Electrical connectors – With insulation other than conductor sheath – Insulating body having plural mutually insulated terminals...
Reexamination Certificate
1998-07-09
2001-02-06
Bradley, Paula (Department: 2833)
Electrical connectors
With insulation other than conductor sheath
Insulating body having plural mutually insulated terminals...
C439S092000, C439S094000
Reexamination Certificate
active
06183311
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a protective conductor clamp, comprising a mounting base for mounting it on a support rail and comprising a contact rail that is connected electrically conducting to the mounting base and is provided with a conductor connection.
A protective conductor clamp is disclosed in European Patent EP 0 554 519 B1, where a contact rail provided with conductor connections and arranged inside an insulating housing is connected to a mounting base serving as mechanical and electrical connection to a support rail that functions as protective conductor bus bar. The contact rail and mounting base must be electrically connected to provide an electrical connection between contact rail and support rail. Said electrical connection can be produced through welding, soldering or through a form-fitting and frictional connection, e.g. by wedging it in. If the contact rail and mounting base are to be welded together to ensure a good electrically and mechanically usable connection, then the contact rail and mounting base cannot both be made of copper, since copper cannot be welded to copper. In that case, other material combinations must be selected. In addition, an artificial transition point is created on the clamp as a result of the welding location or the mechanical connection point, which transition point can have a high transition resistance if conditions are unfavorable. This is a disadvantage, particularly with the appearance of high currents caused by short circuits.
The DE 39 03 752 C2 discloses a series terminal, the contact rail and contact base or mounting base of which are formed as one piece of a highly conductive material, so that no artificial transition point with the aforementioned disadvantages exists. The contact base is shaped like a clamp, wherein the contact force of said clamp is provided by a spring clip that fits around the clamp. The contact force of said known series terminal is thus effected by the elastic deformation of the contact base, shaped as a clamp. This necessitates an unsatisfactory design compromise between the mechanical stability of the contact base and the elastic deformability, necessary for making electrical contact.
It is the object of the invention to specify a protective conductor clamp, which can be produced simply and at low cost and does not have the aforementioned disadvantages of previously published prior art.
SUMMARY OF THE INVENTION
This object is solved with a protective conductor clamp according to the invention comprising a mounting base for mounting it on a support rail and a contact rail that is connected electrically conducting to the mounting base and is provided with a conductor connection, wherein the mounting base has shaped sections, designed to hold a spring element for bracing the mounting base in the support rail. These shaped sections are formed by recesses in the side walls of the mounting base.
The spring element preferably consists of a spring steel sheet, inserted between the side walls, which allows for a simple installation of the spring steel sheet in the mounting base. The spring element is preferably provided with shoulders each side, which project into the recesses to secure the spring steel sheet.
The free ends of the spring steel sheet in particular are each shaped like a T, as seen from above on the flat side.
In a further preferred embodiment of the invention, a leg spring is provided as spring element, both legs of which are braced in the mounting base. As a result of this measure, the spring element is secured frictionally and securely inside the mounting base.
In particular, a L-shaped leg spring is provided that engages especially easily in the corresponding recesses. It is preferable if the long leg of the leg spring is arranged inside the mounting base in such a way that it is braced resiliently between support rail and mounting base, if the support rail is inserted into a fastening hook in the side wall of the mounting base.
The mounting base and the contact rail in particular form a one-piece contact element, wherein the one-piece contact element preferably is a bent, stamped part. Owing to this, a low-cost production is possible by using a one-step operation of stamping out and subsequently bending the part, wherein the shaped sections required for holding the spring element can also be produced in one operational step during the stamping and bending operation. In particular, a single piece of sheet metal can be used as starting material or semi-finished product for the stamping and bending operation.
In particular, the bending point cross section of the contact element at the transition point between contact rail and a side wall of the mounting base is nearly the same as the cross section of the contact rail in its free region, thereby ensuring a nearly constant current density in the contact element in case of a short circuit.
The contact element preferably is made of copper, which ensures a particularly good electrical connection between the contact rail and the support rail.
In one preferred embodiment of the invention, the protective conductor clamp comprises a housing, having a base section with a rear wall and shaped sections for holding the contact elements, as well as a lid to be fitted onto the base section, which lid closes off the base section on the side opposite the rear wall, at least in the region of the conductor connection. The base section is reinforced through this.
In a particularly advantageous embodiment, the lid is provided on the inside, in the region of the outside legs of a U-shaped contact rail, with respectively one cheek for bracing the outside leg against the force exerted by the spring leg if the connecting clamp spring is actuated. Owing to this measure, it is no longer necessary to bend the outside legs of the contact rail in the region of the connecting clamp spring at a U-shaped angle as reinforcement, so as to prevent the outside legs from bending outward if the connecting clamp spring is actuated. A closed space is created at the same time by the lid for accommodating the connecting conductor that is pressed by the connecting clamp spring against the outside leg, thereby ensuring that no stranded conductors or wires can project on the side over the protective conductor clamp and into the outside space.
Such a design can also be used advantageously for a through terminal, where the mounting base does not produce an electrically conductor connection between the support rail and the contact rail. By omitting the metallic mounting base on the one hand and, on the other hand, owing to the fact that the angled reinforcement strips are no longer needed due to the outside legs of the contact rails being stabilized between base part and lid, only a simple metal strip having the inherent width of the contact rail is therefore needed in this case. As a result of this, the required material and production expenditure for the contact rail is reduced considerably, especially for simple through terminals.
REFERENCES:
patent: 5022873 (1991-06-01), Kollman
patent: 5049094 (1991-09-01), Heng et al.
patent: 5694288 (1997-12-01), Shortt et al.
patent: 3903752C2 (1993-06-01), None
patent: 19631436C1 (1997-10-01), None
patent: 0554519B1 (1993-08-01), None
Strack Holger
Suess Christian
Bradley Paula
Gilman Alexander
Kinberg Robert
Spencer George
Venable
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