GB2048579A

GB2048579A - Screwless electrical terminal unit

Info

Publication number: GB2048579A
Application number: GB8008078A
Authority: GB
Original assignee: CA Weidmueller GmbH and Co
Current assignee: Weidmueller Interface GmbH and Co KG
Priority date: 1979-04-17
Filing date: 1980-03-10
Publication date: 1980-12-10
Also published as: FR2454711B3; CH648697A5; FR2454711A1; IT1136104B; DE7911182U1; GB2048579B; IT8012414A0

Abstract

In an electrical terminal unit having a pair of fixed contacts 3,3' and a common leaf spring 5 with respective free limbs 5c, 5d arranged obliquely relative to the contacts for providing contact pressure, one contact 3 is a channel to receive a wire and the associated spring limb 5c is straight, whereby the wire is retained with a wedging action, whereas the other contact 3' is flat and the associated spring limb 5d has a convex curved end 5e, so that a contact pin 14 or the like inserted in this position can easily be withdrawn manually. <IMAGE>

Description

SPECIFICATION Screwless electrical terminal unit The invention relates to a screwless electrical terminal unit having at least two adjacent terminals comprising respective contacts formed from a current-carrying part, and a common leaf spring for both contacts of adjacent terminals which spring has free ends orientated obliquely towards the contacts.

German utility model No. 77 17020 discloses a screwless terminal unit for electric conductors having at least two adjacently disposed terminals comprising respective channels formed from a currentcarrying part for holding the conductors, and a common leaf spring disposed between the two channels of the adjacent terminals, in which the leaf spring has a substantially central bend, a respective first limb adjoining the said bend on each side and extending to respective oppositely oriented second bends with an opposite curvature, and respective free limbs extending from said second bends obliquely towards the channels, the substantially central bend of the leaf spring is secured on a retaining member and each second bend is disposed facing an abutment member disposed between said second bands and arranged to resist motion of the second bends away from the associated channels.

By providing the leaf spring with the said shape and by supporting the leaf spring in the said manner, three-point support is provided on both sides of the leaf spring, namely firstly at the conductor-clamping place, secondly between the central bend and the retaining member, and thirdly between each of the reverse bends and the abutment member, i.e. between the first and second support points. The three-point support for each side of the spring ensures that clamping a conductor as well as releasing the clamping connection of a conductor at one terminal leaves the conductor at the other terminal unaffected. The oblique arrangement of the leaf spring limbs produces a wedging action whereby inserted conductors are firmly retained. To release a conductor it is necessary to use a tool.

There are many situations in which easy release is important, for example when the member to be connected and released is not a wire but an isolating plug, a cross-connector (for connecting neighbouring terminal units), a test connector, etc. For such members, easy manual release without the use of tools is very important. It would be possible to incorporate in the terminal unit special devices for releasing the spring, but this measure is impractical and uneconomic, as the special release devices would take up too much space and would greatly complicate the manufacture of the terminal units.

It is an object of the present invention to provide a screwless terminal, in which easy manual release is possible, without the aid of a tool or any built in release mechanism.

The present invention resides in a screwless electrical terminal unit with at least two adjacently disposed terminals which are provided with contacts formed from a current-carrying part and are associated with a common leafspring which bears on abutments of the current-carrying part, has a middle arc and two oppositely curved arcs disposed opposite thereto, the free limb of each of which is oriented obliquely towards the associated contact, characterised in that at least one of the free limbs of the leaf spring is rounded at its free end.

The invention also resides in a screwless electrical terminal unit having at least two adjacently disposed terminals comprising respective contacts formed form a current-carrying part, and a common leaf spring disposed between the two contacts of the adjacent terminals, in which the leaf spring has a substantially central bend, a respective first limb adjoining the said bend on each side and extending to respective oppositely oriented second bends with an opposite curvature, and respective free limbs extending from said second bends obliquely towards the contacts, the substantially central bend of the leaf spring is secured on a retaining member, each second bend is disposed facing an abutment member disposed between said second bends and arranged to resist motion of the second bends away from the associated contacts, and at least one limb has an arcuate free end presenting a convex surface to the associated contact.

Preferably, one limb has a rounded end and faces a flat contact, and the other limb is not rounded and faces a channel-section contact for receiving a wire conductor.

Preferably the leaf spring is made broader than the channel so that it is possible to apply a tool to the projecting leaf spring edge for releasing the clamping.

By virtue of the present construction it is possible for the plug of a test connection, or a break jack with electric and/or electronic components such as overcurrent fuses and the like, or the pins of crossconnectors, to be readily and reliably secured without difficulty while on the other hand the plugs and pins can readily withdrawn from the terminal unit without the aid of tools. Conveniently, a rounded portion is provided on the free limb disposed nearer the middle of the terminal unit because crossconnectors, isolating plugs, test connections and the like are normally connected to a terminal at that position.

One exemplifying embodiment of the invention will be described hereinbelow by reference to the accompanying drawing, which shows a terminal unit according to the invention in side view, as seen from its open side.

The drawing shows a block terminal unit of the kind comprising a generally slab-shaped insulating body or casing 1 of moulded plastics material incorporating mounting means 11 adapted to be clipped onto and unclipped from a metal supporting rail 12, shown as being of symmetrical cross section with out-turned flanges engageable by notches of the mounting means.

The terminal unit has two adjacent interconnected pairs of interconnected terminals for receiving electrical conductors 13 inserted through holes 9 in the top narrow face 10 of the casing. Each pair of terminals comprises a current-carrying part 2 of sheet metal, and a common generally W-shaped leaf spring 5. In the embodiment shown, the two currentcarrying parts 2 are formed by a single piece of metal, but they could be separate parts interconnected permanently or separably e.g. by a switch.

The casing 1 is recessed in one of its major side faces, to receive the terminals. In use the recess, which is open, is covered by an adjacent terminal or a cover plate.

One terminal of each pair comprises a channel 3, in which a conductor can lie. The channels 3 have a prismatic cross-section (in particular a V-section channel), and are sufficiently deep to ensure that an inserted conductor bears not merely in the top edge region of the cross-section of the prism but, owing to the prismatic form, is guided relatively far into the opening of the prism on being inserted so that it is able to bear flush on both surfaces of the prism. A recess 4 is provided in the middle region of each channel 3 in the region where the inserted conductor is clamped by the associated leaf spring. The recess 4 offers the advantage that relatively thin conductors can also be reliably clamped, since it enables the spring 5 to approach closely the bottom of the channel 3.The recesses can be formed by cutting away or flattening the metal of the part 2 in the appropriate region.

The other terminal of each pair has its contact 3' in the form of a substantially flat smooth lug pressed out from the metal part 2.

A common leaf spring 5 is provided for both contacts 3, 3' of a pair of terminals. The leafspring 5 has an arcuate central bend 5a between limbs 5f which in turn merge into oppositely disposed and oppositely arcuately curved reverse bends Sb beyond which respective free or end limbs 5c, 5d, extend obliquely towards the channel 3 and flat contact 3' at an oblique angle to the conductor insertion or extraction direction. In conjunction with the channel 3, the straight free end Sc of the spring defines clamping gaps and can resiliently clamp an inserted conductor 13 in the channel 3. The obliquity of the spring limb facilitates insertion and resists extraction of the conductor.

From the current-carrying part there is also formed a hook-shaped retaining lug 6which engages in an opening at the apex of curvature of the central bend 5a of the leaf spring 5. Opposite the lug 6 is a support or abutment lug 7, formed from the current-carrying part 2 and situated between the two bends Sb of the leaf spring 5 so that the two bends 5b bear on opposite sides of the lug 7. Each half of the leaf spring 5 is thus provided with three-point support, firstly at the free end, secondly by virtue of the bend Sb bearing on the lug 7 and finally by retention ofthe middle bend 5a on the retaining lug 6.As a result, any manipulation of one clamping portion of such a leaf spring has no effect on the clamping action of the other clamping portion of the leaf spring.

The contacts 3 and 3' as well as the lugs 6 and 7 are conveniently formed by raising portions from the current-carrying part 2.

The leaf spring 5 is broader than the greatest distance between the walls of the channel.This means that the limb Sc projects laterally beyond the channel 3. This permits access to the projecting part of the leaf spring in order to release the spring from clamping a conductor. Corresponding insertion slots 17 for a releasing tool are provided in the plastics casing, which extend downwardly obliquely from the front and the rear narrow sides of the casing.

The free end of the other free limb 5d of the leaf spring 5, on the other hand, is rounded. In the illustrated example the rounded portion is formed by a curve Se. The curve 5e is convex towards and co-operates with the smooth wall of the contact 3' to detachably secure an inserted plug, for example of test connections, break jacks with electrical and/or electronic components, such as overcurrent fuses and the like, or a pin 14 of a cross-connector 8 as indicated in the left-hand part of the drawing. The plug or pin is secured with sufficient reliability but can nevertheless be readily released, manually without the aid of a tool. The fact that such plugs or pins are normally provided with small detent indentations 15 contributes to providing a sufficiently secure locating action. The radius of the curve 5e is selected so that the rounded portion is able to enter such an indentation, as can be seen by reference to the drawing.

Claims

1. A screwless electrical terminal unit with at least two adjacently disposed terminals which are provided with contacts formed from a currentcarrying part and are associated with a common leafspring which bears on abutment of the currentcarrying part, has a middle arc and two oppositely curved arcs disposed opposite thereto,.the free limb of each of which is oriented obliquely towards the associated contact, characterised in that at least one of the free limbs of the leaf spring is rounded at its free end.

2. A terminal unit according to claim 1, characterised in that the rounded end is formed by bending ofthefreeend of the limb.

3. A terminal unit according to claim 1 or 2, characterised in that the contact adapted to cooperate with the rounded free limb comprises a smooth wall which is bent out from the currentcarrying part.

4. Aterminal unit according to claim 1,2or3 having two sets of said adjacent terminals which sets are on opposite sides of the centre of the terminal unit, the rounded end being provided only on the limb nearerthesaid centre.

5. Aterminal unit according to claim 1,2,3 or 4 in which only one end of the leaf spring is rounded and the other end is straight.

6. A screwless electrical terminal unit having at least two adjacent disposed terminals comprising respective contacts formed from a current-carrying part, and a common leaf spring disposed between thetwo contacts of the adjacent terminals, in which the leaf spring has a substantially central bend, a respective first limb adjoining the said bend on each side and extending to respective oppositely oriented second bends with an opposite curvature, and respective free limbs extending from said second bends obliquely towards the contacts, the substan tially central bend of the leaf spring is secured on a retaining member, each second bend is disposed facing an abutment member disposed between said second bends and arranged to resist motion of the second bends away from the associated contacts, and at least one limb has an arcuate free end presenting a convex surface to the associated contact.

7. Aterminal unit according to claim 6, in which the or each contact associated with a said arcuate free end has a substantially flat surface facing the said free end.

8. A terminal unit according to claim 6 or 7 in which only one limb of the leaf spring has a said arcuate free end, the other end being straight.

9. A terminal unit according to claim 8 in which the contact associated with the other limb of the leaf spring is channel-shaped.

10. An electrical terminal unit substantially as herein described with reference to the accompanying drawings.