Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Multiple contact type
Patent
1991-12-19
1993-04-27
Donovan, Lincoln
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Multiple contact type
200506, H01H 6702
Patent
active
052066177
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an auxiliary switch for an electromagnetic switching device, this switch comprising, in a multipartite housing equipped with fixed contacts, a contact bridge support secured in its position by means of a pressure spring and movable against the spring force upon energization
onenergization of the drive, this contact bridge support being provided with bridge contacts.
Auxiliary switches with positively guided auxiliary contacts, which can be designed as make and/or break contacts, for attachment to electromagnetic contactors have been conventional. Customarily, the pressure spring holding the contact bridge support against the tension of the magnet is arranged adjoining the contact bridge support in the axis of movement of the latter and is accommodated in a corresponding chamber formed by the housing sections encompassing the contact bridge support.
The invention is based on the object of further developing the conventional auxiliary switch in such a way that the balance of forces of the electromagnetic switching device and thus the response values of the basic device are altered only insubstantially by the attachment of an additional auxiliary switch.
This object has been attained according to the invention for an auxiliary switch by providing that two pressure springs located outside of the axis of movement of the contact bridge bearer are supported in the manner of a two-armed toggle joint respectively with one end in respectively one of blind holes or the like formed on mutually opposite sides of the contact bridge bearer and with the other end in respectively one of recesses provided in the housing sections, and exhibit a negative return spring characteristic against the tensile force of the drive.
The arrangement according to this invention of two obliquely disposed, mutually counteracting pressure springs, especially coil springs, brings about a decreased counter force with an increasing stroke distance, i.e. when the spring axes approach the perpendicular to the stroke movement axes. Consequently, the task according to this invention is accomplished. This arrangement of two pressure springs also makes it possible to reduce the structural length of the auxiliary switch without restricting the spring stroke.
In a further development of the invention, the principle of negative spring characteristic for the restoring force is to be designed so that the spring axes of the pressure springs in the holding condition (upon excitation of the magnet) extend almost perpendicularly to the axis of movement of the contact bridge support.
A simplified mounting of the auxiliary switch is made possible according to another suggestion provided by the invention by the feature that the recesses formed in the housing sections on the side facing the contact bridge support exhibit a pass-through opening toward the topside of the housing, through which the pressure springs can be introduced with the housing having been assembled. This means that the pressure springs are inserted only after the contact bridge support has been assembled with the housing sections. The housing sections of the auxiliary switch are connectible with each other in a shape-mating fashion, for example, by means of detent lugs, projecting along the parting joint at the housing walls of a housing section, and associated detent grooves at the second housing section. In a preferred embodiment of the housing sections of the auxiliary switch, the provision is made that the recess for the mounting and support of the pressure spring is arranged in each housing section between the contact switching chambers of the housing sections centrally as a chamber oriented into the interior of the housing.
It is to be noted that the principle of negative spring characteristic by means of two C-shaped wire springs and, respectively, the use of two obliquely disposed mutually counteracting springs effecting a lower counter force with increasing stroke have been known for the armature return of electromagnetic switching devices; in this connection
REFERENCES:
patent: 4117429 (1978-09-01), Streich et al.
patent: 4578659 (1986-03-01), Suter et al.
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