GB2071419A

GB2071419A - Electric Switching Device

Info

Publication number: GB2071419A
Application number: GB8106218A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1980-02-29
Filing date: 1981-02-27
Publication date: 1981-09-16
Also published as: JPS645732B2; BE887729A; CA1152544A; JPS56136424A; MX149443A; BR8101148A; NZ196373A; GB2071419B; ES8204875A1; ES499873A0

Abstract

An electric switching device, such as an electromagnetic contactor, relay or the like is provided with auxiliary contact means which includes stationary contact and terminal assemblies (29-33) supported in an insulating structure (1, 3) containing the operating coil of the device, and an auxiliary contact operating member (25) which is mounted in an insulating contact carrier (5) of the device as an integral part thereof sufficiently movable relative to the contact carrier to permit over-travel of the movable assembly (5, 8) following closure of the auxiliary contacts, the operating member (25) being spring-loaded in a contact- pressure providing sense. The auxiliary contact means are suitable for use with switching devices too small or otherwise not adapted to utilize unitary interlocking assemblies, and also for increasing the interlocking capability of switching devices which are designed to employ such unitary interlocking assemblies. <IMAGE>

Description

SPECIFICATION Electric Control Device This invention relates generally to electric control devices and, more particularly, to control devices utilizing auxiliary contact means.

Auxiliary contacts are commonly employed in conjunction with electric control devices, such as contactors, relays, and the like, to serve as electrical interlocks, for example for holding a control device energized after initial energization thereof through momentary closure of a switch, for providing undervoltage protection by disconnecting the operating coil of such device from its energizing source when the coil voltage undesirably drops to an extent causing the main contacts of the device to open, or for performing other circuit interlocking functions.

A typical apparatus designed for use with auxiliary contact structures is described in Applicant's U.S. patent specification No.

3,296,567 showing an electric control device, the insulating housing of which is provided with outwardly open cavities each adapted to receive a mechanical or electrical interlock. The interlocks used with this known device are not integral parts of the latter but are separate structural units of an add-on type which, when placed into the respective cavities, are in a position to be actuated by portions of the contact carried or crossbar, of the control device extending into said cavities.

The present invention has for its principal object to provide auxiliary contact means suitable for use both with control devices too small or otherwise not adapted to employ interlocking units of the add-on type, and with control devices which are designed to employ add-on type interlocks but require additional interlocking capability.

The invention accordingly resides in an electric control device comprising stationary contact; movable contacts cooperable with the stationary contacts; a stationary assembly comprising an insulating structure and, disposed therein, a magnetic core and an electric coil associated with the core; a movable assembly comprising an insulating contact carrier carrying said movable contacts, and a magnetic armature mounted in said contact carrier, said movable assembly moving to an actuated position upon energization of said coil and returning to a normal position upon deenergization of the coil, thereby to move the movable contacts to one and the other of contact open and contact closed positions with respect to the stationary contacts; and at least one auxiliary contact structure comprising contact and terminal assemblies including stationary contact means, movable contact means, and an operating member acting upon the movable contact means to effect movement thereof into and from contact engagement with said stationary contact means upon movement of said movable assembly to one and the other, respectively, of said actuated and normal positions, said contact and terminal assemblies being fixedly mounted on said insulating structure, and said operating member being supported in said contact carrier as an integral part thereof and being mounted therein such manner as to allow sufficient freedom of relative movement between the operating member and the contact carrier to permit overtravel of said movable assembly following engagement of said movable contact means with the stationary contact means, said operating member being spring-biased in a direction providing contact pressure between the movable and stationary contact means when engaged.

This arrangement of the auxiliary stationary contact means mounted on the insulating support structure of the stationary assembly, and of the operating member mounted on the contact carrier effectively utilizes space ordinarily available in control devices but heretofore left unused.

Moreover, the auxiliary contact means thus arranged will not interfere in the proper operation of a control device designed to use interlock units of the above-mentioned add-on type and, hence, can be applied to such device to increase its interlocking capability.

A further advantage of the novel control device is derived from the auxiliary stationary contact means being supported on the same insulating support structure as the electric coil, thus permitting the stationary contact means to be directly and permanently wired to the coil, if desired.

In order to render the auxiliary contact structure more shock and vibration resistant, it preferably includes means effective, when the auxiliary contacts are closed, to resiliently maintain contact engagement therebetween under shock and vibration.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one part of an electric control device embodying the invention, including the movable assembly thereof; Fig. 2 is an exploded perspective view of another part of the control device showing a portion of the stationary assembly thereof; Fig. 3 is an exploded perspective view of the base plate and magnetic core forming the remaining portion of the stationary assembly; and Fig. 4 is a cross-sectional view of the assembled control device.

The control device to which the invention is shown applied, by way of example, is of the general type disclosed in the above-mentioned U.S. patent specification No. 3,296,567, and therefore will be described herein only to an extent deemed desirable to impart a clear understanding of the invention.Thus, and referring in particular to Figs. 2, 3 and 4 of the drawings, the control device illustrated therein is an electromagnetic contactor comprising a lower or stationary assembly which comprises a base plate 2, a generally U-shaped magnetic core 7 (Fig. 3) supported on the base plate, a coil structure 1 (Fig. 2) comprising an insulating body provided with windows and having an electric coil (not seen) encapsulated therein, and a lower insulating housing part 3 supported on the base plate 2 and surrounding the magnetic core 7 as well as the coil structure 1 which is retained in the housing part 3 in such position that the two legs of the U-shaped core 7 extend through the two windows formed in the coil structure.

Referring now to Figs. 1 and 4, the upper part of the contactor comprises an insulating housing part 4, stationary contact and terminal assemblies 14 including stationary contacts and supported in the housing part 4, and a movable assembly guided in the housing part 4 for reciprocating movement between contact closed and contact open positions. The movable assembly comprises an insulating contact carrier 5 and a magnetic armature 8 supported therein.For each pole unit of the contactor, the contact carrier 5 has a contact-carrying portion with a window formed therein in which are disposed a movable contact member 15, and a compression spring 21 acting, through a spring seat 40, upon the movable contact member 1 5 to keep the latter seated against a ledge portion of the associated window when the movable assembly is not in its contact closed position, and to provide contact pressure between the movable contact member 15 and the associated stationary contacts 14 when closed.

The insulating contact carrier 5 includes further a portion, often referred to in the art as a crossbar, deffefining a cavity in which is seated the magnetic armature 8, the latter being securely retained in place within the cavity in a suitable manner, such as by means of a supporting pin or rod 12 extending through an opening in the armature and resting upon ledges formed in the contact carrier.

The upper and lower parts of the contactor are held securely together by means of bolts 35 which extend through aligned passages formed in the two housing parts 3 and 4, and which are threadedly engaged in tapped holes 36 formed in the base plate 2.

There are two compression or kickout springs 22 (Fig. 2) which are seated at their lower ends in apertures 23 formed in the lower housing part 3, and which act at their other ends upon the contact carrier 8 so as to bias the movable assembly toward a normal or unactuated position which, in the particular embodiment illustrated, happens to be its contact open position. The contact carrier 8 has formed thereon two spring retaining portions 24 which extend axially into the helical kickout springs 22 so as to stabilize them during compression.

With the movable assembly disposed in its normal position, as shown in Fig. 4, energization of the operating coil in the coil structure 1 will magnetize the magnetic core 7 sufficiently to attract the armature 8 and thereby effect movement of the movable assembly to the other or actuated position thereof in which the movable contact members 1 5 are engaged with the stationary contacts 14. Of course, subsequent deenergization of the operating coil will enable the kickout springs 22 to return the movable assembly to the normal, that is, in this case, the contact open position thereof.

As described thus far, the control device and its operation are conventional.

Referring now to Figs. 1, 2 and 4 of the drawings, the control device shown therein as embodying the invention includes auxiliary contact structures each comprising a pair of stationary contact and terminal assemblies 2933 which are disposed in spaced relationship side-by-side and include stationary contact means 30, movable contact means 27 cooperating with the stationary contact means 30, and an operating member 25 for the movable contact means 30. As seen best from Fig. 2, each stationary contact and terminal assembly comprises a generally Z-shaped terminal member 29 which carries a pressure plate 33 together with a terminal screw 31 on one end portion thereof, and a stationary contact 30 secured, e.g.

brazed, to the intermediate portion of the terminal member 29. The stationary contact and terminal assemblies are supported on the insulating support structure which comprises the insulating body of the coil structure 1 and the lower housing part 3. More particularly, each terminal member 29 has its end portion, opposite to the one carrying the terminal screw 31, lodged in a suitable recess or pocket formed in the insulating body of the coil structure 1, has its contactcarrying intermediate portion disposed adjacent a wall portion of the housing part 3, which wall portion thus prevents the terminal member from slipping from its retaining pocket in the coil structure 1, and has its terminal-screw carrying end portion seated in a recess formed in said wall portion of the housing part 3.An opening 32 extending from the recess into said wall portion is provided to accommodate the free end of the associated terminal screw 31, as best shown in the left-hand portion of Fig. 4.

The operating member 25 of each auxiliary contact structure is supported in the contact carrier 5 as an integral part thereof, moving together with the carrier to open and close the associated auxiliary contact means. The operating member 25 is mounted on the contact carrier 5 in such manner that there is sufficient freedom of relative movement between the two to permit overtravel of the movable assembly following engagement of the movable contact means 27 with the stationary contact means 30, and the operating member is spring-biased in a direction to provide contact pressure between the auxiliary contact means when closed.

More specifically, the operating member 25 of each auxiliary contact structure, preferably molded from a suitable insulating material, is shown in Figs. 1 and 4 as a slide or plunger slidably retained in a guide slot which is formed in the contact carrier 5 adjacent the cavity thereof containing the armature 8, and in which slot there is also disposed a spring 26 biasing the operating member in the above-mentioned direction to provide contact pressure between the closed auxiliary contacts and thereby also resist contact lift-off during vibration or shock.

In the particular embodiment illustrated, the movable contact means 27 of each auxiliary contact structure is represented as a bridging contact secured to the operating member 25.

Preferably, the bridging contact 27 is made of resilient stock and is so constructed that, when in bridging engagement with the stationary contact means 30, it will remain engaged and maintain contact pressure even under conditions of heavy vibration and/or shock.

Of course, the movable contact means of each auxiliary contact structure, shown herein as a bridging contact secured to and carried by the operating member 25, could also be a contact arm (not shown) separate from the operating member. Such contact arm would have one end thereof connected to one of the two terminal members 29 of the associated pair, and would be pivotable to permit its opposite end to be moved into and from contact engagement with the stationary contact 30 on the other terminal member 29, actuation of the contact arm being effected by the operating member 25 cooperating therewith. The contact arm could be a resilient spring contact naturally biased toward one contact position, and actuated by the associated operating member 25 to its other contact position upon a corresponding movement of the movable assembly.

As initially mentioned herein, the control device to which the invention is shown applied, by way of example, is generally as disclosed in U.S.

patent specification No. 3,296,567. Accordingly, and as also previously explained herein, it is adapted for use with auxiliary contactor interlock units to be inserted into cavities formed, as appears from Fig, 2, in the corners of the insulating support or housing structure. It will be noted, especially upon referring to Fig. 2, that the auxiliary contact means of the invention will not interfere with the operation of any auxiliary contact or interlock units disposed in said cavities, and therefore they can be used in combination therewith to increase the interlocking capability of the control device.

Of course, the number of auxiliary contact structures utilized (two, as shown, or just one) and the manner of connecting them will depend upon the interlocking functions desired. Thus, the two auxiliary contact structures shown in the drawings on opposite sides of the control device can be connected each to a different external circuit to be controlled. Or one of these may be connected to such circuit and the other omitted altogether, if not needed.Alternatively, the.two auxiliary contact structures together may be employed as an electrical interlock for the operating coil of the control device itself, in which event the opposite ends of the coil will be connected each to the stationary contact 30 of one of the two contact and terminal assemblies of the respective contact structure, and the other contact and terminal assembly of the respective contact structure will be used for connection to the external coil energizing circuit. If to be used in this manner, the auxiliary contact structures according to the invention offer an additional advantage derived from their close proximity to the coil which enables the contact means and the coil to be directly wired together to provide a compact, unitary assembly comprising the insulating structure 1,3 and the auxiliary contact and terminal assemblies 29-33 disposed thereon.

It will be appreciated that certain modifications may be made to the control device illustrated herein, such as, for instance, converting the normally open auxiliary contacts shown into normally closed auxiliary contacts, without departing from the teachings of the invention.

Claims

1. An electric control device comprising stationary contacts; movable contacts cooperable with the stationary contacts; a stationary assembly comprising an insulating structure and, disposed therein, a magnetic core and an electric coil associated with the core; a movable assembly comprising an insulating contact carrier carrying said movable contacts, and a magnetic armature mounted in said contact carrier, said movable assembly moving to an actuated position upon energization of said coil and returning to a normal position upon deenergization of the coil, thereby to move the movable contacts to one and the other of contact open and contact closed positions with respect to the stationary contacts; and at least one auxiliary contact structure comprising contact and terminal assemblies including stationary contact means, movable contact means, and an operating member acting upon the movable contact means to effect movement thereof into and from contact engagement with said stationary contact means upon movement of said movable assembly to one and the other, respectively, of said actuated and normal positions, said contact and terminal assemblies being fixedly mounted on said insulating structure, and said operating member being supported in said contact carrier as an integral part thereof and being mounted therein in such manner as to allow sufficient freedom of relative movement between the operating member and the contact carrier to permit overtravel of said movable assembly following engagement of said movable contact means with the stationary contact means, said operating member being spring-biased in a direction providing contact pressure between the movable and stationary contact means when engaged.

2. An electric control device according to claim 1, wherein said operating member is slidable and retained in a slot formed in said contact carrier.

3. An electrical control device according to claim 2, wherein said slot has disposed therein a spring which biases the operating member in said direction.

4. An electric control device according to claims 1 , 2 or 3, wherein said movable contact means comprises a resilient member adapted, when engaged with said stationary contact means, to resiliently remain in contact engagement therewith under shock and vibration.

5. An electric control device according to any one of the preceding claims, wherein said insulating structure comprises an insulating housing part, and an insulating body which has said electric coil encapsulated therein and is supported in said insulating housing part, the latter and said insulating body cooperating to hold said contact and terminal assemblies securely in place.

6. An electric control device according to claim 5, wherein each of said contact and terminal assemblies includes a terminal member which has an end portion thereof lodged in a retaining pocket formed in said insulating body, and has an intermediate portion thereof disposed adjacent an interior surface portion of said insulating housing part preventing dislodgement of the terminal member from said retaining pocket.

7. An electric control device according to any one of the preceding claims including two said auxiliary contact structures, wherein said coil is connected between and directly to the stationary contact means of said two auxiliary contact structures.

8. An electric control device substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.