US3550048A

US3550048A - Electromagnetically operated switch having a movable contact carrier shock absorber

Info

Publication number: US3550048A
Application number: US843994A
Authority: US
Inventors: James E Stallman
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1969-07-23
Filing date: 1969-07-23
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22

Description

Dec. 22, 1970 J. E. STALLMAN 355,048

' ELECTROMAGNETICALLY OPERATED SWITCH HAVING A MOVABLE CONTACT CARRIER SHOCK ABSORBER Filed July 23, 1969 FIGJ n2 114 Q 3Q 28 I68 3 9. 96 4a 96 4s- 4s 96 Z5 86 57 57 79 I60 |?62 92 5 92 92 |66 [NV/LV'HHQ.

94 52 JAMES E. STALLMAN United States Patent 0 3,550,048 ELECTROMAGNETICALLY OPERATED SWITCH HAVING A MOVABLE CONTACT CARRIER SHOCK ABSORBER James E. Stallman, White-fish Bay, Wis., assignor to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed July 23, 1969, Ser. No. 843,994 Int. Cl. H01h 3/60 US. Cl. 335-193 10 Claims ABSTRACT OF THE DISCLOSURE An electromagnetically operated switch having shock absorbers for reducing the bounce of the movable contacts when the contacts are moved to a circuit closing position by a movable contact carrier. The shock absorbing function is provided by a pair of elastomeric members, such as butyl rubber, which are positioned on the movable contact carrier to be compressed and absorb the rebound energy of the movable contact carrier when the movable contact carrier overshoots the normal contact closing position and to be relaxed when the movable contact carrier is at the contact closing position.

The present invention relates to switching devices, and more particularly, to a structure which will absorb the rebound energy of a movable contact carrier in an electromagnetically operated switch.

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

While the proportions of the device shown in the Gribble et al. patent may be increased to control amperes 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. It is well known that any conductor is heated by the current passing therethrough and therefore it follows that an increase in the current controlling capability of a device requires a corresponding increase in the cross sectional mass of the current carrying metal parts of the device. Inherently, any electrical switch which relies on an abutting engagement between two metal parts to complete an electric circuit will operate with a phenomenon known as contact bounce, which is generated when the movable contacts initially are in effect slammed into enagagment with the stationary contacts. Contact bounce is a well-known cause of wear, and thus is objectionable. One possible solution which may be used to reduce contact bounce is to employ extremely strong springs in the movable contact structure. However, this solution is impractical for a number of reasons, including the necessity of requiring an operating magnet structure which would have to be excessively large in physical size. The presence of contact bounce is particularly objectionable in switches of larger sizes and becomes more difficult to control because of the weight of the movable contacts which is required to enable the switch to control the large Patented Dec. 22, 1970 "ice currents. As any conductor is heated by the current passing therethrough, common practices which have been heretofore followed dictated that each current carrying part in a switch be designed to operate independently of the remaining components in the switch and act as its own radiator for the heat generated therein. However, in any electric switch, the components carrying current must be in firm physical contact with each other, if overheating of the switch is to be avoided. In the contact structure as used in the switch as will be hereinafter described, the stationary contact structures, which have a large mass in relation to the current passing therethrough, are engaged by the movable contact which has a small mass in relation to the current passing therethrough so that the heat generated within the movable contact will be conducted and dissipated by the stationary contact structures.

This philosophy of design is incorporated into a movable contact structure disclosed in an application for US. patent, Ser. No. 844,151, which has been filed by the inventor Merlin Y. Turnbull concurrently herewith. An additional contributing cause of contact bounce is provided by the rebounding of the armature and the movable contact carrier when the carrier moves the movable contacts into engagement with the stationary contacts. It is to be appreciated during the movement of the movable contacts into engagement with the stationary contact, the movable contact carrier will overshoot its energized position and thereby over-compress the spring supports for the movable contacts. Thus the over-compressed contact springs will supply a force which will tend to drive the movable contact carrier to a contact opening position and cause the contact carrier to oscillate about the energized position and contribute to the bouncing of the movable contacts on the stationary contacts. The present invention is concerned with a shock absorber arrangement which will reduce the oscillation of the movable contact carrier when the carrier in initially moved to the energized position.

It is an object of the present invention to provide a movable contact structure which will operate with a low degree of contact bounce and can be readily serviced.

Another object is to provide an electromagnetically operated switch with shock absorbers that will reduce the oscillation of the carrier about its energized position when the carrier initially moves to its energized position and more specifically, to position a pair of elastomeric shock absorbers on the carrier so the shock absorbers will be compressed when the carrier moves beyond its energized position and are relaxed when the carrier is in its energized position.

A further object is to provide an electric switch with a movable contact structure that includes a contact carrier having a portion movable in a slot in an insulating base and portions extending through openings in the base to the front surface of the base to provide a surface on the carrier whereon the movable contact is positioned, and to connect the movable contact to the contact carrier by a spring biased rotatable plunger that acts as an air piston to reduce the contact bounce when the carrier moves to an energized position wherein the movable contacts firmly engage the stationary contacts that are mounted on the front surface of the base and to position a pair of elastomeric shock absorbers on the carrier so the shock absorbers will be compressed when the carrier moves beyond the energized position and are relaxed when the carrier is at the energized position to thereby reduce the oscillation of the carrier when the carrier is initially moved to the energized position.

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

FIG. 1 is a side view, partly in cross section, of an electric switch incorporating a shock absorber for a movable contact carrier according to the present invention.

FIG. 2 is a view partly in cross section taken along line 2-2 in FIG. 1.

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 dis closed and described in an application for United States patent, Ser. No. 844,148, which was filed by the inventor Merlin Y. Turnbull, 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 mounting

feet

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. 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 which act as mounting holes which are used to secure the insulating sheetlike member 24 and base 26 to the plate 22.

The sheet 24 is preferably formed as a molded insulating part having a relatively thin cross section having a fiat 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 a vertical center of the plate 22. The ribs 44 act as seats for a pair of springs 46, as will be later described.

As disclosed in the application for United States Pat., Ser. No. 844,148, supra, the base 26 and the barrier 28 are formed of a molded insulating material having arc suppresing capabilities and cooperate with each other to provide a cavity which is divided into three compartments 48, having equal widths. The base 26 has a rear surface 50 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 housing holes in the plate 22. Extending into the material of the base 26 forwardly of the rear surface 50 and through the side walls of the base 26 is a slot 52. The slot 52 is centered on a center-line equidistant between a top wall 54 and a bottom wall 56 of the base 26 and is exposed to each of the compartments 48 by an opening 57. The compartments 48 each extend between the top wall 54 and the bottom wall 56 and each have a pair of terminal and stationary contact assemblies secured therein.

The terminal and stationary contact assemblies in each of the compartments 48 are arranged so that the contact assemblies of each pair are spaced equidistantly on opposite sides of the slot 52 and face in opposite directions. Each of the contact assemblies includes a terminal member 58 and a contact member 60. When the pairs of terminal and contact assemblies are secured at the opposite ends of the compartments 48, the terminal members 58 will have a wire connecting portion 62 extending external of the top wall 54 and the bottom wall '56 and the contact members 60 will have an inclined stationary contact surface 64 positioned on opposite sides of the slot 52.

As disclosed in an application for United States patent, Ser. No. 844,148, supra, the barrier 28, the metal housing 30 and cover 32 define an internal closed cavity 66 wherein an electromagnet 68 is included. The electromagnet 68 operates a bell crank lever 70 which has a pair of arms 72 connected to a movable U-shaped contact carrier 74. The U-shaped contact carrier 74 has a bight portion 76 which is movable forwardly and rearwardly in the slot 52. The movable contact carrier 74, including the bight portion 76, is most clearly disclosed in an application for United States patent, Ser. No. 844,100, concurrently filed herewith which has been assigned by the inventors Merlin Y. Turnbull and Harold E. Whiting to the assignee of the present invention. The barrier 28 has a body portion 78 which provides a front wall for the compartments 48 and suitable ribs 79 which provide side walls for the compartments. Extending from the body portion 78 are ears 80 that are arranged to seat upon the forward ends of a pair of posts 82 at the top and

bottom walls

54 and 56. The posts 82 each has a threaded insert molded therein and each of the ears 80 has an opening therein which permits the barrier 28 to be removably secured to the front surface of the base 26 by screws 84 which pass through the openings in the ears 80 into the threaded inserts in the posts 82. It is readily apparent that the removal of the screws 84 'will permit the assembly including the barrier 28, the housing 30 and the cover 32 to be detached from the base 26 to permit access to the stationary and the movable contacts within the compartments 48 in event the contacts require inspection or replacement.

The movable contact carrier 74 is preferably formed as a U-shaped molded part that includes the bight portion 76. The bight portion 76 is received in the slot 52 while arms 86, which extends from opposite ends of the bight portion 76, extend externally of the side walls of the base 26 have free ends received in channels in the housing 30 defined by portions on the housing 30. The free ends of the arms 86 each receive a bearing 88 on a terminal end on an arm 72 of the bell crank lever 70. Extending forwardly of the bight portion 76 are a plurality of spaced projections 92 each of which extends into one of the compartments 48. The bight portion 76 has a rear surface 94 and each of the projections 92 has a front surface whereon a movable contact assembly 96 is positioned, in a manner disclosed in an application for United States patent, Ser. No. 844,151, which has been filed by the inventor Merlin Y. Turnbull concurrently herewith.

Each of the movable contact assemblies 96 includes a U-shaped channel-like member 97 having a central portion 98 positioned adjacent the front surface of the projections 92 and a pair of portions 99 extending at an angle from opposite ends of the central portion whereon a pair of contact members providing contact surfaces 100 are secured. The angle of incline of the portions 99 corresponds to the angle of incline of the stationary contact surfaces 64 so the contact surfaces 100 will properly engage the contact surfaces 64. The central portion 98 has an opening therein which receives a stern 101 portion on a plunger 102. The free end of the stern portion 101 has a pin 103 extending therethrough which maintains the member 97 assembled on the free end of the plunger 102. The stem portion 101 of the plunger 102 extends through an opening in the front surface of the projection 92 to a cylindrical portion 104 which is guided and movable in a cylindrical bore 105 in the projection 92. The pin 103 is held in tight engagement with a forward surface of the central portion 98 by a spring 106 which surrounds the stem portion 101 and has its opposite ends resting on the cylindrical portion 104 and a spring seat at the end of the bore 105 that is adjacent the front surface of the projections 92. If desired, the cylindrical portion 104 may be provided with an annular groove which receives an O-ring seal 107 which will improve the air piston-like action of the cylindrical portion 104 in the bore 105 when the contact surfaces 100 engage the contact surfaces 64.

The housing preferably is formed as a cast metal part which has a high thermal conductivity. While aluminum may be used to form the housing 30 in that it possesses high thermal conductivity and is light weight, because of its resistance to impact, the housing part 30 is preferably formed of a Zinc die cast material to have a bottom wall 108, a top wall 110 and a pair of

side walls

112 and 114 which has a rear edge 115 resting on a front surface of the barrier 28 and an open front wall 116 which is closed by the cover 32. The front surface of the barrier 28 and the

walls

108, 110, 112 and 114 define the cavity 66 which has a front side closed by the cover 32. The cover 32, when removed, provides access to the electromagnet 68 that is positioned within the cavity 66 for inspection and for service purposes. Extending inwardly from the walls of the housing 30 are suitably located ledges each having an opening therein which are arranged to engage portions of the front surface of the barrier 28 which receive screws that are threaded into suitably located threaded inserts that are embedded in the barrier 28 to secure the housing 30 to the barrier 28. Additionally extending inwardly along the rear edge 115 from the top wall 110 at the intersection of the

side walls

112 and 114 are a pair of ledges 118 each of which has a rear surface resting on the front surface of the barrier 28 and has a front surface whereon a pair of spring biased supports 120 are secured. The spring biased supports are identical and are fully disclosed in an application for United States patent, Ser. No. 844,029, which has been filed by the inventors Harold E. Whiting and Merlin Y. Turnbull concurrently herewith. Each of the supports 120 includes a support portion 122, a slider 124 and a spring 126. As shown in FIG. 1, secured to a rear surface of the cover are a pair of spring biased supports 128 which are identical and face in opposite directions to the spring biased supports 120.

The electromagnet 68, which is positioned within the cavity 66, includes a magnet coil 130, an armature 132 and a magnet core 134. The magnet coil 130 is positioned by portions of the cover 32 and the front surface of the barrier 28 so that a centrally located opening through the coil 100 extends along an axis perpendicular to the top and the bottom walls 110 and 108. The armature 132 includes a laminated stack 136 of T-shaped laminated magnet iron pieces and a member 138. The member 138 has a pair of arm portions secured on opposite sides of the laminated stack 136 by rivets which secure the laminated stack 136 and the arm portions of the member 138 together and a portion 140 which is generally U-shaped and box-like and provides a connection with an end portion of an operating arm 142 on the bell crank lever 70 in a manner described in the application for United States patent, Ser. No. 844,100, supra.

The magnet core 134 includes a laminated stack of E- shaped laminated magnet iron pieces designated by a numeral 144 and a pair of

members

146 and 148. The

members

146 and 148 are secured on opposite sides of the laminated stack 144 by rivets which secure the laminations of the stack 144 and the

members

146 and 148 together. The laminated stack 144 has an upper wall 150, a pair of pole faces 152 facing downwardly on the outer legs of the E-shaped pieces. The upper wall 150 is substantially flat and extends substantially over the entire upper end of the E-shaped stack of laminated pieces. The

members

146 and 148 each have a pair of identical ears 154 formed thereon. Each of the ears 154 extends perpendicular to the main body portion of the

respective members

146 and 148 so as to present a surface 156 that is displaced a slight distance downwardly of the upper wall 150 and a surface that faces in the same direction as the pole faces 152. Further, each of the ears 154 is provided with a notch, not shown, that extends from a free end of the ears 154 toward the laminated stack 144.

Extending forwardly in the rear surface 94 of the movable contact carrier 74 are a pair of circular recesses 158 which provide seats for one end of the pair of springs 46 that have their opposite ends positioned by the circular ribs 44. Also extending forwardly in the rear surface 94 adjacent the outer ends of the bight portion 76 are a pair of circular recesses 160, each of which receives one of a pair of shock absorbers 162. The stock absorbers are cylindrical and have a circular bore 164 extending therethrough. The shock absorbers 162 are tightly received within the recesses 160 so as to be held assembled with the contact carrier 74 and have a portion 166 extending a predetermined distance from the rear surface 94 so as to engage the front surface 36 when the carrier 74 initially causes the contact surfaces 64 and to engage each other as will be described.

The mounting plate 22, the insulating member 24, the base 26, the stationary contacts assemblies, the movable contact carrier 74 with the movable contact assemblies 96 thereon, the barrier 28, the housing 30 and the bell crank lever 70 which is positioned within the cavity 66 are all assembled in a manner disclosed in the application for United States patent, Ser. No. 844,148, supra. After the foregoing mentioned parts are assembled, the electromagnet 68 is installed in the cavity 66 by assembling the armature 132, coil 130 and the magnet core 134 in the cavity 66 and securing the cover 32 to the housing 30 as disclosed in the application for United States patent, Ser.

No. 844,034, supra.

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 the armature 132 will be moved by the combined forces furnished by gravity and the springs 46 to a position whereat the pole faces of the armature 132 are separated from the pole faces 152 of the magnet core 134. The energization of the coil 130 causes a mutual magnetic attraction to be generated between the armature 132 and the magnet core 134. The armature 132 is connected to the rotatable bell crank lever 70. The upper wall 150 of the magnet core 134 is resiliently maintained in engagement with the top wall by the spring biased supports and 128 that are respectively carried by the housing 30 and the cover 32. It is well known that the magnetic attraction between the armature 132 and the magnet core 134 increases exponentially with the decrease in the distance between the pole faces of the armature 132 and the magnet core 134 and is at a maximum when the pole faces engage each other. The magnetic attraction between the armature 132 and the magnet core 134 causes the armature 132 to move upwardly toward the magnet core 134 and the bell crank lever 70 to rotate about its pivot. The rotating bell crank lever 70 causes the movable contact carrier 74 to move toward the plate 22 to a position wherein the surfaces 100 on the movable contact assemblies 96 engage the contact surfaces 64. The initial movement of the contact carrier 74 is opposed by the force of gravity on the armature 132 and by the springs 46. The subsequent movement of the contact carrier 74, which occurs after the movable contacts surfaces 100 engage the contact surfaces 64, is opposed by the force of gravity on the armature 132 and the springs 46 as well as the springs 106 which are associated with the movable contact assemblies 96. Thus the resistance to the movement of the armature 132 toward the magnet core 134 progressively increases as the springs 46 are compressed and markedly increases as the force required to compress the springs 106 is added to the force required to compress the springs 46. The magnet core 134 is exclusively supported in the cavity 66 by the spring biased

supports

120 and 128 to have its upper wall 150 tightly pressed against the top wall 110 when the

springs

46 and 106 are fully compressed. Thus the heat generated within the electromagnet 68 when the coil 130 is energized will be readily transmitted to the metal housing so the metal housing may serve as a heat sink and dissipate the heat energy generated within the electromagnet 68. However, the springs 126 biasing the

supports

120 and 128 are selected to provide a force which will permit the magnet core 134 to move in the direction of the armature 132 in response to the mutual flux between the armature 132 and the magnet core 134 just prior to the engagement between the pole faces on the magnet core 134 and the pole faces on the armature 132. Thus at the instant of impact the armature 132 and the magnet core 134 will :be moving in opposite directions with the magnet core 134 reversing its direction of movement and moving with the armature 132 after the impact has occurred between the armature 132 and the magnet core 134. While the causes therefore are not completely understood, it has been found that resiliently supporting, rather than rigidly supporting, the magnet core 134 on the housing 30 reduces the noise generated and the shock imparted to the housing 30 which accompanies the impact between the armature 132 and the magnet core 134. Further, it has been found that the resilient support for the magnet core 134 reduces the shock imparted to the housing 30 when the electromagnet 68 is de-energized and the armature 132 is returned to its dropped-out position by the combined force provided by gravity and the springs 46, as well as the springs 106.

The switch 20 is shown in the de-energized position in FIG. 1. The movement of the armature 132, as caused by the energization of the electromagnet 68, causes the bell crank lever 70 to rotate in a clockwise direction and the contact carrier 74 to move from a retracted position as shown toward the mounting plate 22 to an operative position. Initially the movement of the carrier 74 is opposed by the compression of the springs 46 as the bight portion 76 moves in the slot 52 toward the mounting plate 22. A continued movement of the carrier 74 toward the plate 22, which occurs after the contact surfaces 100 engage contact surfaces 64, causes the central portion 98 to move out of its engagement with the front surface of the projections 92 along a path guided by a pair of spaced walls 168 that extend from the front surface of the projections 92. The movement of the central portion 98, because of the connection provided by the pin 103, causes the cylindrical portion 104 of the plunger 102 to move in the bore 105 and the springs 106 to be compressed. When the electromagnet 68 is energized for a period of time sufficient to permit the armature 132 to be at its energized position and the movable contact carrier 74 to be at its operative position, the springs 106 will be compressed and have a predetermined length so as to apply a predetermined pressure between the contact surfaces 64 and 100. However, neither the armature 132 or the movable contact carrier 74 will move directly to their energized and operative positions because of the momentum which is stored therein during their movement. It will be seen that the moving contact carrier 74 together with the movable assemblies 96 provide a considerable mass which is moving rapidly toward the mounting plate 22 at an appreciable velocity. The intial engagement between the contact surfaces 64 and 100 will be in a direction which will tend to cause the contact surfaces 64 and 100 to separate with a rebound action. The rebounding of the contact surfaces 100 and 64 is opposed by the operation of the cylindrical portion 104 in the bore 105 which acts as an air cylinder shock absorber in a manner described in the application for United States patent, Ser. No. 844,151, supra.

The momentum of the contact carrier 74 will cause the carrier 74 to continue to move toward the plate beyond the operative position so that the

springs

46 and 106 will be compressed to have a length shorter than the length which they have when the carrier 74 is at the operative position. The excess compression of the

springs

46 and 106 thus supply a force which will tend to cause the carrier 74 to move in a direction which would cause the contact surfaces 64 and to separate with a contact bouncing action. The shock absorbers 162 are located on the rear surface 94 to be uncompressed or relaxed when the carrier 74 is at the operative position; that is, when the

springs

46 and 106 are compressed to have a predetermined length. The shock absorbers 162 are formed of an elastomeric material, such as butyl rubber (isobutylene-isoprene) which has a poor resilience or rebound characteristic at normal ambient and operating temperatures of the switch 20 and are positioned on the rear surface 94 to engage the plate 22 and be progressively compressed as the carrier 74 progressively moves beyond its operative position in the direction of the plate 22. The shock absorbers 162 have a bore 164 extending therethrough. Thus as the carrier 74 moves beyond its operative position toward the plate 22, the shock absorbers 162 will be compressed throughout their entire length and absorb the force created by the momentum of the carrier 74 and reduce the rebound of the carrier 74 to a minimum and thereby reduce the bounce between the contact surfaces 64 and 100.

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 be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. In an electromagnetically operated switch, the combination comprising: a mounting plate, an insulating base secured to the mounting plate, said base providing a row of compartments that are electrically isolated from each other, a slot in a rear Wall of the base extending transversely of the row of compartments along a center line of the base, said slot having a rear side closed by the mounting plate and providing an individual entry into each of the compartments through an opening in the rear wall of each of the compartments, 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 opening, a housing mounted on a front surface of the base providing a closed cavity on a front wall of the base, an electromagnet assembly and a bell crank lever positioned within the cavity, said electromagnet having an armature movable in a linear path parallel to the rear wall of the base from a de-energized position to an energized position in the cavity when the electromagnet is energized, said bell crank lever having an actuating arm portion movable by the armature and a pair of spaced arms having a free end movable in a path toward the base during the movement of the armature toward the energized position, a U-shaped movable contact carrier having a bight portion movable in the slot along a path that is perpendicular to the rear wall of the base and a pair of arms connected to the free ends of the pair of arms of the bell crank lever to move the bight portion in a direction toward the mounting plate to a contact closing position during the movement of the armature toward the energized position, said bight portion having a rear surface facing and spaced from the mounting plate and portions on a front surface extending through the openings in the base to present a movable contact supporting surface in each of the compartments, a movable contact assembly resiliently supported by the bight portion on each of the movable contact supporting surfaces, said movable contact assemblies each being arranged to resiliently engage the stationary contact in the compartments when the armature is at the energized position and the bight portion is at the contact closing position, and a pair of shock absorbers positioned on the rear wall of the bight portion to be compressed between the bight portion and the mounting plate when the contact carrier is moved in said direction beyond the contact closing position and to be relaxed when the bight portion is at the contact closing position.

2. The switch assembly as recited in claim 1 wherein the rear surface of the bight portion includes a pair of spaced bores each including one of the shock absorbers for positioning the shock absorbers on the rear surface of the bight portion.

3. The switch assembly as recited in claim 2 wherein the shock absorbers have a cylindrical shape.

4. The switch assembly as recited inclaim 1 wherein each of the movable contact assemblies includes a spring that is compressed to have one length when the bight portion is at the contact closing position and the armature is at the energized position and the shock absorbers extend from the rear surface of the bight portion a distance sufiicient so that the shock absorbers engage the mounting plate and are compressed when the springs are compressed to have a length shorter than the said one length and are relaxed when the springs are compressed to have a length equal to the said one length to reduce the bounce of the movable contacts on the stationary contacts during the movement of the armature to the energized position.

5. The switch assembly as recited in claim 4 including a pair of springs reacting between the rear surface and the mounting plate for constantly opposing the movement of the bight portion toward the mounting plate.

6. The switch assembly as recited in claim 1 wherein each of the shock absorbers is formed as a cylinder of butyl rubber material.

7. The switch assembly as recited in claim 6 wherein each of the shock absorbers has a bore extending therethrough.

8. The switch assembly as recited in claim 7 wherein each movable contact assembly includes a portion that is received in a bore in the bight portion which acts as a shock absorbing air piston in the bore to further reduce the contact bounce of the switch assembly.

9. In an electromagnetically operated switch, the combination comprising: an insulating base providing a row of compartments that are electrically isolated from each other, a pair of stationary contacts in each of said compartments with the contacts of each pair spaced on opposite sides of a plane defined by a center line through the base, an electromagnet having an armature movable from a de-energized position to an energized position when the electromagnet is energized, a movable contact carrier having a portion operatively connected to the armature and a plurality of contact support portions movable in the plane in one direction from a retracted position to an operative position in response to the movement of the armature from the de-energized position to the energized position, a movable contact assembly resiliently supported by each of the contact support portions to resiliently engage the stationary contacts in each compartment when contact support portions are at the operative position, and at least one elastomeric shock absorber carried by the movable contact carrier to be compressed when the contact support portions are moved in the said one direction beyond the operative position and to be relaxed when the contact support portions are at the operative position.

10. The switch assembly as recited in claim 9 wherein the shock absorber is formed of butyl rubber and each of the movable contact assemblies includes a spring that is compressed to have one length When the contact support portions are at the operative position and the shock absorbers extend from the carrier a distance sufficient so that the shock absorbers engage portions of the base and are compressed when the springs are compressed to have a length shorter than the said one length and are relaxed when the springs are compressed to have a length equal to the said one length to reduce the bounce of the movable contact assemblies on the stationary contacts during the movement of the armature to the energized position.

References Cited UNITED STATES PATENTS 2,531,025 11/1950 Bradley 335l93 2,946,872 7/1960 Siebers 335--193 3,196,231 7/1965 Meyer 335193 3,354,415 11/1967 Gribble 335132 FOREIGN PATENTS 731,713 6/1955 Great Britain 335193 HAROLD BROOME, Primary Examiner 3 3". UNITED STATES PrkTENTpFFICE CERTIFICATE OF CORRECTION Patent No. 3,55 Dated December 97 Ioventofls) James Stallman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01. t, line A,- cancel "extends" and insert -extend- C01. 5, line 19, cancel "has and insert --have-.

001. 6, line 38, cancel "No. 8Mh034" and insert "No. 8 4 502 Signed and sealed this 27th day of April 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, J'R. Attesting Officer Commissioner of Patents