DESC:Field of the Invention

[001] This invention relates to a junction box for electrical connections, for example for use in electric vehicles.

Background to the Invention

[002] A junction box or a terminal block is generally used for making connections between an electric power source and the electrical components with which the power source is connected. Electrical junction boxes are used in variety of applications; one such application is in vehicles, more particularly electric vehicles.
[003] The junction box housing is generally made of plastic. The junction box typically includes mounting provisions, for example electric connector mounting studs of conductive material which connect a plurality of electric elements with each other, for example the batteries and the operating components of an electric vehicle such as its electric motor. An electrical junction box includes a housing for electrical connections which protects the connections from any external impacts, dust, water, dirt etc. and therefore act as a safety barrier.
[004] Conventionally, a junction box is provided with a heat resistant barrier in the form of separate heat and fire resistant sheets which are arranged in layers or around the electrical connections to resist heat and flammability or fire. Electric studs for mounting connections are then provided separately for assembly. The provision of separate heat and fire resistant sheets increases manufacturing time and also leads to increase in the weight and size of the junction box since the heat barrier sheets are placed over an entire housing surface in the stack format which increases overall height of the junction box. In addition, while manufacturing may be convenient, the heat barrier sheets may also extend into areas where not required leading to a wastage of material. Further, heat resistant barrier sheets as currently used may not provide secure protection against arcing and temperature resistance of up to 350ºC or more rather than 120ºC.
[005] In one application, a junction box may be utilized in electric vehicles. From that perspective, a strong trend to electric vehicle manufacture and use is now becoming evident as concerns with climate change and availability of fossil fuels become evident. Electric vehicles include at least one but more typically a number of batteries, each including a large number of electric cells. The number of batteries required for an application is driven largely by the required vehicle range. At the present time, readily available batteries remain bulky and this may limit their use particularly where desired vehicle range conflict with small vehicle size.
[006] Compact vehicle design is necessary for many applications and the Applicant has developed compact electric vehicle designs as described in the Applicant’s co-pending Indian Provisional Patent Application Nos. 201721045778, 201721045779 and 201721046004, the contents of which are incorporated herein by reference. These and other electric vehicles include an electric battery module including the above-mentioned batteries and also a junction box assembly as the terminal block for making connections between the at least one battery and at least the electric motor using flexible wired connections. Of course, the requirement for electrical junction boxes is not confined to electric vehicles; other automotive vehicles also include at least one junction box and this is not to preclude potential non-automotive applications.
[007] In a desirable compact type of vehicle layout, space constraints are a major problem. Therefore, each component requires to be designed to have optimum size to minimise space while at the same time enabling convenient position. Another design criterion is for minimum weight to reduce overall weight acting on a vehicle chassis, to reduce vehicle inertia and so on.
[008] It is an object of the present invention to provide a junction box with compact design and reduced weight compared to currently available junction boxes.
[009] It is a further object of the present invention to provide a junction box with reduced cost and manufacturing time.

Summary of the Invention

[010] With this object in view, the present invention provides a junction box comprising:
a housing;
a heat resistant barrier material; and
a plurality of electric connector mounting studs located in a portion of the housing;
wherein the housing portion comprises a moulding including at least heat resistant barrier material and said plurality of electric connector mounting studs.
[011] The moulding, conveniently an insert moulding. Alternatively, the housing portion may comprise a first moulding including the heat resistant barrier material and a second moulding located over the first moulding and including the plurality of electric connector mounting studs. The mentioned number of mouldings is not critical, but rather exemplary, the objective being to configure the moulding(s) to simplify construction and lowering weight and material cost of the junction box.
[012] Typically, the housing portion is a bottom portion or cover of the junction box which may advantageously be insert moulded with the heat resistant barrier and then over moulded with the electric connector mounting studs to form a single assembly. Any convenient moulding technique may however be used.
[013] Heat resistant barrier material, which desirably provides protection against arcing and suitable temperature resistance to 350C or more, is preferably distributed in the moulding to extend selectively around electrical connector mounting studs where heat is generated and there is also a higher possibility of arcing or sparking. As the heat resistant barrier material comes at appreciable higher cost and thus laying it across the complete housing surface is a potentially uneconomical way of manufacturing avoided by selective distribution of the heat resistant barrier in the moulding. This avoids weight and cost associated with the prior installation of heat resistant barrier sheets into the housing.
[014] Further, since the electrical studs and heat resistant barrier material are provided in the housing portion/bottom cover itself as a single component so there is no need to provide the electric studs, heat resistance barrier material and cover as a separate components thereby further saving the number of components and cost. The bottom portion of the housing including the moulding(s) with heat resistant barrier and the necessary electrical connections is desirably closed with a top cover. Such top cover is preferably removable. Desirably, the junction box is also sealed when the top cover is in position with a sealing means such as a rubber grommet and sealing gasket being located to prevent any entry of water, dirt, moisture etc. into the box.
[015] The above described junction box construction helps in reducing the overall weight and size enabling improved and compact packaging which is advantageous for example in vehicle design but potentially non-automotive applications as well. Manufacturing time required is also less as the electric connector mounting studs and heat barrier sheets are not required to be assembled separately.
[016] In a further aspect, the present invention provides a method for manufacturing a junction box comprising:
forming a housing; and
providing a heat resistant barrier and electric connector mounting studs for the housing
wherein at least the heat resistant barrier material and electric connector mounting studs are moulded into the housing.
[017] Desirably, the electric connector mounting studs are also moulded into the housing, again desirably so that heat resistant barrier material is distributed in the moulding to extend selectively around the electrical connector mounting studs where heat is generated and there is also a higher possibility of arcing or sparking.
[018] The heat resistant barrier and/or electric connector mounting studs may be moulded into the housing in one or more steps. The heat resistant barrier and electric connector mounting studs could be moulded into the housing of the junction box in a single moulding step. Alternatively, the heat resistant barrier can be moulded into a first moulding with the electrical connector mounting studs then being included in a second over moulding.
[019] Insert moulding is convenient for the moulding steps. However, the present invention is not limited to the method of insert moulding. Other convenient methods for providing the studs, barrier sheets and housing together as a single component may be evident to the person skilled in the art.
[020] In a still further embodiment, the present invention provides an electric vehicle comprising an electric battery module for powering an electric load such as an electric motor wherein connections are made using the junction box as above described.
[021] The junction box as described herein functions effectively with size and weight suitable for application to vehicles. At the same time, the method for manufacturing the junction box reduces cost, bulk and weight in comparison to conventional junction boxes. Such junction boxes are well suited to inclusion in compact layouts in automotive and not automotive applications.

Short Description of the Drawings
[022] The junction box and other aspect of the present invention may be more fully understood from the following description of preferred but non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
[023] Fig. 1 is a schematic top view of a junction box of the prior art.
[024] Fig. 2 is a schematic section view of the prior art junction box of Fig. 1.
[025] Fig. 3 is a top view of a junction box according to one embodiment of the present invention.
[026] Fig. 4 is a top view of the junction box of Fig. 3 with connectors in position.
[027] Fig. 5 is a rear view of the junction box of Figs. 3 and 4.
[028] Fig. 6 is a top view of the junction box of Figs. 3 to 5 with the connectors in position and a junction box cover removed.
[029] Fig. 7(a) is a schematic cutaway view of the junction box of Figs. 3 to 6.
[030] Fig. 7(b) is a detail from Fig. 7(a) showing connection of the junction box cover for sealing to a bottom portion of the junction box housing.
[031] Fig. 8 is a further cutaway view of the junction box of Figs. 3 to 7(b) along a projection perpendicular to that of Fig. 7(a)
[032] Fig. 9 is a schematic view showing the relative disposition of junction box to electric battery module and protective frame structure in an electric vehicle
[033] Fig. 10 is a detail view from Fig. 9 showing connection of the junction box to the protective frame structure.
[034] Fig. 11 is a partial rear view showing the junction box in position within an electric vehicle.

Detailed Description of Preferred Embodiments

[035] Referring first to Figs. 1 and 2, there is shown a junction box 125 of the prior art. Junction box 125 has a housing 125A which accommodates the heat barrier 127 as well as the electric connection mounting studs or terminals 129 and the connectors 130, 140 for connecting the junction box to an electric components such as the electric motor of an electric vehicle (not shown). Both positive and negative terminal studs 129 are included within junction box 125. Junction box 125 protects these components from water, dirt and other influences which could adversely affect the operation of the electric motor and electric vehicle.
[036] The heat barrier 127 includes a number of sheets of heat and fire resistant material which are fixed together and to the housing 125A by screws 128. It will be observed that the heat barrier 127 extends to areas away from the studs 129 even though the primary risk of fire or sparking is at the studs 129 themselves.
[037] The housing 125A, the studs 129 and heat barrier sheets 127 are provided separately and these must be assembled together being placed in the stack format which increases overall height of the junction box 125. The studs 129 are assembled on top of the heat barrier sheets 127. The manufacturing process takes time and, as noted above, the heat barrier sheets 127 extend into areas where not required leading to a wastage of material.
[038] Referring now to Figs. 3 to 8, there is shown a junction box 25 – again with a bottom housing portion or cover 25A which accommodates the heat resistant barrier 27, of heat resistant material rated for arcing protection up to 350C, as well as the electric connection mounting studs or terminals 29 and the connectors 30, 40 for connecting the junction box to an electric motor of an electric vehicle as described below. Both positive and negative terminal electrical connection mounting studs 29 are included within junction box 25. Junction box 25 protects these components from water, dirt and other influences which could adversely affect the operation of the electric motor and electric vehicle. The junction box 25 includes a top cover 25AA which may be removed to access its componentry if required. The top cover 25AA also forms a seal when in position in the junction box 25 with sealing rubber grommet and sealing gasket 25AB being located to prevent any entry of water, dirt, moisture etc. into the junction box 25.
[039] Junction box 25 is manufactured, for example, in a multi-step moulding process. First, junction box housing portion 25A is preferably moulded from a suitable plastic as known in the art and the next steps in the manufacturing method proceed as follows.
[040] First, the heat resistant barrier 27 is insert moulded into a first moulding for the housing portion 25A using an insert moulding method as well understood in the art of plastic moulding.
[041] Second, the electrical connection mounting studs 29 are then included in housing cover 25A a second over moulding. The moulding steps are conducted so that the heat resistant barrier material is distributed to extend selectively around the electrical connector mounting studs 29 where heat is generated and there is also a higher possibility of arcing or sparking. This selective use of heat resistant barrier material saves the major amount of cost as well as reducing the weight of junction box 25. In addition, because the heat resistant barrier material are not provided in multiple overlaid sheets this reduces the total height of junction box 25 by almost 40% in comparison to prior art junction box 125 thereby making junction box 25 more compact.
[042] Insert moulding is convenient for the moulding steps. However, the present invention is not limited to the method of insert moulding. Other convenient moulding methods for providing the studs, barrier sheets and housing together as a single component may be evident to the person skilled in the art.
[043] Referring now to Figs. 9 to 11, there is shown the relative disposition of junction box 25 and electric battery module 22 including batteries 24 to power the electric motor 20 of an electric vehicle 10.
[044] The batteries 24 are positioned inside the protective frame structure 23 in the manner described in the Applicant’s co-pending Indian Patent Application Nos. 201721045778, 201721045779 and 201721046004, the contents of which are incorporated herein by reference.
[045] Junction box 25 is connected to the rear, and outside of, protective frame structure 23. In this position, junction box 25 acts as a safety barrier at the rear of electric vehicle 10. Being located outside and rearward of the protective frame structure 23 such that heat transfer from the batteries 24 should not affect its operation.
[046] Mounting of junction box 25 to protective frame structure 23 is straightforward, with mounting brackets 26 being fastened to protective frame structure members 23a by suitable fasteners 70. The mountings may include vibration damping means. It will be apparent that during operation of the vehicle significant vibration is generated which constantly acts on the wires leading from the junction box 25 to the electric motor 20 and so on. Such vibration should not be transferred to the electrical connections present inside the junction box 25 as this would cause loosening of connections at the electric connection mounting studs 29. To prevent this, the wires are held together at a suitable distance from the junction box 25 using connectors 30, 40 and clipping members 30a thereby fixing the position of the wires and minimizing the possibility of loosening electric connections inside junction box 25.
[047] Modifications and variations to the junction box described in the present specification may be apparent to skilled readers of this disclosure. Such modifications and variations are deemed within the scope of the present invention. For example, the junction box – while being described in the context of an electric vehicle – is also suitable for other applications including vehicle applications. ,CLAIMS:We Claim:

1. A junction box comprising:
a housing;
a heat resistant barrier material; and
a plurality of electric connector mounting studs;
wherein at least a portion of said housing comprises a moulding including the heat resistant barrier material and said electric connector mounting studs.

2. A junction box as claimed in claim 1 wherein; the housing portion comprise a first moulding including the heat resistant barrier material and a second moulding located over the first moulding including the plurality of electric connector mounting studs.

3. A junction box as claimed in claim 2 wherein; the housing portion is insert moulded with the heat resistant barrier material and then over moulded with the electric connector mounting studs to form a single assembly.

4. A junction box as claimed in claim 1 wherein; the heat resistant barrier material, is distributed selectively around electrical connector mounting studs.

5. A junction box as claimed in claim 1 wherein; the moulding of heat resistant barrier and electric connector mounting studs into the housing is carried out in a single moulding step.

6. A junction box as claimed in claim 1 wherein; the housing portion is a bottom portion or cover of the junction box.

7. A junction box as claimed in claim 6 wherein; the housing comprises a removable top cover used to cover the bottom portion of the housing including the moulding(s) with heat resistant barrier material and the electrical connections.

8. A junction box as claimed in claim 7 wherein; the housing is sealed with a sealing means such as a rubber grommet and sealing gasket.

9. A junction box as claimed in any of the claim above wherein; the housing is formed of a plastic material.

10. A method for manufacturing a junction box comprising steps of:
forming a housing;
providing a heat resistant barrier material and plurality of electric connector mounting studs for the housing; and
wherein at least the heat resistant barrier material and the electric connector mounting studs are moulded into at least a portion of said housing.

11. A method for manufacturing a junction box as claimed in claim 10 wherein; the moulding of heat resistant barrier material comprises step of distributing said heat resistance barrier material in the moulding selectively around the electrical connector mounting studs.

12. A method for manufacturing a junction box as claimed in claim 10 wherein; the heat resistant barrier material is first moulded into said housing portion and the electric connector mounting studs are over moulded and located over the first moulding.

13. A method for manufacturing a junction box as claimed in claim 10 wherein; the moulding of heat resistant barrier and electric connector mounting studs into the housing of the junction box is carried out in a single moulding step.

14. The junction box as claimed in any of the claim above is provided in an vehicle comprising an electric battery module for powering and at least an electric load wherein electric connections between said electric battery and said electric load are made using said junction box.

15. The junction box as claimed in claim 14 wherein; the vehicle is an electric vehicle including a two-wheeled, three-wheeled and four-wheeled/ quadricycle type electric vehicle.