US2504912A - Contactor - Google Patents

Description

April 18, 1950 M. WIBELL ETAL 2,504,912

CONTACTOR Filed Aug. 51, 1945 2 Sheets-Sheet l Insulation .g abvh B. 112712761. WE.

ATTORNEY April 18, 1950 M WEBELL ETAL 2,504,912

CONTACTOR Filed Aug. 51, 1945 2 Sheets-Sheet 2 WlTNSSES: INVENTORS 5% M ATTOR NEY M 'M Mam Patented Apr. 18, 1950 CONTACTOR Martin Wibell and Ralph B. Immel, Wllkinsburg,

Pa., assignora to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 31, 1945, Serial No. 613,760

3 Claims.

1 This invention relates to electromagnetic contactors in which a movable contact structure is pivotally mounted on a rocking armature so as to be capable of limited angular motion relative to the armature and in opposition to a spring bias.

In known contactors of this type, the armature-operated contact structure performs a sliding, wiping or rolling motion relative to the appertaining stationary contact during the period of the so-called armature over-travel which occurs after the movable contact has touched the stationary contact and hence stopped its forward motion while the armature, in opposition to the spring force effective between armature and contact, is permitted to continue travelling over a limited additional distance (overtravel).

In relays with circuit-closing contacts of silver or the like highly conductive material, the abovementioned sliding, wiping or rolling motion is apt to cause arcing, burning and transfer of contact material and hence reduces the useful life of the contacts and consequently the period of undisturbed contactor operation. It has been proposed to diminish these detrimental effects by pivoting the above-mentioned contact structure to the contactor armature in such a manner that the pivot axis of the contact coincides substantially with the rocking axis of the armature so that a wiping, rolling, or bouncing motion of the closing contacts during the overtravel period is minimized.

It is an object of our invention to improve contactors of the last mentioned type in order to obtain a further considerable increase in the life or operating time of its highly conductive circuit-closing contacts. More specifically, it is an object of the invention to provide these contactors with a double-pole contact structure of such a design that the prevention of wiping or the like detrimental motion between the closing contacts is not predicated upon high accuracy of mechanical adjustment and remains effective even if the contacts of both poles wear unequally or if these contacts are accidentally or inadvertently brought in misalignment.

For achieving these objects and in accordance with essential features of our invention, we link a double contact structure to the rocking armature of the contactor in such a manner that the structure is capable of universal motion relative to the armature about a pivot point located near, or substantially on, the rocking axis of the armature, and we design the two contacts" 2 of the structure so that the just-mentioned pivot point and the two spaced points of contact engagement form together a. three-point support or bearing, thus rendering the contact structure self-aligning.

These and other objects and features of the invention will be apparent from the following description of the embodiment exemplified by the drawings, in which:

Figures 1, 2 and 3 show a top view, lateral view and front view. respectively, of a time delay contactor according to the invention;

Figs. 4, 5 and 6 show three diiferent views of the pivotally mounted contact structure of the same contactor while Fig. 7 is a schematic perspective view of the contact structure and of other relay parts with which the structure is associated.

Referring to the drawings, numeral I denotes a magnetic frame structure which is substantially L-shaped and carries a magnet core 2 in parallel to a limb portion 3 of the frame. A coil 4 is mounted on core 2. The coil has two separate windings, one forming the main winding of the relay and the other an auxiliary or neutralizing winding for providing a definite time limit. The neutralizing winding is provided with terminals 5 and the main winding with terminals ii (Figs. 1, 2). The use of two coils is not essential to the present invention, but is advantageous in timing relays for the reasons explained in United States Patent No. 1,979,709 to W. Schaelchlin et al.

An abutment plate I (Figs. 1, 2) is firmly secured to the limb 3 of the frame structure l by means of screws 8. The abutment plate I is bifurcated and forms two legs 9 and I0 separated from each other by a recess ll (Fig. 1). The legs 9 and I0 have each an opening I2 and I3, respectively.

An insulating body I5 is mounted on the struc-' ture l and carries two pairs of stationary contacts such as those denoted in Fig. 2 by It and I1. These contacts are provided with terminals l8, [9, H8, and H8, respectively (Fig. 3). Mounted on the insulating body 15 are two stationary contact members 20 and I2!) which are firmly attached to the insulating body 15 by means of screws 22 and I22, respectively (Figs. 2, 3). Each member carries a contact 23 or I23 consisting preferably of silver or the like highly conductive material (Fig. '7). The above-described elements in totality form substantially the stationary assembly of the relay. I

The movable relay assembly includes a magnetic material armature 25 which has one oi its edges beveled so as to form a knife-type edge at 25 (Pig. 2). This edge rests against the dihedral pivot bearing formed in the corner between the two adjacent surfaces of the limb 3 and the abutment plate I. The armature 25 thus lies in a magnetic circuit formed by the magnet core 2, the base portion of the structure i, the limb 3 and the armature 25.

An insulating member 21 (Figs. 2, 3) is firmly mounted on the armature 25 by means of screws 22 and I23, and carries two parts 2! and HI each of which has a saddle 25 (Fig. 2) for guiding a bridge piece 35 and a coiled compression spring 3i. Two contacts" and 33 are attached to each bridge piece 35 in order to cooperate with the adjacent pair of stationary contacts I and II, respectively. Consequently, when the armature assembly is in the position illustrated in Fig. 2, the circuit between stationary contacts I5 and I1 is interrupted, while, when the armature is attracted by the magnet core 2 upon proper energization of the relay main winding, the bridge piece 35 is pressed against the stationary contacts under compression of spring 3|, and hence establishes a conductive connection between contacts l5 and II.

It should be understood that the just-mentioned contact devices are not part of the invention proper. They serve an auxiliary purpose and are referred to for the purpose of a complete description of the illustrated contactor because they are usually present in time delay contactors of this type. These auxiliary contacts may be designed as make or break contacts in various ways different from the illustrated example. The three-point supported main contact structure essential to the invention proper cooperates with the above-mentioned members and I25 and their respective contacts 23 and I23, and will be described in a later place.

A hinge plate 35, located at the surface of the armature 25 away from the magnet, is firmly secured to the armature, and has one of its ends extending close to the pivot edge at 25. The outermost end of plate 35 is bent away from the armature (Fig. 2) and has an opening 34 (Fig. 'l) which forms a hinge for the movable contact structure described hereinafter.

A rigid bracket 31, for instance of steel, is also attached to the armature, a screw 38 serving to connect the bracket 31 and the hinge plate 35 to the armature 25. The limb 39 of bracket 31 has an opening traversed by a bolt which carries a helical compression spring 4i (Figs. 2, 3). A cross bar is firmly secured to the bolt 45 and has its lateral short edges bent away at a right angle so as to form lugs at 42 and 43 (Figs. 1, 2). When in the illustrated operative position, the spring 4| is compressed between leg 35 of bracket 31 and a washer carried by the bolt 45. As a result, the spring 4| pulk lugs 42 and 43 into the respective openings I2 and I3 in legs 5 and III of the abutment plate I. In this manner, the armature assembly is yieldingly secured in proper working position relative to the stationary parts of the relay structure and is limited to angular movements about the pivot axis at 25.

A rigid contact member 45 which carries two contacts 45 and I45 is pivoted to the armature in the following manner. The end portion 41 away from contact 45 is bent at an angle to the main portion of member 45 and passes at its outermost end 43 through the opening 34 in thshingeplate35 (Flgs.2,4to'l).' Ind45o1 member 45 has a pointed projection 45 whicl: rests against the apertured portion of hinge plate 35 and thus forms a bearing point whicl: permits the member 45 a limited universal pivoi motion relative to hinge plate 35 and armatun 25. As a result, the structure 45 is not onh capable of angular motion relative to the armature about an axis substantially coincident with the armature pivot axis determined by edge 25, but can also move angularly with respect to thai pivot axis about a point determined by projection 45.

A compression spring 53, placed in a cavity 24 of the armature 25 and pr against the member 45, bias% the member away from the armature. The relative motion between contact member and armature is limited by a stop 44 formed by the bracket 31 (Figs. 2, 3).

Aterminalilisattachedtotheportionfl oi the movable contact member 45 and is connected by a flexible cable 5i with a terminal 52 serving to supply electric current through the movable contact member to its contact 46.

The contacts 45 and I45 cooperate with the stationary contacts 23 and I23 respectively, and consist also of a highly conductive material, such as silver. The surfaces of contacts 45 and I45 are preferably rounded. When the contacts 45 and I45 are in engagement with respective contacts 23 and I23 (Fig. 7), the two points of engagement and the bearing point at 45 form together a threepoint support so that, during the contact closing operation, the structure 45 can align itself by tilting about the bearing point.

A time delay contactor of the type here exemplified has the main function of performing a contact closing operation upon the elapse of a given period of delay after the deenergization of the contractor coil main winding. In order to place the contactor in operative condition, the main winding is energized so that the armature assembly i normally attracted by the magnet and closes the auxiliary contacts at i5, 32 and I1, 33 (Fig. 2), while the main timing contacts between 23, 45 and I23, I45 are kept open. This condition of the main timing contacts is represented in Fig. 7.

Upon deenergization and after the elapse of the timing period, the armature 25 is magnetically released and moves away from the magnet under the bias of spring 4| (Pig. 2). The movable contact structure 45 pivoted to the armature is at first pressed by spring 53 against the stop 44 (Figs. 2, 'l), and hence participates in the motion of the armature without performing any motion relative to the armature. This concurrent motion continues until either or both of contacts 45 and I45 hit the appertaining stationary contact, and thus are stopped from further motion away from the magnet 2. This, however, does not stop the further angular motion of the armature 25 because the main spring II of the relay is stronger than the spring 53, and continues to force the armature 25 farther away from the magnet until at the end of this overtravel, the armahn'e is also stopped.

This overtravel motion of the armature 25 does not cause a wiping, rolling or the like motion of the contacts 45 and I45 relative to the stationary Is on the structure 45. During the period of overtravel, the structure 45, if necessary, will align itself into the position in which both contacts 48 and I46 are held against their respective stationary contacts 23 and I23. That is, when due to some irregularity or misalignment, the engagement is first established between one pair of contacts, such as 46 and 23, the structure 45 is capable of adjusting itself angularly relative to the armature pivot axis to also secure a proper contact engagement between the other pair of contacts. Because of this aligning performance, the occurrence of detrimental relative motion between the closing contacts is safely prevented without requiring an exacting adjustment of the contactor during the manufacturing and assembling procedure and also if the contactor contacts become subsequently misaligned.

The just-mentioned advantage of relays according to the invention has been verified by numerous tests, as well as in actual use of time contactors designed as illustrated and described in the foregoing. In tests made under a load of 300 amps, 220 volts, three-phase alternatin current of 60 cycles in a circuit for shorting out the starting resistor of a wound rotor motor after a suitable time delay, a sequence of 100,000 operations failed to produce any noticeable detrimental eiTect on the contactor contacts. The contacts and the appertaining parts were not appreciably worn, and these parts remained capable of aligning themselves even when the stationary contacts were deliberately misaligned. In contrast thereto comparative tests made with contactors not involving the three-joint support feature of the present invention showed noticeable defects of the contacts after approximately 33,000 operations.

It should be noted that aside from these advantages the above-described relay according to our invention is of simple construction and advantageous to manufacture and assemble. Thus. the entire movable armature assembly of the relay is attached to the stationary structure merely by the force of the main spring 4|. Consequently, the movable assembly can be removed from the relay by pulling the lugs 42 and 43 out of the openings l2 and I3 and then movin the entire armature assembly away from the stationary structure. The assembly can just as easily be reinserted. This facilitates manufacturing and assembling the contactor and affords free access to the magnet for the purpose of making repairs or adjustments.

It will be obvious to those skilled in the art that the construction of contacts according to the invention can be modified in various respects and as regards different details without departing from the essence of the invention and within the essential features set forth in the claims attached hereto.

We claim as our invention:

1. A contactor, comprising a structure having two mutually spaced stationary contacts, an armatur pivoted to said structure for limited angular motion relative to said structure, said armature having a pivot axis spaced from the connecting line of said stationary contacts, a movable contact member having two mutually spaced contacts engageable with said respective stationary contacts and rigidly integral with said member, said member having universal joint means with a pivot point substantially coincident with the pivot axis of said armature, and spring means disposed between said member and said armature for biasing said contact member toward a given position relative to said armature, whereby said pivot point and said stationary contacts form a three-point support for said member to permit self-alignment of the latter when said armature moves said member into engagement with said stationary contacts.

2. A contactor, comprising a structure having an electromagnet and two stationary contacts spaced from each other, an armature pivoted on said structure for angular motion relative thereto and being biased away from said magnet and movable toward said magnet when the latter is energized, said armature having a pivot axis spaced from the connecting line of said stationary contacts, a movable rigid contact member having two contacts rigidly integral with said member and engageable with said respective stationary contacts, said member having universal joint means to be capable of limited universal motion relative to said armature, said joint means having a pivot point substantially coincident with the pivot axis of said armature, and spring means disposed between'said armature and said member for biasing said member toward a given position relative to said armature so that said member is disengaged from said stationary contacts when said armature is moved toward said magnet, while said member engages said stationary contacts in opposition to the bias of said spring means when said armature is released by said magnet and moves away therefrom, said pivot point and said stationary contacts forming a three-point support for said member to permit self-alignment of said member when its contacts enter into engagement with said stationary contacts.

3. A contactor, comprising a structure forming two aligned pivot bearings axially spaced from each other and having two stationary con tacts, said stationary contacts being spaced from the alignment axis of said bearings and being spaced from each other in a direction extending parallel to said alignment axis, an armature having two mutually spaced portions in engagement with said pivot bearings so as to be capable of limited angular motion relative to said structure, a rigid contact member comprising two contacts for engaging said respective stationary contacts, universal joint means joining said member to said armature at a point located between said portions and substantially on the axis of said pivot bearings, means for biasing said member toward a given position relative to said armature when the latter is moved away from said stationary contacts, and means for biasing said armature toward a. position in which said contacts of said member engage said respective stationary contacts in opposition of said first biasing means.

MARTIN WIBELL. RALPH B. IMMEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,092,478 Sommermeyer Sept. 7, 193'! 2,239,624 Powell Apr. 22, 1941 2,397,228 Young et a1 Mar. 26, 1948 2,414,468 Immel Jan. 21, 1947

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