Relay with overtravel adjustment

An electromagnetic relay has an overtravel adjustment to set the gap in the contact arrangement. The armature is actuated by a relay coil and linked to a pusher to drive the pusher to operate the contact system. The pusher includes a rotary dial disposed in a slot on the pusher adjacent to the armature. The rotary adjustment increases or decreases a gap of the contacts to provide an over-travel adjustment. The pusher includes bifurcated tines defining the slot for receiving an armature linkage and the rotary adjustment. The rotary adjustment includes a head and a post depending from the head. The post is disposed within the slot and the head portion in contact with the armature linkage portion. The rotary adjustment sets the distance between the forward edge and the armature to achieve the desired overtravel for the contact arrangement.

BACKGROUND

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.

SUMMARY

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.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring now toFIG. 1, an electromagnetic relay operating mechanism10includes a contact arrangement12and a relay coil14fixedly mounted on a frame28. The relay coil14operates on a movable hinged armature16to move the armature16between two positions, one position corresponding to the relay coil14energized state and one corresponding to the relay coil14deenergized state. The armature16is linked to the contact arrangement12by a pusher18. The contact arrangement includes a set of stationary contact springs26and a set of moveable contact springs20. The moveable contact springs20are connected at one end to the pusher18and at the opposite end to a pivot point38(see, E.g.,FIG. 2). The armature16pivots about a connection point, causing the pusher18to move linearly, to a forward position and return position, in response to the actuation force generated by the relay coil14. The movement armature16pushes against the pusher18. The pusher18transfers the armature movement to the moveable contact springs20to make contact with the stationary contact springs26when the armature16moves to the forward position, and to break contact when the armature16returns to the return position. The relay operating mechanism10may optionally include a test button32for manually actuating the armature16through the exterior of the relay housing66(See, e.g.,FIG. 5). When driven to the forward position, the moveable contact springs20engage with stationary contact springs26at contacts22,24, respectively. The spacing of the moveable contact22from the stationary contact24is set by the dial30. The contact arrangement12also includes external connection terminals42that provide electrical termination points on the exterior of the relay housing66(See, e.g.,FIG. 5). In addition, the frame28has external termination points34that connect through the relay housing66, for interconnecting the relay coil14to a control circuit or other voltage source. In the exemplary embodiment ofFIG. 1, the contact arrangement12is illustrated as a two-pole relay, i.e., two sets of stationary contact springs26that interface with two sets of moveable contact springs20, to control two independent sets of external connection terminals42. It will be appreciated by those skilled in the art that the two-pole relay configuration is merely exemplary, and that more or less poles may be controlled using the operating mechanism10disclosed herein, within the scope of the present invention.

Referring next toFIG. 2, a side view of the relay operating mechanism10is shown. Over-travel of the moveable contact springs20is required when initially setting the position of the moveable contact springs20. Over-travel compensates for contact erosion over time. The additional travel length allows the contacts22,24to meet cycle life requirements as they wear, and the thickness T1of the contact tips22,24is diminished. In conventional relays, as the thickness t1diminishes, the gap s1between one or more pairs of the contact tips22,24increases, until eventually the gap is too great to permit contact to occur when required. The present over-travel adjustment dial30provides a means to ensure more even wear and spacing to achieve the desired cycle life. To achieve desired performance a fixed, predetermined gap spacing44is provided between the armature16and the core36. The core36is magnetized when the relay coil14is energized, and the armature16moves forward due to the magnetic force applied by the core36. The armature16is spring-biased or otherwise urged away from the core36when the core36is de-magnetized. The pusher18is directly linked by linkage46to the armature16, and travels forward and back an equal distance when the armature16moves. Due to molding and stamping tolerances inherent in the manufacturing of various parts, e.g., the terminals42,34and relay coil14the position of the armature16relative to the contact arrangement12may vary inconsistently. The distance d1between the armature linkage46and the forward edge48of the pusher18is adjustable by turning the dial30, as will be presently explained. The adjustment of distance d1changes the spacing s1proportionally, so the contact tips20,26are set to a desired initial spacing including overtravel.

Referring next toFIGS. 2 and 3, the pusher18includes a slot54for receiving the armature linkage46and the dial30. The dial30has a geometric head portion60and a post58depending from the head portion60. The post58is disposed within the slot54defined by a pair of bifurcated tines68,70extending from a trailing edge72of the pusher18. Travel of the post58is limited in the forward direction by the end wall50(FIG. 4) of the slot54, and in the rearward direction by a pair of opposing stop limits74adjacent to the armature linkage46. The dial30may include a recessed screwdriver slot52for receiving a screwdriver tip, or other tool receiving configuration, to facilitate rotation of the dial within the slot54. The head portion60is shown in an octagonal configuration, although other configurations with more or less sides may be employed, including triangular, rectangular, pentagonal and hexagonal, depending on the desired number of adjustment increments. Reference marks61are provided along each edge of the head portion60, to indicate the adjustment increments as set forth below in Table 1. The increment values set forth in Table 1 are exemplary, and may be greater or less as required to suit the geometry of the operating mechanism. Referring next toFIG. 4, a side view of the dial30illustrates the adjustment increments for one dial position. The distance d2from the dial side62to the axis64varies in increments, e.g., of 0.05 mm, progressively from dial position0to dial position7. Dial position0corresponds to the shortest distance d2, and for each successive dial position, i.e., dial positions1through7, d2increases by 0.05 mm up to a maximum of d2plus 0.35 mm, providing a 0.35 mm overtravel adjustment to the moveable contact springs. Accordingly, the head portion60having a center point63that is offset from the axis64of post58. The head portion60is positioned axially off-center to provide the necessary incremental distances as the head portion60is rotated about the axis64of the post58. Since the moveable contact springs20are affixed to the forward edge48of the pusher18, rotation of the dial30provides precise, uniform adjustment for all of the moveable contact springs20concurrently, and equalizes the overtravel setting.

In a one embodiment, the dial30is 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 dial30having 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.

Referring next toFIG. 5, an assembled relay66includes the relay operating mechanism10disposed within housing66, depending from the external screw terminations34,42. The coil external screw terminations42and the contact external screw terminations34face upward to provide access for wiring external control or power circuits.

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.