US2565467A

US2565467A - Electromagnetically operated switch

Info

Publication number: US2565467A
Application number: US43495A
Authority: US
Inventors: Besag Ernst; Hill Walter Edward; Wintle Thomas Daniel Guy
Original assignee: JA Crabtree and Co Ltd
Current assignee: JA Crabtree and Co Ltd
Priority date: 1947-08-14
Filing date: 1948-08-10
Publication date: 1951-08-28
Anticipated expiration: 1968-08-28
Also published as: GB633395A; US2565468A

Description

Aug. 28, 1951 E. BESAG ET AL ELECTROMAGNETICALLY OPERATED SWITCH 5 Sheets-Sheet 1 Filed Aug. 10, 1948 Inventors;

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Aug. 28, 1951 Filed Aug. 10, 1948 Aug. 28, 1951 E. BESAG ET AL 2,555,467

ELECTROMAGNETICALLY OPERATED SWITCH Filed Aug. 10, 1948 5 Sheets-Sheet 5 e ml IHMW mm uwm 8.11.112 3 AttorneyS,

Aug. 28, 1951 E. BESAG ETAL ELECTROMAGNETICALLY OPERATED SWITCH 5 Sheets-Sheet 5 Filed Aug. 10, 1948 All MIN mn mm am 2% Attorneys Patented Aug. 28, 1951 UNITED STATES PATENT OFFICE ELECTROMAGNETICALLY OPERATED SWITCH Application August 10, 1948, Serial No. 43,495 In Great Britain August 14, 1947 7 Claims. 1

This invention relates to improvements in and connected with electromagnetically operated switches, and is more particularly concerned with contactor switches and motor protective switches.

The principal object of the present invention is to provide an improved arrangement of simple and compact construction adapted to be economically produced and assembled, and in which the terminals, the coil adjustment scale, operating buttons and contacts are accessible from the front, thereby facilitating inspection and renewal and replacement.

According to this invention, on a back plate there are removably mounted upper and lower boxes and a magnet, a traverse slidably mounted between these boxes carrying an armature cooperating with the magnet and having moving contacts engageable with fixed contacts on the front of the boxes. The traverse may be guided for movement in a direction approximately horizontal and parallel to the lines of force of the magnet, and may be loosely and pivotally mounted on means in the lower box, the gap between such boxes being adapted to be increased to permit withdrawal of the traverse from its mounting. For example, a screw for securing the upper box on the back plate can be loosened to permit lifting of the upper box, whereupon the traverse can be disengaged from its pivot. The improved arrangement facilitates dismantling, and enables ready access to the coil of the magnet, while avoiding the necessity for breaking the electrical connections.

In order to enable the invention to be readily understood, reference will now be made to the accompanying drawings wherein there is shown one example of the construction of a motor protective switch embodying overload release devices, in which drawings:

Figure 1 is a perspective view of the switch.

Figure 2 is a front elevation thereof.

Figure 3 is a perspective view of the switch showing the upper box raised to permit removal of the armature traverse and coil.

Figure 4 is a sectional View, on a larger scale, taken on the line IV--IV of Figure 2, certain parts being shown in elevation, the chain lines showing the position of the upper box when raised for enabling removal of the traverse and other parts.

Figure 5 is a plan view of the bottom of the switch, also on a larger scale.

Figure 6 is a fragmentary, perspective view of a mounting means for the upper box.

, thereto.

Figure '7 is a perspective view of a modified construction of moving contact arrangement.

Figure 8 is a central vertical section of the traverse and one of the moving contacts shown in the modified construction of Figure 7.

Referring to the drawings, a substantially rectangular metal back plate a has upper and lower boxes b c and a magnet d, removably secured The magnet and an armature f are each of E-shape in plan, and around their middle limbs is disposed a coil e.

The upper box b is constructed for containing in a partitioned intermediate chamber b overload release devices, while end chambers b b house, respectively, the ambient temperature compensating means and the trip mechanism.

The lower box 0 contains the pivotally mounted carrier g for the traverse h carrying the armature f, and attached to side lugs c on one or both sides of the central compartment for the pivot mounting 9, there may be removably mounted a narrow box or boxes 1' for housing auxiliary devices such as contacts for signalling or interlocking circuits.

The traverse h is disposed between the opposed faces of the upper and lower boxes be, and is adapted to move between them in a horizontal direction substantially parallel to the lines of force of the magnet d, while being loosely supported on the carrier g mounted in the lower box 0. The side edges of the box and of the traverse are ribbed and recessed as at k for the purpose of imposing guidance on the traverse during movements incident to a switching operation, said ribs and recesses restricting tilting movement of the traverse in its approach and withdrawal to and from the magnet, and providing a positive stop to the traverse movement in the outward direction.

The traverse h is made of insulating material and is formed on its rear face with a deep rectangular recess m in which the armature f is secured by a pin 12, which passes through laminations of the magnet and through an opening formed in a hook 0 secured to the traverse h and inserted into a slotted part of the armature. The armature f has secured to the bottom thereof, a plate having depending hooks m which are removably engaged with the carrier g. The carrier g may, for example, be an oscillating carrier such as that shown in our copending application Serial No. 43,496, filed August 10, 1948.

The moving contacts 10 are removably mounted in compartments on the front of the traverse h, and are formed at their upper and lower ends with buttons for engagement with fixed contacts rr disposed in arc chambers a at the front of the upper and lower boxes b and c, respectively. The disposition of the contacts as above described, permits ready access from the front of the switch. The stop" and "start" buttons tt respectively, disposed at one side of the switch between the boxes I) and c; the terminals u for the.

additional switch mechanism housed in the intermediate compartment of the lower box c; the main terminals w for the contacts 11 on the upper and lower boxes b and 0, respectively; and the terminals 1: for the contacts a mounted in the box i; are all likewise presented for operation from the front of the switch.

The fixed contacts 1- are separated from the terminals w by arc shields w A conductor strip .1: leads from each main terminal 1' at the front of the upper box 12, to a stud connected with one end of a heater coil (not shown) for each thermal release device. the other end of the coil being connected by a second strip l to a flxed contact 1' which may be connected by a strip a with a terminal 3 provided for interconnections to reversers or other mechanisms. The strips 2 may be tapped at the front for engagement by screws 4 which hold them to the moulded box b.

The upper box b is secured at its rear end to the back plate a by a pair of headed bolts 5 (Figures 4 and 6) which enter tapped bushes t which have a drive fit in holes in the plate a. The box 1) is formed at each side with lugs 11 which are slotted and are adapted to rest on the bolts 5. Eachslot I is enlarged at l at its front end for receiving the head of the bolt 5. The box It is secured in position by turning each bolt 5 so that a washer 8 thereon abuts tightly against the face of the lug 1! around the slot l When it is desired to have access to the coil e, the armature b, or the magnet d, the bolts 5 are turned so as to retract the washers 8 to the position shown in chain lines in Figure 4, to permit upward tilting of the box b into the position shown in Figure 3, whereupon the armature b and traverse h can be removed from its hooked engagement m with the carrier g, after which the coil e can be disengaged from the magnet d. The upper box b is formed on its rear surface near its upper end with studs t having reduced eccentric projections lil which freely enter holes I l to allow the lifting of the box I) from its mounting in the back plate. When the box b is secured in position, it seats on the front flange e of the coil e. This flange e which can be accurately moulded, determines the distance between the horizontal traverse guides afforded by the upper and lower boxes, while the seating of the upper box b on this flange also ensures that its end is not pulled tightly down on to the bushes 6. The lower box 0 is secured to the back plate a by means of bolts l2 extending through the side lugs c of the box.

The traverse h has lateral noses b for engagement with a sliding plate i of the signal contact device i after actuation of the latter by the start button t According to the construction shown in Fi ures 7 and 8, a pair of short moving contact strips It has a common plate 13 formed at each end with a transverse groove or corrugation M, in which is received a part circular corrugation I5 on each strip II. The short strips are clamped between the plate I3 and a flat plate 86 loosely secured to the insulating carrier h 'for the armature, by springs ll operative on each end of the holding plate 63. Each strip i2 projects beyond the latter and the traverse, and is provided with a contact button It.

The spring I! is coiled around a T-shaped stem 20 disposed in an opening in the traverse, which stem has a pin it passing transversely therethrough, which spring exerts pressure on the holding plate I3 for clamping each strip l2 in position. The plate I3 is formed at each end with a slot 23 which permits the introduction of the pin 2 l which, together with the stem 20, is turned into the position shown in the drawings for securing the parts.

Each strip l2 has a formation 22 at the and remote from its contact button l8 to enable it to be pivoted on the plate l6 which is located on the traverse by the passage of the stems 20 through openings therein. The pressure exerted by the springs H on the holding plate I3 is resolved at a point about midway of the width of the semicircular groove or corrugation therein. The distance between the pivot and this point is only a fraction of the distance between such point and the contact button. As a result, a high pressure is exerted on the frictional surfaces constituted by the titer-engagement between their corrugations, while only a reduced pressure which has to be overcome by the magnet is produced between the fixed and moving contacts.

For use as a multipole contactor switch, the upper box b is of similar construction to that of the lower box 0, the central compartment of the upper box housing a time lag or other devices for star delta change-over or reversing connections, instead of having the thermal release device mounted therein.

Having thus described our invention, we claim:

1. In an electromagnetic switch, a traverse movable in a horizontal direction and having spaced contacts mounted thereon; an armature mounted on said traverse; a vertically disposed back plate; a magnet mounted on said back plate for attracting said armature to effect movement of said traverse toward said magnet; horizontally disposed and vertically spaced upper and lower boxes mounted on said back plate and having fixed contacts thereon adapted for engagement by the contacts on said traverse when the armature thereon is attracted by said magnet, said magnet being mounted on said back plate between the spaced opposed faces of said upper and means for mounting said upper box on said back plate being adjustable to permit the space between the opposed faces of said upper and lower boxes to be increased whereby said traverse may be lifted off its supporting means in the lower box and may be readily withdrawn from the switch.

2. An electromagnetic switch as defined in claim 1, in which the'means for securing the upper box to the back plate comprises a bolt which may be loosened to permit lifting of said box to permit the traverse to be lifted oif its supporting means in the lowerbox and to be readily removed from the switch.

3. An electromagnetic switch as defined in claim 1. in which the upper box, in addition to its adjustable fastening means, has a stud thereon adapted to enter a locating hole in said back plate, and in which there is a coil surrounding said magnet with its forward end spaced from said back plate, said upper box normally resting on the forward end of said coil.

4. An electromagnetic switch as defined in claim 1 in which the fixed contacts on the upper and lower boxes are disposed in arc chambers and are separated from other fixed terminals on said upper and lower boxes.

5. An electromagnetic switch as defined in claim 1, in which the armature has 9. depending hook on the lower surface thereof, and in which the means in the lower box for supporting the traverse and its associated armature includes slot engaged by said hook.

6. An electromagnetic switch as defined in claim 1, in which the traverse is provided with laterally projecting ears, and in which the switch includes auxiliary contacts mounted on one of said boxes and actuated by said projecting ears when the armature on said traverse is attracted by said magnet.

7. An electromagnetic switch as defined in claim 1, in which the opposed faces of the upper and lower boxes are provided with spaced ribs, and in which the upper and lower edges are provided with recesses adapted to receive said ribs whereby said traverse is guided by said cooperating ribs and recesses during the movements of said traverse with respect to said magnet.

ERNST BESAG. WALTER EDWARD HILL. THOMAS DANIEL GUY WINTLE.

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

UNITED STATES PATENTS