GB2158303A

GB2158303A - Insulation piercing terminal block

Info

Publication number: GB2158303A
Application number: GB08510264A
Authority: GB
Inventors: Hans Woertz
Original assignee: Oskar Woertz
Current assignee: Oskar Woertz
Priority date: 1984-04-27
Filing date: 1985-04-23
Publication date: 1985-11-06
Also published as: FR2563661A1; FR2563661B1; GB8510264D0; DE3508939C2; DE3508939A1; GB2158303B

Abstract

A conductor entraining body (28;29) (two are shown) is provided with a recess (32;33) for an insulated conductor. Movement of the entraining body (28;29) forces the conductor into a slit (24) of an insulation-piercing contact, whereby blade-shaped edges (24A, 24B) of the slit (24) cut through the insulation and make contact with the conductor. In order to make an improved contact possible, particularly for conductors in the form of strands, the contact (15) is composed of a plurality of sheets (15', 15'', 15''') in which the blade-like edges (24A, 24B) are transversely offset alternately (Fig. 4). A pair of insulation-piercing terminals are formed in one unit. The entraining body is spring biassed. <IMAGE>

Description

SPECIFICATION Electric terminal block The invention concerns an electrical terminal block having a housing made of an insulating material and at least one contact member arranged in the housing, the contact member having a slit shaped opening which is bordered in its transverse direction by mutually oppositely lying blade-like edges for cutting through the insulation of an electrical conductor and for making contact with the conductor and having a widened aperture at one end of the slit-shaped opening, and an entraining body guided in the housing for displacement at least approximately parallel to the blade-like edges of the contact piece in order to bring the conductor into engagement with the said edges.

In practical use of terminal blocks of the above type, it has been shown that they are very well suited for the electrical connection of large conductors, i.e. conductors with a full cross-section, but are less well suited for the connection of conductors in the form of strands consisting of a plurality of relatively thin wires. Hence, the task of the present invention is to form an electrical terminal block of the above-mentioned type which is equally well suited for the connection of insulated strand-like electrical conductors and insulated massive or large conductors.

This task for electrical terminal blocks of the above-mentioned type is achieved according to the invention in that the contact piece or member is composed of at least two mutually superposed sheet parts and the slit-shaped opening and the widened aperture pass through each of the sheet parts and in that on each side of the slit shaped opening, bladelike edges of the mutually adjacent sheet parts are relatively offset transversely to the longitudinal direction of the slit-shaped opening.

By means of this construction of the contact member of the terminal block, faultless contacting of bulky and strand-shaped conductors is achieved and at the same time, cutting through the insulation of the conductor to be connected is facilitated.

In an expedient embodiment of the terminal block according to the invention, the contact piece may be composed of three to six sheet parts, wherein the mutually corresponding blade-like edges of successive sheet parts are offset alternately to one side and the other side.

Advantageously, all sheet parts of the contact member may have slit-shaped openings of equal length and equal width, wherein these apertures in the successive sheet parts have alternately offset positions to one side and to the other side whereby at the mutually adjacent sheet parts the blade-like longitudinal edges of the slit-shaped apertures are offset transversely relative to each other.

Further details and advantages of expedient embodiments of electrical terminal blocks according to the invention follow from the dependent patent claims, from the description of a preferred embodiment that now follows and from the associated drawing in which the subject matter of the invention is illustrated purely by way of example.

Figure 1 shows a preferred embodiment of an electrical terminal block according to the invention; partly in side view and partly in section along the line 1-1 in Fig. 2; Figure 2 shows a view of the terminal block seen from the left in Fig. 1; Figure 3 is a view of the contact member of the terminal block; Figure 4 illustrates a cross-section on an enlarged scale, along the line 4-4 in Fig. 3.

The illustrated electrical twin series terminal block has a housing 10 made of an insulating material which in the known manner is provided with two retaining feet 11 and 1 2 for securing the terminal block on a non-illustrated fixed carrier rail. Two cavities 1 3 and 1 4 formed and arranged in mirror symmetry in the housing 10 are open towards one flat side of the housing 10 (to the right in Fig. 2) and towards the end face remote from the retaining feet 11 and 12 (to the left in Fig. 1).

A common contact member 1 5 traverses through both the cavities 1 3 and 14, according to Fig. 4, is composed of several mutually superposed sheet metal parts 15', 15" and 15"' which expediently have the property of a spring. All the sheet parts, 15', 15", 15"' have the form of a profiled member of Ushaped cross-section and are so matched to each other that both the central webs as well as the lateral U-shanks of mutually adjacent sheet parts lie directly against each other.

Thus, the U-shaped sheet parts 15', 15" and 15"' sit astride each other. The central part of the contact piece 1 5 traverses an opening 1 8 of the housing 10, as may be seen in Fig. 1.

A screw nut 1 6 is pressed into the central part of the contact piece 1 5 into which a screw 1 9 passing through a bore 20 of the housing may be screwed (Fig. 3).

The sheet parts 15', 15" and 15"' forming the central web of the contact piece 1 5 are each provided with two relatively large apertures 22 and 23 (Fig. 3) which have the same shape, size and position for all sheet parts 15', 15" and 15"'. Further, at each end part of the contact piece 15, there is provided a respective slit-shaped opening 24 and 25 extending in the longitudinal direction of the contact piece and joining or going over into a respective aperture 26, 27 which widens in a funnel-like manner to the aperture 22, 23, respectively. The slit-shaped openings 24 and 25 as well as the widened apertures 26 and 27 traverse through the central webs of all the sheet parts 15', 15" and 15"'. The widened apertures 26 and 27 have the identical shape, size and position for all sheet parts.In contrast thereto, the slit-shaped openings 24 and 25 are formed by slit-shaped openings, e.g.

24', 24" and 24"' (Fig. 4) in the sheet parts 15', 15" and 15"'; although these openings have the same length and width, they have in the successive sheet parts an offset alternately to one side and the other side transversely to the. longitudinal direction of the slit-shaped opening 24, 25 relative to a central longitudinal plane 60 of the contact piece 15, as shown in Fig. 3 and particularly, Fig. 4. In the transverse direction, each of the slit-shaped openings 24', 24" and 24"' is bordered by two parallel, blade-like edges 24A and 24B.

Due to the above-mentioned lateral offset of the slit-shaped openings of the sheet parts 15', 15" and 15"' it follows that the mutually corresponding (i.e. lying respectively on the same side of the slit-shaped opening 24) blade-like edges 24A, 24B respectively of the successive sheet parts are also transversely offset alternately to one side and the other side. These blade-like edges 24A and 24B are destined to cut through the insulating material of an insulated electrical conductor to be connected to the terminal block and to make contact with the conductor, as will be explained below. The same is true by analogy for the other slit-shaped opening 25 and the blade-like edges 25A, 25B bordering it in the transverse direction (Fig. 3).

Expediently, the section about which the blade-like edges 24A, 24B and 25A, 25B respectively are transversely offset relative to each other and which correspond to each other, i.e. lie on the same side of the slitshaped opening 24, 25 respectively, is approximately of the same thickness as that of each individual sheet part 15', 15" and 15"'.

For example, for electrical conductors of a cross-section 1.5 mm2 to be coupled, the sheet parts 15', 15" and 15"' have preferably a thickness of 0.2 to 0.3 mm each, and the number of the mutually superposed sheet parts is expediently 3 to 6. Self-evidently, the breadth or inner width of each slit-opening 24, 25 respectively must be matched to the cross-sectional dimensions of the electrical conductor to be connected and should expediently measure about 80% of the nominal diameter of a massive conductor to be coupled thereto or approximately 65% of the nominal diameter of a conductor formed as a strand.

A respective displaceable entraining body 28, 29 is disposed in each of the two cavities 1 3 and 14 of the housing 10 and projects through the aperture 22, 23 respectively of the contact piece 15, being pivotally mounted in the housing 10 by way of pivot-shaft 30, 31 respectively.The shafts 30 and 31 extend perpendicularly to the longitudinal direction of the slit-shaped openings 24 and 25, more particularly at the side of the contact piece 1 5 which faces the retaining feet 11, 1 2. Expediently, the shafts 30 and 31 are formed integrally with the housing 1 0. Each entraining body 28, 29 has an opening 32, 33 respectively for receiving an insulated conductor which openings extend approximately radially to the relevant shaft 30, 32, and are open at the end of the entraining body which is remote from the shafts 30, 31.It may be seen clearly in Fig. 1 that the opening 33 present in the entraining body 29 has partly the form of an open groove 33A and partly the form of a bore 33B with a closed peripheral wall and with a closed end 33C for limiting the depth of insertion of the insulated conductor. The opening 32 in the other entraining body 28 is formed identically in mirror symmetry. Further, each entraining body 28, 29 has a mouth-like notch 34, 35 into which the part of the contact piece 1 5 having the slit-shaped opening 24, 25 and the widened aperture 26, 27 engages with sufficient play so as not to impede the pivotal movement of the entraining body.

The entraining bodies 28, 29 may each be pivoted between a conductor insertion position and a contacting position. In Figs. 1 and 2 one of the entraining bodies 29 is shown in the conductor insertion position and the other entraining body 28 in the contacting position.

When the entraining bodies 28, 29 are disposed in the conductor insertion position, the recess 32, 33 registers with a position of the contact piece lying in the region of the widened apertures 26, 27 at one end of the slitshaped opening 24, 25 of the contact piece so that an insulated conductor may without hindrance be inserted into the recess 32, 33 up to the closed end 32C, 33C respectively of the latter. When, however, the entraining bodies 28, 29 are in the contacting position, then the recesses 32, 33 are aligned with a position between the blade like edges 24A, 24B and 25A, 25B respectively of the slitshaped openings 24, 25 respectively near the closed ends of the latter, as may be seen clearly in Fig. 2 in the case of the entraining body 28. To secure the conductor insertion position of each entraining body 28, 29 an abutment boss 36, 37 respectively is provided within the relevant cavity 13, 14 respectively of the housing 10.

Each of the two entraining bodies 28, 29 is subjected to the bias of a respective compression spring 61, 62 which is accommodated mostly in an associated recess 63, 64 respectively of the housing 10. One end of each spring 61, 62 is supported at the closed end 65, 66 respectively of the recess 63, 64 while the other end of the spring bears against a nose-shaped projection 67, 68 respectively of the relevant entraining body 28, 29. The spring 61, 62 respectively urges the relevant entraining body 28, 29 to the above mentioned contacting position, as is shown for instance for the entraining body 28 in Fig.

1. Finally, each entraining body 28, 29 has yet another bore 69, 70 respectively for insertion of a rod-like manual tool, e.g. a screwdriver 71, (Fig. 1) with the aid of which entraining body may be pivoted against the bias of the associated spring 61, 62 out of the contacting position into the conductor insertion position, as shown in Fig. 1 for the entraining body 29.

The mode of utilisation and operation of the described series terminal block is as follows: It is assumed that the terminal block is secured on a fixed carrier rail by means of the retaining feet 11 and and 1 2 of the housing 10 and that the electrical conductors to be coupled to the terminal block each have a diameter which somewhat exceeds the width of the slit-shaped openings 24, 25 in the contact piece 1 5. Accordingly, the insulating material of the conductor has a larger outer diameter. By way of preparation of the connection of an electrical conductor to the end of the contact piece 1 5 shown in Figs. 1 and 2 as the lower end, the entraining body 29 is pivoted into the conductor insertion position shown in Fig. 1, e.g. by means of a screwdriver 71 inserted into the bore 70.Then the recess 33 of the entraining body 29 is aligned with a position in the region of the widened aperture 27 of the slit-shaped opening 25 of the contact piece 1 5. Thereafter, without any previous removal of the insulation, the electrical conductor to be connected is inserted into the recess 33, and more particularly until the leading end of the insulating conductor abuts against the closed end 33C of the recess 33.

Then, with the aid of the screwdriver 71, utilised as a lever, the entraining body 29 is pivoted into the contacting position. In this way, the insulated conductor is forced into the widened aperture 27 and subsequently into the slit-shaped opening 25 of the contact piece 1 5 wherein the movement of the conductor is approximately parallel to the bladelike edges 25A and 25B along the slit-shaped opening. In this way, by means of the bladelike edges 25A and 25B, the insulation of the conductor is transversely cut through so that at the positions where it has become bared, the conductor makes contact with the said edges. Since the insulated conductor is guided in the recess 33 of the entraining body 29, deformation or bending of the conductor while being forced into the slit-shaped opening 25 is prevented.When the width of the slit-shaped opening 25 is matched in the already described manner to the diameter of the conductor, a certain deformation of the conductor in the transverse direction of the slit-shaped opening results, as well as a light resilient expansion of this opening. Because of the relatively small thickness of the individual sheet parts 15', 15" and 15"', the electrical conductor may relatively easily press close to the alternately laterally offset blade-shaped edges 25A, 25B whereby the electrical contact between the conductor and the contact member 1 5 is significantly improved. This is displayed particularly when the conductor is a strand.Under the bias of the spring 62, the connected conductor continues to be pressed by means of the entraining body 29 to the closed end of the slit-shaped opening 25, whereby not only is an inadvertent release of the conductor from the contact piece 1 5 effectively prevented, but also in the case of a conductor formed as a strand, the wires of the strand are constantly pressed against each other and against the contact piece. Because of the springy property of the individual sheet parts 15', 15" and 15"', the blade-like edges 25A and 25B also press from both sides resiliently on the connected electrical conductor. In the aggregate there results an excellent electrical contact between the contact members 25 and the coupled conductor independently of whether one is concerned with a solid conductor or as a conductor formed as a strand.

In a fully analogous manner a second insulated conductor may be contacted with the blade-like edges 24A and 24B of the other slit-shaped opening 24 of the contact piece 15, wherein the second conductor is introduced into the recess 32 of the entraining body 28 and thereafter is forced into the slitshaped openng 24 on angular displacement of the entraining body 28. In this way, an electrical connection between both of the conductors connected to the contact piece 1 5 arises.

The described terminal block also permits the connected conductor to be released from the contact piece 1 5 and removed from the terminal block. To release a conductor making contact with the edges 24A, 24B of the slitshaped opening 24, one inserts again a rodlike manual tool, e.g. a screwdriver, into the bore 69 of the entraining body 28, whereafter one forces the latter by means of the said tool in the opposite end position. In this way, the electrical conductor is pushed by means of the closed peripheral wall of the inner part 32B of the recess 32 present in the entraining body 28 out of the slit-shaped opening 24 into the widened aperture 26 and thus out of engagement with the blade-shaped edges 24A, 24B of the opening 24. Finally, the conductor may be pulled out of a recess 32.One proceeds analogously to release and remove a conductor contacted with the edges 25A, 25B of the other slit-shaped opening 25.

It may be seen that both the connection as well as the removal of insulated conductors may be carried out simply, quickly and without trouble wherein it is not necessary either to remove a part of the insulation nor to actuate any clamping screw or terminal screw.

The pivotaily journalled entraining bodies 28 and 29 may in given cases be replaced by entraining bodies formed as sliders which are journalled for reciprocal sliding in the housing 10.

Finally, it is to be mentioned that another embodiment of the terminal block according to the invention may be useful and expedient wherein there is only a single entraining body such as 28 or 29. In this case, a second current connection of the contact piece 1 5 must be realised, e.g. by means of a screw 19.

Claims

1. Electrical terminal block comprising a housing consisting of insulating material and at least one contact member arranged in the housing, the contact member having a slit-like opening bounded in the transverse direction by mutually oppositely lying blade-like edges for cutting through the insulation of an electrical conductor and for making contact with the conductor, as well as an enlarged opening at one end of the slit-shaped opening, and at least one entraining body displaceably guided in the housing which is displaceable at least approximately parallel to the blade-like edges of the contact member in order to bring the conductor into engagement with the said edges, wherein the contact member consists of at least two mutually superposed sheet membes, and the slit-shaped opening and the enlarged opening pass through each of the sheet members, and on each side of the slit shaped opening the blade-like edges of the mutually adjacent sheet members are offset relatively to each other transversely to the longitudinal direction of the slit-shaped opening.

2. Electrical terminal block according to claim 1 wherein the contact member consists of at least three sheet members and the mutually corresponding blade-like edges of successive sheet members are offset alternately to one side and to the other side.

3. Electrical terminal block according to claim 2 wherein all the sheet members have slit-shaped openings of equal length and equal width and the slit-like openings have an offset position in the successive sheet members, alternatingly to one side and to the other side.

4. Electrical terminal block according to one of claims 1 to 3 wherein viewed in the longitudinal direction of the slit-shaped opening, all sheet members are U-shaped with both the central web as well as the U-limbs of the mutually adjacent sheet members lying directly next to each other and the slit-shaped opening and the widened opening passing through the central web of the U-shaped sheet members.

5. Electrical terminal block according to any preceding claim, wherein the section about which the mutually corresponding blade-like edges of the sheet members are offset relative to each other transversely of their longitudinal direction is of approximately the same thickness as that of the individual sheet members.

6. Electrical terminal blocks according to any preceding claim wherein each of the sheet members has a thickness of 0.2 to 0.3 mm.

7. Electrical terminal block according to any preceding claim, wherein the number of superposed sheet members is from 3 to 6.

8. Electrical terminal block according to any preceding claim, wherein the entraining body has a recess serving for receiving the end part of an insulated conductor and is reciprocable between a conductor insertion position and a contact-making position in such a manner that in the conductor insertion position of the entraining body its recess is aligned with a position in the region of the enlarged opening of the slit-shaped opening of the contact piece and in the contact making position of the entraining body its recess is aligned with the slit-shaped opening between the blade-like edges in the vicinity of the opposite end, and the entraining body is biased by a spring which urges the entraining body to the contact-making position.

9. Electrical terminal block according to claim 8 wherein the spring is a compression spring one end of which is supported on the open end of a cavity partially accommodating the spring while the other end of the spring bears against a nose-shaped projection of the entraining body.

10. Electrical terminal block according to one of claims 1 to 9 wherein the sheet members forming the contact piece have the properties of a spring.

11. Electrical terminal block substantially as herein described with reference to and as shown in the accompanying drawing.