "traction motor" may drive a wheel axle. For example, a front wheel axle may be driven by a front traction motor, and a rear wheel axle may be driven by a rear traction motor. It is also possible for a single traction motor to drive a single axle. The term "traction motor" is herein used to refer to the motors that are used for the propulsion of the vehicle, and to distinguish these motors from other electrical motors used for auxiliary systems on the vehicle, e.g. for air conditioning, window control, mirror adjustment, etc. Throughout the present disclosure, the term motor may generally be understood to refer to traction motors. The term "battery" within the present disclosure may be understood to refer to the battery or battery pack used for propulsion. The power delivered by the battery is DC power, whereas the electrical traction motors operate with AC power. A power inverter may be used to convert DC current from the battery to AC current for the motors. If a front and a rear motor are provided, each may be connected to its corresponding inverter, i.e. both a front inverter and a rear inverter may be provided. An electrical junction box is an enclosure housing electrical connections. Junction boxes generally serve the purpose of protecting these electrical connections. A junction box in a vehicle may e.g. be provided to electrically connect the electrodes of the battery (positive and negative or "cathode" and "anode") to the inverter(s) and/or to other electrical components or circuits. Such a junction box may generally comprise a housing with a plurality of busbars to conduct current. In the junction box, other electrical components such as fuses, different types of relays, and common mode filters may also be provided. The connections inside the junction box can selectively distribute power from the battery to other electrical systems, such as the aforementioned inverters. The positions of the electrical connections to the outside of the junction box may be determined by the vehicle design or vehicle manufacturer. Arranging the busbars within a junction box to make the necessary electrical connections in a safe, insulated, manner and providing thermal heat dissipation thus can become complicated. Junction boxes are well known in the art. JP2002084629A discloses a junction box including a circuit substrate in which a busbar is molded. Many known junction boxes however suffer from excessive heating. The busbars heat up significantly in use as a high level of current is provided through them and it is a significant engineering challenge to provide for sufficient heat dissipation of these busbars. It is known to provide a heat sink or cooling system at the outside of the housing of the junction box to reduce the temperatures. The cooling of the busbars is however not necessarily very effective, and thus a relatively large amount of energy is needed to keep the temperature of the busbars under control. In examples of the present disclosure, at least some of the aforementioned problems are resolved or at least reduced. SUMMARY In an aspect of the disclosure, a junction box for a vehicle according to claim 1 is provided. The junction box comprises: a plurality of busbars, and a housing to substantially enclose the plurality of busbars. The housing comprises a base, a cover, and one or more sidewalls connecting the base with the cover. The base is made of an electrically insulating material, and comprises an inner side facing an inside of the junction box, and an outer side facing an outside of the junction box. A portion of at least one of the plurality of busbars is embedded within the base. According to this first aspect, heating of one or more of the busbars can be avoided or reduced since at least a portion of a busbar is embedded in the base of the junction box. Thermal dissipation can take place through direct conductive contact between the busbar and the base, rather than through convection. At the same time, the portions of the busbars are electrically insulated by being embedded in a suitable material, such as a resin or a polymer, e.g. a thermoplastic polymer. In examples, the base may be made by injection molding. The portions of the busbars to be embedded in the base may be arranged in a mold, and subsequently injection may take place to form the base around the portions of the busbars. The base includes one or more gro