Patent Application
20090153277
The application generally relates to an electromagnetic relay. The application relates more specifically to an electromagnetic relay having a relay actuator with an adjustment dial for setting an overtravel adjustment for electrical contacts.
A relay is an electromagnetically actuated electrical switch. Conventional relays include stationary contacts and moving contacts corresponding with the stationary contacts. When the relay is electromagnetically actuated, the moving contacts engage or disengage with the stationary contacts, to respectively close or open an electrical circuit.
A conventional relay has a base structure, a housing, a relay coil, an armature, a pusher and a contact system. The base structure and housing are made of an electrically insulating material and support and enclose the operative electromagnetic parts of the relay. The relay coil has a coil and a magnetically permeable core connected to the tilting armature to move the armature. The coil is a cylindrical hollow member with a rectangular internal cross section corresponding to a cross section of the core, and is spring loaded to return to a specified position when the coil is de-energized. The pusher links the tilting armature and the contact system and transfers the coil force applied to the armature to the contact system.
In manufacturing, the relay stationary contact springs and moving contact springs are set to make contact concurrently when closing. Both the moving and stationary springs include metallic pads or tips, i.e., electrical contacts, which serve as the mutual point of contact. The spring contacts absorb wear and tear caused by the actuation force, electrical arcing, repetitious movements, and other deteriorating factors. To account for this deterioration due to repeated use, an over-travel adjustment is provided in manufacturing. This process involves manipulating the contact springs, which are generally made from copper, copper alloy or similar conductive material. The contact springs must be bent, turned, twisted or otherwise manipulated to attempt to set a uniform overtravel position for the multiplicity of contact springs. Due to the mechanical properties of the metallic contact springs, it is difficult to achieve a reliable and precise overtravel setting.
There is a need for an apparatus and system for automatically achieving a uniform overtravel adjustment for contact springs in an electromagnetic relay.
Intended advantages of the disclosed systems and/or methods satisfy one or more of these needs or provides other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.
One embodiment relates to an electromagnetic relay. The electromagnetic relay includes a relay coil, an armature, a pusher and a contact system. The armature is pivotably actuated by the relay coil, and linked to a trailing end of the pusher to drive a forward edge of the pusher to operate the contact system. The pusher includes a rotary adjustment disposed in a slot of the pusher adjacent to the armature. The rotary adjustment when rotated increases or decreases a gap of the contact system to provide an over-travel adjustment of the contact system.
Another embodiment relates to a pusher assembly for use in an electromagnetic relay. The pusher assembly includes a pusher having a pair of bifurcated tines defining a slot for receiving an armature linkage portion and a rotary adjustment. The rotary adjustment includes a head portion and a post depending from the head portion. The post is disposed within the slot and the head portion disposed against the armature linkage portion. Rotation of the rotary adjustment adjusts a distance between the forward edge and the armature by a predetermined interval.
Certain advantages of the embodiments described herein are a simplified, easily replicated and precise mechanism for overtravel adjustment in an electromagnetic relay.
Another advantage is a graduated adjustment dial to set the advance position of the pusher.
Yet another advantage is a slotted adjustment dial to accommodate a screwdriver tool for rotating the dial.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
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In a one embodiment, the dial 30 is permanently fixed, e.g., with adhesive glue or epoxy, after the appropriate dial position or overtravel adjustment is selected, so that the relay may not be adjusted again after leaving the factory, since it is contemplated that the dial 30 having been factory set, will require no further adjustment over the cycle life of the relay. Alternately, if desired, the dial may be configured for later adjustment by qualified personnel if desired.
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It should be understood that the application is not limited to the details or methodology set forth in the following description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.
While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.
It is important to note that the construction and arrangement of the relay with over-travel adjustment, as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.
