US3325616A

US3325616A - Electromagnetic contactor construction

Info

Publication number: US3325616A
Application number: US314212A
Authority: US
Inventors: Oswald M Bundy; John F Brick
Original assignee: A O CORP
Current assignee: Commander Electrical Equipment Inc; A O CORP
Priority date: 1963-10-07
Filing date: 1963-10-07
Publication date: 1967-06-13
Anticipated expiration: 1984-06-13

Description

Jun '13, 9 o. M. BUNDY ETAL ELECTROMAGNETIC CONTACTOR CONSTRUCTION 4 Sheets-Sheet 1 Filed Oct. 7, 1963 INVENTOR5.

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floAerf L lehqyren June 13, 1967 v o. M. BUNDY E'i'AL 3,325,616

ELECTROMAGNETI C CONTACTOR CONSTRUCTION Filed Oct. 7, 1965 4 Sheets-Sheet 4 I, am

/)i fiw INVENTORfi United States Patent 3,325,616 ELECTROMAGNETIC CONTACTOR CONSTRUCTION Oswald M. Bundy and John F. Brick, Cleveland, Ohio, assignors, by mesne assignments, to A. O. Corporation,

Milwaukee, Wis., a corporation of New York Filed Oct. 7, 1963, Ser. No. 314,212 9 Claims. (Cl. 200-147) This invention relates to an improved electromagnetically actuated switching device designed for use in electric power circuits requiring repeated circuit openings and closings.

The switching device of the invention utilizes modular construction in a manner such that the power circuit being controlled by it is fully insulated from the supporting base member of the device. The switching device may therefore be mounted on any type of control panel, i.e. conducting or non-conducting. This construction also permits the front mounting of the device and connection in the power circuit from the front thereof. No space is required behind the control panel upon which the device is to be mounted to permit installation, servicing, electn'cal connection or replacement of the switching unit. Since .the supporting base member of the device of the invention is rendered nonconducting, the need to use bulky and highly expensive slate mounting slabs is also eliminated.

The electromagnetically actuated armature of the switching device utilizes an inverted double fulcrum knife edge arrangement for support during pivotal movement. The knife edges project upwardly and engage their respective fulcrums from beneath and thereby produce a self-cleaning action. Both are fully shielded from particles falling from above such as might be expected from the wearing of the contact tips. Both the inner and outer knife edges of the armature are positioned to permit the gravitational discharge of foreign matter from the areas of the knife edges and to prevent any accumulation of such matter in the areas of the knife edges which might eventually lead to the malfunctioning of the armature.

The movable contact of the switching device is insulated from the magnetic portion of the armature by a glass filament filled insulating member to produce a nonpolarized arm. To increase impact strength, the member is maintained under compression by a compression clamp which is associated with a movable contact backing im pact spring. Both the spring and the material of the member act to product a cushioning effect on the impact of the electrical contacts when the electromagnet is energized and the contacts are slammed together. This cushioned impact response aids in substantially extending the life of the contact elements.

The flexible connector or power circuit shunt in the device of the invention is connected at a point spaced from the supporting base member and is electrically insulated therefrom. It does not, as in the case of presently available devices, require the mounting of the unit on a separate insulating support prior to final installation nor mounting or electrical connection from behind a control panel.

The supporting base member of the subject invention while being fully insulated from the power circuit forms a part of the magnetic circuit of the armature actuating electromagnet.

A glass-filled polyester member is secured to the supporting base member and is employed to support the arc blow-out assembly of the unit and the stationary contact. It also serves as the pivot point and point of attachment for the arc chute. Since the glass-filled polyester is an insulating material, the supporting base is electrically in- Patented June 13, 1967 sulated from the blow-out assembly and the stationary contact of the power circuit.

A self-extinguishing glass-filled polyester resin is used in the manufacture of the arc shield of the device of the invention. The are shield or chute is easily and positively attached to the unit by a pivot support and a spring clip arrangement at the head of the shield and a spring clip engageable with a circuit connector element at the foot of the shield.

Other objects and advantages of the invention shall become apparent in the following description and drawings which illustrate the best mode presently contemplated for carrying out the invention.

In the drawings:

FIGURE 1 is a side elevation of the switching device of the invention;

FIG. 2 is an exploded fragmentary view of the device shown in FIGURE 1;

FIG. 3 is a side elevation of the device with parts broken away; and

FIG. 4 is a side elevation of the device with the armature of the invention shown in section to particularly illustrate the pivot construction of the moveable contact and the inner knife edge arrangement.

The drawings and following description describe a direct current or DC magnetic contactor type switching device. The contactor is designed to handle motor circuits and their contingent overloads and is capable of performing a large number of opening and closing operations without attendance.

The contactor shown in FIGURE 1 generally includes an electromagnet 1, an armature assembly 2 carrying a movable contact 3, a stationary contact 4, and an arc shield 5 associated with a blowout structure 6.

As may be best seen in FIG. 2, the coil 7 of the electromagnet 1 is slipped over core 8 and aligned with base member 9 by a locating and position maintaining projection 10 which fits into an opening 11 in the base. The electromagnet is secured to base member 9 by a combination of a coil spring washer 12 located between the base and the coil and a coil retainer 13 which is bolted to the core and the outer end of the coil. The coil is also provided with a pair of terminals 14. This construction utilizes base member 9 as a portion of the magnetic circuit of electromagnet 1 and permits realization of an appreciable space and material saving.

The portion of the armature assembly 2 of the contactor which acts in response to the energization of the magnet 1 to complete the magnetic circuit is electrically insulated from the movable contact 3 by a chopped glass fiber filled polyester molded member 15. FIG. 4 shows a tang or uppermost portion of arm 16 projecting into a cavity in the body of member 15 and at a slight angle to the longitudinal axis thereof. The space between the tang portion of arm 16 and the cavity in member 15 is filled with an epoxy cement of high compressive strength. This provides an insulated arm that is capable of withstanding the impact forces of the armature closing and the forces exerted on the arm by contact 3. The lower end of molded member 15 is secured to arm 16 by screws 17.

Member 15 overlaps and extends above the upper edge of arm 16. The backside of the member is formed with a vertically extending recess 18 which serves to receive the stem portion of movable contact 3. Recess 18' includes a laterally extending notch 19 which acts as a main pivot suppor for contact 3. An auxiliary pivot bearing plate 20, which acts as a backing support for molded member 15, is fitted into recess 18. Plate 20 is formed to project into lateral notch 19, as is shown in FIG. 4, and to serve as a high strength pivot hearing at that point.

The upper portion of plate 20 extends laterally outwardly from molded member 15 and is secured in firm contact with the surfaces of recess 18 between compression clamp 21 and spring retainer 22 by screws 23. Plate 20 acts in conjunction with the upper tang portion of arm 16 and clamp 21 to maintain the glas filled polyester molded member under substantial compressive stress. This aids in preventing the fracture or breaking of the molded member due to repeated armature impact while taking advantage of the materials insulating and impact damping characteristics.

The lower stern portion of movable contact 3 is pro vided with a pivot 24 which projects into that portion of plate 20 which conforms to notch 19. The movable contact which is held again plate 20 by a compression spring 25 is permitted a degree of recoil movement in response to the closing impact of the contact during op eration by the pivoting of contact 3 about pivot 24 on plate 20. The recoil action of the contact thus attained serves to damp the impact shock of the closing contacts on both the movable contact and the arm 16.

The recoil response to the energization of magnet 1 serves to assure the reliable making of electrical contact between the contacts. This is accomplished by the production of a contact wiping and rolling action as the movable contact 3 strikes the stationary contact 4 and slides vertically along it as the movable contact begins to pivot in response to the impact force. While it slides, the movable contact scrapes off any accumulation of foreign contact disrupting elements in its path insuring good electrical conductivity between the contacts.

When contact 3 comes to rest against contact 4, the combination of the force of compression spring 25 on contact 3 and the pivoting action of the contact in relation to armature 2 maintains a parting force between the contacts while the coil is energized. When the coil is de-energized, this parting force acts to bring about the rapid breaking of the electrical circuit between the contacts.

A space of predetermined magnitude exists between the leading edge of the stem of movable contact 3 and auxiliary pivot bearing plate 20. This space provides a means for readily inspecting the extent of contact wear. It is only necessary to raise arc shield and to measure the spacing with armature 2 fully closed. When this spacing has been reduced by contact wear to a predetermined minimum below which adequate spring pressure on the contacts cannot be assured, the contacts may be replaced. In operating with contactors at the 100 to 150 ampere level, the spacing of a new contact from the bearing plate has been generally about 7 and it has been found to be desirable to replace worn contacts when this spacing is reduced to about FIGS. 2 and 4 show the armature construction most clearly. Arm 16 is shown extending vertically downwardly from the molded member 15. At a point almost in line with the lowermost portion of the molded member, both of the outer edges of arm 16 are bent at an angle nearly normal to the plane of the arm to form outer Pivot elements 26 and outer knife edges 27. A generally rectangular shaped opening 28 is provided in arm 16 initiating at about the level of the pivot elements '26 and extending downwardly therefrom. Near the lower extremity of opening 28, the lower portion of arm 16 is bent in a direction nearly parallel to that of pivot elements 26. The outer end of the bent portion of arm 16 is reduced in crosssection at shoulders 29 to form arm stop 30. A pivot support plate 31, which is engageable with inner knife edges, is secured to arm 16 just above the level of outer pivot elements 26. Plate 31 extends outwardly from arm 16 between and nearly parallel to outer pivot elements 26 and to the line described by knife edges 27 and then downwardly therefrom to form an inner pivot support 32.

To position armature assembly 2 in operative relation with base member 9, a plate 33 is secured to base 9 and extends therefrom in a direction normal to the plane of base 9 and parallel to a pair of frame elements 34 which are secured to base 9. The frame elements are connected at their extremities by a glass filled polyester connector mounting block 35. The outer end of plate 33 is forked to provide a pair of outer knife edge supports 36 and a space therebetween to provide freedom for the pivoting movement of pivot support plate 31 of arm 16.

As is shown in FIGS. 2 and 4, a pivot plate 37, formed with a pair of forked inner pivot elements 38 and inner knife edges 39, is located in openings 40 of plate 33 by dowels 41 and secured thereto by shoulder bolts 42. Armature assembly 2 is inserted between frame elements 34 from the underside thereof and in a manner such that inner knife edges 39 engage the inner pivot support 32 of plate 31. Support 32 then serves as a bearing surface for the pivotal motion of armature 2 on inner knife edges 39. The outer knife edges 27 on arm 16 are designed to lie generally on a line with edges 39. The outer knife edges engage the outer knife edge supports 36 of plate 33 and co-operate with the inner knife edges to produce a pivotal armature movement under greatly reduced frictional conditions.

Shoulders 29 of arm 16, in assembled position, lie in close proximity to shoulder bolts 42 and arm stop 30 extends between the bolts. When the contactor is in a deenergized condition, the beveled edge of the arm stop 42 engages the complementing beveled edge of a resilient stop block 43 which is fixed to base 9. The complementing beveled edges of the arm stop and stop block and the resilient material from which the stop block is fabricated co-operate to produce a shock damping effect on armature assembly 2. This damping effect minimizes the bouncing tendency of armature assembly 2 when the contactor is de-energized and the contacts are broken apart, which is of considerable importance as it has been found that this bounce tendency can act to prolong or re-establish the are produced by the separation of the contacts.

To reduce the possibility of knife edge rattle during the opening and closing operations of the contactor, a compression spring 44 is provided which extends through arm opening 28 and between the forked inner pivot elements 38 and bears against the inner surface of pivot support plate 31. The opposite end of spring 44 bears against spring retainer 45 which projects through opening 28 and is bolted to the underside of pivot plate 37. The spring serves to force the knife edges, and particularly outer edges 27, into firm engagement with their respective bearing surfaces and to maintain such engagement during repeated contactor operations. Spring 44 will also act to exert some degree of parting force to contacts 3 and 4 when the electromagnet of the device is de-energized.

One of the advantages of employing inverted knife edges as 27 and 39 which bear on double fulcrum supports lies in their self-cleaning action during operation. The inner knife edges 39 which pivot about the underside of support plate 31 are fully shielded from foreign matter and particularly eroded material from the contacts falling from above the plate. Any particles which should reach the area of the knife edges will gravitate therefrom. The construction thereby eliminates the difficulties which would be encountered if an accumulation of foreign matter could develop in the area of the knife edges. Such an accumulation would increase the friction on the knife edges and accelerate the wear thereof. In time, the accumulation could reach such a magnitude that the pivoting arc of the knife edges might become severely curtailed or frozen. The armature movement, therefore, could be reduced to a point where electrical contact of the devices contacts cant be consistently made or broken thereby greatly reducing the reliability of the contactor. The outer knife edges 27 are similarly protected from foreign particle accumulation and are able to discharge by gravity, any particles which might work into the area of the knife edges. The armature 2 of the contactor of the invention will, therefore, pivot during repeated openings and closings of the electrical contacts in a reliable, trouble-free manner wit-h a minimum of wear.

The magnetic contactor is connected to a source of electrical power through front connector plate 46. The bottom of this plate, as is shown in FIG. 2, is formed with extensions which are adapted to be connected to the leads of a power source. The upper portion of plate 46 is provided with similar extensions which are bent at angles normal to the plane of the plate and are designed to serve as a suitable surface for snap-attaching the lower end of arc shield 5 and to establish an electrical connection therewith. Plate 46 is bolted to connector block 35 and insulated from frame elements 34 and base member 9 thereby.

To establish a circuit between plate 46 and contact 3, a flexible connector 47, which is resiliently responsive to the pivoting motion of armature assembly 2, is electrically connected at one end to connector plate 46 and at the other end to the base portion of movable contact 3. This electrical circuit is fully insulated from base member 9 and the magnetic circuit of the device by connector block 35 and molded member 15.

The blowout structure of the DC. contactor, generally designated 6, is electrically insulated from base member 9 by base insulator 48 which is generally fabricated from a material such as a glass reinforced polyester resin. The base insulator serves as an insulated mounting medium for the blowout assembly.

As may be seen in FIG. 3, the blowout coil assembly 49 is bolted at one endto insulator 48. The stationary contact 4 of the device is bolted to the other end of, assembly 49. The coil assembly further includes a coil 50 in the circuit with contact 4 and a connector 51 for completing a circuit through the DC. cont-actor. A cylindrical insulating sleeve 52 is inserted into coil 50 and a blowout core 53 is inserted into the sleeve. Blowout ears 54 are mounted on each side of the coil assembly 49 and cooperate therewith to produce a magnetic flux-field which acts both to control the lateral path of an electric arc and to co-operate with the arc shield 5 to elongate and extinguish the are. A rear arc runner 55 is assembled to the leading edge of assembly 49 adjacent stationary contact 4. The trailing edge of arc runner 55 is bolted to arc shield pivot support 56 and both are assembled to base insulator 48. An arc shield spring clip 57 is bolted to insulator 48 with pivot support 56 and acts with it tofirmly engage the pivoting endof arc shield 5.

The arc shield 5 of the device is generally. L-shaped in configuration and is fabricated in two symmetrical elongated sections which are. bolted together.. The materials used in fabricating the arc shield are generally glass filled polyester resins which are hot molded for added strength. The polyester material usually selected is one which produces a gas when subjected to an electric arc to :aid in the extinction thereof.

To couple the arc shield 5 to base insulator 48, a pin 58 is secured transversely to the assembled shield halves. This pin is snapped into the opening provided between pivot support 56 and spring clip 57 and is free to rotate therein as is arc shield 5. The lower edge of the shield is provided with an electrically conductive spring clip 59 which engages the upper portion of front connector plate 46 when the shield is in closed operative position. As may be best viewed in FIG. 3, spring clip 59 is formed with a pair of extensions which extend upwardly along both sides of the shield and are electrically connected to a front arc runner 60. This are runner is secured between the halves of arc shield 5 at an angle to the longitudinal axis thereof. The innermost edge of arc runner 60 is positioned closely adjacent to movable contact 3 when the contact is in the open position. Below are runner 60, a transverse insulating barrier 61 is molded between the shield halves, and a similar barrier 62 is formed at the upper end of the shield below pin 58. The space between these barriers is open and provides an arc elongation and confining path.

In operation, front connector plate 46 and connector 51 are joined to the leads of a power circuit. Leads 14 of the coil 7 of electromagnet 1 are connected in a magnet operating circuit.

The movable contact 3 is shown in the drawings to be normally Open although in some applications it may be desirable to employ normally closed contacts, The movable contact remains in the open position by the force of gravity. The at rest position of contact 3 with respect to stationary contact 4 is determined 'by the engagement of arm stop 30 with stop block 43.

When it is desired to complete a circuit through contacts 3 and 4, the coil 7 of the electromagnet is energized. This acts to quickly draw armature assembly 2 against the coil retainer 13 of the electromagnet. The relatively frictionless pivotal motion of the armature is permitted by substantially a line engagement of the knife edges 27 and 39 With their

respective supports

36 and 31. The low friction motion extends the life of the contactor and reduces power requirements.

Compression spring 44, which is connected to spring retainer 45 of the base, is biased against pivot plate 31 and thereby acts to urge knife edges 27' of armature assembly 2 securely against their supports 36. In so doing, any tendency the knife edges have of working loose and rattling is minimized.

During the pivotal motion of armature 2 in response to the energization of electromagnet 1, movable contact 3 impacts against stationary contact 4. Due to spring biased pivotal mounting of contact 4 on molded member 15, the contact responds to the impact by pivoting about pivot 24 in the notch 19 to which the auxiliary pivot bearing plate 20 conforms. Spring 25 acts to exert a resisting force against the pivotal motion of contact 4, and, in so doing causes the frictional engagement of the surfaces of both contacts 3 and 4 and produces a wiping action thereupon. The wiping action will scrape or disrupt any non-conducting oxide or other coating or accumulation which may develop on the contacts during periods of inactivity. The reliable completion of a circuit through the contacts when required is thereby assured.

The strength of electromagnet 1 is maintained at a level sufiicient to keep movable contact 3 in secure engagement with contact 4 in spite of the contact separating force being exerted upon contact 3 by the combination of pivot 24 and spring 25. The distance separating the leading edge of the stem of contact 3 from the auxiliary pivot bearing plate 20, as mentioned earlier, must be maintained above a predetermined minimum if this separating force is to be consistently produced to rapidly separate the contacts upon de-energization of the electromagnet.

The glass filled polyester material of molded member 15 is protected from direct effects of the impactshock of the contacts. This is accomplished by compressing the material on one side between clamp 21 and the upper tang portion of arm 16 and by compressing the material on the other side between the tang and the inner surface of auxiliary pivot plate 20. The compression of the glass filled polyester material produces the necessary fracture resistant rigidity required while still permitting utilization of the impact damping qualities of the material.

The power circuit from front connector plate 46 is completed through flexible connector 47, contacts 3 and 4, blowout assembly 49, and connector 51. When it is desired to break this circuit, electromagnet 1 is de-energized. At this moment, the combined action of pivot 24 and spring 25 quiclaly separates the contacts. Spring 44 serves to assist in the separation of the contacts at this point.

As contacts 3 and 4 begin to separate, an electric arc is drawn between them. One end of this are is transferred from contact 4 to the rear arc runner 55, and the other end is transferred from contact 3 to the front are runner 60 of arc shield 5. The circuit through arm 16 is shunted at this time through front connector 46 and spring clip 59 to are runer 60. The magnetic flux created by blowout assembly 49 acts to extend and elongate the are which is confined between the walls of arc shield 5 until it becomes extinguished. Arc shield barriers 61 and 62 prevent the are from progressing beyond the limits of the arc runners.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. An electromagnetic contactor comprising a metallic mounting plate-like base for mounting upon another surface with a front face of the base exposed, a pair of separable electrical contacts positioned on the front face of the base and electrically insulated from the base, circuit connecting means disposed to the front face of the base for connecting the contacts in a circuit, an arc blowout assembly mounted on the front face of the base and electrically insulated from the base, the arc blowout assembly co-operating with the contacts to extinguish an electric are initiated by the separation of the contacts, means associated with one of the contacts to effect the movement thereof relative to the other of the contacts, and an arc shield coupled to the arc blowout assembly to confine the are produced by the separation of the contacts; the contacts, circuit connecting means, are blowout assembly and are shield being removable from the front face side of the base and thereby removable and replaceable with the base secured to the surface and permitting mounting of the metallic mounting base on conducting or non-conducting surfaces.

2. An electromagnetic contactor comprising a base, a stationary contact mounted upon the base, a second Contact having a fulcrum thereon adapted to engage a knife edge disposed in a generally vertical plane and secured to the base, the second contact being disposed to pivot on the knife edge and to repeatedly make and break electrical circuits with the stationary contact in response to the operation of a contact operatingmeans, the second contact having a knife edge aligned with the first knife edge secured to the base and pivotally engageable with a fulcrum secured to the base, the fulcrums of both knife edges being positioned to shield the respective edges from the effects of falling matter, and an arc blowout device associated with the contacts, the blowout device serving to dissipate the are produced by the separation of the contacts in response to the action of the contact operating means.

3.'An electromagnetic contactor comprising first and second contacts, the first contact being immobile and electrically connected to an arc blowout assembly adapted to produce an arc dissipating flux; the blowout assembly including a blowout coil in the circuit with the first contact, blowout ears, a core and an arc runner associated with the blowout coil and ears; metallic mounting base having a top and a bottom, the arc blowout assembly and first contact being mounted upon the upper portion of the metallic mounting base; the second contact being positioned for pivotal movement with respect to the first contact; the second contact being supported on the base by a knife edge disposed below the contacts and with the knife edge facing upwardly, the second contact being disposed for pivotal response upon the knife edge to the action of a movable contact operating means; the mounting of the knife edge acting to shield the edge from foreign matter and to permit gravitation of any such matter from the area of the knife edge; electrical connector means for connecting the first and second contact in a circuit which may be opened or closed by the action of the movable contact operating means in combination with the arc dissipating effect of the blowout assembly; and an arc shield associated with the blowout assembly and the contacts; the arc shield having an arc runner which is adapted to receive an electric are from the movable contact upon the opening thereof and to act with the arc runner of the blowout assembly to elongate and dissipate the are formed by the separation of the contacts.

4. An electromagnetic contactor comprising a metallic plate-like base for mounting upon another surface with a front face of the base exposed and having a top edge and a bottom edge, a pair of electrical contacts assembled upon'a base and electrically insulated therefrom, the contacts including means for connecting them into a circuit and from the front of the base, one of the contacts being movable in relation to the other contact and separable therefrom in response to a contact actuating means, an arc blowout assembly including a coil in the circuit with one of the contacts, a core, blowout ears and an arc runner in electrical communication with one of the contacts and adapted to receive an arc from the contact upon separation of the contacts, the blowout assembly being mounted upon and insulated from the base to produce in conjunction .with the insulated contacts an electrically isolated base which may be mounted upon a conducting or non-conducting surface, an arc shield having a pivot means at a first extremity thereof, the pivot means being removably and pivotally engageable with a pivot support and retaining means disposed adjacent the blowout assembly, said shield extendingover the blowout assembly and the contacts in close proximity thereto, the arc shield having an insulating barrier adjacent the pivot means and the blowout arc runner to block arc travel, the shield having a shield arc runner spaced from the other of the contacts and adapted to receive an arc upon the separation thereof, the shield having a longitudinal opening extending from the shield are runner to the first barrier to permit the extension and elongation of an are produced by the separation of the contacts, a second insulating barnet in the arc shield positioned in insulating proximity to the shield are runner to halt arc travel at the outer extremity of the arc runner, and conducting 'means extending from the arc runner of the arc shield to the means connecting one of the contacts into the circuit to permit transfer of the current upon contact separation from the contact to the arc runner.

5. The electromagnetic contactor of claim 4 wherein the means connecting the movable contact is a connector plate and conducting means of the arc shield extending from the arc runner to the extremity thereof opposite the pivot means is removably engageable with the connector plate to permit the pivoting of the arc shield to inspect contact wear.

6. The electromagnetic contactor of claim 4, wherein a magnetically actuable armature is pivotally supported to the base below the blowout assembly, the armature having an insulating member assembled to an extremity thereof, said second electrical contact being pivotally mounted on the insulating member and electrically insulated from the armature thereby, means resiliently biasing the second electrical contact against the insulating member to dampen the impact shock thereon of the closing contacts and to aid in reliably completing an electrical circuit therethrough by producing a wiping action across the first contact, electromagnetic means connected to the base and having a magnetic circuit including the base and said armature and attracting the armature upon energization thereof and producing the pivotal motion of the armature on the knife edges in response thereto to make and break an electrical circuit through the contacts, and means for connecting the first and second electrical contacts in a circuit.

7. An electromagnetic contactor comprising a fiat platelike metallic base for mounting upon another surface with a front face of the base exposed and having a selected top edge and bottom edge, a first electrically insulating element secured to the base, a fixed electrical contact secured to the insulating element, a knife edge member secured to the front surface of the base and extending outwardly therefrom and terminating in an upwardly facing knife edge, a magnetic armature having a plate-like fulcrum overlying and resting upon the knife edge to pivotally support the armature upon said knife edge, a knife edge member secured to the armature and terminating in a knife edge disposed in general alignment with the knife edge of the base member and facing upwardly on the metallic base, a fulcrum member secured to the base and terminating in a plate-like fulcrum overlying the knife edge secured to the armature, an insulating member secured to the outer extremity of the armature, a pivoting contact resiliently and pivotally mounted to the insulating member of the armature and terminating in alignment with the fixed contact secured to the insulating element, the resilient mounting of the pivoting contact providing movement of the pivoting contact with respect to the insulating member and including movement of the pivoting contact over the fixed contact to provide a cleaning and wiping action across the fixed contact, an electromagnetic means connected to the base and including a magnetic core member interconnected to the base to define a magnetic path including the core and the base and said armature, the energization of the electromagnetic means being such as to attract the armature to pivot the armature on said knife edges, means exposed and operable from the front of said contactor to connect said contacts in an electrical circuit, energizing means con- 10 nected to said electromagnetic means from the front of said assembly, and an arc blowout assembly mounted to said insulating element and mounted with respect to said contacts to elongate and dissipate any are formed during the separation of said contacts.

8. The electromagnetic contactor of claim 6 wherein the material of the insulating member carrying the pivoting contact is maintained under compression by compressing means to prevent the fracture thereof during repeated contact making impacts.

9. The electromagnetic contactor of claim 6 including a pivot plate compressively secured to the insulating member thereof by compressing means and wherein the pivoting contact is disposed in pivoting relation to the pivot plate while being resiliently biased thereagainst to reduce the effect of contact impact during operation and to force the contacts apart upon tie-energization of the electromagnet.

References Cited UNITED STATES PATENTS 1,398,982 12/1921 Tritle 200-147 2,145,327 1/1939 Van Valkenburg 200147 X 2,231,973 2/ 1941 Van Valkenburg et al.

200147 X 2,432,899 12/ 1947 Immel 200147 X 2,669,620 2/1954 McLane et al 200-147 X 2,943,170 6/1960 Vradenburgh 200-166 X 3,155,801 11/1964 Pokorny 200-447 X ROBERT K. SCHAEFER, Primary Examiner.

R. S. MACON, Examiner. I

Claims

1. AN ELECTROMAGNETIC CONTACTOR COMPRISING A METALLIC MOUNTING PLATE-LIKE BASE FOR MOUNTING UPON ANOTHER SURFACE WITH A FRONT FACE OF THE BASE EXPOSED, A PAIR OF SEPARABLE ELECTRICAL CONTACTS POSITIONED ON THE FRONT FACE OF THE BASE AND ELECTRICALLY INSULATED FROM THE BASE, CIRCUIT CONNECTING MEANS DISPOSED TO THE FRONT FACE OF THE BASE FOR CONNECTING THE CONTACTS IN A CIRCUIT, AN ARC BLOWOUT ASSEMBLY MOUNTED ON THE FRONT FACE OF THE BASE AND ELECTRICALLY INSULATED FROM THE BASE, THE ARC BLOWOUT ASSEMBLY CO-OPERATING WITH THE CONTACTS TO EXTINGUISH AN ELECTRIC ARC INITIATED BY THE SEPARATION OF THE CONTACTS, MEANS ASSOCIATED WITH ONE OF THE CONTACTS TO EFFECT THE MOVEMENT THEREOF RELATIVE TO THE OTHER OF THE CONTACTS, AND AN ARC SHIELD COUPLED TO THE ARC BLOWOUT ASSEMBLY TO CONFINE THE ARC PRODUCED BY THE SEPARATION OF THE CONTACTS; THE CONTACTS, CIRCUIT CONNECTING MEANS, ARC BLOWOUT ASSEMBLY AND ARC SHIELD BEING REMOVABLE FROM THE FRONT FACE SIDE OF THE BASE AND THEREBY REMOVABLE AND REPLACEABLE WITH THE BASE SECURED TO THE SURFACE AND PERMITTING MOUNTING OF THE METALLIC MOUNTING BASE ON CONDUCTING OR NON-CONDUCTING SURFACES.