Mechanical interlock for a pair of electromagnetic switches

Abstract: A pair of electromagnetic switches with an interlock, including operating members pivoted by movement of armatures of the switches. Ring segment cams are carried by the respective operating members along arcuate paths which intersect so that movement of one switch out of the off position mechanically blocks movement of the armature of the other switch out of the off position. For side by side electromagnetic switches, the operating members are directly confronting. For other arrangements, one above the other, the operating member of one switch includes a first pivot member pivoted by the associated armature, and a second pivot member on which the ring segment cam is carried, confronting the second operating member, and connected to and pivoted with the first pivot member by a connecting member.

Description: This invention relates to electromagnetic switches, and in particular to an interlock arrangement for preventing two electromagnetic switches from being turned on at the same time, and has particular application to forward and reverse controllers for electric motors. There are applications where two electromagnetic switches must not be energized at the same time. One such application involves the forward and reverse controllers for electric motors. Simultaneous operation of both controllers would result in short circuiting of the phases of the power supply. There are a variety of mechanical interlock designs in use today for preventing the simultaneous energization of two controllers. Probably the most common type of mechanical interlock is of the type of interlock that relies on the high closed gap force of an electromagnet compared to the, open gap force to prevent the closure of the second controller and generally known as the see-saw design. However, it is possible to cause a transition from a primary controller to a secondary controller by the application of an external mechanical force. Also, the linear nature of this design results in substantial travel of both controllers before interlocking action begins. Another common mechanical interlock is based on using a "four bar" linkage as disclosed in the specification of U.S. Patent No. 3,815,063. An advantage is to have an interlock adapted for interlocking forward and reverse motors controllers. The present invention consists in an interlock in combination with two spaced apart electromagnetic switches each having an armature which moves between open and closed positions to open and close the electromagnetic switch, said interlock comprising a first operating member pivoted by movement of the armature of said first switch between open and closed positions, a second operating member pivoted by movement of the armature of said second switch between said open and closed positions, first cam means carried along a first arcuate path by said pivoting of said first operating member, and second cam means carried along a second arcuate path by said pivoting of said second operating member, said arcuate paths intersecting at an intersection point through which neither cam means extends when both electromagnetic switches are open, and through which extends one cam means carried by the pivoting of one operating member by movement of the armature of one switch out of the open position to block the other cam means so as to prevent movement of the armature of the other electromagnetic switch out of the open position. Conveniently, cams are carried along arcuate paths by the pivoting of each of the operating members. The arcuate paths along which the cams are carried intersect at an intersection point located such that when one of the switches is out of the off position the associated cam is pivoted to extend through the intersection point, thereby mechanically blocking pivoting of the other cam, and therefore the associated switch armature, out of the off position. The intersection point of the arcuate paths along which the cams travel is spaced adjacent one end of each of the cams only by a distance providing clearance for one cam only to be carried along its arcuate path without interference from the other cam. In the preferred embodiment of the invention, the cams are ring segments aligned with the respective arcuate paths. In one embodiment of the invention, wherein the electromagnetic switches are positioned side by side with their armature aligned for movement in a common plane, the two operating members of the interlock confront one another with the respective cams projecting toward the other operating members so that the arcuate paths followed by the cams are in a common plane. In another embodiment of the invention where the electromagnetic switches are positioned with their armatures spaced apart for movement in parallel planes, one operating member comprises a first pivot member pivoted by movement of the armature of the associated switch, a second pivot member confronting the operating member of the other switch and a connecting member connecting the second pivot member to the first pivot member for pivoting the second pivot member with movement of the first armature. The second pivot member carries the cam for the one operating member along the arcuate path which intersects the arcuate path of the cam carried by the other operating member. The invention, will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a front elevation view of a pair of motor controllers interlocked in accordance with the invention. Figure 2 is a side elevation view of the interlocked controllers shown in Figure 1. Figure 3 is a front elevation view of the operating components of the interlock utilized in Figures 1 and 2. Figure 4 is a side elevation view of the interlock of Figure 3 shown in the rest position with both of the interlocked controllers open. Figure 5 is an elevation view similar to Figure 4 showing the configuration of the interlock with the lower controller in the closed position. Figure 6 is a view similar to Figure 4 showing the configuration of the interlock with the upper controller in the closed position. Figure 7 is a front elevation view of two controllers mounted side by side and interlocked with another embodiment of the invention. Figure 8 is an exploded front elevation view of the interlock of Figure 7. Figure 9 is a vertical view with one half of the housing removed on the interlock of Figure 8 shown with both controllers open. Figure 10 is a view similar to Figure 9 showing the configuration of the interlock with one switch closed. The invention will be described as applied to a forward and reverse motor controller pair. Referring to Figures 1 and 2, a forward motor controller 1 is shown mounted in direct alignment above a reverse motor controller 3. The controllers 1 and 3 have armatures 5 and 7, respectively, which move in horizontal planes 9 and 11. An interlock device 13 is provided to prevent simultaneous closure of the two controllers 1 and 3. The interlock device 13 includes an upper housing 15 secured to the side of circuit controller 1 by a pair of locking jaws 17 and a lower housing 19 similarly secured to the side of controller 3 by locking jaws 21. Referring to Figures 3 through 6, as well as 1 and 2, the upper housing 15 contains an upper operating member 23 which includes a first pivot member 25. Extending laterally from the pivot member 25 and into engagement with the armature 5 of the controller 1 is a shaft 27. As the armature moves forward and backward between an open and closed position, respectively, the shaft 27 rotates the first pivot member about a pivot pin 29. The lower housing 19 supports a second operating member 31 which includes a pivot member 33 having a shaft 35 extending into and engaging the armature 7 of the controller 3 and pivoted about a pivot pin 37. The first operating member 23 includes a second pivot member 39 mounted in the lower housing 19 for rotation about a pivot pin 41. The second pivot member 39 is connected to the first pivot member 25 by a connecting rod 43 such that rotation of the first pivot member 25 causes corresponding rotation of the second pivot member 39. The pivot member 33 of the lower operating member 31 has a slot 45 which provides clearance for the pivot member 33 relative to the pivot 41. The pivot members 33 and 39 are mounted in a confronting relation with their pivot pins 37 and 41 mounted equidistantly above and below, respectively, the plane of movement of the armature 7 of the lower controller 3. The pivot member 33 has a cam in the form of a ring segment 47 which projects laterally toward the pivot member 39 and is carried along an arcuate path 49 with pivoting of the pivot member 33. Similarly, a cam in the form of ring segment 51 extends laterally from a pivot member 39 toward the pivot member 33 and is carried along an arcuate path 53 with pivoting of the pivot member 39. The ring segment cams 47 and 51 are in the same plane such that the arcuate paths 49 and 53 intersect at an intersection point 55. The centers of curvature of the ring segment cams 47 and 51 are coincident with the pivot pins 37 and 41, respectively. With both of the controllers 1 and 3 "open" the interlock mechanism is in the condition shown in Figure 4 in which neither of the cams 47 or 51 extend through the intersection point 55 of their arcuate paths. If the lower or reverse controller 3 is energized causing the armature 7 to move rearward, the pivot member 33 of the lower operating member 31 is rotated counter-clockwise as shown in Figure 5 by the shaft 35. This carries the cam 47 along the arcuate path 49 so that it extends through the intersection point 55 as shown in Figure 5. With the cam 47 in this position, the upper controller 1 cannot be energized because the pivot member 39 cannot be rotated due to interference by the cam 47 and, thus, the armature 5 of the controller 1 cannot be moved because of its rigid interconnection with the pivot member 39 through the shaft 27, first pivot member 25, and the connecting the rod 43. If, on the other hand, with both controllers "open" as shown in Figure 4, the upper controller 1 is energized thereby drawing its armature 5 toward the rear, the shaft 27 rotates the pivot member 25 which in turn rotates the pivot member 39 through the connecting rod 43 to carry the ring segment cam 51 along its arcuate path 53 to the position shown in Figure 6 in which it extends through the intersection point 55. This blocks rotation of the pivot member 33 so that the lower controller 3 cannot be closed as long as the upper controller 1 is not open. The cams 47 and 51 are positioned when the respective switches are "open" with one end 57 spaced from the intersection point 55 only by a clearance necessary to prevent interference with the other cam. Thus, initial movement of the armature of either controller is sufficient to block operation of the other controller. Hence, very little travel of the armature of the first controller to be energized is required to provide the interlock function. In addition, the mechanical interference effected by this interlock prevents manual override through application of a mechanical force to the armature of the second controller. The interlock device, also includes switches which can be used to perform an electrical interlock function. Cantilevered movable spring contacts 59 are deflected into electrical contact with fixed contacts 61 by auxiliary camming surfaces 63 and 65 on the pivot members 25 and 33, respectively, when the associated controller is "open". Figures 7 through 10 illustrate a second embodiment of the invention which is adapted for use with a pair of controllers 1 and 3 mounted side by side for movement of their armatures 5 and 7 in a common plane perpendicular to the plane of Figure 7. The interlock 67 includes a single housing having housing halves 69A and 69B, best seen in the exploded view of Figure 8. The housing 69 is secured to the controllers 1 and 3 by pairs of jaws 71A and B, respectively. A first operating member 73 includes a pivot member 75 which is pivoted for a movement within the housing 69 about a pivot pin 77. Extending outward from the pivot member 75 through the housing section 69A and into engagement with the armature 5 of the controller 1 is a shaft 79. The interlock 67 includes a second operating member 81 comprising a pivot member 83 pivoted in the housing about a pivot pin 85 and having a shaft 87 which extends through the housing section 69B and into the controller 3 to engage the armature 7. A ring segment cam 89 on the pivot member 73 is carried along a arcuate path 91 by pivoting of the pivot member 73 by the armature 5 of the controller 1 through the shaft 79. Similarly, a ring-shaped cam 93 on the pivot member 83 is carried along arcuate path 95 by movement of the armature 7 of the controller 3. The pivot members 75 and 83 are mounted in the housing 69 in confronting relation with the cams 89 and 93 extending toward the other pivot member so that the arcuate paths 91 and 95 are coplanar and intersect at a point 97. Figure 9 illustrates the position of the operating members 73 and 81 when both of the controllers 1 and 3 are open. In this position, neither of the cams 89 or 93 extend through the intersection point 97 of the arcuate paths 91 and 95. Figure 10 illustrates the condition where the controller 1 has been energized which causes rotation of the pivot member 75 of the operating member 73 to carry the cam 89 along the arcuate path 91 so that it extends through the intersection point 97. In this position, the cam 89 blocks rotation of the pivot member 83 to prevent movement of the armature 7 to close the controller 3. With both controllers off as shown in Figure 9, closing of the controller 3 will result in rotation of the pivot member 83 so that its cam 93 would extend through the intersection point 97 so as to mechanically block closing of the controller 1. The interlock 67 also include switches 99 which are closed by auxiliary cam surfaces 101, 103 on the pivot members 75 and 83 to a closed position when the respective controllers 1 and 3 are open. The intersection point 97 of the arcuate paths 94 and 95 is spaced from the ends of the cams 89 and 93 when the respective controllers are in the open position, only by a distance required for clearance for the other cam, so that very little travel of the armature of one of the switches is required to effect the interlock. Interlocks provide a simple, positive, mechanical interlock which operates with a minimum of armature travel and cannot be overridden by application of a mechanical force to the armature of one of the controllers.

Claims: An interlock (1,3,67) in combination with two spaced apart electromagnetic switches (1,3) each having an armature (5,7) which moves between open and closed positions to open and close the electromagnetic switch, said interlock comprising a first operating member (23) pivoted by movement of the armature (5) of said first switch (1) between open and closed positions, a second operating member (31) pivoted by movement of the armature (7) of said second switch (3) between said open and closed positions, first cam means (47;89) carried along a first arcuate path (49;91) by said pivoting of said first operating member (23), and second cam means (51;93) carried along a second arcuate path (53;95) by said pivoting of said second operating member (31), said arcuate paths intersecting at an intersection point (55;97) through which neither cam means extends when both electromagnetic switches are open, and through which extends one cam means (47;89) carried by the pivoting of one operating member (31) by movement of the armature (7) of one switch (3) out of the open position to block the other cam means (51;93) so as to prevent movement of the armature (5) of the other electromagnetic switch (1) out of the open position. A combination according to claim 1, wherein each of the cam means (47,51;89;93) has one end (57) adjacent the intersection point (55;91) and spaced therefrom only by a distance providing clearance for one cam means only to be carried along its arcuate path without interference from the other cam means. A combination according to claim 2, wherein the first and second cam means each comprise a ring segment (47,51) aligned with the first and second arcuate paths (49.53). A combination according to claim 1, 2 or 3, wherein the first (1) and second (3) electromagnetic switches are positioned side-by-side with the armatures (5,7) aligned for movement in a common plane with the first (23) and second (31) operating members confronting one another and in which the first (49) and second (53) arcuate paths are coplanar. A combination according to claim 4, wherein the first operating member (23) is pivoted about a first pivot axis on one side of the common plane, and the second operating member (31) is pivoted about a second pivot axis on an opposite side of said common plane. A combination according to claim 5, wherein the first cam means comprises a first ring segment (47) on said first operating member (23) having a center of curvature coincident with the first pivot axis, and in which said second cam means comprises a second ring segment (51) on said second operating member (31) having a center of curvature coincident with the second pivot axis. A combination according to claim 1, 2 or 3, wherein the electromagnetic switches (1,3) are positioned with the first (5) and second (7) armatures spaced apart for movement in parallel planes, and in which the first operating member (73) of the interlock (67) comprises a first pivot member (75) pivoted by movement of the armature (5) of the first switch (1) between the open and closed positions, a second pivot member (83) confronting the second operating member (81), and a connecting member connecting said second pivot member to said first pivot member for pivoting said second pivot member with movement of said first armature (5) between said open and closed positions, the first (91) and second (95) arcuate paths being coplanar. A combination according to claim 7, wherein the second operating member (81) is pivoted about a first pivot axis on one side of the plane of movement of the second armature (7), and the second pivot member (83) is pivoted about a second pivot axis on the opposite side of said plane in which the second armature moves. A combination according to claim 8, wherein the first cam means comprises a first ring segment (89) on the second pivot member (83) having a center of curvature coincident with the second pivot axis, and wherein the second cam means comprises a second ring segment (93) on the second operating member (81) and having a center of curvature coincident with the first pivot axis. A combination according to claim 9, wherein the operating members (73,81) and the pivot members (75,83) are pivotally mounted in a common housing (69, 69A, 69B).

Inventors: DEVAULT BIRCH LEROY, EDWARDS GLENN HOWARD, DEVAULT, BIRCH LEROY, EDWARDS, GLENN HOWARD
Applicants: EATON CORP, EATON CORPORATION
Application year: 1992
Main classification: H01H9
IPC codes: H01H9, H01H50, H01H51