WO1992019032A1

WO1992019032A1 - A terminal block of modular construction

Info

Publication number: WO1992019032A1
Application number: PCT/SE1992/000207
Authority: WO
Inventors: Björn KARDEFELT
Original assignee: Thorsman & Co. Ab
Priority date: 1991-04-12
Filing date: 1992-04-01
Publication date: 1992-10-29
Also published as: NO933643L; FI934473A0; SE9101098D0; NO933643D0; FI934473A; SE467230B; SE9101098L

Abstract

An electric terminal block for connecting electrical conductors comprises a number of connection points, each having an electrical contact and fixing device for mechanically fixing conductors which are to be mutually connected at respective connection points and for obtaining electrical contact between the conductors. The terminal block includes a number of connection-point modules (3-7), each of which has at least one connection point and at least one mechanical joining device (12, 13) intended for coaction with a corresponding and complementary joining device (12, 13) on another connection-point module (3-7) for joining the modules together.

Description

A TERMINAL BLOCK OF MODULAR CONSTRUCTION

TECHNICAL FIELD

The present invention relates to a terminal block pref¬ erably for use in a junction box in which connections are made between electrical conductors.

BACKGROUND ART

Junction boxes are used in electrical installations at points where electrical conductors are concentrated and branched, and also, for instance, at transition points between different types of cable. Many types of junction boxes are constructed for cable-connection from several directions, including from the bottom of the box.

In order to enable these electrical connections to be made in a junction box, the box may be provided with a terminal block, i.e. a composite physical arrangement of connection points, into which the electric conductors are inserted and held in electrical contact with one another.

The afore-indicated flexibility in the connection possi¬ bilities afforded by the junction box places high de¬ mands on the terminal blocks with regard, among other things, to the number of available connection points and their respective positions in the junction box, and also on the possibility of viewing the entire interior of the box and enabling the connections to be made readily and quickly. In one earlier known junction box construction, a peg is provided internally of the box, preferably in the centre of the bottom of the box, and the peg may be provided with an axially extending screw hole for coaction with a screw which secures the box cover plate and on which there can be mounted different ancillary devices, such as terminal blocks of different kinds or load-relieving devices which function to relieve the connected cables from loads acting axially thereon. One junction box of this kind is described in Swedish Patent Specification 449 279.

Terminal blocks intended for this type of junction box are known to the art, in which the connection points are disposed in a row, i.e. in-line. The terminal block is provided with a mounting hole for coaction with the aforesaid peg. The peg is provided externally with devices, such as splines, for coaction with complementa¬ ry devices in the mounting hole of the terminal block, such as axially extending flutes, for instance. When the terminal block is fitted in position, this arrangement prevents the block from being rotated relative to the peg.

The internal measurements of the junction box and the requirement of insulation between mutually adjacent connection points therewith restrict the number of connection points that can be provided on a terminal block in which the connection points are in-line.

When the number of connection points required is greater than that afforded by one such row-oriented terminal block, it is usual to use another type of terminal block in which the additionally required connections points are arranged laterally in the vicinity of the peg hole, such that the terminal block obtains a cruciform config¬ uration.

One common feature of the aforesaid terminal blocks is that the connection points are arranged in a fixed arrangement on the block. When fitting a terminal block of this kind in a junction box of the aforedescribed kind, the flexibility afforded by the terminal. block is at best such as to enable the block to be turned to alternative positions when fitting the block on the peg. This will provide a limited possibility of arranging the positions of the connection points in the terminal block, but when the position of one connection point is changed, it will, of course, also be necessary to change the respective positions of all other connection points at the same time.

It is also known to connect cables together electrically either within or outside junction boxes with the aid of a so-called cable clamp, with which two conductors are twisted together and held in electrical contact with one another. Each such cable clamp thus corresponds to a connection point and cannot be referred to as a terminal block in the actual meaning of the term. One such cable clamp is described, for instance, in Swedish Patent Application 8301094.

Other known cable-connecting devices of the kind dis¬ cussed here are the so-called push-in type connectors in which the bare ends of cables from which insulation has been stripped are simply pushed into a respective one of a number of holes arranged side-by-side. The holes are provided internally with devices for mechanically grip¬ ping the ends of the cable conductors and to hold said ends in electrical contact with corresponding devices in the laterally disposed holes. A typical contact arrangement of this kind may have four laterally dis¬ posed holes which are all connected electrically one with the other. Thus, one such contact device may repre¬ sent a connection point which mutually connects four conductors.

Such a device cannot be referred to as a terminal block in the actual meaning of the term, since each device only includes one connection point.

When any of these latter types of separate conductor- connecting devices are used in a junction box, it is difficult to obtain a clear view of the connections made, besides being difficult to search for faults, and to check the connections and to make any subsequent installatio .

DISCLOSURE OF THE INVENTION

One object of the present invention is to provide a compact, flexible terminal block in which the connection points have variable configurations and which is primar¬ ily intended to be fitted in a junction box having a mounting peg of the aforedescribed kind.

An inventive terminal block enables the positions of the connection points in a junction box to be disposed with particular attention to, for instance, the cable inlets in the box or other units which are also housed in the box. The number of connection points can also be varied readily as required.

One advantage afforded by the inventive terminal block resides in the greater flexibility of the block in comparison with terminal blocks in which the connec¬ tion points are arranged in rows or in a cruciform configuration, besides providing a clearer view of the connections than has hitherto been possible with indi¬ vidual cable-clamp or push-in type.

Another advantage afforded by the inventive terminal block resides in the greater safety in which the termi¬ nal block can be handled, in comparison with the use of individual connecting devices, particularly when connec¬ tions are made while a voltage is applied. Separate connectors of the cable-clamp or push-in type require the fitter to use both hands when making the connec¬ tions, which involves a risk typical in this kind of work. When using an inventive terminal block, the con¬ ductors can be connected with the use of one hand, which is much safer.

The aforesaid object is achieved with a modular con¬ struction of connection points in a connection field on the terminal block, and also with a terminal block having the characteristic features set forth in the following Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the present invention will be more readily understood and further advantages thereof made apparent, the invention will now be described in more detail with reference to a number of exemplifying embodiments there¬ of and also with reference to the accompanying drawing, in which

Figure 1 is a top view of an open junction box in which electrical conductors have been connected together with the aid of so-called cable clamps; Figure 2 illustrates a junction box provided with a terminal block constructed in accordance with the inven¬ tion;

Figure 3 illustrates a junction box in which the conduc¬ tors of three cables entering the box are connected by means of an inventive terminal block; and

Figures 4 and 5 illustrate further embodiments of an inventive terminal block module holder.

BEST MODE OF CARRYING OUT THE INVENTION

Figure 1 is a top view of an open junction box 1 in which six cables are connected through the side walls of the box. The cable conductors are connected within the junction box in accordance with known techniques, using so-called cable clamps 2 by means of which two or more bared cable ends have been twisted together at each connection point.

As will be seen from the Figure, the cable-connections cannot be clearly seen and the work entailed by fault searching and possible subsequent installation becomes unnecessarily complicated.

Figure 2 illustrates a junction box which is fitted with an inventive terminal block of module construction. In the illustrated case, the terminal block comprises a module holder 8 and five connection-point modules 3-7 of the push-in type. In the case of this embodiment, the holes 11 which accommodate the conductors that are to be connected together extend vertically towards the bottom of the block, when fitted. Naturally, other types of connection-point modules may be used and different types of modules may be used in one and the same terminal block. The module holder 8 is comprised of a tubular part 10 which is placed coaxially on the mounting peg 9 extending from the bottom of the terminal block, and is provided internally with flutes which coact with exter- nal splines on the peg 9, as described above. Extending tangentially from the tubular part 10 are two legs 14, 15, which in the illustrated case define therebetween an angle of 90°. Other embodiments of the module holder 8 will be described below. Each connection-point module 3- 7 and also the two legs 14-15 are provided on two mutu¬ ally opposing side surfaces with complementary joining de-vices 12-13 by means of which the modules can be joined together or to the module holder. In the case of the illustrated embodiment, the joining devices comprise mutually coacting grooves 12 and strips 13 which are so configured that the strips on one side surface can be inserted into the grooves on another side surface and therewith lock a module to another module or to a module holder. According to one embodiment, the grooves and strips have a dovetail configuration.

The module holder illustrated in Figure 2 defines four quadrants in the junction box. The illustrated modules can be used to construct a terminal block and to arrange connection points in any desired manner, a maximum of three connection points. It will be noted, however, that any three quadrants whatsoever can be chosen, by step¬ ping the module holder through 90°. All quadrants can be covered by also providing the two outermost side sur- faces of each module with respective strips and grooves, said modules extending perpendicular to the bottom of the box when fitted.

Because of the flexibility afforded by the module-con- struction, the terminal block can be positioned with regard to the location of the cable through-lets in the box housing.

It will be understood that the greatest advantages afforded by the inventive module-constructed terminal block are manifested when the block is used in a junction box of the exemplified kind, although the terminal block may, of course, also be used in. other cases.

Each module of the illustrated embodiment is constructed to enable it to be used as a normal push-in contact device, with the module free-standing either within or outside a junction box.

The module holder may also be constructed as a straight prism having a polygonal cross-section in a plane per¬ pendicular to the axis of the mounting hole. In this case, the side surfaces of the prism are provided with the necessary joining devices. A holder of square cross- section according to Figure 4 is particularly advanta¬ geous. The connection-point modules illustrated in Figure 2 can be used to construct a cruciform terminal block and when the two remaining side surfaces of the modules are also provided with joining devices, as before mentioned, the terminal block can be expanded to cover the whole of the bottom surface of the box if so desired.

Figure 5 illustrates a further embodiment of the module holder 8 which has a rectangular, elongated configura¬ tion and which enables the terminal block to be extended on one side or the other, or on both sides of a median plane that extends longitudinally through the holder. In all of the aforedescribed cases, the terminal block may, of course, be assembled outside the junction box and then fitted onto the peg provided in the box, or may alternatively be assembled inside the box. Subsequent additions to the terminal block will, of course, be fitted within the box.

Figure 3 illustrates a junction box that is fitted with an inventive terminal block in which conductors are connected from three cables entering the box. The module holder 8 used is of the aforedescribed kind and has two legs 14, 15 which extend at 90° relative to one another, and the modules are of the same kind as those used in the Figure 2 embodiment. Subsequent to mounting the terminal block in the junction box, the fitter can connect the conductors in the push-in type modules very easily with the use of only one hand, which is benefi¬ cial from the safety aspect, as mentioned above.

Claims

1. An electric terminal block for connecting electric conductors, said block comprising a number of connection points, each having an electric contact and a fixating device which functions to mechanically fix the conduc¬ tors to be mutually connected in respective connection points and to obtain electrical contact between said conductors, c h a r a c t e r i z e d in that the terminal block also includes a number of connection- point modules (3-7), each having at least one connection point and at least one mechanical joining device (12, 13) which is intended to coact with a correspond- ing, complementary joining device (12, 13) on another connection-point module (3-7).

2. An electric terminal block according to Claim 1, c h a r a c t e r i z e d in that the terminal block is also provided with a module holder (8) which includes at least one joining device (12, 13) for coaction with a corresponding, complementary joining device (12, 13) on a connection-point module.

3. An electric terminal block according to Claim 2, c h a r a c t e r i z e d in that the module holder (8) is provided with a mounting hole for coaction with a peg (9) mounted on the bottom plate of a junction box.

4. An electric terminal block according to one of

Claims 2 and 3, c h a r a c t e r i z e d in that the module holder (8) is provided with two legs (14, 15) which are disposed at an angle of preferably 90° in relation to one another, and in that each of said legs is provided with at least one joining device (12, 13).

5. An electric terminal block according to one of Claims 2 to 4, c h a r a c t e r i z e d in that the joining devices (12, 13) have the form of a groove (12) or a strip (13) and are disposed on a flat side surface of a connection-point module (3-7) or a module holder (8).

6. An electric terminal block according to Claim 5, c h a r a c t e r i z e d in that said grooves and strips have a generally round section.

7. An electric terminal block according to any one of the preceding Claims, c h a r a c t e r i z e d in that the connection points are of the push-in type.