US3553613A - Magnet and movable contact support structure for a multiple contact electromagnetically actuated switch - Google Patents

Abstract

A MULTIPLE CONTACT ELETROMAGNETICALLY ACTUATED CONTACTOR HAVING A BELL CRANK CONNECTION BETWEEN A MAGNET ARMATURE AND A MOVABLE CONTACT CARRIER. THE CONTACTOR INCLUDES AN ARRANGEMENT WHEREBY THE ELECTROMAGNET AND THE CONTACTS ARE ENCLOSED IN SEPARATE HOUSING. THE HOUSING FOR THE CONTACTS INCLUDES AN INSULATING BASE AND A BARRIER WHICH ACTS AS A COVER FOR THE BASE AND COOPERATES WITH THE BASE TO PROVIDE A ROW OF COMPARTMENTS. EACH OF THE COMPARTMENTS HAS A PAIR OF STATIONARY CONTACTS AND A MOVABLE CONTACT THEREIN AND THE WALLS OF THE COMPARTMENTS PROVIDE A HIGH DEGREE OF INTERPHASE ISOLATION BETWEEN THE CONTACTS IN ADJACENT COMPARTMENTS. THE MOVABLE CONTACTS ARE OPERATED BY A U-SHAPED CONTACT CARRIER THAT IS MOVABLE IN A SLOT IN A REAR WALL OF THE BASE AND HAS PORTIONS EXTENDING THROUGH OPENINGS IN THE REAR WALL INTO THE COMPARTMENTS. THE CONNECTION BETWEEN THE BELL CRANK AND CONTACT CARRIER IS ARRANGED SO THAT THE BARRIER CAN BE REMOVED WHEN THE CONTACTS ARE SECURELY WELDED TOGETHER AND WILL CAUSE THE MOVABLE CONTACTS TO SEPARATE FROM THE STATIONARY CONTACTS DURING LIGHT WELDS BETWEEN THE CONTACTS.

Description

Jam-5, 1971 M TURNBULL ET AL 3,553,613

MAGNET AND MOVABLE CONTACT SUPPORT STRUCTURE FOR A MULTIPLE CONTACT ELECTROMAGNETICALLY ACTUATED SWITCH Filed July 25, 1969 v 2 SheetsSheet 1 34 64 40 INVIJN'I'UR MERLIN Y. TURNBULL HAROLD E. WHITING Jan. 5, 1971 M. Y. TURNBULL ETAL 4 3,553,613 MAGNET AND MOVABLE CONTACT SUPPORT STRUCTURE FOR A MULTIPLE CONTACT ELECTROMAGNETICALLY ACTUATED S WITCH Filed July 23, 1969 2 Sheets-Sheet INVEN'IUR.

' MERLIN Y.TURNBULL HAROLD EWHITING United States Patent 01 hce 3,553,613 Patented Jan. 5, 1971 3,553,613 MAGNET AND MOVABLE CONTACT SUP- PORT STRUCTURE FOR A MULTIPLE CONTACT ELECTROMAGNETICALLY AC- TUATED SWITCH Merlin Y. Turnbull, Brookfield, and Harold E. Whiting, Milwaukee, Wis., assignors t Square D Company, Park Ridge, Ill., a corporation of Michigan Filed July 23, 1969, Ser. No. 844,100 Int. Cl. H0111 50/16 US. Cl. 335-132 Claims ABSTRACT OF THE DISCLOSURE A multiple contact electromagnetically actuated contactor having a bell crank connection between a magnet armature and a movable contact carrier. The contactor includes an arrangement whereby the electromagnet and the contacts are enclosed in separate housings. The housing for the contacts includes an insulating base and a barrier which acts as a cover for the base and cooperates with the base to provide a row of compartments. Each of the compartments has a pair of stationary contacts and a movable contact therein and the walls of the compartments provide a high degree of interphase isolation between the contacts in adjacent compartments. The movable contacts are operated by a U-shaped contact carrier that is movable in a slot in a rear wall of the base and has portions extending through openings in the rear wall into the compartments. The connection between the bell crank and contact carrier is arranged so that the barrier can be removed when the contacts are securely welded together and will cause the movable contacts to separate from the stationary contacts during light welds between the contacts.

The present invention relates to electromagnetic type switching devices and more particularly to the constructional details and the arrangement of the components of a multiple contact electromagnetically operated switching device.

Electromagnetic switching devices of the type with which the present invention is concerned are commonly known as contactors and are furnished as devices of varying sizes having ratings in accordance with standards promulgated by the National Electrical Manufacturers Association, commonly known as NEMA. An example of a contactor construction which is particularly suited to control loads of 50 amperes or less, which corresponds to a NEMA Size 2 device is disclosed in US. Pat. No. 3,354,415, which was granted on Nov. 21, 1967 to the inventors Joseph I. Gribble, Kenneth J. Marien and Harold E. Whiting.

While the proportions of the device shown in the Gribble et al. patent may be increased to control currents greater than 50 amperes, economic and physical size limitations dictate that additional features should be incorporated therein if currents having a magnitude two or three times 50 amperes are to be controlled by the device. The structure according to the present invention provides a higher degree of interphase isolation between adjacent switching contacts, a greater capability to extinguish arcs generated by the opening of the switching contacts, increased pressures between the switching contacts as well as a greater contact mass to enable the device to conduct the higher current values without overheating and without increasing the contact bounce characteristics of the device than was included in the structure disclosed in the Gribble et al. patent. Thus while the device according to the present invention incorporates the desirable features and advantages included in the device as disclosed in the Gribble et al. patent, it additionally includes an improved movable contact carrier and an arrangement which will permit access to the contacts which are operated within closed compartments when the contacts are firmly welded together and will break the welds between the contacts when the contacts are lightly welded together.

Accordingly, it is an object of the present invention to provide an electromagnetic switching device, commonly known as a contactor which, without a proportionate increase in cost or physical size, will be capable of switching larger currents without sacrifice of the features and advantages incorporated into the structure disclosed in the Gribble et al. patent.

An additional object is to provide a contactor that has a plurality of stacked components including an insulating base having spaced stationary contacts mounted on its front surface, an insulating barrier detachably mounted on the front surface of the base and cooperating with the base to define a plurality of spaced compartments that are substantially closed and electrically isolated from each other with each of said compartments having a pair of spaced stationary contacts therein, and a U-shaped contact carrier that has a portion movable in a slot in the rear wall of the base and a plurality of spaced projections extending into the compartments carrying movable contacts which are arranged to bridge the stationary contacts in the compartment when the magnet is energized.

A further object is to provide a contactor with an insulating base and an insulating barrier which is detachably mounted on a front surface of the base and cooperates with the base to provide a row of substantially closed electrically isolated compartments with each of the compartments containing a pair of stationary contacts that are disposed in spaced relation on opposite sides of a slot in a rear wall of the base, a U-shaped movable contact carrier that has a bight portion movable in the slot carrying spaced movable contacts which are arranged to bridge the stationary contacts and arm portions extending from the bight portion externally of a front surface of the barrier and a connection between open ended sockets on the free ends of the arms of the carrier and free ends on a pair of arms of a bell crank lever which will permit the bell crank lever to be disengaged from the contact carrier when the barrier is detached from the base and cause light welds between the movable contacts and the stationary contacts to be broken when the bell crank is rotated in a direction to separate the movable contacts from the stationary contacts and to guide the movements of the carrier from three points which include the connection between the arms of the bell crank lever and the carrier and a guide groove centrally located in the slot in the rear wall of the base.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

FIG. 1 is a perspective view of a switching assembly incorporating the features of the present invention.

FIG. 2 is a cross sectional view taken generally along line 22 in FIG. 1.

FIG. 3 is a perspective view of the components of a bell crank lever used in the switching assembly in FIG. 1.

FIG. 4 is a perspective view of the molded components of the movable contact carrier used in the switching assembly in FIG. 1.

FIG. 5 is a side view of a bearing assembly that is carried on the arms of the bell crank lever in FIG. 3.

FIG. 6 is a cross sectional view taken along line 6-6 in FIG. 5.

Referring to the drawing, and particularly to FIG.1, there is shown an electromagnetic switch assembly 20 having a plurality of components that are stacked one upon the other. The components of the assembly include a metal mounting plate 22, an insulating sheet-like member 24, an insulating base 26, an insulation barrier 28, a metal housing 30, and a cover 32, each of which is disclosed and described in an application for U.S. patent, Ser. No. 844,188, which was filed concurrently herewith.

The metal mounting plate 22 is formed of a stamped metal part and provides a means to secure the switch assembly 20 to a vertical panel and the like, not shown. When the plate 22 is secured to a panel, an edge 34 becomes a bottom edge of the plate 22 and a surface 36 the front surface of the plate 22. The plate 22 has a pair of rearwardly extending indentations 38 along its bottom edge 34 providing a pair of spaced mounting feet having openings therein. The plate 22 also has an indentation 40 extending across its top edge which provides an elongated mounting foot having an opening, not shown, therein. The indentations 38 and 40 with the openings therein are provided for the purpose of securing the plate 22 to a vertical panel. The plate 22 also includes an indentation 42 which extends from the bottom edge 34 rearwardly in the front surface 36 to'the indentation 40. The indentation 42 is provided to permit passage of control wires, not shown, from the upper to the lower ends of the switch 20 in the space provided by the indentation 42. The control wires may be connected in circuit with the switching contacts of a device known as an overload relay in a manner well known to those skilled in the art. The plate 22 also is provided with suitably located threaded openings, not shown, which act as mounting holes which are used to secure the insulating sheet-like member 24 and base 26 to the plate 22.

The sheet 24, as shown in FIG. 2, is preferably formed as a molded insulating part having a relatively thin cross section having a flat rear surface engaging the front surface 36 to cover a central portion of the indentation 42 so as to act as a cover for the wire trough. The sheet 24 is provided with a pair of circular ribs 44 which are raised on the front surface of the sheet 24 on opposite sides of the indentation 42. The ribs 44 act as spring seats, as will be later described. The sheet 24 also is provided with portions 46 which are formed along the top and bottom edges of the sheet 24 in alignment with the indentation 42. The portions 46 act as scoops and aid in directing the wires in the portion of the wire trough disposed between the sheet 24 and the plate 22.

The base 26 is formed of a molded insulating material having arc suppressing capabilities as are well known. The base 26 has a rear surface 48 positioned on the insulating sheet 24 and the plate 22 in a secured position by suitable screws which pass through openings in the base 26 and the sheet 24 and are threadedly received in the mounting holes in the plate 22. Extending forwardly of a front surface 50 of the base 26 are a pair of spaced side Walls 52 and pairs of posts 54 at the top and at the botom edge which effectively define in internal cavity 56 on the front surface 50. Extending between the posts 54 are suitably located ribs which are spaced on the front surface 50 to effectively divide the cavity 56 into three compartments 58 having equal widths. Extending into the material of the base 26 forwardly from the rear surface 48 and through the side walls 52 is a slot or passage 60. The slot 60 is centered on a center line equidistant between the top and bottom ends of the base 26 and is exposed to each of the compartments by an opening 62. The compartments 58 extend to provide open exposed ends at the top and the botom ends of the base 26;"Embedded within the material of the base adjacent the open ends at the top and the bottom of each of the compartments 58 is a threaded insert 64 which is used to secure terminal and stationary contact assemblies in the compartments.

Each of the compartments 58 has a pair of stationary contact assemblies positioned therein so the contacts of each pair are spaced equidistantly on opposite sides of the respective openings 62 and face in opposite directions. Each of the contact assemblies includes a terminal member 66, a contact member 68 and a conducting bar member 70. The bar member 70 has a threaded opening adjacent one of its ends and an unthreaded opening adjacent its other end. The terminal member 66 and the bar member 70 are secured adjacent an open end of one of the compartments 58 by a screw 72. The screw 72 passes through an opening in the terminal member 66 and the unthreaded opening in the bar member 70 and is threaded into the insert 64. The contact member 68 in turn is secured to the bar member 70 by a screw 74 which passes through an opening in the contact member 68 and is threaded into the threaded opening in the bar member 70. As shown in FIG. 2, when the contact assemblies are secured at the opposite ends of the compartments 58 the terminal members 66 will each have a wire connecting portion 76 extending external of the top and bottom wall of the base 26 and the contact member 68 will have an inclined contact surface 78 positioned adjacent one of the openings 62.

The insulating barrier 28 is formed of a molded insulating material having arc supressing capabilities as are well known. The barrier 28 has a front surface 80 and a rear surface 82 on a body portion 84 with ears 86 extending from the bottom and the top edges of the body portion 84 that are arranged to seat upon the forward ends of the posts 54. The posts 54 each have a threaded insert, not shown, molded therein and each of the ears 86 has an opening therein which permits the barrier 28 to be secured to the front surface of the base by screws 88 which pass through the openings in the cars 86 into the threaded inserts in the posts 54. Extending rearwardly of the rear surface 82 are suitably located ribs which extend vertically and cooperate with the ribs on the base to divide the internal cavity 56 into the three compartments 58. Also extending horizontally along the top and the bottom edges of the barrier 28 are ribs 90 which are located and have their outer surfaces positioned adjacent the cavity 56 side of the posts 54 with the rear edges of the ribs 90 juxtaposed to the heads of the screws 74 at the top and the bottom ends of the compartments 58. Thus the ribs extending from the rear surface 82 effectively cause the compartments 58 to be electrically isolated from each other and substantially causes the compartments 58 to be closed with the only openings into the closed compartments 58 being provided by the space between the rear edges of the ribs 90 and the front surface 50 of the base 26.

The front surface of the barrier 28 has a configuration arranged to provide a socket for a rear end of a magnet coil 92 of an electromagnet 94, suitably located guide surfaces for an armature 96 of the electromagnet 94, a suitably located groove, not shown, which receives a pivot pin 98 for a bell crank lever 100 and suitably located bosses, not shown, each having a threaded insert embedded therein which are used to secure the housing 30 to the front surface 80. Secured to the front surface of the barrier is a pad 102 of resilient elastomeric material which is engaged by the rear end of the coil 92.

The metal housing 30 preferably is formed as a die cast metal part with vertical walls arranged to extend forwardly in alignment with the side walls, the top wall and the bottom wall of the barrier 28 when the housing 30 is secured to the front surface 80 of the barrier 28. The vertical walls of the housing 30 and the front surface 80 of the barrier 28 define a cavity 104 having an open front end that is closed by the cover 32. Extending inwardly from a bottom wall 106 of the housing 30 is a portion 108 that is arranged to overlay the groove wherein the pivot pin 98 is received. Also extending inwardly from the intersection of the top and the bottom walls 106 and the side walls 110 are suitable located ledges, not shown, having openings therein which are aligned with the bosses on the front surface 80 on the barrier 28 so that screws extending through the openings may be used to secure the housing 30 to the front surface 80.

Additionaly extending inwardly at the intersection of the side walls 110 and the top wall 106 are ledges 112 which rest on the surface of the barrier 28. The ledges 112 provide a support for a pair of spring biased supports 114 for a stationary magnet part 116 of the electromagnet 94 in a manner and for the purpose disclosed in an application for U.S. patent Ser. No. 844,029, concurrently filed herewith which has been assigned by the inventors Merlin Y. T urnbull and Harold E. Whiting to the assignee of the present invention. The side walls each have a portion 118 that projects outwardly to overhang the side walls of the barrier 28. The portions 118 provide channel-like extensions for the cavity 104 with each of the channels 119 having a ledge therein. The ledges, not shown, are provided with threaded openings to receive screws 120 which secure the cover 32 to the front edge of the housing 30.

The cover 32 is preferably formed of a molded material to have a configuration which matches the shape and length of the side walls 110 and the top and the bottom walls 106 of the housing 30 so that when the cover 32 is applied to the front edges of the housing 30, the cavity 104 will be closed. The cover is provided with an opening which receives portions of the coil 92 and openings which are aligned with the channels formed by the projecting portions 118 to permit screws 120 to be threaded into the threaded openings in the ledges to secure the cover 32 to the housing 30. The cover 32 also has a pair of spring biased supports 124 secured thereon which are used to position the stationary magnet part 116 in a manner described in the patent application No. 844,029, supra. Additionally, the cover 32 is provided with an indented portion 126 which is formed as shown. The indented portion 126 provides access to the terminals 128 of the coil 92, permits observation of the operative condition of the electromagnet 94 through an opening 130 in the indented portion and attachment of auxiliary devices, such as a pilot light, in accordance with the disclosure of the Gribble et a1. patent, supra.

A movable contact carrier 132 which is shown in FIG. 4 is preferably formed as a U-shaped mold part to have a bight portion 134 and a pair of arms 136 and 138 extending from opposite ends of the bight portion 134. The bight portion 134 is received in the slot 60 while the arms 136 and 138 extend externally of the side walls 52 and have ends received in the channels 119. Extending forwardly of the bight portion 134 are a plurality of projections 140 each of which extends through one of the openings 62 in the rear wall of the base 26 into one of the compartments 58 to provide a support surface 142 for a movable contact assembly indicated by the numeral 144 and fully disclosed in an application for U.S. patent, Ser. No. 844,151, which was filed by the inventor Merlin Y. Turnbull concurrently herewith. The movable contact carrier 132 is constantly urged in a forward direction to a position wherein the movable contacts 144 are sepa rated from the contact surfaces 78 of the stationary contacts by a pair of springs 146. The springs 146 are of the compression type and each have one end seated in the spring seats defined by the circular ribs 44 and another end positioned in a recess, not shown, in the rear wall of the bight portion 134.

The arms 136 and 138 have free ends 148 and 150 received in the channel 119. Extending from the free ends 148 and 150 on the inner surfaces 152 and 154 of the arms 136 and 138 toward the bight portion 134 are sockets 156. The sockets 156 in the arms 136 and 138 are identical and present mirror images of each other. Each socket 156 includes a substantially semicircular base portion 160 having an entry way 162 extending from 6 the free ends 148 and 150. One side of the entry way 162 is provided by a wall 164 extending perpendicular to the bight portion 134 and tangentially from one side of the semicircular base portion 160. The outer side of the entry way 162 is provided by an inclined wall 166 which terminates in a ledge 168 that faces the semicircular base portion 160. The ledge 168 is provided by an inclined wall 170 that extends as a tangent to a portion of the semicircular base portion 160 and at an angle to the wall 164. Centrally located in the bight portion 134 is a notch 172 which provides a seat for a bearing member 174. The bearing member 174 is formed of a resilient material having a shape which will embrace the notch 172 and provides a low friction wear resistance engagement with the material of the base 26. The member 174 includes a pair of arms 176 which are received in grooves which are spaced equidistantly between the side walls 52 in the opposite side walls forming the slot 60. The arms 176 each have a depression 178 therein which receive a projection 180 on the walls forming the notch 172 when the arms 176 are flexed and moved into position in the notch 172. The bearing member 174 acts as a guide for the movement of the bight portion 134 of the movable contact carrier 132 during the movement of the carrier 132.

The bell crank lever 100, which is most clearly shown in FIG. 3 and is rotatably positioned within the cavity 104, is formed of a molded insulating material to have a pair of spaced pivot portions 182 which are interconnected by a solid lever portion 184 which acts as the actuating lever portion of the bell crank lever 100. Extending outwardly from each of the pivot portions 182 on opposite ends and at an angle to the actuating lever portion are a pair of spaced arms 186 each of which has a free end 188 which has a cylindrical projection 190 extending along an axis that is parallel to the axis of bores 192 which extend through the pivot portions 182. The bores 192 in the pivot portions 182 are axially aligned with one another and act as a bearing for the metallic pivot pin 98. The pivot portions 182 each have a surface 194 which is positioned adjacent the side walls of a boss containing the groove for the pivot pin 98 on the front surface 80 to axially position the bell crank lever 100 in the cavity 104. Centrally located on a free end 196 of the actuating lever 184 is a modified ball portion 198 of a ball and socket combination. The ball portion 198 includes a raised lentilshaped portion which is formed on opposite sides of the free end 196 with the lentil-shaped portions each having a plano-convex cross section both along the longitudinal axis and a substantially circular cross section along the transverse axis of the free end 196. Positioned on the ball portion 198 is an insert 200 which is preferably formed of a resilient molded plastic material having good bearing characteristics with the molded material forming the bell crank lever 100. The insert 200 is formed as a U- shaped channel-like member having appreciable length and arms having sockets 202 therein complementary in shape to the shape of the ball portion 198 to provide an appreciable bearing surface between the insert 200 and the free end 196 which maintains the insert 200 against axial movement along the free end 196. The insert 200 and the free end 196 are received in an opening in a bottom wall of a member 205 that is secured to the armature 96 so as to provide a connection between the armature 96 and the actuating lever 184. Located on the free end 188 of each arm 186 is a stop surface 204 that faces generally toward the top wall 106 of the housing 30 and a stop surface 206 provided by a projection 208 that extends in the same di rection from the side wall as the cylindrical portion 190. The projection 208 is spaced from the cylindrical portion 190 and aligned with a groove, not shown, in the cylindrical portion 190. Positioned on each cylindrical portion 190 is a bearing member 210 having a shape most clearly shown in FIGS. 5 and 6. Each of the bearing members 210 is formed of a molded plastic material having good bearing characteristics with the molded material forming the bell crank lever 100 and the movable contact carrier 132. The bearing members 210 are provided to provide a rotatable connection between the free ends 188 of the bell crank lever 100 and the free ends 148 and 150 of the movable contact carrier 132. The bearing members 210 have a cylindrical body portion 212 and a portion 214 integral with the body portion 212 that overlays a rounded surface on the free ends 188. The body portion 212 has a cylindrical bore 216 which receives the cylindrical portion 190 to position the bearing member 210 on free ends 188 and a cylindrical outer surface 218 having substantially the same curvature as the semicircular surface 160 of the sockets 156. Extending outwardly from the outer surface 218 on the body portion 212 is a projecting portion 222 which is arranged to be positioned adjacent the ledge 168 when the outer surface 218 is within the sockets 156. The overlaying portion 214 extends from the body portion 212 to present an inner curved surface 224 which rests upon the rounded curved surface on the free ends 188 and provides a stop surface 226 and a hook surface 228. The stop surface 226 is arranged to engage the stop surface 204 to prevent rotation of the bearing member 210 on the cylindrical portion 190 and the hook surface 228 is arranged to engage a portion which provides the stop surface 204 to prevent disassembly of the bearing member 210 from the cylindrical portion 190. Also extending from the body portion 212 is a projection 230 providing a stop surface 232. A torsion spring 234 which is positioned in a groove in the cylindrical portion 190 is provided to react between the stop surface 232 and the stop surface 206 and thereby constantly urge the stop surface 226 against the stop surface 204 and resiliently oppose separation of the stop surface 226 from the stop surface 204 when the bearing member 210 is rotated on the cylindrical portion 190.

The components of the switch assembly may be assembled as follows. Initially the insulating sheet 24 is positioned on the mounting plate 22. The movable contact carrier 132 is then positioned so the bight portion 134 is within the slot 60 and the arm portions 136 and 138 extend external of the side walls 52 of the base 26. The base 26 and the movable contact carrier 132 are assembled on the insulating sheet 24 and the mounting plate 22 by positioning the rear surface 48 adjacent on the sheet 24 with the springs 146 positioned between the insulating sheet 24 and bight portion 134 and tightening screws, not shown, which extend through suitable openings in the base 26 into the threaded openings in the mounting plate 22. The stationary contact assemblies are then secured to the base 26 by tightening the screws 72 which pass through the unthreaded openings in the terminal member 66 and the bar member 70 into the threaded inserts 62 and tightening the screws 74 which extend through the unthreaded opening in the contact member 68 into the threaded opening in the bar member 70. The movable contacts 144 are then installed in the movable contact support surfaces 142 in a manner disclosed in the US. application for patent Ser. No. 844,151, supra. The barrier 28 is then installed on the front surface of the base by positioning the barrier 28 as previously described and tightening screws 88 extending through openings in the ears 86 into the inserts in the posts 54.

The bell crank lever 100 is then positioned on the front surface 80 by installing the pivot pin 98 in a groove, not shown, on the surface 80 with the surfaces 194 adjacent the surfaces of a raised portion which includes the groove wherein the pin 98 is received. When the bell crank lever 100 is installed on the front surface 80, t e bearing members 210 will be received in the sockets 156. During the installation of the bearing members 210 into the sockets 156, a surface on the projection portion 222 will engage the inclined wall 166 and if the pivot pin 98 is seated in its groove, the torsion spring 234 will permit the bearing members 210 to rotate on the cylindrical portion 190 in a direction which will permit the projecting portion 222 to pass over the pointed edge provided at the intersection of the inclined wall 166 and the ledge 168 as the bearing member 210 passes from the entry way 162 into the sockets 156. When the bearing member 210 is in the socket 156, the torsion spring 234 will constantly position the bearing member 210 on the cylindrical portion 190 so the stop surfaces 204 and 226 engage each other and the projecting portion 222 has a surface arranged to engage the ledge 168 when the bearing member 210 is in the socket 156. The housing 30' is then positioned on the front surface of the barrier 28 so the portion 108 maintains the pin 98 in its groove when suitable screws extending through openings in the ledges on the inner walls of the housing 30 are tightened into the inserts in the top surface 80. The electromagent 94 including the coil 92, the stationary magnet part 116 and the armature 96 is installed in the cavity 104 in a manner disclosed in the application for US. patent, Ser. No. 844,029, supra. The installation of the cover 32 on the open side of the cavity 104 completes the assembly of the switching assembly when the screws 120 are tightened in suitable openings in the housing 30. It should be noted that the cover 32, when secured, causes both the coil 92 and the stationary magnet part 116 to be properly positioned within the cavity 104.

The operation of the switching device 20 is as follows. While the switch 20 will operate when mounted on a horizontal support, it is particularly suited to be mounted on a vertical panel, not shown, so that when the electromagnet 94 is de-energized the armature 96 will be moved by the combined forces of gravity and the springs 146 to a dropped-out position whereat the pole faces of the armature 96 are separated from the pole faces of he stationary magnet part 116. The energization of the coil 92 through suitable wires connected to terminals 128 causes a mutual magnetic attraction to be generated between the armature 96 and the stationary magnet part 116. The armature 96 is connected to the actuating lever 184 of the rotatable bell crank lever 100 by the member 205 and the insert 200. The stationary magnet part 116 is resiliently maintained in engagement with the top wall 106 by the spring biased supports 114 and 124 that are respectively carried by the housing 30 and the cover 32. It is well known that the magnet attraction between the armature 96 and the stationary magnet part 1116 increases exponentially with the decrease in the distance between the pole faces of the armature 96 and the stationary magnet part 116 and becomes a maximum when the pole faces engage each other. The magnetic attraction between the armature 96 and the stationary magnet part 116 causes the armature 96 to move upwardly toward the stationary magnet part 116 and the bell crank lever 100 to rotate in a clockwise direction in FIG. 2 about the pivot pin 98. The clockwise rotation of the bell crank lever 100 and the arms 186 causes the movable contact carrier 132 to move toward the plate 22 and the contact surfaces on the movable contact assemblies 144 to engage the contact surfaces 78. The initial movement of the contact carrier 132 is opposed by the springs 146. The subsequent movement of the contact carrier 132, which occurs after the movable contact surfaces on the contact assemblies 144 engage the contact surfaces 78, is opposed by the springs 146 as well as the springs associated with the movable contact assemblies 144. Thus the resistance to the movement of the armature 96 t ward the magnet part 116 progressively increases as the springs 146 are compressed and markedly increases as the force required to compress the springs associated with the movable contact assemblies 144 is added to the force required to compress the springs 146. The magnet part 116 is exclusively supported in the cavity 104 by the two pairs of spring biased supports 114 and 124 to have its base tightly pressed against the top wall 106 when the springs biasing the movable contact assemblies 144 and the springs 146 are fully compressed. Thus the heat generated within the electromagnet 94 when the coil 92 is energized will be readily transmitted to the metal housing 30 so the metal housing may serve as a heat sink and dissipate the heat energy generated within the electromagnet 94. However, the springs biasing the supports 114 and 124 are selected to provide a force which will permit t e magnet part 116 to move in the direction of the armature 96 in response to the mutual flux between the armature 96 and the magnet part 116 just prior to the engagement between the magnet part 116 and the armature 96. Thus at the instant of impact, the armature 96 and the magnet part 116 will be moving in opposite directions with the magnet part 116 reversing its direction of movement and moving with the armature 96 after the impact has occurred between the armature 96 and the magnet part 116. While the causes therefor are not completely understood, it has been found that resiliently supporting rather than rigidly supporting the magnet part 116 on the housing 30 reduces the noise generated and the shock imparted to the housing 30 which accompanies the impact between the amature 96 and the magnet part 116. Further it has been found that the resilient support for the magnet part 116 reduces the shock imparted to the housing: 30 when the electromagnet 94 is de-energized.

The de-energization of the electromagnet 94 permits the armature 96 to move downwardly to its dropped-out position under the combined forces provided by gravity and the springs 146. The movement of the armature 96 to its dropped-out position causes the bell crank lever 100 to rotate in a counter clockwise direction about the pivot pin 98 to the position shown in FIG. 2. The counter clockwise rotation of the bell crank lever permits the springs 146 to move the movable contact carrier 132 in a forward direction and the movable contact assemblies 144 to move out of engagement with the contact surfaces 78. In the event the contact surfaces of the movable contact assemblies 144 are slightly welded to the c ntact surfaces 78 when the electromagnet 94 is de-energized to an extent that the force provided by the springs 146 is insuflicient to cause the contact surfaces of the movablt= contact assembly to separate from the contact surfaces 78, the components of the switching device 20 will operate as follows. The de-energized electromagnet 94 will permit the armature 96 to move downwardly and the bell crank lever 100 to rotate in a counter clockwise direction. The counter clockwise rotation of the bell crank lever 100 will permit the springs 146 to move the movable contact carrier 132 in a forward direction without disturbing the engagement between the bearing member 210 and the socket 156 until the engagement of the movable contact assembly 144 with the support surface 142 prevents further forward movement of the movable contact carrier 132 because of the weld between the contact surfaces. The force of gravity on the armature 96 causes the armature 96 to continue its downward movement and the bell crank lever 100 to continue to rotate in a counter clockwise direction while the movable contact carrier 132 is' held against movement so that the bearing member 210 moves out of engagement with the semicircular base 160 to the position whereat the projecting portion 222 engages the surface of the ledge 168 and exerts a hammer-type blow on the movable contact carrier 132, The hammer-type blow will aid in breaking the light welds which have been formed between the movable contact assemblies 144 and the contact surfaces 78.

The switch 20 is arranged so either the electromagnet 94 structure of the contact structure can be serviced independently without disturbing any wire connections to the wire connection portions 76. When the electromagnet 94 is to be inspected or serviced, ready access may be had thereto by merely removing screws 120 and the cover 32 so that the components of the electromagnet 94 are fully accessible for inspection and replacement in the cavity 104. When the contact structures are to be inspected or replaced, all that is required is to remove the four screws 88 so that the barrier 28, the housing 30, the cover 32 and the assembly including the electromagnet 94 and the bell crank lever may be separated from the base 26 as a unit. During the separation of the barrier 28 from the base 26, the bell crank lever 100 will rotate in a clockwise direction to a position which will permit the projecting portion 222 to pass with clearance out of the socket 156 through the entry way 162 without engaging the ledge 168 so that the bearing members 210 may be separated from the movable contact carrier 132 without difiiculty. After the barrier 28 and the switch components which are secured thereto have been removed from the base 26, the movable contact carrier 132 together with the movable contact assemblies 144 will remain assembled with the base 26 so that in event the movable contacts should be welded to the stationary contacts, ready access may be had thereto for service and replacement purposes.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. An electric switch assembly comprising: an insulating base, an insulating barrier detachably mounted on a front surface of the base and cooperating with the base to provide a row of compartments that are substantially closed and electrically isolated from each other, said base having a slot extending transversely of the row of compartments along a centerline of the base, a pair of stationary contacts in each of said compartments with the contacts of each pair disposed in spaced relation on opposite sides of the center line, a housing mounted on a front surface of the barrier, a cover detachably secured on a front end of the housing and cooperating with the housing and the barrier to provide a closed cavity which is opened when the cover is detached from the housing, an electromagnet assembly and a bell crank lever positioned within the cavity, said electromagnet having an armature movable along a linear path parallel to the front surface of the base, said bell crank lever having an actuating arm portion movable by the armature and a pair of spaced arms integrally formed at opposite ends of the actuating arm with each of the pair of arms having a free end movable in a path toward the base when the actuating arm portion is moved by the armature in one direction, a U-shaped movable contact carrier having a bight portion movable in the slot along a linear path perpendicular to the front surface of the base and a pair of arms extending from opposite ends of the bight portion, each of the arms of the carrier extending to a free end that is disposed forwardly of the front surface of the barrier, a socket in the free ends of each of said arms rotatably receiving a portion of the free ends of one of the pair of arms of the bell crank lever and an entrance extending from the free end into the sockets in each of the arms of the carrier providing a passage for the portion on the free ends of the arms of the bell crank lever when the barrier is separated from and installed on the front surface of the base.

2. The switch assembly as recited in claim 1 wherein the slot in the base extends in a rear surface of the base and each of the compartments is connected to the slot by an opening in the front surface.

3. The switch assembly as recited in claim 2 wherein the base has a pair of side walls and the slot provides an opening in each of the side walls.

4. The switch assembly as recited in claim 3 wherein a portion of the slot intermediate the side walls is provided with a guideway and a portion of the bight portion intermediate the arms of the carrier includes a bearing surface that is received in the guideway for guiding the movement of the bight portion in the slot.

5. The switch assembly as recited in claim 4 wherein the free end of each of the arms of the bell crank lever 1 1 has a bearing member attached thereto which is received in one of the sockets of the carrier.

6. The switch assembly as recited in claim 5 wherein the bearing member guides the movement of the arms of the carrier during movement of the bight portion in the slot.

7. The combination as recited in claim 6 wherein the bight portion provides a support for a plurality of movable contacts which are arranged to engage the stationary contacts in each of the compartments when the bight portion is moved in one direction and to be separated from the stationary contacts when the bight portion is moved in a direction opposite said one direction and each of the bearing members includes a surface portion which engages a surface portion of the socket wherein it is received for moving the bight portion in the said opposite direction in event the movable contacts are welded to the stationary contacts.

8. The combination as recited in claim 7 wherein each bearing member is rotatably mounted on the arms of the bell crank lever and a mounting for the bearing member includes a spring which constantly urges a portion of the bearing member against a stop surface on the free end portion of the arms of the bell crank lever.

9. The switch assembly as recited in claim 8 including a pair of springs each having an end engaging the bight portion for constantly urging the bight portion in the said opposite direction.

10. The switch assembly as recited in claim 9 including a member of bearing material having a snap fit on a portion of the bight portion, said member having surface portions received in the guideway for guiding the movement of the bight portion in the slot.

References Cited UNITED STATES PATENTS 3,354,415 11/1967 Gribble 335132 HAROLD BROOME, Primary Examiner US. Cl. X.R. 335--202

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