US3806849A

US3806849A - Small definite purpose contactor

Info

Publication number: US3806849A
Application number: US00370769A
Authority: US
Inventors: P Hughes
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1973-06-18
Filing date: 1973-06-18
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: CA1004712A

Abstract

A contactor assembly having an arc chute fixed to a base plate. Each of a plurality of stationary contacts are fixed within a respective compartment formed within the arc chute. A movable contact assembly includes a movable magnetic member and a plurality of movable contacts attached to a movable contact carrier. Each of the movable contacts extends within a respective compartment of the arc chute and is located in juxtaposition with each of the respective stationary contacts. A stationary magnet member is fixed to the base plate and an operating coil is mounted on the stationary member. The arc chute contains a pair of bosses extending outwardly from each side thereof and the base plate contains a respective hole for receiving each respective boss of the arc chute. A tab extending from each side of the base plate presses against the bottom portion of the arc chute so as to push the arc chute away from the bottom of the base plate thereby forcing the top portion of each boss to press against the top of the respective hole receiving the boss.

Description

United States Patent Hughes Apr. 23, 1974 [5 SMALL DEFINITE PURPOSE CONTACTOR [57] ABSTRACT inventor! Phflip 88 Hughes, A contactor assembly having an arc chute fixed to a Bloommgton, base plate. Each of a plurality of stationary contacts [73] Assign: General Electric Company New are fixed within a respective compartment formed York NY. within the arc chute. A movable contact assembly 1ncludes a movable magnetic member and a plurality of Filedi J e 8, 1973 movable contacts attached to amovable contact car- [21] Appl' No; 370,769 rier. Each of the movable contacts extends within a respective compartment of the arc chute and is located in juxtaposition with each of the respective sta- [52] US. Cl. 335/201, 335/132 tionary contacts A stationary magnet member is fixed [51] h lt. Cl. "01h 50/02 to the base plate and an operating coil is mounted on [58] Field Of Search 335/201, 132, 202 the stationary member The are chute contains a pair of bosses extending outwardly from each side thereof References Cited and the base plate contains a respective hole for re- UNITED STATES PATENTS ceiving each respective boss of the arc chute. A tab 3,215,800 11/1965 Hurteretal. 335/132 extending from each Side the base Plate Presses 3,451,019 6/1969 Auer et al 335/201 against the bottom PQfiion Of the are chute 80 as to 3,469,215 9/1969 Brovedan 335/132 push h arc chu e away from the bottom of the base plate thereby forcing the top portion of each boss to press against the top of the respective hole receiving the boss.

9 Claims, 7 Drawing Figures PATENTEDAPR 23 m4 3.806349 SHEET 3 BF 3 MTENTED APR 2 3 SHEEI 3 UP 3 SMALL DEFINITE PURPOSE CONTACTOR BACKGROUND OF THE INVENTION 1. Field of The Invention This invention relates to contactor assemblies and more particularly to small definite purpose contactors of the type used in air conditioning and heating systems.

2. Description of The Prior Art In prior art contactor assemblies the movable and stationary contacts, the movable and stationary magnets, and the operating coil were all held within the combination of an arc chute and base plate. The arc chute was generally screwed to the base plate using standard bolts, tapped holes and nuts. However such an assembly procedure is time consuming and costly. Furthermore, if such a contactor is serviced in the field, the bolts for assembling the base plate to the arc chute can become lost thereby rendering it difficult or impossible to place the contactor back into operation.

When attempting to reduce the size of the contactor, the size of the operating coil is generally the limiting factor. The operating coil must be large enough to carry sufficient current to insure closure of the switch contacts regardless of worse case tolerance variations. One such serious tolerance variation is created by the fact that the arc chute, which is generally a molded plastic member, has a mold parting line extending around the periphery of the arc chute in a plane approximately parallel to the bottom of the base plate. If the critical components, such as the stationary and movable contacts, are so located with respect to each other that their spacing depends on the dimension of the mold parting line, then the coil burden must be increased since the mold parting line can introduce an overall variation in spacing between the movable and stationary contacts of approximately percent. Therefore in order to take into consideration variations in the dimension of the mold parting line, the coil size has to be considerably increased thereby causing an overall increase in the size of the contactor.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide an improved contactor which can be easily assembled.

It is another object of this invention to provide a contactor assembly which eliminates the need for bolts and nuts in the fastening of the contactors base plate to its arc chute.

It is another object of this invention to provide a more compact contactor.

It is another object of this invention to provide a contactor assembly having an operating coil which is as small as possible. g

It is another object of this invention to provide a contactor assembly which has a coil burden that is independent of the variations in dimension of the mold parting line on the plastic arc chute.

Other objects of the invention will be pointed out and understood hereinafter.

SUMMARY OF THE INVENTION In accordance with a broad aspect of this invention there is provided an improved contactor which is easy to assemble and is more compact in size. Movable and stationary contacts and movable and stationary magnets are assembled within the contactors housing formed by the combination of an arc chute and a base plate. The are chute, which is a molded plastic member, has a pair of bosses extending from each of its opposite sides wherein a mold parting line passes through and bisects each of the bosses along the periphery of the arc chute in a plane approximately parallel to the bottom of the base plate. The base plate has a pair of side members extending from opposite edges of its bottom member wherein each of the side members has a pair of holes therein for receiving the respective bosses of the arc chute. Each of the side members also has a tab extending inwardly toward the arc chute which is positioned therebetween. The tabs press against a lower portion of the arc chute in such a manner that they force the top portion of each boss to press against the top of the respective hole in the side of the base plate which is receiving the boss. The movable and stationary contacts are positioned in the arc chute above the mold parting line, and all the critical dimensions of the movable and stationary contacts are determined relative to the top of the bosses in the arc chute so that the actual spacing therebetween does not depend on variation in mold closing tolerances which cause corresponding variations in the dimensional thickness of the mold parting line.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side view of the assembled contactor wherein side walls of the arc chute and base plate have been broken away to show details of the assembled components therein;

FIG. 2 is a front sectional view taken between lines 22 in FIG. 1 showing a boss extending from the arc chute and being received within a hole in the side of the base plate;

FIG. 3 is a top perspective view of the molded arc chute showing the separate compartments for the switch contacts;

FIG. 4 is an exploded side view of the arc chute and base plate;

FIG. 5 is a top perspective view of the base plate showing the holes and tabs in the sides of each of the base plates;

FIG. 6 is an exploded perspective view of the stationary magnet, operating coil, return springs, movable magnet and movable contact carrier; and

FIG. 7 is a partial front view of the assembled movable magnet and movable contact carrier.

DESCRIPTION OF A PREFERRED EMBODIMENT The invention will now be explained with reference to FIGS. 1-7. As shown in FIG. 1 a small definite purpose contactor 10 is comprised of two main structurally supporting elements, specifically a base plate 12 and an arc chute 14. A stationary magnetic member 16 is supported on a bottom or base member 18 of base plate 12. A standard operating coil 20 is mounted on stationary magnetic member 16. Two pairs of protrusions 22a and 22b shown in FIG. 4 depend from the bottom of arc chute 14 and press against a top surface 23 of coil 20 so as to insure that coil 20 and magnet 16 are held stationary within base plate 12. A movable magnetic member 24 is fixed to a movable contact carrier 26. A pair of stationary contacts 28 (only one pair of stationary contacts are shown in FIG. 1) are fixed within the base of each of

compartments

30a, 30b and 30c formed in arc chute 14, and each of the stationary contacts extend outwardly to form external terminals 32 (only one external terminal shown in FIG, 1). A movable contact bridge 34 and a pair of movable contacts 36 attached to the underside of the respective opposite ends of the bridge (shown in FIG. 1) are fixed within each window 38a, 38b and 380 in movable contact carrier 26 (shown in FIG. 6). Each bridge and its associated contacts are held against the bottom of its respective window by a spring 40 (shown in FIG. 1) which traverses the full height of the window.

As shown in FIG. 3

compartments

30a, 30b and 30c within arc chute 14 are formed between a pair of

side walls

42a and 42b and a pair of intermediate walls 44a and 4417. A pair of bosses 46 extend outwardly from each respective side. The base of each compartment has ridges 48 formed therein defining a channel for receiving a respective pair of the stationary contacts which are force fit between the ridges. Alternatively, if so desired the stationary contacts can be attached thereto using other known fastening techniques such as bonding, welding, etc. Arc chute 14 is a rigid'plastic member which is molded using standard split molding techniques so that a mold parting line 50 extends through and bisects each boss and continues along the remainder of the outer periphery of the arc chute in a plane which is essentially parallel to the bottom of both the arc chute and base plate, wherein the stationary and movable contacts are located within the arc chute above the mold parting line. As stated previously the dimension of the mold parting line will vary depending upon variations in the mold closing tolerance involved during the molding of the arc chute. The arc chute has a centrally located slot 52 extending from its bottom surface 54 to each of the compartments, while also extending through a portion of each side wall to a point below the mold parting line and through each intermediate wall to a point above the mold parting line. Each vertically extending

section

56a, 56b and 560 of contact carrier 26 is slidably movable through slot 52 in the bottom surface of the arc chute and into

respective compartments

30a, 30b and 306, while a portion 58a which extends between

sections

56a and 56b and a portion 58b which extends between

sections

56b and 560, slide within portions of slot 52 which extend vertically into respective

intermediate walls

44a and 44b of arc chute 14.

Base plate 12 can be constructed of rigid sheet metal, and as shown in FIG. 5, side walls 600 and 60b extend upward from opposite edges of and at'right angles to they bottom 18 of base plate 12. Side walls 60a and 60b have a respective pair of holes 62a and 62b extending therethrough, wherein each hole receives a respective boss 46 extending from arc chute 14 as shown in FIG. 2. Tabs 64a and 64b extend inwardly from respective side walls 60a and 60b so that their uppermost portions press against the bottom of the arc'chute when the contactor is assembled. Flanged sections 66a and 66b also extend from respective side walls 60a and 60b of base plate 12 in a plane parallel to and adjacent the bottom As shown in FIG. 6 magnetic member 16 is a standard E-shaped magnet such that its intermediate leg 70 extends through a slot 72 in coil 20, wherein coil 20 is mounted on the surface of the base 71 of member 16 and between its adjacent legs. Coil 20 has a pair of current carrying terminals 74a and 74b which are accessable externally from the contactor. Coil 20 also has a pair of raised cylindrical sections 76a and 76b, each of which receive one end of a pair of return springs 78a and 78b. The other end of return spring 78b presses against the bottom surface of a horizontal frontwardly extending section 80 of contact carrier 26, while the other end of return spring 78a presses against the bottom surface of a horizontally rearwardly extending section 82 (shown in FIG. 1) of carrier 26 so as to raise the contact carrier to such a position within slot 52 of arc chute 14 that the movable contacts are disengaged from stationary contacts when the contactor is deenergized. Movable magnetic member 24 has a dovetail slot 84 formed therein and extending from a top surface thereof to receive mating flange sections 86a and 86b which extend from the bottom central portion of movable carrier 26 as shown in FIG. 7. A flat spring 88 having downwardly extending curled edges 90a and 90b is placed between the base of slot 84 of member 24 and sections 86a and 86b of movable carrier 26. A portion 92 extends downwardly from the central bottom portion of carrier 26 so as to press against the top of spring 88 thereby causing the curled edges of the flat spring to dig against the base of the slot in the movable magnetic 'member thereby locking member 24 to carrier 26.

The assembly and operation of the contactor will now be explained. Stationary magnetic member 16 is positioned within base plate 12 in such a manner that slots 68a and 68b in the stationary magnetic member receive respective flanged sections 66a and 66b which extend from the sides of the base plate. Coil 20 is mounted on E-shaped magnetic member 16 in such a manner that its intermediate leg 70 passes through slot 72 in coil 20. The stationary contacts are fixed within respective compartments of the arc chute. Movable magnetic member 24 is placed into engagement with the bottom central section of movable contact carrier 26 and these components are locked together using flat spring 88. The vertical sections of movable contact carrier 26 are then moved through slot 52 in the bottom of arc chute 14 so that each vertical section of carrier 26 is positioned within a respective compartment of the arc chute. Each movable contact bridge and holding spring is then assembled within a respective window of each vertical section of the movable contact carrier so that each pair of movable contacts is aligned with a respective pair of stationary contacts. Retrun springs 78a and 78b are then placed into position between coil 20 and the respective horizontal frontwardly and rearwardly extending sections of movable contact carrier 26. The sides of the base plate are then pulled sufficiently outward until the bosses which extend from the sides of the arc chute can be placed in engagement within the respective holes in the sides of the base plate. Once this alignment occurs the outward pressure on the sides of the base plate is released and each of the bosses become positioned within a respective hole in the sides of the base plate as the sides of the base plate are pressed against the respective sides of the arc chute by the return spring force in the sides of the base plate.

inwardly extending tabs 64a and 64b of the base plate exert a force against the lower portion of the are chute such that each of the top portions of the bosses are forced against the top portions of their respective holes in the sides of the base plate. While the contactor has been assembled in the sequence of steps just described above, it should of course be understood that the sequence of various steps can be changed without deviating from the spirit of the invention.

As previously described when the contactor is deenergized, return springs 78a and 78b cause the vertical sections of movable contact carrier 26 to be so positioned within the respective compartments of the arc chute that the respective movable contacts are disengaged from the respective stationary contacts. When an appropriate current source is applied to the terminals of operating coil 20, sufficient magnetic flux is created to cause movable magnetic member 24 to move towards the pole faces of stationary magnetic member 16 and thereby overcome the opposing force of return springs 78a and 78b so that each of the respective movable contacts engages their respective stationary contacts, and in this condition the contactor is energized. Upon deenergization of coil 20, return springs 78a and 78b again move carrier 26 in a direction away from stationary magnetic member 16 so that each of the movable contacts become disengaged from the respective stationary contactsto deenergize the contactor.

It is thus seen that the contactor is so designed, and more particularly the base plate and are chute are so designed that they can be easily assembled together without the use of bolts and nuts and other time consuming assembly techniques. Furthermore, the contactor can be easily disassembled without fear that some bolts might be lost. Still further, by causing the top portion of each of the bosses in the arc chute to press against the top of the respective holes in the base plate, and by locating the stationary and movable contacts above the mold parting line of the arc chute, the variations in mold closing tolerance which cause variations in the dimension of the mold parting line are no longer a factor in the design of the contactor. Therefore the spacing between the stationary and movable contacts and the stationary and movable magnetic members can be more definitively designed so as to reduce the contactors coil burden, thus resulting in the use of a coil having smaller dimensions which in turn allow for the construction of a more compact contactor.

Although the invention has been described with reference to a specific embodiment thereof, numerous modifications thereof are possible without departing from the invention and it is desirable to cover all modifications falling within the spirit and scope of this invention. I a

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A contactor comprising in combination:

a. an electrically insulating arc chute having a pair of oppositely disposed side walls and a plurality of compartments formed therebetween, each of said side walls having at least one boss extending outwardly therefrom;

b. a plurality of stationary contacts, each of said stationary contacts fixed within one of said compartments of said are chute;

c. a movable contact carrier having a plurality of windows therewithin;

d. a plurality of movable contacts, each of said movable contacts mounted within a respective one of said windows in said contact carrier and extending therefrom so as to be in juxtaposition with a respective one of said stationary contacts;

e. a movable magnetic member fixed to said movable contact carrier;

f. an operating coil;

g. a base plate having a base member and a pair of rigid side members extending from opposite edges of said base member, each of said side members having a hole therein for receiving said boss extending from a respective one of said sides of said are chute as said side members press against adjacent respective side walls of said are chute, said base plate including means for forcing said are chute away from said base member so that the top portion of each of said bosses presses against a respective top portion of each of said holes;

h. a stationary magnetic member mounted on said base plate and supporting said operating coil, and in juxtaposition with said movable magnetic member; and

i. spring means for moving said movable magnetic member away from said stationary magnetic member when said contactor is deenergized so that each of said movable contacts is disengaged from each of said respective stationary contacts whereby upon energization of said contactor said movable magnetic member moves towards said stationary magnetic member thereby causing each of said movable contacts to engage each of said respective stationary contacts.

2. A contactor according to claim 1, wherein said forcing means is comprised of a tab extending inwardly from each side of said base plate, the top portion of each of said tabs pressing against a lower portion of said are chute to force said are chute away from said base members of said base. plate. I

3. A contactor according to claim 1, wherein said are chute has a mold parting line extending through each of said bosses and around the periphery of said are chute in a plane approximately parallel to said base member.

4. A contactor according to claim 3, wherein each of said stationary and movable contacts is positioned above said mold parting line so that the location of said movable and stationary contacts and said movable and stationary magnetic members are determinablefrom the top portion of each of said bosses in said are chute.

5. A contactor according to claim 1, wherein said spring means is comprised of a pair of springs extending between said coil and said movable contact carrier.

6. A contactor according to claim 1, wherein each side of said base plate has a flange extending inwardly therefrom approximately parallel to said base member and said stationary magnetic member has a pair of slots for receiving a respective one of said flanges for holding said magnetic member within said base plate.

7. A contactor according to claim 1, further including a flat spring for locking said movable contact carrier and said movable magnetic member together.

8. A contactor according to claim 1,.wherein said are chute includes a pair of sections protruding from a botboss located midway through the plane of said mold parting line,'and each of said side members of said base plate includes an additional hole for receiving a respective one of said additional bosses.

Claims

1. A contactor comprising in combination: a. an electrically insulating arc chute having a pair of oppositely disposed side walls and a plurality of compartments formed therebetween, each of said side walls having at least one boss extending outwardly therefrom; b. a plurality of stationary contacts, each of said stationary contacts fixed within one of said compartments of said arc chute; c. a movable contact carrier having a plurality of windows therewithin; d. a plurality of movable contacts, each of said movable contacts mounted within a respective one of said windows in said contact carrier and extending therefrom so as to be in juxtaposition with a respective one of said stationary contacts; e. a movable magnetic member fixed to said movable contact carrier; f. an operating coil; g. a base plate having a base member and a pair of rigid side members extending from opposite edges of said base member, each of said side members having a hole therein for receiving said boss extending from a respective one of said sides of said arc chute as said side members press against adjacent respective side walls of said arc chute, said base plate including means for forcing said arc chute away from said base member so that the top portion of each of said bosses presses against a respective top portion of each of said holes; h. a stationary magnetic member mounted on said base plate and supporting said operating coil, and in juxtaposition with said movable magnetic member; and i. spring means for moving said movable magnetic member away from said stationary magnetic member when said contactor is deenergized so that each of said movable contacts is disengaged from each of said respective stationary contacts whereby upon energization of said contactoR said movable magnetic member moves towards said stationary magnetic member thereby causing each of said movable contacts to engage each of said respective stationary contacts.

2. A contactor according to claim 1, wherein said forcing means is comprised of a tab extending inwardly from each side of said base plate, the top portion of each of said tabs pressing against a lower portion of said arc chute to force said arc chute away from said base members of said base plate.

3. A contactor according to claim 1, wherein said arc chute has a mold parting line extending through each of said bosses and around the periphery of said arc chute in a plane approximately parallel to said base member.

4. A contactor according to claim 3, wherein each of said stationary and movable contacts is positioned above said mold parting line so that the location of said movable and stationary contacts and said movable and stationary magnetic members are determinable from the top portion of each of said bosses in said arc chute.

8. A contactor according to claim 1, wherein said arc chute includes a pair of sections protruding from a bottom portion thereof and located adjacent the top of said coil for holding said coil against said stationary magnetic member.

9. A contactor according to claim 3, wherein each of said side walls of said arc chute includes an additional boss located midway through the plane of said mold parting line, and each of said side members of said base plate includes an additional hole for receiving a respective one of said additional bosses.