Electrical connectors – Metallic connector or contact having movable or resilient... – Hinged jaw type having alignable conductor receiving bores
Reexamination Certificate
1999-12-14
2001-03-06
Nguyen, Khiem (Department: 2839)
Electrical connectors
Metallic connector or contact having movable or resilient...
Hinged jaw type having alignable conductor receiving bores
C439S828000, C439S835000
Reexamination Certificate
active
06196883
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a connection spring allowing an electrical connection to a stripped wire to be made in a terminal strip for electrical conductors.
DESCRIPTION OF THE PRIOR ART
It is known to use springs for keeping the end of a stripped conductor held against a current supply rail in a terminal strip. Documents DE 3,727,091 and DE 4,237,733 describe terminal strips of this type. Found in these documents is a pinching spring made of a flat springy material formed in a kind of loop. The pinching spring has a stop branch, intended to bear on a current rail, and a pinching branch bent back from the back part of the pinching spring, extending transversely to the current supply rail, as well as a springy bow which links together, at the rear, the back part and the stop branch. The pinching branch is provided with a pinching cavity. The current supply rail passes through this cavity. The spring is such that, when the stripped end of an electrical conductor is inserted into the pinching cavity, the spring presses the stripped end of this wire against the current supply rail.
When making a connection, the pinching branch is moved in order to allow insertion of the wire to be connected. A screwdriver generally causes this movement by it acting on the springy bow. With such connection devices, problems may arise when connecting the stripped end of a conductor. If the spring is not bottomed, it may happen that, when inserting the end of the conductor, the latter pushes the pinching branch of the spring and bends it. On releasing the spring, the latter presses the badly connected conductor against a wall of the casing and the operator believes that he has made a good connection. However, the electrical contact is bad and the terminal strip may become scorched or burnt. This problem happens especially with large conductors.
The terminal strip having the connection spring is generally placed in an insulating casing. Sometimes provided in this casing is a support for taking the free end of the pinching branch when the spring is tensioned. However, when for one reason or another the spring is deformed, it may happen that the free end of the pinching branch, instead of bearing on the support made in the casing, ends up underneath this support. As a result, the connection spring undergoes even greater deformation and/or this spring is jammed in the casing.
To solve these problems, it is known to guide the pinching branch. In the aforementioned documents of the prior art, this guiding function is provided by part of the current supply rail, this part also being called a strap. The latter is then bent twice: once to form a lateral face, the upper edge of which serves to guide the pinching branch of the spring, and a second time to form the bearing branch for the stripped wire, or vice versa. A figure in document DE-19,641,206 clearly shows such bending.
In this solution, only the upper edge of the strap serves to guide the spring. Only the upper edge of the entire lateral part of the strap is useful. A great deal of material is then used solely to produce a guiding edge. This increases the cost of the strap.
Another drawback with this solution is that the pinching branch is guided only on one side. The first problem mentioned above (the conductor bending the pinching branch as it is being inserted) is then only partially solved. This is because, if a large conductor bears on the opposite side from the guiding edge of the strap, the pinching branch may all the same be deformed.
Another drawback with this solution is that it is solely adapted to the case in which the strap lies beneath the connection spring, that is to say on the same side as the springy region linking the bearing branch to the pinching branch. This solution is not at all suitable for mounting a strap above the spring, as shown in document EP-0,735,629.
The object of the present invention is to provide a novel connection device ensuring that, when the spring is stressed and relaxed, the pinching branch is guided and supported better. Advantageously, this device will have a lower manufacturing cost than the known spring devices and can be adapted to the case in which the linking strap is placed above the compression spring, as shown in document EP-0,735,629.
SUMMARY OF THE INVENTION
For this purpose, the present invention provides a connection spring allowing an electrical connection to a stripped wire to be made in a terminal strip for electrical conductors, which is made from a flat springy material and has a bearing branch intended to bear against a conducting fixed part of the terminal strip and a rear branch, facing the bearing branch, linked via a springy linking region to the latter and the free end of which is bent back toward the bearing branch in order to form a moveable pinching branch having, on the same side as its free end, an appreciably plane part provided with an opening intended for passage of the conducting fixed part and of the stripped wire in such a way that the edge of the opening lying on the same side as the free end of the moveable pinching branch keeps the stripped end of the wire pressed against the conducting fixed part, a linking region springingly linking the two branches.
According to the invention, the bearing branch, on the opposite side from the rear branch, is provided with a guiding region which extends parallel to the pinching branch.
Thus, guiding is achieved at the connection spring. This position makes it possible to minimize the amount of material needed for providing the guiding function. The additional material used to produce the guiding zone on the connection spring can easily be less than the amount of material generally used for the guiding on the conducting fixed part. The guiding region may also easily extend over the entire width of the spring. This makes it possible to ensure that the pinching branch is reliably supported.
In one embodiment of the connection spring, the guiding region extends so as to be approximately perpendicular to the bearing branch.
Advantageously, the guiding region is attached to the bearing branch at some distance from the free edge of the bearing branch that bears against the conducting fixed part.
In order to allow the pinching branch to be guided and supported symmetrically, the guiding region advantageously includes a window through which the conducting fixed part and the stripped wire to be connected pass.
In a preferred embodiment of the spring according to the invention, the guiding region is obtained by cutting at the bearing branch and then by bending. In this case, the cut produced in the bearing branch advantageously has the shape of a U, the base of the U lying on the same side as the free end of the bearing branch.
The invention also relates to a terminal strip for electrical conductors, which includes a connection spring as described above. Such a terminal strip may be fitted into any type of electrical apparatus requiring a wire to be connected. This may, for example, be a switch, a circuit breaker, etc. Such a terminal strip is particularly suitable for a terminal block. It is then placed in an insulating casing. Preferably, this insulating casing has a support on which a free end of the guiding region of the connection spring bears.
In any event, the invention will be more clearly understood with the aid of the following description which presents, by way of nonlimiting example, one embodiment of a connection spring according to the invention.
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English Abstract of DE-
Bechaz Bernard
France Philippe
Prost Stéphane
Entrelec S.A.
Hyeon Hae Moon
Nguyen Khiem
Oliff & Berridg,e PLC
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