US3064104A - Electrical interlock - Google Patents

Description

Nov. 13, 1962 B. c. WELLS ETAL ELECTRICAL INTERLOCK 2 Sheets-Sheet 1 Filed Aug. 7, 1959 INVENTORS Donald D. Armstrong 8 Bruce C. Wells.

BY M ATTORNEY gill-28,2182 X W Nov. 13, 1962 B. c. WELLS ETAL ELECTRICAL INTERLOCK 2 Sheets-Sheet 2 Filed Aug. 7, 1959 rangement, the arc blowout features and the United States This invention relates to electric switches and more particularly to interlock type contacts, and auxiliary switches, for use on an electromagnetic contactor to be actuated by the magnetic armature, or other actuating member, of such contactor.

Interlock contact devices are well known in the art wherein the contact arrangement is such that one and the same unit can operate as a make contact or as a break contact.

It is one specific object of this invention to provide an improved non-polarized contact device which combines, with a single unit that provides selectively make and break operation, a permanent magnet blowout system to extinguish the are together with a. double-break contact arrangement.

It is a further specific object of this invention to provide, in a switching arrangement wherein a bridging member bridges a pair of spaced stationary contacts and wherein either circuit closure or circuit interruption is simultaneously effected at two separate spaced points, for independent arc blowout means functioning simultaneously but independently at two separate points in a circuit.

It is a further object of this invention to provide an interlock that is readily convertible from a normally open to a normally closed switch, and vice versa, and that is also compact, rugged, and small, yet capable to interrupt much larger currents than prior art devices of the same size, thus avoiding the need for interposing relays in circuits containing multiple, or large, contactor coils.

It is a specific object of this invention to provide a closed insulated construction, except for the region where circuit connections are to be made, which thus simplifies installation since electrical creepage and are striking distances need not be considered in mounting the interlock.

The objects recited are merely illustrative. Other objects and features of this invention will become more apparent from the embodiment shown by the drawings, in which:

FIGURE 1 is a perspective view of the contact aractuator assembly all shown disassociated from the housing;

FIG. 2 is a showing of the invention from the side with the front half of the housing removed, and showing the interlock contacts arranged as a normally open switch;

FIG. 3 is a showing like FIG. 2 but with the contacts arranged as a normally closed switch;

FIG. 4 is a showing of the interlock on section line IV-IV of FIG. 2;

FIG. 5 is a showing of the interlock on section line VV of FIG. 2; and

FIG. 6 is a showing of a portion of the interlock, the section being taken on line VI-VI of FIG. 2.

The showings in FIGS. 4, 5 and 6 are made on the.

assumption that both halves of the housing are in position.

In the drawings the switching unit is shown enclosed in a housing comprising two identical moldings, or side members, 1 and 2 of insulating material. Two iron pole pieces, or shoes, 3 and 5 are molded in member 1 and two iron pole pieces, or shoes, 4 and 6 are molded in side member 2.

The two side members 1 and 2 are provided with matching holes having recesses, at their outer ends so that eyelets, or hollow rivets, as HR may be used to rivet the parts together as shown in FIG. 4. Since the rivets are hollow, bolts may be inserted through the holes and any number of interlocks stacked together and rigidly mounted on the contactor with which the interlock coacts.

The two side members together are so shaped as to provide recesses for the relatively short cylindrical ceramic permanent magnets 7 and 8 of insulating material. The ends of the magnets fit snugly up against the pole shoes and the arrange ent is such that like poles of the magnets are directed in opposite directions. The pole shoes are fiat cylindrical members and are eccentrically disposed with reference to the magnets so that pole shoes 3 and 4 straddle the stationary contact 9 and pole shoes 5 and 6 straddle the stationary contact 10.

These contacts and 10 are silver buttons each fastened to a copper strap as the straps 11 and 12, respectively. Strap It is bent around magnet 7 and strap 12 is bent around magnet 3 to thus form are horns around each of the magnets. This construction aids in arc lengthening and thus in arc blow out and since each stationary contact has its own magnet and arc horn, two separate and independently functioning blowout structures, are provided. The outer ends of the straps 11 and 12 are provided with the terminal screw arrangements l3 and 14, respectively.

At the bottom center, the two members are so shaped to provide a square hole to slidably engage the squarein-section lower end of the plunger, or push rod 19. The upper end of the rod is shaped as shown and fits through a matching opening in the housing. The plunger may thus be moved along its axis in the housing, but can not rotate about its axis.

The plunger has a frame shaped middle portion 20. A contact member 15 is seated in the bottom end of the frame, and has two silver contact buttons 17 and 18 engageable with the stationary contact buttons 9 and 10, respectively, for electrically bridging the two contact straps 11 and 12.

The engagement between contact member 15 and the bottom portion of the frame portion 20 of the plunger is such, as shown, that contact 15 is prevented from revolving relative to the plunger but can slide axially. A positioning, or back-u member 21 is seated in the top end of the frame and is also axially movable in the frame. The positioning member has sectors cut out at the edge so that it may also be angularly moved about the plunger axis through a selected angle. In FIGS. 1, 2 and 4, the positioning member is shown in its upper position with reference to the housing.

A helical compression spring 22 is disposed between the positioning member 21 and the contact 15 and biases them away from each other toward the respective axial sides of the frame 20 which thus act as stops. Another helical compression spring 23 is disposed on the plunger between the bottom of a Well 24 in the housing and the cylindrical portion 25 of the plunger. In the assembled condition of the device the spring 22 is stronger than spring 23 at least when spring 22 is in the compressed condition as shown in FIG. 3.

The side members 1 and 2 at the upper boundaries of the side holes are provided with oppositely disposed notches 26 and 27 for receiving and retaining in position the outer rounded ends 28 and 29 of the back-up member. When the ends 28 and 29 are in the notches 26 and 27, as shown in FIG. 2, the interlock is a normally open switch.

The side members 1 and 2 are provided with oppositely disposed lower notches 30 and 31. When the ends 28 and29 are in the notches 30 and 31, the interlock is a normally closed switch as shown in FIG. 3. The change-over is made by depressing 21 and moving it clock-wise, it seen from the top, until the ends fit into the notches. than in the showing in PEG. 2. The interlock is turned around on the, contactor so that actuating of the contactor, not shown, operates the interlock by engaging the lower end of the plunger 19. i

Regardless of the manner of use made of the interlock, namely as a normally open switch or a normally closed switch, interruption'of the circuit occurs simultaneously at 9 and 17, and 1t) and 18 and the arcs are rapidly Spring 23 will be more compressed moved along each arc horn by the permanent magnets and are rapidly extinguished; Since the arc horns extend to both sides of the, fixed contacts, interruption is independent of the current polarity. Further, since the magnets are mounted with the same poles directed in opposite directions, onearc blows toward and the other away from the push rod 19. Further, the kickout Spring 23 is hooded, that is, being disposed ina well with the cylindrical portion 25 closing the well, it is protected against the inward moving arc.

, While but one embodiment of this invention has been disclosed, other arrangements are possible, all falling within the spirit of this invention. i

We claim as our invention: 1. An electric switch comprising, a housing, a plunger slidably mounted in said housing, a spring biased elongated contact mounted transversely of the plunger on the plunger to move with movement of the plunger, a pair of stationary contacts mounted in the housing, one stationary contact'being disposed at one side of the plunger and the other at the other side of the plunger and so disposed with reference to the elongated contact and the plunger that movement of the plungeor in onedirection causes circuit closure at each of the stationary contacts and movement of the plunger in an opposite direction causes circuit interruption at each of the stationary contacts, a permanent magnet disposed below each stationary contact, the disposition of each magnet being such that the magnet axes are parallel and the other at the other side of the plunger and the disposition being such that their axes are parallel with like poles directed in opposite directions and with one stationary'contact partly encircling one magnet and the other stationary contact partly encircling the other magnet, pole shoes disposed at the ends of each magnet so projecting transversely of the magnets that one pair of pole shoes of one magnet straddles one stationary contact and the other pair of pole shoes of the other magnet straddles the other stationary contact to provide magnetic arc blowout fields directed in oppositedirections transversely of the respective stationary contacts to effect are blowout at each stationary contact when the contact on the plunger is moved to circuit interruption, and the curvature of each of the stationary'contacts partly. encircling the magnets provide arc horns to aid in lengthening the arcs at the stationary contacts and thus expedite V blowout of the arcs.

3. An electric switch comprising, a housing, a plunger slidably mounted in said housing, a spring biased elongated contact mounted transversely of the plunger on the plunger to move with movement of the plunger, a pair of stationary contacts mounted in the housing, one stationary contact being disposed at one side of the plunger and the other at the other side of the plunger and so disposed with reference to the elongated contact and the plunger that movement of the plunger in one direction causes circuit closure at each of the stationary contacts and movement of the plunger'in an opposite direction causes circuit interruption at each of the stationary contacts, a pair of relatively short cylindrical ceramic permanent magnets of insulating material mounted in spaced relation to each other in the housing one being at one side of the plungerand the other at' the other side of the plunger and the disposition being such that their axes are parallel with like poles pointing in opposite directions, one stationary contact partly enand generally normal'to the direction of movement of the elongated contact'and the plunger with like poles of the magnets being directed in the opposite directions, pole shoesv disposed at the ends of each of the magnets so projecting transversely of the magnet axes that one pair of 'poles straddles one stationary contact and the other pair of poles straddles the other stationary contact to provide a magnetic arc blowout ,field in one direction transversely of one stationary contact and a magnetic arc blowout field in the opposite direction transversely of the other stationary contact whereby the magnets efiect arc blowout in the same direction at each sta- V tionary contact when the elongated contact on the plunger is moved to circuit interruption. g

2. An electric switch comprising, a housing, a plunger slidably mounted in said housing, a spring biased elon- I gated contact mounted transversely of the plunger on the plunger to move with movement of the plunger, a pair of stationary contacts mounted in the housing, one stationary contact being disposed at one side of the plunger and theiother at the other side of the plunger and so disposed with reference to the elongated contact and the plunger that movement of the plunger in one direction causes circuit closure at each of the stationary.

contacts and movement of the plunger in an opposite direction causes'circuit interruption at each of the sta-s tionary contacts, a pair of relatively short cylindrical permanent magnets mounted in spaced relation to each other in the housing, one being at one side of theplunger circling one magnet and the other stationary contact partly encircling the other magnet, pole shoes 'at the ends of'the'magnets so transversely projecting from the magnet ends as to straddle the stationary contacts, whereby the magnets eifect arc blowout in the same. direction ateach stationary contact when the elongated contact on the plunger is moved to circuit interruption and the curvature of the stationary contact partly encircling the magnets form are horns to aid in lengthening the arc and thus expedite blowout of the arcs.

4. An electric switchcomprising, a housing of insulating material, a plunger having a pair of spaced stops and being slidably mounted in said housing, an elongated electric contact member disposed on the plunger against one of the stops, a back-up member slidably mounted on the plunger and disposed against the other stop, a biasing spring between'the back-up member and elongated contact member to thus bias the back-up membet and elongated contact member against the stops, a-

pair of stationary contact members mounted in the housing, a biasing spring for the plunger for normally biasing the plunger and thus the elongated contact member on the plunger in sucha direction that the movable elongated contact member does not bridge the stationary contact members, means on said housing for selectively securing said back-up member in either of two positions namely, in one position the switch isa normally open switch and in another position the switch is a normally closed switch, whereby longitudinal movement of the plunger may selectively effect either contact closure or contact interruption, a permanent magnet under each stationary contact member with the magnets disposed transversely of the ends of the elongated contact memher on the plunger with like poles directed in the opposite direction, whereby the magnets, on interruption of an electric current by the switch, blows the arcs out by lengthening both arcs in the same direction with reference to the stationary contact members.

5. An electric switch comprising, a housing of insulating material, a plunger having a pair of spaced stops and being slidably mounted in said housing, an elongated electric contact member disposed on the plunger against one of the stops, a back-up member slid'ably mounted on the plunger and disposed against the other stop, a biasing spring between the back-up member and elongated contact member to thus bias the back-up member and elongated contact member against the stops, a pair of stationary contact members mounted in the housing, a biasing spring for the plunger for normally biasing the plunger and thus the elongated contact member on the plunger in such a direction that the movable elongated contact member does not bridge the stationary contact members, means on said housing for selectively securing said back-up member in either of two positions namely, in one position the switch is a normally open switch and in another position the switch is a normally closed switch, whereby longitudinal movement of the plunger may selectively efiect either contact closure or contact interruption, a permanent magnet under each stationary contact member with the'magnets disposed transversely of the ends of the elongated contact member on the plunger with like poles directed in the opposite direction, pole shoes at the ends of the magnets having portions projecting transversely of the ends of the magnets so as to straddle the sationary contact members, whereby the magnets, on interruption of an electric current by the switch, blows the arcs out by lengthening both arcs in the same direction with reference to the stationary contact members.

UNITED STATES PATENTS 752,552 Hewlett Feb. 16, 1904 2,153,402 Tritle Apr. 4, 1939 2,337,949 Walle Dec. 28, 1943 2,571,951 Schaelchlin Oct. 16, 1951 2,629,035 Yingst Feb. 17, 1953 2,822,450 Goudy et a1 Feb. 4, 1958 2,846,528 Burrell Aug. 5, 1958 2,896,043 Andrews July 21, 1959 FOREIGN PATENTS 136,167 Australia Feb. 1, 1950

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