Electrical connectors – Metallic connector or contact having movable or resilient... – Screw-thread operated securing part
Patent
1991-12-16
1993-10-05
Paumen, Gary F.
Electrical connectors
Metallic connector or contact having movable or resilient...
Screw-thread operated securing part
439813, H01R 434, H01R 438
Patent
active
052499898
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to a terminal screw assembly for the electrical connection of cables or wires, in particular cables and wires provided with ear-shaped cable terminals. In one exemplary embodiment, the terminal screw assembly comprises a housing and a clamping screw which, in the screw in direction, penetrates through a first clamping plate and, when the terminal is closed, through a second clamping plate and, when the terminal is open, remains sunk in a bore of the first clamping plate and opens up the interspace between the first and the second clamping plate, the clamping screw being screwconnectable in the bore of the first clamping plate, and the second clamping plate comprising a bore having a screw thread, and wherein the shank of the clamping screw is reduced to a small diameter in a region which is adjacent to the screw head and the axial length of which at least corresponds to the axial length of the engagement of the first clamping plate in threads of the clamping screw.
Terminal screw assemblies of this kind are, for example, used as connecting terminals for switches, electrical apparatus, such as motors, or also for sockets. Such a terminal assembly has been disclosed in U.S. Pat. No. 4,611,876. According to that U.S. patent, the second clamping plate is arranged in the housing in a fixed manner, whereas the first clamping plate is displaceable in the axial direction. In order, in this case, to limit the screw-out movement of the clamping screw and to retain the clamping screw in the bore of the first clamping plate, in the open position of the terminal, the clamping screw is guided in a cage which is connected to the first clamping plate. This cage is guided to be non-rotatable and to be axially displaceable in the housing, with clearance. Depending on the position of the terminal, said cage, therefore, either falls with the first clamping plate on to the second clamping plate, or it moves away therefrom. Thus, when the terminal is open, the free spacing between the first and the second clamping plate is not ensured, with the result that, when the terminal is open, the insertion of the cable or the cable terminal between the first and the second clamping plate is rendered more difficult. This is the case, in particular, when the terminal screw is not readily accessible or during overhead installation. In addition, the design of the first clamping plate comprising a cage retaining the clamping screw is complex.
The object of the invention is, therefore, to develop a terminal screw of the kind mentioned at the outset in such a way that the insertion of cables, in particular cables having ear-shaped cable terminals, is substantially simplified. In order to meet this object, the design according to the invention essentially comprises that the first clamping plate is non-displaceable and non-rotatable in the axial direction of the clamping screw, and the second clamping plate is guided to be non-rotatable and, when the terminal is open to the maximum, to be displaceable, in the axial direction of the clamping screw, out of its position, and that the second clamping plate is held by a slight resistance (for example, by friction) in the maximum open terminal position, in which position the clamping screw, when completely screwed through the first clamping plate, engages the internal screw thread of the second clamping plate, the opening path of the clamping screw being defined by its stopping against a part of the wall of the housing.
As a result of the fact that the first clamping plate is designed to be axially non-displaceable and non-rotatable, the limit stop for the opening path of the clamping screw can, in a simple manner, be formed by a part of the wall of the housing, without requiring additional components. The opening path of the clamping screw is, in this regard, dimensioned such that the clamping screw, in the open position, remains in the bore of the first clamping plate and does not project beyond the clamping face of the first clamping pl
REFERENCES:
patent: 3994556 (1976-11-01), Jensen et al.
patent: 4478478 (1984-10-01), Durand et al.
patent: 4611876 (1986-09-01), Barrabes
patent: 4830627 (1989-05-01), Heng et al.
Naimer Hubert L.
Paumen Gary F.
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