GB1585463A - Junction boxes - Google Patents

Description

(54) IMPROVEMENTS RELATING TO JUNCTION BOXES (71) We, AMP INCORPORATED, a corporation organised and existing under the laws of the State of New Jersey, United States of America, of Eisenhower Boulevard, Harrisburg, Pennsylvania, U.S.A., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to junction boxes for interconnecting a large number of conductors for use, for example, as the main junction box for a harness system of an automobile.

It is important that such junction boxes be both robust and compact and yet that manufacturing and assembly costs are acceptable.

According to the invention, a junction box comprises a rigid insulating housing with spaced opposed faces having pairs of aligned terminal-receiving apertures, a stack of terminal boards sandwiched between the faces of the housing, each terminal board comprising a metal layer laminated with an insulating layer, the metal layer being divided into areas defining discrete current paths and being provided with preformed perforations at locations in alignment with the terminalreceiving apertures where contact with the metal layer is not required; terminals each having a post portion with a pointed end and a contact portion, the post portions extending through respective pairs of the aligned housing apertures and through the stacked terminal boards and being of rectangular cross-section smaller than the cross-sectional size of the said perforations so that the post portions are freely received in the perforations and pierce the metal layers at various levels in the stack at previously unperforated locations aligned with the perforations, each post portion being gripped on opposite sides by a pair of spring metal arms pushed out from a layer during piercing by the respective post portion thereby establishing electrical contact with the layer.

An example of junction box according to the invention will now be described with reference to the accompanying drawing which is a fragmentary perspective view of the junction box.

The junction box comprises a bipartite rigid plastics housing 11 containing a stack of terminal boards 12 in a snug fit. Each terminal board comprises a layer of roll hardened copper 13 laminated with an insulating paper layer 14 and divided in separate strips each defining a discrete circuit path. Terminals 15 having post portions 16 and tabs 17 are staked through aligned apertures 18 and 19 in the housing passing freely through perforations 20 and 21 preformed in the copper and paper layers respectively where electrical contact is not required and piercing the copper layers at various levels in the stack to establish electrical contact where desired. The perforations 21 are smaller than the perforations 20.

The post portions are of square crosssection smaller than the cross-sectional size of the perforations and one pair of opposite sides 22 is chamfered to provide a sharp wedge-shaped point which pushes out two spring arms 23 from the copper layer during piercing, the resilience of the arms ensuring a permanent and reliable electrical connection with opposite sides of the post. The opposecl housing apertures 18 and 19 are formed as elongate and square sections, respectively, to receive the tab and post portions of the terminals. The terminals have lugs more snugly to locate the terminals in the slots and prevent over-insertion.

The housing is moulded with circular feet 24 strengthening the area around each aperture and the housing contents encapsulated in epoxy resin (not shown) and stand-offs (not shown) may be provided on the feet to permit resin flow around the terminal post.

In manufacture, the copper and paper layers are perforated where necessary and laminated together in pairs. At this stage, the copper strips are interconnected by bridges which are stamped out after lamination to define the discrete circuits. The laminates are then stacked and enclosed between the housing halves. The terminals are then staked through the boards from both sides of the housing as required. The epoxy resin may then be injected into the housing for complete sealing and additional mechanical support.

The resultant junction box is very robust and completely sealed. It is therefore, suitable for use in an adverse environment subject to vibration in an automobile. The copper layer is of sufficient thickness to carry appliance currents and to grip the posts. Different numbers of terminal boards of different circuit configuration can be stacked within housings of identical dimensions to provide junction boxes of identical external dimensions with different functions with a consequential reduction in the number of different parts to be manufactured and stocked and obviating alteration to the automobile mounting. The same boxes can also be staked with different terminal arrangements to provide different functions.

Consequential savings arise in manufacturing and applied costs.

The invention should be contrasted with prior proposals in which terminals posts of circular cross-section were driven through stacked circuit boards preformed with undersize apertures where connection with the post was desired and subsequently assembled in a rigid housing. Such method of construction is not satisfactory where the terminal boards are stacked in a housing prior to connection to the posts, as variation in moulding tolerances preclude precise alignment of the preformed board apertures and the housing apertures. In this event, with a copper layer of sufficient thickness, posts will be deflected out of alignment with housing apertures 19 during staking. Furthermore, circular posts do not push out discrete spring arms and additional steps (such as soldering) must be taken to ensure contact between the posts and the circuits.

WHAT WE CLAIM IS: 1. A junction box comprising a rigid insulating housing with spaced opposed faces having pairs of aligned terminal-receiving apertures, a stack of terminal boards sandwiched between the faces of the housing, each terminal board comprising a metal layer laminated with an insulating layer, the metal layer being divided into areas defining discrete current paths and being provided with preformed perforations at locations in alignment with the terminal-receiving apertures where contact with the metal layer is not required; terminals each having a post portion with a pointed end and a contact portion, the post portions extending through respective pairs of the aligned housing apertures and through the stacked terminal boards and being of rectangular cross-section smaller than the cross-sectional size of the said perforations, so that the post portions are freely received in the perforations and pierce the metal layers at various levels in the stack at previously unperforated locations aligned with the perforations, each post portion being gripped on opposite sides by a a pair of spring metal arms pushed out from a layer during piercing by the respective post portion thereby establishing electrical contact with the layer.

2. A junction box according to Claim 1 in which one aperture of a pair of apertures is of elongate cross-section and the other aperture of that pair of apertures is of square cross-section.

3. A junction box according to Claim 1 or Claim 2 in which the pointed ends are wedge-shaped.

4. A junction box substantially as described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. housing halves. The terminals are then staked through the boards from both sides of the housing as required. The epoxy resin may then be injected into the housing for complete sealing and additional mechanical support. The resultant junction box is very robust and completely sealed. It is therefore, suitable for use in an adverse environment subject to vibration in an automobile. The copper layer is of sufficient thickness to carry appliance currents and to grip the posts. Different numbers of terminal boards of different circuit configuration can be stacked within housings of identical dimensions to provide junction boxes of identical external dimensions with different functions with a consequential reduction in the number of different parts to be manufactured and stocked and obviating alteration to the automobile mounting. The same boxes can also be staked with different terminal arrangements to provide different functions. Consequential savings arise in manufacturing and applied costs. The invention should be contrasted with prior proposals in which terminals posts of circular cross-section were driven through stacked circuit boards preformed with undersize apertures where connection with the post was desired and subsequently assembled in a rigid housing. Such method of construction is not satisfactory where the terminal boards are stacked in a housing prior to connection to the posts, as variation in moulding tolerances preclude precise alignment of the preformed board apertures and the housing apertures. In this event, with a copper layer of sufficient thickness, posts will be deflected out of alignment with housing apertures 19 during staking. Furthermore, circular posts do not push out discrete spring arms and additional steps (such as soldering) must be taken to ensure contact between the posts and the circuits. WHAT WE CLAIM IS:

1. A junction box comprising a rigid insulating housing with spaced opposed faces having pairs of aligned terminal-receiving apertures, a stack of terminal boards sandwiched between the faces of the housing, each terminal board comprising a metal layer laminated with an insulating layer, the metal layer being divided into areas defining discrete current paths and being provided with preformed perforations at locations in alignment with the terminal-receiving apertures where contact with the metal layer is not required; terminals each having a post portion with a pointed end and a contact portion, the post portions extending through respective pairs of the aligned housing apertures and through the stacked terminal boards and being of rectangular cross-section smaller than the cross-sectional size of the said perforations, so that the post portions are freely received in the perforations and pierce the metal layers at various levels in the stack at previously unperforated locations aligned with the perforations, each post portion being gripped on opposite sides by a a pair of spring metal arms pushed out from a layer during piercing by the respective post portion thereby establishing electrical contact with the layer.

2. A junction box according to Claim 1 in which one aperture of a pair of apertures is of elongate cross-section and the other aperture of that pair of apertures is of square cross-section.

3. A junction box according to Claim 1 or Claim 2 in which the pointed ends are wedge-shaped.

4. A junction box substantially as described with reference to the accompanying drawing.