US2897316A - Electromagnetic switch - Google Patents

Description

y 28, 1959 I c. F. BRAUNECK 2,897,316

ELECTROMAGNETIC SWITCH Filed Sept. 4, 1957 I 4 Sheets-Sheet l INVENTOR. CHAKLL? I. BBAUNECK ATTORNEY July 28, 1959 4 Sheets-Sheet 2 Filed Sept. 4, 1957 6 I. 2 8 O 5 2 2 2 5 5 v 1 a w 5 4 M a i 6 2 9 4 2 w m 2 a INVENTOR. Cf/lfLfSFfi/UUA/[CK ATTORNEY 4 Sheets-Sheet 3 INVENTOR.

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ATTORNEY United States Patent Ofiiice 2,897,316 Patented July 28, 1959 ELECTROMAGNETIC SWITCH Charles F. Brauneck, Glen Cove, N.Y., assignor to Murray Manufacturing Corporation, Brooklyn, N.Y.

Application September 4, 1957, Serial No. 682,023

Claims. (Cl. 200- 104) This invention relates to an electromagnetically operated switch which is particularly useful in motor control devices.

An electromagnetic switch is essentially a contacting mechanism, the opening and closing of which is controlled by an electromagnet.

In general, electromagnetically operated switches are classified either as Vertical Lift Armature or Clapper Type. In the vertical lift armature switch, the motion of the armature is in the vertical plane, the contacts are in the horizontal plane and the electromagnet pulls the armature up to close the contacts. The contacts are opened by force of gravity.

In the clapper type switch the motion of the armature is pivotal about the lowest edge of the armature, the contacts are in the vertical plane and the electromagnet pulls the armature to close the contacts. The contacts are opened by force of gravity augmented by a spring.

Each of the above-mentioned switches has certain disadvantages. For example, in the vertical lift switch, the supporting base is located in a plane parallel to the direction of the operating forces. Therefore, the switch is subjected to tension and shearing forces. This requires the construction to be sufficiently heavy and rugged to withstand these forces. The size of the switch is, therefore, rather large to prevent mechanical failure.

Accordingly, it is an object of this invention to provide a compact, relatively simple electromagnetic switch.

It is a feature of this invention to provide a switch of unique construction in which the forces operate into the plane of the base supporting the device. Thus, the construction may be made lighter and yet is mechanically more rugged than the known switches.

It is a further feature of this invention to provide such a switch, which is constructed so as to permit ease of wiring, inspection and maintenance.

It is still a further feature of my invention to provide an electromagnetic switch which can readily be converted to a motor controller by adding overload relays in line with the switch, an auxiliary contact mechanism on either side of the switch and a push button control on top of the switch.

In accordance with an aspect of my invention, there is provided an electromagnetic switch comprising a base member, preferably mounted in the vertical plane, and a pair of side members attached to opposite sides of the base member. An electromagnet is mounted on the base member between the side members and drives an armature spaced in cooperative relation therewith. The direction of movement of the armature is in a plane perpendicular to the base. An insulating bridge member is mounted on the side members and supports a plurality of stationary contacts mounted in spaced and aligned pairs. One side of the pairs of contacts is connected to the line and the other side to the circuit to be controlled. A plurality of bridging contacts are provided for contacting and shunting respective pairs of the stationary contacts. The bridging contacts are supported on an insulator carrier which is attached to the armature. The armature is normally urged into a position in which the bridging contacts are separated from the stationary contacts. When it is desired to close the stationary contacts, the electromagnet is energized and the armature is drawn to a position in which the bridging contacts engage the stationary contacts.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a front view of one embodiment of the electromagnetic switch.

Fig. 2 is a cross-sectimonal view taken along lines 2-2 of Fig. 1;

Fig. 3 is a cross-sectional view taken along lines 33 of Fig. 1;

Fig. 4 is a front and top View of a frame designed to support an armature of the switch;

Fig. 5 is an end View of an insulator bridge member;

Fig. 6 is a cross-sectional front and top view of contact supporting means; and

Fig. 7 is a front and end view of a cover for the switch.

Referring first to Figs. 1-3, the electromagnetic switch comprises a flat base member 1 for supporting the switch components, and is adaptable for mounting in the vertical or horizontal planes. However, in accordance with the preferred embodiment, the mounting position is in the vertical plane, and the following description will contemplate such mounting.

Attached rigidly to the base 1, are a pair of C- shaped side members 2, 3. The side members 2, 3 are positioned at opposite sides of the base 1 facing each other.

An electromagnet comprising an E-shaped core 4 is mounted to the base member 1 between the side members 2, 3. For mounting, the core is provided with slides which fit snugly under flanges of the side members (Fig. 1). In addition a lug 5 is struck-up from the base which is provided with a tapped hole for a screw 6 which passes through a hole in the core 4 and is threaded into the lug 5. As shown, the legs of the core 4 extend perpendicular to and away from the base 1.

A coil 7 is positioned around the center leg of the core and extends beyond the end 8 thereof.

The electromagnet acts upon an armature 9 movably mounted in cooperative relation with and located in front of the core 4. The armature is in the form of a similar E-shaped core member with the legs thereof aligned with the legs of the core 4-. The center leg 10 of the armature core is adapted to move into the extending portion of the coil 7.

The armature 9 is supported by a U-shaped frame member 11 (Figs. 2, 4). The cross-arm 12 of the U is provided with flanges 13 which engage the opposite sides of the armature core 9. The frame is secured to the core preferably by rivets, such as shown at 14 in Fig. 3. The legs 15, 16 of the frame extend towards the base member and comprise flanges 17, 18 respectively at the ends thereof, extending toward the side members.

The movement of the armature 9 is substantially perpendicular to the base 1 and is controlled by a linkage arrangement. The linkage arrangement comprises two pairs of parallel arms, one pair of which 19, 20 is shown in Fig. 3. The two pairs of arms are pivotally mounted on pins 21, 22 and 23, 24 attached respectively to the legs 15, 16 of the frame 11. The opposite ends of each pair of arms are pivotally connected to similar pins 25, 26 (Fig. 3) attached to the side members. The location of the pins 25, 26 is such that the arms are parallel to the base when the armature is midway through its travel.

The inward movement of the armature 9, towards the base 1, is limited by the legs thereof coming in contact with the electromagnet core. The outward movement, away from the base, is limited by means of stops 27, 28, which are struck-up from the respective side members 2, 3 and located in the path of the leg flanges l7, 18.

The armature is normally urged to the outward position by helical springs 29, 3d. The springs are positioned by pins 31, 32 extending from one end of the respective C-shaped side members to the other end thereof, passing through holes in the flanges and stops.

The forward part of the switch, to be described in'de tail hereinafter, includes the switching contacts which are opened and closed by operation of the armature. For example, if the switch is utilized for motor control, two or more contacts are provided at one end of the switch for connection to the line and a corresponding number of contacts are connected to the opposite end for connection to the motor. The number of contacts required depends on the type of motor being controlled.

By way of example, I have shown a switch comprising four pairs of aligned and spaced contacts 33, 34, 35 and 36 (Fig. 1). Wire connectors, such as shown at 37 are respectively connected to each of the contacts. Preferably a single screw, e.g. 38 (Fig. 3) is used to attach each connector-contact assembly to an insulator bridge member 39.

The bridge member 39, best seen in Fig. 5, is screwed at 40 into the side members 2, 3. The bridge member is provided with raised portions 41 for separating adjacent pairs of contacts. The raised portions 41 are each provided with a groove 42 for reasons to be discussed later.

Thus, the stationary contacts which are connected to the line and to the motor are mounted on the bridge member. The means for closing these contacts are carried by the armature 9.

As best seen in Figs. 2 and 6, an insulator contact carrier 43 is rigidly mounted on the outside of the armature frame 11 by means of screws 44. The carrier 43 comprises a base portion 45, and a plurality of posts 46 which pass through holes in the bridge member. The number of posts 46 corresponds to the number of pairs of stationary contacts; in the illustrated embodiment four posts are employed.

A plurality of bridging contacts 47 (Fig. 3) are mounted respectively on the posts 46. Each contact 47 is provided with an elongated hole slightly larger than the neck portion 48 of the post; the post being correspondingly shaped. The contacts are supported on the shoulders 49 of the respective posts and are spring urged against the shoulders by helical springs 50. The springs are retained by cup-shaped caps 51. The caps 51 are each provided with an elongated slot which is adapted to fit over a correspondingly shaped head 52 of a retaining to prevent chatter between the cores during energization of the coil.

A cover 55 (Figs. 2, 3, and 7) is provided for the switch and is mounted by screw 56 (Fig. 2) to the bridge member 39. The cover is slotted along the opposite sides at 57 to provide access to the wire connectors. The underside of the cover is grooved at 58 to provide space for movement of the bridging contacts. On opposite sides of the grooves and extending from one end to the other, rail-like extensions 59 are provided to fit into the grooves 42 in the bridge member 39. This type of joint between the cover and bridge member prevents arcing between adjacent contacts.

While I have described above the principles of my in vention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. An electromagnetic switch, comprising a base member, a pair of side members attached to opposite sides of Said base member, an E-shaped electromagnet pin 53. The cap is mounted by depressing the cap against the spring slightly below the head, where the width of the slot is slightly greater than the thickness of the pin, and turning the cap 90 degrees. The cap is preferably formed with a depression for accommodating the head after the cap is turned 90 degrees. The retaining pins 53 may be molded in the posts or may be secured by any other suitable means.

Theseparation between the bridging contacts 47 and the aligned spaced contacts 33 is slightly less than the separation between the armature and the electromagnet core. In this way, the bridging contacts are held under tension against the spaced contacts when the armature is drawn to the electromagnet.

When it is desired to close the circuit between the line and the motor, the coil is energized, thereby converting thecore 4 into a magnet which attracts the armature 9.

As best seen in Fig. 2 shading poles 54 are provided core mounted on said base member between said side members, a coil surrounding the center leg of the core and extending beyond the end thereof, an E-shaped armature similar in shape to said electromagnet and movably mounted parallel to said electromagnet, the direction of movement being in a plane perpendicular to said base and the center leg of the armature core being dimensioned to be normally free of said coil when not attracted by said electromagnet and adapted to move into the extending portion of said coil when attracted by said electromagnet, a frame member in the shape of a U, means securing said armature to the underside of the cross arm of said U, linkage arms pivotally connected to the opposite leg members of said U and to said side members respectively, the connection to the side members being such that the movement of said armature is substantially linear and perpendicular to said base, an insulating bridge member rigidly mounted on said side members, a plurality of contacts mounted in pairs in spaced alignment on said bridge member, contact carrying means attached to said armature and extending through holes provided therefor in said bridge member, a plurality of bridging contacts secured to said contact carrying means and positioned to shunt respective pairs of said spaced contacts, means positioned between said base member and said armature adapted normally to separate said armature from said electromagnet, whereby said bridging contacts are separated from said spaced contacts, and when said electromagnet is energized, the armature is attracted thereto causing said bridging contacts to engage said respective pairs of contacts.

2. The switch according to claim 1, wherein said linkage arms comprise a pair of parallel arms mounted to each side of said frame respectively, the arms of each pair being mounted parallel to each other and so connected to the side members that when said armature is mid-way through its travel the linkage arms are approximately parallel'to said base.

3. The switch according to claim 1, wherein the crossarm of the U shaped frame member comprises flanges engaging the opposite sides of said armature, the legs of the U having flanges extending respectively towards the side members, a stop extending from each of said side members into the path of the respective leg flanges for limiting the movement of said armature away from said electromagnet, a pair of pins fixed to said side members respectively and passing through holes in said stops and end flanges, and a pair of helical springs positioned around said pins respectively, between said flanges and said base, urging the endyflanges against said stops.

4. An electromagnetic switch, comprising aflat base member adapted to be mounted in the vertical plane, a

pair of C-shaped side members mounted so as to face each other at opposite sides on said base member, an electromagnet comprising an E-shaped core mounted on said base member between said side members, the legs thereof extending perpendicular to and away from said base, a coil surrounding the center leg of said core and extending beyond the end thereof, an armature movably mounted in front of said electromagnet and comprising a similar E-shaped core member with legs thereof aligned with the legs of said electromagnet core, the center leg thereof being adapted to move into the extending portion of said core, a frame member in the shape of a U, means securing said armature to the underside of the cross-arm of said U, the respective legs of the U extending towards said base and flanged at the ends thereof toward the side members, linkage arms pivotally connecting the respective legs of said U to the adjacent side members, the connection to the side members being such that the movement of said armature is substantially perpendicular to said base, a stop extending from each of said side members into the paths of the respective leg flanges, for limiting the outward movement of said armature, a pair of pins fixed respectively to the side members and extending from one end of the C to the other end, passing through holes in said stops and end flanges, a pair of helical springs positioned around said pins respectively between said flanges and the inner ends of the C-shaped side members, thereby urging the end flanges against said stops, an insulating bridge member mounted rigidly on the outer ends of said C-shaped side members and spaced a given distance from said armature, a plurality of contacts mounted in spaced and aligned pairs on the outside of said bridge member, a plurality of contact supporting means in the form of insulating posts attached to said armature and extending through holes provided therefor in said bridge member, a corresponding plurality of bridging contacts secured to said posts and positioned to shunt respective pairs of said spaced contacts, the bridging contacts being separated from the pairs of contacts by operation of said helical springs, whereby when said electromagnet is energized the armature is drawn thereto, moving said bridging contacts into contact with said spaced pairs of contacts.

5. The switch according to claim 4, and further comprising a cover comprising a plurality of rail-like projec tions on the underside thereof, spaced to fit into grooves in said bridge member said pairs of spaced contacts, whereby arcing between adjacent pairs is prevented.

References Cited in the file of this patent UNITED STATES PATENTS Re. 20,676 Wilms et al. Mar. 22, 1938 2,304,972 Van Valkenburg Dec. 15, 1942 2,411,894 Peters Dec. 3, 1946 2,773,948 Pelz et a1. Dec. 11, 1956 2,794,093 Morschel May 28, 1957 2,823,280 Davies Feb. 11, 1958 2,853,577 Scagnelli et a1 Sept. 23, 1958 FOREIGN PATENTS 752,870 Great Britain July 18, 1956

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