WO2005034300A1

WO2005034300A1 - An electrical termial block and a connector thereof

Info

Publication number: WO2005034300A1
Application number: PCT/SE2004/001355
Authority: WO
Inventors: Tommy DAHLSTRÖM; Johan Pellas
Original assignee: Dellner Couplers Ab
Priority date: 2003-10-07
Filing date: 2004-09-22
Publication date: 2005-04-14
Also published as: SE0302664D0; SE525946C2; EP1671402A1; SE0302664L

Abstract

In a first aspect, the invention relates to an electrical terminal block of the type that comprises a block having a plurality of forward open seatings for connectors (3), which individually include a front head (4) and a rear shank (5). The same shank is mountable in a through hole in a back piece positioned behind the seating and serves as connection member for an electric cable. As means for fixation of the shank (5) there is arranged, on one hand, a locking washer (23), which is immovably anchored in the block and has an out of round socket (24) in which an out of round section (22) of the shank (5) engages with the purpose of making turning of the same impossible, and on the other hand a shim (31) of an elastically resilient material placed between the locking washer (23) and an axially locked stop washer (28), which shim has the purpose of holding the head (4) of the connector resiliently pressed against the back piece of the block independently of variations in the ambient temperature. In a second aspect, the invention also relates to a connector as such.

Description

AN ELECTRICAL TERMINAL BLOCK AND A CONNECTOR THEREFOR

Technical Field of the Invention In a first aspect, this invention relates to an electrical terminal block, which comprises a block formed with a front side and a back side and having a plurality of forward open seatings for electrical connectors, which individually include a front head and a rear shank, which is mounted in a through hole in a back piece positioned behind the seating and serves as connection member for an electric cable . In a second aspect, the invention also relates to a connector as such intended for such terminal blocks.

Description of the Prior Art Terminal blocks of the above generally mentioned kind are used within railway engineering in order to interconnect the electrical systems in such locomotives and cars, which together form a continuous train unit. More precisely, the terminal blocks are mounted on predetermined places at each end of the individual car, and include a varying, although usually large number of connectors (10- 50) , which are brought into contact with the corresponding connectors in a co-operating terminal block, when two cars are connected mechanically, e.g., via automatic couplers. Said connectors may be divided into two categories, namely fixed and resilient, respectively, the first-mentioned ones of which have the heads thereof fixedly mounted in the block, while the last-mentioned ones include a spring- loaded, front piston, which is movably mounted in a cylinder forming the head and which is pressed into the same, when it is brought into contact with an analogous connecting device in a co-operating terminal block. Generally, the connectors are made from metal, e.g., steel or aluminium, which is electrically conducting. Furthermore, it should be pointed out that the rear shank of the individual connector most often is formed with a male thread on which nuts, having the purpose of fixing a cable grip on a connecting cable, can be tightened. Previously known terminal blocks and connectors, respectively, of the above-mentioned type are impaired by disadvantages, which manifest themselves in that the connectors break and become unusable. The most common fault is that the rear, comparatively thin shank of the connector is broken as a consequence of fatigue in the material. Although many complex, co-operating factors may cause such ruptures, a fundamental factor would probably be that the connector is kept fixed solely by means of one or more nuts, which are tightened on one and the same male thread utilized for the cable grip nuts. More precisely a jamb nut - possibly via an intermediate metallic washer - is tightened in close contact with the back piece positioned behind the seating in the block, and then the jamb nut is secured by means of a lock nut. However, the terminal block and the components included in the same are exposed to alternating ambient temperatures, where the difference between the highest and the lowest temperatures may amount to 60 °C or more. This means that the shank, jamb and lock nuts, and the back piece in the block alternatingly shrink and are widened. This in combination with the terminal blocks during ride being exposed to intermittent and at times intensive joltings and vibrations may lead to the jamb nut coming loose or at least loosing the fixing capacity thereof. In such a way, the shank may be set into oscillations, which eventually result in material break in the shank. In this connection, it should also be pointed out that the front head of the connector has an outer diameter that is somewhat smaller than the inner diameter of the seating in which the head is housed. In practice, this means that the head is free to oscillate backward and forward in motions, the amplitude of which is determined by the difference in diameter.

Objects and Features of the Invention The present invention aims at obviating the above- mentioned disadvantages of previously known terminal blocks with the utmost object of improving the service life and reliability of the same. Therefore, a primary object of the invention is to provide a terminal block, the different connectors of which can be mounted in such a way that the risk of rupture due to fatigue of material is counteracted. An additional object is to provide a terminal block, which enables a simple and reliable mounting of connectors of fixed as well as resilient type. It is also an object to provide a terminal block, which does not infringe on the possibility of being able to connect a cable grip to the shank of the individual connector in a simple way. According to the invention, at least the primary object is attained by means of the features that are defined in the characterizing clause of claim 1. In a second aspect, the invention also relates to a connector as such. The features of this connector are seen in claim 2. Preferred embodiments of the connector according to the invention are furthermore defined in the dependent claims 3-6.

Brief Description of the Appended drawings In the drawings

Fig. 1 is a perspective view regarded obliquely from the front of a terminal block according to the invention,

Fig. 2 is a perspective front view of an individual connector in assembled state,

Fig. 3 is an enlarged, partial section through a block included in the terminal block and that is adjacent to a seating in which a connector is mounted,

Fig. 4 is a perspective exploded view illustrating the different components that are included in the connector, and

Fig. 5 is an enlarged detailed section A in fig. 3,

Detailed Description of a Preferred Embodiment of the Invention In fig. 1, a terminal block in its entirety designated 1 is shown, which comprises a block 2, as well as a limited number of connectors 3 mounted in the block. In the example, the connectors are of a resilient type and com- prise a front head 4 (see also fig. 2), and a rear shank 5, which is thinner than the head. The block 2 is of a generally flat and rectangular basic shape having a front side 6 and a back side 7 (see fig. 3) . For each connector, a seating 8 is formed, which rearward is delimited by a back piece 9 in which there is a through hole 10 through which the shank 5 extends. The seating as well as the head of the connector is cylindrical, the outer diameter of the head 4 being somewhat smaller than the inner diameter of the seating 8. The diameter of the hole 10 is considerably smaller than the diameter of the head, the bottom of the seating forming a shoulder surface 11 against which the rear end of the head is pressed. The shank 5 is of a cylindrical, long narrow shape and has at the rear a male thread 12 for two nuts 13, which have the purpose of fixing a cable grip 15 connected to an electric cable 14. In this case, the head 4 of the connector includes a cylindrical sleeve 16, which at the rear is united to an end wall 17, which is integrated with the shank 5, e.g., by being made integrally with the same. In connection with the front end of the sleeve, an internal, circumferential flange 18 is formed, which serves as a stopping element for an axially movable piston or piston-like body 19 having a collar 19'. Between the piston 19 and the end wall 17, a compression spring is arranged in the form of a screw compression spring 20, which always strives to distance the piston from the end wall 17, and against the action of which it is possible to press the piston into the interior of the cylinder sleeve 16. The piston as well as the end wall 17 and the appurtenant shank 5 are made from an electrically conducting material, e.g., aluminium, one or more electrical conductors 21, e.g., copper wire or the like, being arranged between the piston and the end wall. On the front end surface thereof, the piston 19 is formed with a plurality of mutually spaced-apart tumblers 19", which form the proper contact surfaces of the piston against analogous connectors in a co-operating terminal block. As far as the shown terminal block together with the appurtenant connectors has been described hitherto, the same is in all essentials previously known. However, in the previously known connectors, the male thread 12 of the shank 5 extends all the way from the back piece 9 to the free, rear end of the shank in order to be able to receive, besides the cable grip nuts 13, one or more additional nuts, which have the purpose of fixing the connector in the shown position by. being tightened against said back piece. The disadvantages of this mounting technique have been accounted for above. Characteristic of the present invention is that the shank 5 of the connector includes a section 22 located between the male thread 12 and the head 4 and being of an out of round cross-section shape. In the example shown, the same section 22 is of a hexagonal cross-section shape. On the section 22, a locking washer 23 may be applied, which can be anchored in relation to the back piece 9 and which includes an out of round socket 24. More precisely, the socket 24 has the form of a gap open at one end, which gap is defined between two branches having planar, parallel edge surfaces 25. The distance between said edge surfaces 25 is a little larger than the distance between two opposite side surfaces of the hexagonal section 22. Along the periphery thereof, the locking washer 23 has a projecting flap 26, which is insertable in a countersink 27 (see fig. 3) in the rear end surface of the back piece 9. Accordingly anchored, the washer cannot be angularly displaced in relation to the block, and because the hexagonal section 22 of the shank cannot be angularly displaced in relation to the locking washer 23, the connector in its entirety cannot be angularly displaced in relation to the block. In order to secure the connector also axially in relation to the block, a stop washer 28 is arranged, which in the example co-operates with a Seeger ring 29, which is applicable in a groove 30 in the shank. Between the stop washer 28 and the locking washer 23, a ring-shaped shim 31 of an elastically resilient material, e.g., rubber, is arranged. Upon mounting of the individual connector in an appurtenant seating, the shank 5 is brought from the front into and through the hole 10 in the back piece 9, and then the locking washer 23, the shim 31 and the stop washer 28 are applied on the shank. In the next step, the stop washer 28 is pressed in the direction of the back piece 9 far enough so that the Seeger ring 29 can be mounted in the groove 30. In doing so, the elastic shim 31 is compressed, and then the same by the inherent elasticity thereof always will hold the back piece 17 of the head 4 resiliently pressed against the shoulder surface 11, more precisely independently of the temperature that prevails in the surroundings . After fixation of the connector, the grip 15 of the cable 14 is connected by means of the nuts 13, which in a conventional way are tightened on the exposed male thread 12. In accordance with a preferred embodiment of the invention, a circumferential groove 32 (see fig. 5) is formed in the front part of the cylinder sleeve 16, in which groove an O-ring 33 is mounted. The same has an outer diameter that is somewhat larger than the inner diameter of the seating 8. When the sleeve 16 is inserted into the seating 8, therefore the elastic 0-ring will be compressed and in such a way resiliently hold the sleeve centred in relation to the geometrical centre axis of the seating. In such a way, each tendency of the head to be set in oscillations in relation to said centre axis is efficiently counteracted. A primary advantage of the joint formed by the washers 23, 28 and the shim 31 between the connector and the block is that the joint in question locks the connector tangentially as well as axially in relation to the block, independently of varying temperature conditions, because the shim by virtue of the inherent elasticity thereof always holds the head 4 resiliently pressed against the back piece 9. In addition, the O-ring 33 will, in a resilient way, counteract tendencies of oscillations of the head 4 in its entirety. Feasible Modifications of the Invention The invention is not only limited to the embodiment shown above and in the drawings. Thus, the invention is also applicable to fixed, i.e., non-resilient connectors of the type that includes a front head in the form of a solid body of an electrically conducting material. Furthermore, it is feasible to form the out of round section of the shank in another way than being of hexagonal cross-section shape. It is also feasible to axially lock the stop washer or element 28 in another way than by means of a Seeger ring.

List of Reference Designations

1 = terminal block

2 = block

3 = connector

4 = head

5 = shank

6 = front side of block

7 = back side of block

8 = seating

9 = back piece

10 = hole in back piece

11 = shoulder surface

12 = male thread

13 = nuts

14 = cable

15 = cable grip

16 = cylinder sleeve

17 = end wall

18 = stop flange

19 = piston 19'= collar 19"= tumblers

20 = compression spring

21 = conductor

22 = out of round shank section

23 = locking washer

24 = socket

25 = edge surfaces

26 = anchorage flap

27 = countersink

28 = stop washer

29 = Seeger ring

30 = groove for Seeger ring

31 = elastic shim

32 = groove for 0-ring

33 = O-ring

Claims

1. Electrical terminal block comprising a block (2) formed with a front side (6) and a back side (7) and having a plurality of forward open seatings (8) for connectors (3), which individually include a front head (4) and a rear shank (5), which is mounted in a through hole (10) in a back piece (9) positioned behind the seating (8) and serves as connection member for an electric cable, c h a r a c- t e r i z e d in that as means for fixation of the shank (5) there is arranged, on one hand, a locking washer (23), which is immovably anchored in the block (2) and has an out of round socket (24) in which an out of round section (22) of the shank (5) engages with the purpose of making turning of the same impossible, and on the other hand a shim (31) of an elastically resilient material placed between the locking washer (23) and an axially locked stop washer (28), which shim has the purpose of holding said head (4) pressed against the back piece (9) independently of variations in the ambient temperature.

2. Connector for electrical terminal blocks, comprising a front head (4) and a rear shank (5), together with means in order to fix the shank in relation to a block, c h a r a c- t e r i z e d in that said means comprises, on one hand, a locking washer (23) formed with at least one anchorage member (26) and having an out of round socket (24) in which an out of round section (22) of the shank (5) can engage, and on the other hand a shim (31) of an elastically resilient material applicable between said locking washer (23) and a stop washer (28) axially lockable along the shank.

3. Connector according to claim 2, c h a r a c t e ri z e d in that the stop washer (28) is axially lockable by means of a Seeger ring (29) , which is applicable in a circumferential groove (30) in the shank (5) .

4. Connector according to claim 2 or 3, c h a r a c t e ri z e d in that the out of round section (22) of the shank (5) is situated between the head (4) and a rear male thread (12) for nuts (13) with the purpose of fixing a cable grip (15) on the shank.

5. Connector according to any one of claims 2-4, c h a r- a c t e r i z e d in that the out of round section (22) of the shank (5) is of a hexagonal cross-section shape.

6. Connector according to any one of claims 2-5, c h a r- a c t e r i z e d in that the head (4) at a front end has an external, circumferential groove (32) , in which an elastic O-ring (33) is arranged having an outer diameter that in the unloaded state of the ring is larger than the inner diameter of the seating (8).