US2341896A - Circuit controller - Google Patents

Description

G. BELLoWs, JR., ETAL Feb. 115',` 1944.

CIRCUIT CONTROLLER Filed Sept. 2, 1942 Paiented Feb. 15, 1944 UNITED STATESk PATENT OFFICE CIRCUIT CONTROLLER Application September 2, 1942, Serial No. 456,988

9 Claims. (Cl. 20D-87) Our invention relates to circuit controllers and particularly to means for Iavoiding false contact operation in electric overload relays subject to violent shock or severe vibration.

The invention has for its principal object the provision of a new and improved substantially shock-proof electric relay.

It is a specific object of our invention to provide new and improved means for positively preventing false operation of the contacts of an electric overload relay due to violent shock or severe vibration.

It is evident that, where essential sources of electric current supply must be kept in operation by means of the apparatus subject to impact and f vibration, it is not only highly desirable but absolutely essential that false operation of the overload protective means should not result from the shock or vibration. According to our invention, the contacts of an overload protective relay are rendered substantially shock-proof by mounting the movable contact intermediate the ends of a relatively flexible cantilever spring and providing the relay armature With camming means operable both to apply a high degree of contact pressure when the contacts are engaged and to disengage the contacts while holding the spring against vibration at both sides of the movable Contact. Preferably, also, the camming means are so arranged that the relay armature may move at least half way from its circuit closing position to its circuit opening position Without disengaging the contacts.

Our invention will be more fully comprehended by referring now to the following detailed specification, taken in conjunction with the accompanying drawing, in which Fig. 1 is a side elevation, partly in section, of an overload relay embodying our invention; Fig. 2 is an end view of the relay of Fig. 1, certain parts being broken away more clearly to illustrate the underlying construction; and Fig. 3 is a fragmentary perspective view of the relay of Figs. 1 and 2.

Referring now to the drawing, the relay chosen for the purpose of illustration is a bus bar overload relay comprising a U-shaped magnetic frame I defining an elongated central aperture adapted to receive a bus bar II and provided with a pivotally mounted armature I2 to complete a magnetic circuit across the open end of the U-shaped frame. One edge of the armature I2 is beveled to provide a knife edge arranged pivotally to seat at the intersection of one leg of the U-shaped frame I0 and an offset extension I3. The armasition against a non-magnetic stop I4 by means of a tension spring I5 connected between an arm I6 extending from the bight of the frame I0 and a parallel arm I'I extending from the armature I2. One of the parallel arms I6, I1 should be non-magnetic and preferably the arm I'I is of brass. In order to limit lateral vibration of the spring I5 under shock, the spring is closely surrounded centrally by a guide I8 attached to one leg of the magnetic frame I0. Under certain conditions, such as unrestrained lateral vibration of the spring there may be established a torque tending to move the armature I2 to its attracted position. For example, in the relay shown in the drawing, the spring I5 is connected to the armature extension I'I by a pin I9. It will be clear that if the lower end of the pin I9 is moved in a counter-clockwise direction, as by spring oscillation, there will be a tendency to twist the armature I2 to its energized or attracted position.

Bus bar relays of the type described are frequently positioned on one of a plurality of closely adjacent parallel bus bars, so that the adjacent I, bus very likely will set up a stray flux through the therefrom with non-magnetic spacers 23.

air gap 20 between the armature I2 and the frame I0. This iux may be either aiding or opposing the normal relay actuating flux from the bus bar I I, but in either event it will destroy the calibration of the relay. In order to guard against such a condition, we provide a magnetic shunt for the air gap 20 in a form of a U-shaped magnetizable member 2| mounted upon the sides of one leg of the frame ID by means of bolts 22 and spaced The armature I2 preferably is separated from the magnetic shunt 2I by a gap greater than the air gap 20 so that the shunt does not carry an appreciable portion of the main relay ux away from the air gap. It will be understood that diminution of the gap defined by the non-magnetic spacer 23 will increase the eiectiveness'of the magnetic shunt, but will also decrease the pull on the armature I2. Since the relay is calibrated with the shunt in position the loss of some main flux through the shunt does not effect the calibration, and the shunt serves primarily to lead the stray flux of an adjacent bus bar (not shown), such as a flux indicated by the broken line 24,

- away from the air gap and directly into the magnetic frame I0. It will be understood that the stray flux of an adjacent bus baron the other side of the relay will also be carried by the shunt. The presence of this additional flux in a portion ture is biased to a deenergized or unattracted poof the magnetic circuit of the relay is not objectionable since the relay may be designed to operate only when it reaches a condition of saturation.

The shock-prooi contact mechanism is mounted upon o-ne leg of the magnetic frame lil within the magnetic shunt 2l and comprises a pair of stationary contact members 3@ and a pair of cantilever springs 3i mounted in parallel spaced relation and separated by an insulatingv spacer 32. Referring particularly to Figs. 1 and 3, the stationary contact members 30 and the springs 3| are clamped together by means of bolts 33 which pass through an insulating shield Sil, insulating clamping blocks 35, the springs 3l, the insulating spacer 32, and into tapped holes in the xed contact members 3. This entire assembly is mountedupon the frame I by means of bolts 35 which pass through the insulating block 32 between the contact elements and into tapped holes in the adjacent leg of the frame ld. For the purpose of increasing' the length o-i the creepage path between the fixed. contacts 3B, tubes 31 of insulating material' are placed around the cantilever springs 3i and clamped in place between the insulating blocks 3E and 35, the tubes extending some distance along the springs El upon either side of the insulating blocks.

The lower ends oi the xed contact members 3U serve as terminal connectors 38, while the lower ends of the contact springs 3| are connected together by a jumper 39. The upper ends of the contact members 3i! are provided with. iiXed contacts lig, while the cantilever springs 3l' are provided with cooperating movable contacts M attached to the springs intermediate their ends. In this way the cantilever springs and jumper 39 serve as a bridging contact between the fixed contacts 4l).

The cantilever springs are self-biased to retain the contacts 4l in engagement with the fixedcontacts Gil. For the purpose of increasing. the contact pressure when the contacts are in engagingV position and also for the purpose ci separating the contacts, the armature l2 is provided. withv a T-shaped extension comprising an insulatingk block 42 and a substantially T-shaped contact actuating member 53. The member 43 may suitably be formed of metal, such as brass, and includes a head portion M positioned intermediate the two cantilever springs 3| and extending in substantially parallel spaced relation therewith. It will be understood that the actuating member 43 moves in an arcuate path about the knife edge pivot of the armature l2 when the armature moves between its attracted and unattracted positions. The head portion of the actuating member 43 isY provided with three transverse pins ll, 46, and 4l' which extend laterally from both sides of the head portion 1M and into slidingr engagement with the cantilever springs 3l. As clearly shown at Figs 1 and 3, the pins 45 and 46 are spaced apart and engage the outer surfaces of the springs 3l on cpposite sides ofthe movable contacts M. These pinsJiB and 45, are so positioned that when thecontacts are in engagement', they flex the springs 3l' on bothV sidesv oi the movable contacts to increase the contact pressure. For this purpose, also,V the free ends of the cantilever springs 3l are provided with camming portions i8 upon whichthe pin 45 rides in the Contact engaging position" to increase the fle-xure of the springs toward the stationary contacts.

The pin 41 is arranged closely adjacent the pin-46 and on the opposite surface of the cantilever springs 3l. The center of rotation of the armature I2 is so positioned that in moving between its attracted and unattracted positions, it carries the pin lll' along a line oblique to the plane of the contact springs 3l and at a very small acute angle thereto. By referring particularly to Fig. 1, it will be evident that in moving downward along such a line the pin A1 serves to cam the springs Si away from the Xed contacts Ml. In order to permit the contacts to separate under this camming action, the cam portions 13 at the free ends of the contact springs are so shaped that during downward or circuit opening movement of the actuating element 43 the pin i5 rides off of the camming surfaces d8 and permits the free ends of the cantilever springs to move outwardly away from the xed contacts. By proper positioning of the pins 45, 35, and l1 and proper shaping of the cam elements 8, it will be evident that a substantial movement of the actuating element i3 may be required before the contacts are separated. Preferably, in order to minimize the possibility that the contacts will separate due'v to shock, about 50% of the contact disengaging movement of the armature shouldk take place before separation of the contacts occurs.

It is believed that the above detailed description of the various parts of our relay and their manner of interconnection will be of itself sufcient for an understanding of the mode of operation, sothat no further detailed description of the operation is deemed necessary. By way of summary, however, it may be noted that in the Contact separating operation caused by movement of the armature downward from its unattracted to its attracted position, the cantilever springs are at all times firmly held against vibration at both sides of the movable contacts 4l. The fact that the pins 455, 6%, and El are in constant engagement with the cantilever springs at closely spaced points on both sides oi the iixed contacts results in a high natural period of: vibration for the small section of spring included between the pins andV 46. This minimizes the likelihood that the contacts will .bounce closed once they are open. It is most essential, however, that the contacts do not separate due to shock when' they should remain in their. closed' position.` Such a contingency is doubly guarded against, according to our invention, by the fact that, not only must the armature move over halfway toward its contact opening position before' the contacts may be separated, but also when the contacts are in their engaging position they are firmly heldv in, this position with an increased contact pressure by both the pins t5 and 45.

WhileY we have illustrated only one preferred embodiment of our invention by way of illustration, many further modications will undoubtedly occur to those skilled in the art. For eX- ample, while we have shown a relay so arranged that its contacts remain engaged to maintain true spirit and scope and'our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. A cricuit controller comprising a support, a

fixed Contact mounted upon said support, a flexible cantilever spring mounted at one end upon said support, a movable contact connected to said spring intermediate the ends thereof, and actuating means mounted upon said support and having a portion movable obliquely ol said spring at a small acute angle thereto to control movement of said movable contact, said actuating member being provided with spaced cam means on opposite sides of said movable contact in constant engagement with said spring to minimize vibration thereof.

2. An overload protective relay comprising a support, a iixed contact mounted upon said support, a flexible cantilever spring having a movable contact mounted intermediate its ends and movable from a circuit maintaining position to a circuit disabling position with respect to said fixed Contact, said spring being biased to said circuit maintaining position, an actuating member movable obliquely of said spring to move said spring to said circuit disabling position, and cam means movable with said actuating member in constant engagement with said spring on both sides of said movable contact to minimise ribration of said spring, said cam means being arranged positively to increase the circuit maintaining bias of said spring when said actuating member is in said circuit maintaining position.

3. An overload protective relay comprising a support, a fixed contact mounted upon said support, a flexible cantilever spring mounted at one end upon said support and having a movable contact mounted intermediate said ends, said spring being movable from a circuit maintaining to a circuit disabling position with respect to said xed contact and being biased to said circuit maintaining position, an actuating member movable obliquely of said spring to move said spring to said circuit disabling position, said actuating member being arranged to complete a substantial proportion of its travel before eilecting any significant movement of said movable contact, and cam means mounted upon said actuating member for constant engagement with said spring on both sides of said movable contact positively to increase the circuit maintaining bias of said spring when said actuating member is in its circuit maintaining position.

4. An overload protective relay comprising a support, a fixed contact mounted upon said support, a flexible cantilever spring mounted at one end upon said support and carrying intermediate its ends a movable contact for cooperation with said fixed contact, said spring being biased to retain said contacts in engaging position, and actuating means comprising spaced movable camming means slidably engaging said spring on opposite sides of said movable contact, said camming means being arranged when .in a circuit closing position positively to increase the bias of said spring toward said fixed contact and when moved to a circuit opening position to release said additional bias and to separate said contacts.

5. A circuit controller comprising a support, a fixed contact mounted upon said support, a ilexible cantilever spring mounted at one end upon said support and having a movable contact lixed intermediate the ends thereof, and actuating means pivotally mounted upon said support and having a portion extending substantially longitudinally of said spring on either side of said movable contact, said portion of said actuating member comprising a pair of adjacent cam elements engaging said spring on opposite sides thereof, said cam elements being movable obliquely of said spring at a smal acute angle thereto to control movement of said movable contact, and second cam means mounted upon said portion of said actuating member for a constant engagement with said cantilever spring at the opposite side of said movable contact, said second cam means being cooperable with said cam elements to hold the included portion of said spring against vibration.

6. A circuit controller comprising a support, a fixed Contact mounted upon said support. a flexible cantilever spring mounted at one end upon said support and having a movable contact iixed intermediate the ends thereof, said cantilever spring being biased to retain said movable contact in engagement with said xed contact, movable actuating means pivotally mounted upon said support and extending substantially perpendicular to said cantilever spring, said actuating member carrying at the end thereof a head portion extending substantially longitudinally of said spring on either side of said movable contact, said head portion of said actuating member being provided with spaced cam means on opposite sides of said movable contact member arranged slidably to engage said spring positively to hold said contacts in engagement and a camming pin intermediate said movable contact and the ixed end of said spring movable obliquely of said spring to cam said movable contact out of engagement with said fixed contact.

'7. A circuit controller comprising a support, a xed contact mounted upon said support, a ilexible cantilever spring mounted at one end upon said support and having a movable contact iixed intermediate the ends thereof, said spring being biased to a contact engaging position, an actuating member pivotally mounted upon Said support for movement between circuit opening and circuit closing positions, said actuating member including an end portion positioned substantially longitudinally of and adjacent said spring and extending on opposite sides of said movable contact, a camming pin mounted upon said end portion to engage said spring intermediate said movable contact and the fixed end of said spring, said pin being movable slightly obliquely of said spring to cam said movable contact out of engagement with said fixed contact, and cam means at the free end of said spring cooperable with said actuating member to ex said spring in a direction to increase the contact pressure when said actuating member is in said circuit closing position and to release said contact pressure and permit separation of said contacts upon movement of said actuating member toward said circuit opening position.

8. A circuit controller comprising a support, a xed contact mounted upon said support, a iiexible cantilever spring mounted at one end upon said support and having a movable contact xed intermediate the ends thereof, said spring being biased to a contact engaging position, a movable actuating member pivotally mounted upon said support for movement between circuit closing and circuit opening positions, said actuating member being provided vvith a head portion extending in substantially parallel spaced relation with said spring on opposite sides of said movable contact, a pair of adjacent pins extending laterally from said head portion to embrace said spring on opposite sides thereof intermediate said movable Contact and the fixed end of said spring, onev of said pins being positioned to increase the contact pressure of said spring when said actuating member is in said circuit closing position and both said pins being movable slightly obliquely of said spring to cam said movable contact out of engagement with said xed contact upon movement of said actuating member to said circuit opening position, a cam element mounted upon the free end of said spring, and a cam follower pin mounted upon said head portion for cooperation With said cam element to increase the Contact pressure of said spring in the circuit closing position of said actuating member and to release said additional contact pressure upon movement of said actuating member toward said circuit opening position.

9. In a shock-proof electric circuit overload protective relay of the type comprising a magnetizable frame and an armature therefor movable between circuit closing and circuit opening positions, the combination comprising a support, a iixed contact mounted upon said support, a flexible cantilever spring mounted at one end upon said support and having a movable contact fixed intermediate the ends thereof, said spring being biased to a contact engaging position, means for biasing said armature to said circuit closing position, a contact actuating extension attached to said armature and extending in substantially parallel spaced relation with said spring on opposite sides of said movable contact, a pair of adjacent camming pins extending laterally from said actuating extension to embrace said spring on opposite sides thereof intermediate said movable contact and the fixed end of said spring, one of said pins being positioned to increase the Contact pressure of said spring when said armature is in its circuit closing position and both of said pins being movable slightly obliquely of said spring to cam said movable contact out of engagement with said iixed contact upon movement of said armature to its circuit opening position, a cam element mounted upon the free end of said spring, and a cam follower mounted upon said actuating extension for cooperation With said cam element to increase the contact pressure of said spring in the circuit closing position of said armature and to release said contact pressure upon movement of said armature toward said circuit opening position, said cam portion and said pins being so arranged that said armature must cornplete a substantial proportion of its travel from its circuit closing position to its circuit opening position before eiecting any significant movement of said movable contact.

GUY BELLOWS, JR. EARNEST F. WEISER.

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