AU6329899A

AU6329899A - Spring clamp

Info

Publication number: AU6329899A
Application number: AU63298/99A
Authority: AU
Inventors: Dietmar Hillebrand; Jurgen Pries
Original assignee: AEG Niederspannungstechnik GmbH and Co KG
Current assignee: AEG Niederspannungstechnik GmbH and Co KG
Priority date: 1998-10-02
Filing date: 1999-09-28
Publication date: 2000-04-26
Anticipated expiration: 2019-09-28
Also published as: WO2000021160A1; BR9907294A; HUP0004707A3; TR200001540T1; NO20002808L; EG21982A; CN1135659C; AU753112B2; PL340759A1; HUP0004707A2; HU224145B1; DE19845475A1; NO318047B1; CN1286817A; EP1038334A1; NO20002808D0; PL195886B1; DE19845475B4

Description

Spring Tension Clamp Description The invention relates to a spring tension clamp according to the preamble of claim 1. A conventional generic spring tension clamp is known from DE 93 12 380 Ul. It consists of an insulating body in which at least one clamping body receiving portion is provided. The clamping body receiving portion receives a clamping body, for example a cage tension spring. The clamping body can be put in an open position by an opening means; in this position, a conductor to be clamped can be led into the clamping body in order to produce a current connection, for example. For insulating and safety reasons, a lever pro vided in the insulating body and linked thereto is used as an opening means. By pressing down the lever by means of a screw driver or a similar tool, the lever is swiveled around its swivel axis and presses against a loop-like por tion of a clamping leg of the cage tension spring. In doing so, the loop-like portion of the clamping leg is deformed elastically, whereby the cage-like recess in the clamping leg is opened. The clamping body is pre-stressed in the closing direction, so that the clamping body clamps the conductor, which has meanwhile been led in, when the lever pressed down by the screw driver is released. Spring tension clamps of the mentioned kind are generally used as line-up clamps. The insulating body is a housing which is continuous only on one side and open on the oppo site side. The clamping body and a current bar extending therefrom are inserted into this open housing. /sb L In most cases, two or more clamping bodies are located in a spring tension clamp and are connected by a common current bar. The last mentioned spring tension clamps form coupling members whose insulating bodies can be clamped to a top hat rail fixedly mounted to a wall. By lining up plural insu lating bodies side by side, a multipolar line-up clamp is obtained. Optionally, line-up clamps can also be made of one integral housing. It has turned out to be disadvantageous to use a tool for clamping a conductor in the conventional spring tension clamp. Namely, for opening the clamping body, an electri cian has to press the screw driver against the lever with his one hand while leading the conductor into the opened clamping body with his other hand. The lever has to be kept pressed actively while the conductor is actively led into the clamping body. It is exhausting to carry out these two activities for clamping the conductor simultaneously. From DE 39 10 937 Al, a spring tension clamp shown in Fig. 3 is known in which a lever 13 projecting outwardly and linked to an insulating body 15 is used for opening the clamping body 14. In this manner, the connection of conduc tors 16 is simplified, because the lever 13 projecting out wardly is easier to be accessed by the electrician. Yet also in this spring tension clamp, an active actuation by a tool is necessary for opening the clamping body 14; by means of said tool, the lever 13 has to be pressed down in order to lead the conductor 16 into a cage opening 14b in a loop-shaped portion of a clamping leg 14a of the clamping body 14 realized in the form of a cage tension spring. In addition, the same two activities for clamping as already described above have to be carried out here as well.

J The invention is based on the object of further developing a spring tension clamp according to the preamble of claim 1 in such a manner that clamping the conductor becomes as easy as possible. According to the invention, this problem is solved by the features of claim 1. Advantageous further developments are defined in the sub claims. According to the invention, the clamping body can be kept in its open position without any actuation by a tool or the like being required. When the clamping body is automati cally kept in the open position, it is very easily possible to lead the conductor into the spring tension clamp, be cause no further activity has to be carried out simultane ously in addition to the introduction of the conductor. Af ter having introduced the conductor, the electrician can concentrate on clamping the conductor by loosening the clamping body, held without actuation, from its state. Dur ing the clamping procedure, by leading the clamping body back to the close position under its bias acting in the closing direction, no further activity has to be carried out at the same time. During the clamping, the electrician only has to take care that the conductor does not slip out of the clamping body inadvertently. For this purpose, he passively secures the conductor while leading the clamping body back to its close position in which the conductor, which has meanwhile been led in, is clamped. According to an advantageous further development, the clamping body can be engaged in its open position by the opening means. This engagement of the opened clamping body with the opening means guarantees a reliable open position of the clamping body and largely prevents an inadvertent clamping at an undesired point of time. On the other hand, the electrician can deliberately overcome the engagement of the opening means with the clamping body, in order to cause the clamping of the conductor. The design of the opening means as a lever linked to the insulating body and pressing against the clamping body sim plifies the clamping of the conductor, because the linked lever is fixedly connected with the spring tension clamp and is thus reliably available at any place of operation. The use of a cage tension spring as a clamping body is par ticularly advantageous. The cage tension spring shows a loop-shaped clamping leg with a cage opening formed therein, into which the conductor is led. The lever can press on the clamping leg of the cage tension spring with one of its free ends, so that the cage opening is un blocked. In this, an actuation for clamping which is par ticularly smooth and has little susceptibility to trouble is achieved if the lever is linked centrally and gets into a cam-like contact with the clamping leg at the one of its free ends, while its other free end is shaped in an angular manner. When shifting the lever, the contacting free end slides along the fixed clamping leg, so that a jerky or sudden squeezing of the conductor in the cage opening dur ing the closing of the cage tension spring is prevented. Also an opening of the cage tension spring is carried out gradually, so that a jamming of the cage tension spring is prevented. A surface engagement between the lever and the clamping leg can be achieved in a particularly advantageous manner by concavely forming the front of the free end of the lever pointing in the direction of the clamping leg, thus being adapted to the outer shape of the loop-shaped portion of the clamping leg. The shape of the concave front of the free end of the lever is exactly adapted to the outer shape of the clamping leg at the portion at which the free end of the lever contacts the cage tension spring in the open po sition. The concave surface engagement guarantees that the open position of the cage tension spring is maintained in a particularly reliable manner. There is virtually no possi bility that the spring tension clamp snaps shut inadver tently. The link point of the lever is chosen such that the closing force of the cage tension spring acting, via its clamping leg, upon the lever is introduced such that the lever kept in the open position remains in this position in a stable manner. In this case, the biasing force, which points in the closing direction, of the opened cage tension spring acts to hold the lever in the open position. The installation on the spot is particularly simplified for the electrician by the fact that the spring tension clamp is delivered after having been prepared with the clamping body held in the open position. Before clamping a conduc tor, it is not necessary to open the spring tension clamp first, so that the electrician can directly start with the introduction of the conductor without having to carry out any preparatory measures. In the following, the invention will be described in more detail on the basis of a preferred embodiment while refer ence is made to the attached drawings. Fig. 1 shows a lateral view of an embodiment according to the invention of the spring tension clamp in its open posi tion, 0 Fig. 2 shows a lateral view of an embodiment of Fig. 1 in its closed position, and Fig. 3 shows a spring tension clamp according to the prior art. Figs. 1 and 2 show a preferred embodiment of a spring ten sion clamp. An insulating body 1 of the spring tension clamp is formed as a unilaterally continuous housing, preferably of resin or synthetic resin. The external shape of the insulating body is adapted to the particular field of application of the spring tension clamp and shall not be described fur ther. A current bar 5 is formed or laid into the insulating body 1. In the shown embodiment, the current bar 5 serves for leading away or supplying current from or to a cage tension spring 2, respectively, contacting it. Optionally, the current bar can also connect two or more cage tension springs with each other. A guide means 5a is integrally formed with the current bar 5 at the portion contacting the cage tension spring 2. The guide means 5a prevents that spliced cores of a (not shown) conductor to be clamped by the cage tension spring 2 stick out laterally. The cage tension spring 2 shows a clamping leg 2a formed in a loop-like manner. The cage tension spring 2 is laid in the insulating body 1 such that it is held in contact with the current bar 5 at the contacting portion in the proxim ity of the guide means 5a. The clamping leg 2a is provided, in the proximity of one of its free ends, with a cage open ing 2b through which the opposite end of the cage tension spring 2 and the current bar 5 run. In the position shown in Fig. 1, the cage tension spring 2 is in the open posi- I tion, in which it is rendered possible to introduce the conductor through the cage opening 2b at the side of the current bar 5. In the open position, the clamping leg 2a of the cage tension spring 2 is loaded and held by a lever 3 described later, being biased in the closing direction. In the maximum open position, the cage opening 2b abuts on the other free end of the cage tension spring 2 at its side op posite the current bar 5. Fig. 2 shows the unloaded state of the spring tension clamp in which the cage tension spring 2 is released apart from a residual stress and takes its close position. In this posi tion, the side of the cage opening 2b adjoining the current bar 5 contacts the current bar 5. As shown in Figs. 1 and 2, the lever 3 is linked to the in sulating body 1 at a link point 3d. Preferably, the lever 3 consists of an insulating material, such as resin or syn thetic resin. The link point 3d is located approximately in the center of the lever 3, seen in the longitudinal exten sion of the lever 3. By actuating the lever 3, the cage tension spring 2 can be deformed to open and close. For this purpose, the lever 3 is in cam-like contact at one 3a of its free ends with the loop-shaped portion of the clamp ing leg 2a of the cage tension spring 2. At its other end 3b, the lever is formed in a slightly angular shape for ac tuation. A front of the free end 3a of the lever 3 contacting the clamping leg 2a is formed in a concave manner. The front can be surface-engaged with the loop-like portion of the clamping leg 2a in the open position of the cage tension spring 2. As regards this front, the link point 3d of the lever 3 at the insulating body 1 is chosen such that a closing force applied on the lever 3 by the clamping leg 2a 8 pre-stressed in the closing direction holds the lever 3 be ing in the open position in that very position in a stable manner. The contour of the contact-side end of the lever 3 is, at the transition from the concave front to the longi tudinal extension of the lever, rounded off, so that when swiveling the lever 3, the cam-like contact is achieved in which the contact-side end of the lever 3 slides along the clamping leg 2a of the cage tension spring 2 and deforms the latter. The angular end 3b of the lever is provided with an opening 3c in which a tool 4, for example a screwdriver, can be in serted for actuation. The angle-shaped form of the lever 3 on the actuation side is chosen such that the angular end 3b projects above the contour of the insulating body 1 in the closed position. Also the opening 3c in the angular shaped end is outside the contour of the insulating body 1 in the close position. The insulating body 1 shows stop portions la, lb, and 1c formed integrally therewith for each of the end positions of the lever 3. The stop portion la for the closed position of the lever 3 abuts on the actuation-side portion of the lever 3. Two stop portions lb and ic are provided for the open position, one of which engages with the contact-side portion of the lever 3 near the link point 3d, and the other at a greater distance therefrom. It is of particular significance that the spring tension clamp is prepared for assembly in such a manner that it is delivered with the cage tension spring 2 being held in an open position. The clamping of the conductor with the embodiment of the spring tension clamp is carried out as follows: The electrician leads the conductor through the cage open ing 2a along the current bar 5 into the cage tension spring 2 held in the open position without actuation. In this state, the electrician merely has to take care that the in troduced conductor does not slip out of the opened spring tension clamp inadvertently. Then, the electrician actuates the lever engaged with the cage tension spring 2 in the open position by the screw driver 4 inserted in the opening 3c, whereby the engagement is released and the cage tension spring 2 clamps, due to its biasing, the conductor intro duced through the cage opening 2a against the current bar 5. The lever 3 is transferred to its closed position jut ting out from the contour of the insulating body 1, so that the electrician can recognize whether the conductor has been clamped. Even though a cage tension spring is used as clamping body in the shown embodiment, any sort of clamping body can be used instead. It is necessary that the clamping body be made to be in an open position by an opening means. In the shown embodiment, the lever serves as an opening means for the clamping body. It holds the clamping body in the open position without actuation by engaging therewith. Instead of the lever linked to the insulating body, a pin not linked to the insulating body can also be used, by means of which the clamping body can be opened and held in its open position without actuation. This pin can, for in stance, be a one-way pin which is merely added to the de livered spring tension clamp and is intended to be thrown away after the first clamping. When using plural spring tension clamps in the form of a terminal block, a plurality of pins can be connected to a pin unit. By removing this 'u pin unit, all conductors or a selection of the conductors introduced into the terminal block can be clamped at once.

Claims

1. A spring tension clamp consisting of an insulating body (1) comprising at least one clamping body receiving portion for receiving a clamping body (2) which can be put by an opening means (3) into an open position which is biased in the closing direction and into which a conductor to be clamped can be inserted, characterized in that said clamping body (2) can be held in the open position without actuation.

2. A spring tension clamp according to claim 1, characterized in that by said opening means (3), said clamping body (2) can be engaged in the open position.

3. A spring tension clamp according to one of claims 1 or 2, characterized in that said opening means (3) is a lever linked to said insulating body (1), by the actuation of which said clamping body (2) can be deformed for opening and closing.

4. A spring tension clamp according to claim 3, characterized in that said clamping body (2) is a cage tension spring.

5. A spring tension clamp according to claim 4, characterized in that said lever (3) is linked to said insulating body (1) ap proximately centrally in its longitudinal extension, is in cam-like contact with a loop-shaped portion of a clamping 12 leg (2a) of said cage tension spring (2) at one (3a) of its free ends, and is formed at its other end (3b) in a slightly angular manner for actuation.

6. A spring tension clamp according to claim 5, characterized in that the front of said free end (3a) of said lever (3) contact ing said clamping leg (2a) is formed in a concave manner and can be surface-engaged with the loop-like portion of said clamping leg (2a) in the open position of said cage tension spring (2).

7. A spring tension clamp according to claim 5 or 6, characterized in that said angular end (3b) of the lever is provided with an opening (3c) into which a tool (4) for actuation can be in serted.

8. A spring tension clamp according to one of claims 5 to 7' characterized in that said angular end of said lever projects above the contour of said insulating body in the closed position.

9. A spring tension clamp according to one of claims 5 to 8, characterized in that the articulating point (3d) of said lever (3) on said insu lating body (1) is chosen such that a closing force applied to said lever (3) by said clamping leg (2a) biased in the closing direction holds said lever (3), which is in the open position, in that position in a stable manner. 13

10. A spring tension clamp according to one of claims 1 to 9, characterized in that the spring tension clamp is prepared for assembly with said clamping body (2) being held in the open position.