Abstract:
Electromagnetically operated contactor employing contact modules which are converted from normally open to normally closed and from normally closed to normally open operation by inverting the contact module in the contactor. The contact terminals of the contact module are clamped by various arrangements against conductive members of the contactor. Wiring terminals for connecting external wiring to the conductive members are spaced from the arrangement for clamping the contact terminals to the conductive members. Thus, the wiring terminals and the external wiring do not interfere with the module or arrangement for clamping, and the module may be removed, inverted, and replaced without disturbing the external wiring connections.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to electrical switching apparatus. More particularly, it is concerned with electromagnetically operated switching apparatus employing convertible contact modules which operate in either a normally open or normally closed condition depending upon their mounting position. 
     Electrical switching apparatus such as electromagnetic contactors for opening and closing a plurality of switches are well-known. In order to provide versatility contactors of this general type frequently employ switch or contact modules which selectively may be changed to function in either the normally open or normally closed condition. Certain contactors are designed to employ convertible contact modules which when placed in the contactor in one position provide a normally open switch, and when removed and replaced in a different position provide a normally closed switch. With contactors of this type heretofore available, however, it was necessary to disconnect the external wiring in order to remove and convert a contact module. Time was required to disconnect and reconnect the wiring, and in addition there was the possibility of making errors when reconnecting the external wiring. 
     SUMMARY OF THE INVENTION 
     Switching apparatus permitting rapid error free conversion of contact modules is provided by electrical switching apparatus in accordance with the present invention. The apparatus employs a convertible contact module which selectively provides either normally open or normally closed contact operation. The apparatus includes supporting structure with a contact actuator mounted in the supporting structure for reciprocal movement. A convertible contact module having exterior first and second contact terminals is adapted to be removably mounted in the supporting structure in engagement with the contact actuator. The convertible contact module is mounted in either of two positions which respectively provide normally open and normally closed contact conditions between the two contact terminals. Mounted on the supporting structure are first and second conductive members each having a contact region for making contact with a contact terminal of the convertible contact module when the convertible contact module is mounted in the supporting structure in either of the two positions. Holding means releasably hold the convertible contact module in the supporting structure in either of the two positions with the contact terminals making electrical contact with the contact regions of the conductive members. Connecting means on the conductive members permit external electrical connections to be made to the conductive members. Each connecting means is spaced from the associated contact region and from the holding means so that when the convertible contact module is released by the holding means, removed from the supporting structure, and changed from one position to the other the connecting means and the external connections thereto do not interfere with release and movement of the convertible contact module and in addition the connecting means and external connections are not disturbed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a cross-sectional view of an electric magnetically operated contactor in accordance with the present invention; 
     FIG. 2 is a view of the contactor of FIG. 1 partially in cross-section taken generally along the line 2--2 of FIG. 1; 
     FIGS. 3A and 3B are fragmentary views partially in cross-section of the contactor of FIGS. 1 and 2 illustrating in detail the manner of connecting and mounting convertible contact modules in the contactor; 
     FIGS. 4A and 4B are fragmentary views partially in cross-section illustrating a modification of the structure for mounting and connecting convertible contact modules in a contactor; 
     FIG. 5 is a fragmentary view partly in cross-section illustrating another modification of the mounting and connecting structure employed with a modified convertible contact module; and 
     FIGS. 6, 7, and 8 are additional views of the convertible contact module employed in the modification of FIG. 5. 
     For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following discussion and appended claims in connection with the above-described drawings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A contactor in accordance with the present invention for simultaneously switching up to eight circuit paths is illustrated in FIGS. 1 and 2. An electromagnet coil 11 having a core 12 is located against the housing 10 of the contactor. A movable armature 13 is mounted adjacent to the electromagnet coil 11 for reciprocal movement. In the deenergized condition the armature 13 is biased in an upper position as shown in FIGS. 1 and 2 by compression springs 14. When the electromagnet coil 11 is energized the armature 13 is moved downward. The elements of the electromagnet and the manner in which they are mounted in the housing structure are the subject matter of an invention of Robert W. Weeks which is described in detail and claimed in his copending application entitled &#34;Electromagnetic Switching Apparatus,&#34; Ser. No. 050,000, filed June 18, 1979, and assigned to the assignee of the present application. Attached to the armature 13 is a carrier 15 on which vertically extending contact actuator rods 16 are mounted. Lateral members 20 extend from the rods and thus move with the armature 13. The lateral members 20 of the actuator rods 16 engage convertible contact modules 25 as will be explained in greater detail hereinbelow. 
     Eight pairs of wiring terminals 26, 27 to which external electrical wiring may be attached are mounted in the housing 10. Extending from the terminals are conductive members 28 and 29. Identical convertible contact modules 25 are removably mounted within the housing with their terminals 31 and 32 in electrical and mechanical contact with contact regions of the conductive members 28 and 29. 
     In the contactor as shown four sets of wiring terminals 26, 27 and conductive members 28, 29 are positioned at a first level in the housing for receiving four contact modules 25. This arrangement is duplicated at a second level in an upper section 33 of the housing. If desired, a third level may be added. A cover section 34 is positioned on the upper section of the housing. The cover section 34, upper section 33 of the housing, and upper and lower portions of the contact actuator rods 16 and lateral members 20 may readily be disassembled as necessary to provide access to the second and to the first levels of contact modules. The cover section 34 and upper section 33 of the housing are held in place by removable bolts 35 (FIG. 2). The upper and lower portions of the contact actuator rods 16 and lateral members 20 are removably mounted to the carrier 15 by bolts 36 passing centrally through the rods to the carrier. 
     The details of each of the identical contact modules 25 are shown in FIG. 1. The contact module at the lower level is positioned so as to provide normally open contacts (electromagnet coil 11 deenergized). The contact module at the upper level is inverted from the one at the lower level and functions in the normally closed condition. 
     The contact modules 25 are identical. Each includes a housing 40 of generally rectangular parallelopiped configuration. The contact terminals 31 and 32 extend through the housing 40 between the interior and exterior of the module housing. The terminals 31 and 32 are equidistant from the top and bottom surfaces of the housing. The opposite surfaces of each terminal are flat and parallel, and the corresponding upper and lowr surfaces of the two terminals are in the same plane. An open slot extends horizontally along the portion of each contact terminal. A pair of stationary contacts 41 and 42 are mounted on the inner portions of the terminals 31 and 32. A mating pair of movable contacts 43 and 44 are carried on a conductive contact bridge 45. The bridge 45 with movable contacts 43 and 44 is mounted on a plunger 46 so as to permit limited movement with respect thereto. The plunger is mounted in the housing 40 so as to move reciprocally and protrude through openings in the top and bottom walls of the module housing. The plunger 46 extends through a central opening in a movable seat 47 which is also mounted in the housing 40 so as to permit reciprocal movement. A compression spring 48 is compressed between the movable seat 47 and the contact bridge 45. 
     The modules 25 are fastened in place (as will be explained in detail hereinbelow) in either one of the two inverted positions illustrated in FIG. 1 to provide either normally open or normally closed operation. When the contactor is completely assembled the lateral members 20 of the contact actuator rods 16 engage the movable plunger 46 and seat 47 as shown for each contact condition. Movement of the lateral members 20 downward in response to energizing of the electromagnet coil 11 also moves the plunger 46 and seat 47 of a module 25 in the normally open condition as shown at the lower level downward permitting compression spring 48 to close the contacts. The plunger 46 of a module in the normally closed condition as shown at the upper level in FIG. 1 is also moved downward opening the contacts and compressing the compression spring 48. 
     The manner in which a module 25 is mounted in the contactor in electrical connection with the wiring screw terminals 26 and 27 is shown in detail in FIGS. 3A and 3B. As illustrated in FIG. 3A the module 25 fits in the housing with the contact terminals 31 and 32 against the contact regions of the conductive members 28 and 29, respectively. The contact terminals 31 and 32 are clamped against the conductive members 28 and 29 by an arrangement of screws 51 and 52 threaded into mating openings in pivotal retaining rods 53 and 54, respectively. The screws 51 and 52 pass through the open slots in the contact terminals 31 and 32 and aligned slots in the conductive members 28 and 29. The pivotal retaining rods 53 and 54 are mounted in the contactor so as to permit limited pivotal movement. When the screws 51 and 52 are tightened, the module is held fixed in the housing with the contact terminals 31 and 32 making physical and electrical contact with the conductive members 28 and 29. Electrical wires 55 and 56 are connected to the conductive members by the wiring screw terminals 26 and 27. 
     In order to convert the contact module 25 as shown in FIG. 3A from the normally opened to the normally closed or from the normally closed to the normally opened condition, the arrangement as shown in FIG. 3A is exposed by removing the cover 34 and, if appropriate, the second section 33 of the housing in addition to the upper portions of the contact actuator rods 16 and lateral members 20. In order to unclamp the module the screws 51 and 52 are loosened. After the screws 51 and 52 are unthreaded sufficiently, they are pivoted outwardly about the retaining rods 53 and 54 as shown in FIG. 3B. The screws may be held captive in the rods in order to prevent inadvertent removal from the rods. Sideway movement of the screws is permitted by the open slots in the contact terminals 31 and 32 and the slots in the conductive members 28 and 29. When the heads of the screws clear the contact terminals 31 and 32 sufficiently, the module 25 may be removed as by lifting out directly or by tipping and lifting out. 
     The contact module may then be inverted and replaced in the housing in position as shown in FIG. 3B. (The module may contain suitable indicia indicating which position is normally open and which is normally closed.) Since the module is generally symmetrical about the contact terminals 31 and 32 and the opposed surfaces of the terminals are flat and parallel, there is essentially no mechanical difference as to whether the module is mounted in one position or its inverse. After the module is replaced in the housing, the screws 51 and 52 are pivoted inwardly into position and tightened to clamp the module as shown in FIG. 3A. As can be appreciated from FIGS. 3A and 3B, during the procedure of removing, converting, and replacing the module, the wiring 55 and 56 and the wiring terminals 26 and 27 are not disturbed. 
     A modification of the arrangement for holding the contact module in position and making electrical connection thereto is illustrated in FIGS. 4A and 4B. The contact modules 25 are identical with those employed in the previously discussed embodiment. In the modification shown in FIGS. 4A and 4B wires 61 and 62 are held by wiring terminals 63 and 64 in conductive members 65 and 66, respectively. Clamping screws 71 and 72 are threaded into the lower portions of folded hinging elements 73 and 74 which desirably may be of plastic in order to provide resilience. 
     In order to remove the module as for the purpose of changing the normal contact condition the screws 71 and 72 are loosened. When unthreaded sufficiently but still retained in the hinging elements, the screws pivot outwardly as illustrated in FIG. 4B. This action is permitted by the open slots in the contact terminals 31 and 32, aligned slots in the conductive members 65 and 66, and clearance openings in the upper portions of the hinging elements 73 and 74, respectively. The resilience of the plastic hinging elements 73 and 74 biases the screws 71 and 72 outward to the positions shown in FIG. 4B. 
     The module 25 may then be removed as by tipping and lifting out, inverted, and replaced in position on the conductive members 65 and 66. Each screw 71 and 72 is urged into its upright position, and tightened as shown in FIG. 4A. Thus the module may be inverted from one position to the other without interfering with the electrical connections to the wiring terminals. 
     FIG. 5 illustrates a further modification of the contactor in accordance with the present invention employing a modified contact module 80. Electrical wires 91 and 92 are connected to conductive members 81 and 82 by wiring terminals 93 and 94, respectively. In this version the conductive members 81 and 82 are reduced in width in the region in contact with the contact terminals 83 and 84 of the module. A threaded hole is provided in each of these regions. The structure of the module 80 adapted for mating with the conductive members 81 and 82 is best shown in the elevational, side, and plan views, FIGS. 6, 7, and 8, respectively, of the module. 
     Screws 85 and 86 which clamp the contact terminals 83 and 84 against the conductive members 81 and 82 are pivotally held in the contact module. Each screw 85 and 86 is captively mounted for rotation in U-shaped members 87 and 88. The arms of the U-shaped members are slotted to receive tabs extending from the side edges of the contact terminals 83 and 84. The contact terminals 83 and 84 each have open slots along the portion of their major axis. 
     As shown in FIG. 5, the module 80 is fastened in place by screws 85 and 86 threaded into mating threaded openings in conductive members 81 and 82 to clamp the contact terminals 83 and 84 against the conductive members 81 and 82, respectively. The arms of the U-shaped members 87 and 88 fit on opposite sides of the regions of the conductive members of reduced width. 
     The module 80 is removed from its position by completely unthreading the screws 85 and 86 from the conductive members 81 and 82. The module is then removed from the contactor and inverted. The U-shaped members 87 and 88 are then positioned with the tabs of the contact terminals 83 and 84 at the bottom of the slots in the arms of the U-shaped members. The U-shaped members and captive screws are then pivoted through 180° as illustrated by the phantom showing in FIG. 6. With the U-shaped members and captive screws reversed, the module is repositioned in the housing, and the screws 85 and 86 tightened. The module is clamped in position as shown in FIG. 5 with the contact terminals 83 and 84 in contact with the conductive members 81 and 82. Thus, this modification also provides for quick and easy removal and inverting of the contact modules in order to convert the operating condition of the contacts without interfering with the external electrical connections to the wiring terminals. 
     While there has been shown and described what are considered preferred embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.