US2581510A - Electric relays - Google Patents

Description

Jan. 8, 1952 H E, ASHWORTH 2,581,510

ELECTRIC RELAYS Filed Jan. 8. 1949 Z I g55/a: 55

Insulatan IN VEN TOR.

Hit/ig'. Asbwalll BY M HIS A TTRNEY Patented Jan. 8, 1952 ELECTRIC RELAYS Harry E. Ashworth, Penn Township, Pa., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application January 8, 1949, Serial No. 69,954

4 Claims.

My invention relates to electric relays, and particularly to relays oi' the type comprising a contact which becomes closed at the expiration of a time interval of relatively long duration after the relay becomes energized.

There is shown and described in Letters Patent of the United States No. 1,966,965 granted to Branko Lazich and myself on July 17, 1934, for Electrical Relays, a time element relay having two operating windings, two holding windings and two auxiliary windings, which are respectively energized at appropriate times during an operation of the relay. The relay includes a timing contact E which is closed after a predetermined interval following energization of the relay and which controls a holding circuit including the holding windings and the-auxiliary windings, although the latter are not functioning during the holding phase of the relay operation. The relay also includes a main amature which operates additional contacts upon closure of the timing contact.

One object of my invention is to provide an improved relay of the type described in the Lazich et al. patent.

Another object is to provide improved operating circuits for such a relay.

I accomplish the foregoing and other objects of my invention by revising the operating circuits of the Lazich relay so that the circuit for the holding windings is controlled by a contact operated by the main armature rather than by the timing contact. Furthermore, the auxiliary windings are shunted, and therefore deenergized, during the holding phase of relay operation. These results are accomplished without increasing the number of contact iingers required.

The single figure of the drawing is a view partly diagrammatic and partly in elevation, showing one form of relay embodying my invention.

The relay is illustrated diagrammatically in the present drawing, and since a full description of the relay may be had by reference to the above-identied patent, it is believed that for purposes of the present application the following brief description will be suiiicient.

As will be seen from an inspection of the drawing, the relay comprises a core structure consisting of three parallel legs I, 2, and 3 connected together at one end by a backstrap 4, and provided at the other end with pole pieces 5, 6, and 'I, respectively. The leg I is provided with an operating winding 8a and a holding winding 8b, which windings in actual practice are Wound into a single coil, and the leg 2 is similarly provided with an operating winding Ia and a holding winding 9b, which windings in actual practice are also wound into a single coil. The middle leg 2 is surrounded by an electrically conductive sleeve III, the function of which will become apparent as the description proceeds. 'I'he pole piece 5 is provided with two extensions 5a and 5b. and the pole piece I is likewise provided with two extensions Ia and 1b. The extensions 5a and 1a, as shown in the drawing, extend laterally toward each other, but in actual practice these extensions project rearwardly from the pole pieces to a point opposite the middle leg 2, which latter leg is oilset rearwardly from the legs I and 3.. 'Ihe extensions 5b and 'Ib are made U-shaped for a purpose which will appear presently and are provided with auxiliary bucking windings I9a and ISb, the purpose of which will also appear presently.

'I'he relay also comprises a main tractive armature II, an oscillatable timing armature 20, and a clutch armature 2I. 'I'he main tractive armature II is biased by gravity to a retracted position in which nonmagnetizable stops Ila and I Ib that are secured to the underside of the armature rest against pole faces I2a and I2b formed on the extensions 5b and lb, respectively, but is adapted to be at times moved against the action of gravity to an attracted position in which the armature engages nonmagnetic stops I 3a and I 3b provided on the underside of the pole pieces 5 and 1, respectively. The oscillatable armature 20 is pivotally supported by means of a pivot pin 22 between bifurcations which are formed in the pole piece 6, and is arranged to swing toward one or the other of the pole piece extensions 5a and 1a, nonmagnetic stops 20a being attached to the armature to prevent the armature from coming into actual contact with the pole piece extensions. The clutch armature 2| is biased by gravity to a position in which it is separated from the pole piece extensions 5a and 'Ia by means of air gaps, but is adapted to be moved, when the relay becomes energized, to a position in which nonmagnetic stops 2 la and 2 Ib secured to this armature engage the pole piece extensions 5a and 1a.

The main armature II actuates a plurality of contact lingers I4, I5, I6, I'I, and I8 which, when the armature occupies its retracted position in which it is shown in the drawing, engage xed back contact members Ila, I5a, I6a, Ila, and I8a, respectively, to close back contacts I4-AI4a, I5-I5a, i6-I6a, I'I-I'Ia, and I8-I8a. When, however, the armature II occupies its attracted y position, the fingers I4,

i8, i1, and |8 then engage iixed front contact members |4b, |51, |1b. and |8b, to close front contacts |4-|4b, |8|5b. |1-|1b. and I8-I8b. The back contacts Iii-wa, |8|6. and |1|1a and the front contacts |5|5b and |1-|1b control the operating circuits which energize the various windings ot the relay in a manner which will be described more fully hereinafter. The contacts associated with fingers i4 and I8 control circuits external to the relay and not shown in the drawing. These are the circuits which the relay is employed to open or close a Vpredetermined time after closure of a manual starting switch S.

The auxiliary armature 28 actuates a doublethrow contact finger 24 to close a contact 24-24a 4ror 24--24b according as the armature v2|) occupies the extreme position in which it is shown in the drawing, or its opposite extreme position, respectively. The contacts 2li- 24a and 24--24b control the supply of energy to the windings 8a and 9a in such manner that when the manually operable starting switch S is closed to energize the relay, and the main armature ii occupies the position shown, the armature 20 will be made to oscillate as will appear more fully hereinafter.

The armature 2|) also actuates a pawl 23 which cooperateswith a ratchet wheel 23a in such manner that oscillation of the armature 20 will cause a step-by-step rotation of the ratchet wheel in a clockwise direction. The ratchet wheel 23a is operatively connected with a planetary arm F in such manner that when a clutch 25, which is operatively connected with the clutch armature 2|, is engaging a clutch wheel 26, rotation of the ratchet wheel 23a will cause the arm F to rotate in a clockwise direction, but that, -when the clutch 25 is out of engagement with the clutch wheel, the arm F is then free to rotate in a counterclockwise direction, due to the bias of gravity, to a position in which a strip 21, which is secured to the arm F, engages an insulating member 30a, secured to a contact nger 30, and moves the insulating member into engagement with a iixed stop 28 and the linger 38 into engagement with another contact finger 3|. The stop 28 and flnger 3| are secured to a suitable supporting bracket 28, while the iinger 30 is secured to a similar bracket 32. The two fingers 30 and 3| together form a checking contact, the function of which is to indicate when the arm F occupies the position to which itis biased.

The contact arm F controls a contact E comprising two spaced fingers 33 and 3i attached by means of studs 33a and 34a to a block 85 oi' insulating material. The contact E is arranged to be closed, in response to clockwise 'rotation of the arm F, by means of an insulating piece 86 which is secured to the arm F.

Operation When the parts are in the positions shown in the drawing, switch S is open and the windings 8a, 8b, 9a, 9b, /a and lsb are all deenergized. The main armature therefore occupies its retracted position so that contacts |4|4a, |5--|5a, |6|6a, |1|1a, and |8|8a are all closed, and contacts |4-|4b, |5|'5b, i'l-ilb, and |8|8b are all open. The timing armature 20 is swung toward extension 5a of pole piece 5, and normal contact i4-24a is therefore closed. while reverse contact 24-241) is open. The contact arm F is held by gravityin its normal posi= tion, so that contact 3li3| is closed and contactEisopen.

4 I will now assume that with the parts in the positions just described, switch B becomes closed.

81 to the lower terminal of winding 9b, and winding 8a is shunted by a connection which may be traced from the lower terminal of winding 8a through wires 40 and 38, contacts 24-24a. |8-|8a, and |5|5a. and wire 4| to the upper terminal of winding 8a. As a result of energization of winding 8a, auxiliary amature 20 is swung toward extension 1a of pole piece 1, and the clutch armature 2| is attracted to extensions 5a and 1a of the pole pieces 5 and 1. The main armature however, is held away from the pole pieces 5 and 1 under these conditions because the windings |9a and |9b on the pole piece extensions 5b and 1b are deenergized, and the reluctance of the path to the main armature through the magnetic structures of the pole piece extensions 5b and 1b for the ux set up by winding 9a is lower than the reluctance of the path through the air gaps between the pole pieces 5 and 1 and the main armature, and hence more ux therefore reaches the main armature through the pole piece extensions than across the air gap from the pole pieces 5 and 1. It follows that the tractive force exerted to lift the armature toward the pole pieces 5 and 1 is less than the combined force of gravity and the eiect of the iiux through the pole piece extensions 5b and 1b. The contacts |4|4a, |5|5a, |6|6a, |1-|1a, and |8|8a controlled by the main armature theref ore remain closed even though winding '8a is now energized.

When the auxiliary armature 20 is swung toward extension 1a of pole piece 1, normal contact 24-24a becomes opened and reverse contact 24-24b becomes closed. Since contacts |||6a and |1|1a are still closed, the closing of contact 24--24b completes a shunt connection across winding 9a. This connection may be traced from the lower terminal of winding 9a through wires 36 and 42, contact 24-24b, contact IB-Ia and wire 31 to the upper terminal of winding 9a. The field set up by winding 9a commences to decay. Due, however, to the snubbing effects of the circuit for winding 9a. and oi' the conductive sleeve I0, this decay is comparatively slow. The opening of contact 24--24a in the meantime has removed the shunt from winding 8a, thus allowing this winding to become energized upon closure of contact 24-24b, through a circuit which may be traced from terminal B through wire 42, contacts 24-24b, |6-I'6a, |5-|5a, wire 4|, winding 8a. wire 40, and switch S to terminal C. The growth of the ux set up by this latter winding 8a is comparatively slow, however, due to the sleeve l0 on leg 2 and the shunted windings 8b and 9b. but, after an interval of time, the torque exerted on armature 20 by this iiux overbalances the torque exerted on armature 20 by the decaying iiux in winding 9a, and armature 20 then v swings back toward extension 5a of pole piece and 1 during this movement oi' the amature 2l for the reasons pointed out hereinbefore so that contacts I4-I4a, |5-l5a, |6-|6a, |1-I'|a, and Il-ia controlled by armature l I are still closed. and winding 3a therefore again becomes energized and winding 3a again becomes shunted. The shunt connection across windings 6b and 9b is not disturbed. The ileld of winding 6a then slowly builds up, and the field of winding 6a slowly decays, this decay being retarded by the self inductance of winding 8a and by the sleeve Il. It will therefore be seen that timing armature is positively swung to and fro as long as switch S is closed and the windings (3a and |9b remain deenergized, and it will also be clear that a considerable interval of' time elapses between armature movements. It should be pointed out that this time interval is substantially independent of fiuctuations of the electromotive force in the energy supply because the auxiliary armature is acted upon by two opposing forces both of which increase or decrease as the electromotive force of the energy supply increases or decreases.

Each time the auxiliary armature 2U is swung toward pole piece extension 1a, the pawl 23 rotates the ratchet wheel 23a through a small arc, and since the clutch 25 is now held in engagement with the clutch wheel 26 by the clutch amature 2i, the rotation of the ratchet wheel is transmitted through the gearing of the planetary arm F to this arm, thus causing the arm to be rotated in a clockwise direction in response to the rotation of the ratchet wheel. As soon as the contact arm has been rotated through a small arc, the resultant movement of the strip 21 permits contact finger 30 to move out of ensagement with contact finger 3|, thereby opening the contact 30-3|. After the armature 20 oscillates a predetermined number of times, the arm F moves the insulating piece 36 into engagement with the contact finger 33 and deflects it against contact finger 34, thereby closing contact E.

When contact E becomes closed, if contact` 24-24b is then closed, or as soon thereafter as contact 24-24b becomes closed, current is' supplied to the windings lila and I9b over a circuit which may be traced from terminal B through wire 42, contact 24-24b, contacts l1-i1a., wire 43, winding isb, wire 44, winding Isa, wire 45, contact E, wire 46 and switch S to terminal C. Windings 19a and I9b are then in parallel with winding 8a. and lsb are connected in this circuit in such manner that the fluxes created in the extensions 5b and 1b of the pole pieces 5 and 1 thread these extensions in the opposite direction from the fluxes which thread these extensions due to current in either of the windings 8a or 9a, and the parts are so proportioned that the magnitude of the flux in the extensions 5b and 1b due to the current in the windings I9a and iSb is suiiiciently great that the flux which threads the armature Il through the air gaps between the armature Il and the pole pieces 5 and 1 under these conditions exerts a torque on the armature which causes the armature to swing toward the pole pieces 5 and 1. Shortly after the armature Il starts to swing toward the pole pieces 5 and 1, contacts i4l4a. |5-|5a, |6`I6a, and IB-Iaa are opened but contact |1-I1a is adjusted to remain closed until the armature has moved a short distance beyond the point in its upward travel at which the other contacts open.

The windings I9a CII winding 8a is deenergized and the shunt con.

nection for winding 3a, which is normally completed at contact |6-I6a when contact 24-24b is closed. is opened. Winding 9a is then supplied with current in series with the windings 19a and I9b over contact I1-I1a, the circuit being from terminal B through wire 36, winding 3a, wire 31, contact I1-|1a, wire 43, winding lsb. wire 44, winding Isa, wire 45, contact E. wire 46, and switch S to terminal C. Winding 9a, therefore, becomes energized and supplies flux to the armature H in place of winding 8a. The resistance of the windings lila and `|911 will usually be considerably less than the resistance of the winding 9a, so that the insertion of windings Isa and I9b in series with winding 9a does not materially reduce the voltage across winding 8a nor the current through it. Hence the flux due to winding 9a under these conditions is only slightly less than the magnitude of the flux which was supplied to armature il due to current in winding 8a, and it will be apparent, therefore, that the opening of contacts I5-|5a and IG--IGa has very little effect on the torque exerted on the armature Il tending to move the armature toward the pole pieces 5 and 1. As soon as winding 8a becomes deenergized and winding 9a becomes energized in the manner just described, auxiliary armature 20 stops oscillating, and this armature is then held in the position in which its contact 24-24b is closed. When contact I1-I1a opens, the shunt connection which was previously closed for windings 8b and 9b at this contact is opened, and the windings 8a, 6b, 9b, lila, and ISb in series are then all supplied with current from the terminals B and C of the source over contact E and switch S so that these windings are all energized. The windings 8b and 9b are preferably constructed to have a comparatively high resistance in order to limit to a low value the current supplied to the relay after these windings become energized. When armature Il has completed its upward stroke. contacts I4-I4b, |5-`|5b, I1-I1b, and I8-i8b become closed. Closure of contact I5-I5b completes a shunt connection for winding 8a which may be traced from its upper terminal through wire 4|, contactl l5-I5b, and wires 38 and 40 to its lower terminal. Closure of contact |1-I1b completes a shunt connection for the circuit branch which includes windings I9a and |91) and switch E. This shunt may be traced from switch S through wire 38, wire 41, contact |1-i1b and Wire 43 to the upper terminal of winding 19h.

As long as switch S remains closed, windings 8b, 9b and 3a remain energized through a circuit which may be traced from terminal B through wire 36, windings 9a, 9b, 8b, wire 39, contact I1-I1b, wires 41 and 38, and switch S to terminal C. This holding circuit is independent of any contact other than switch S and contact |1-|'lb, which latter contact is held closed by armature Il. In particular, the holding circuit is independent of contact E and therefore of the clutch 25 and the timing mechanism operated by oscillatable armature 20. Opening of contacts E due to vibration at the contacts or to any malfunctioning of the timing mechanism is thereby prevented from affecting the position of the main armature and the contact fingers I4 and I8. When switch S is opened to deenergize the relay; the neutral armature il drops away from the pole pieces 5 and 1, thereby opening contacts l4|4b, I5--i5b, I1-I1b, and i8--I8b and closing contacts iI--ila, i|5a, l6-l8a, I'l-l1a, and |8--I8a. Furthermore, the clutch armature 2| drops away from the extensions ia and la of the pole pieces 5 and l, respectively, thereby permitting the contact arm F to return by gravity to its normal position. When the contact arm returns to its normal position, contact E is opened and contact 3U-3i becomes closed. When contact 30--3I becomes closed, the parts of theA relay are then restored to their normal positions in which they are illustrated in the drawing.

Although I have herein shown and described only one form oi' electric relay embodying my invention. it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A time element relav comprisingtwo operating windings and a holding winding, a timing armature oscillatable by alternate energization of said operating windings, energizing circuits for said operating windings including a double-throw contact nger operated by said timing armature and effective to alternately close said circuits, a timing contact, timing means operated by oscillation of said timing armature and effective after a predetermined number of oscillations thereof to close said timing contact. a main armature, an auxiliary winding effective when energized in conjunction with one oi said operating windings to cause said main armature to move from a retracted position to an attracted position, an energizing circuit for said auxiliary Winding including said timing contact. at least three contact fingers operated by said main armature, back and front contacts associated with one of said three fingers, said one nger being effective when engaging its back contact to complete a shunt for said holding winding and said auxiliary winding energizing circuit and when engaging its front contact to complete a shunt for said auxiliary winding and an energizing circuit for said holding Winding independent of said timing contact, said one finger being effective when moving between its back and front contacts when said timing contact is closed to open both said shunts so that said auxiliary and holding windings are then energized in series over said timing contact, back and front contacts associated with a second of said three iingers. said second finger being effective when engaging its back contact to complete the energizing circuit for one of said operating windings and when engaging its front contact to complete a shunt connection for said one operating winding, and a back contact associated with the third of said three fingers and connected in series with said double-throw contact finger in both said operating winding energizing circuits.

2. A time element relay comprising two operating windings and a holding winding, a timing armature oscillatable by alternateenergization of said operating windings, energizing circuits 8 giz'ed in conjunction with one o f said operating windings to cause said main armature to move from a.4 retracted position to an attracted position, an energizing circuit for said auxiliary winding including said timing contact, a plurality of contact fingers operated by said main armature. back and front contacts associated with one of said plurality of fingers, said one nger being effective when engaging its back contact to complete a shunt for said holding winding and said auxiliary winding energizing circuit and when engaging its front contact to complete a shunt for said auxiliary winding and an energizing circuit for said holding winding independent of said timing contact, said one nger being eiiective when moving between its back and front contacts when said timing contact is closed to open both said shunts so that said auxiliary and holding windings are then energized in series over said timing contact, and back and front contacts associated with a second of said plurality of nngers, said second finger being eiective when engaging its back contact to complete the energizing circuit for one of said operating windings and when engaging its front contact to -complete a shunt connection for said one operating winding.

3. A time element relay comprising two operating windings and a holding Winding. a timing armature oscillatable by alternate energization of said operating windings, energizing circuits for said operating windings including a doublethrow contact finger operated by said timing armature and effective to alternately close said circuits, a timing contact, timing means operated by oscillation of said timing armature and eiiective after a predetermined number of oscillations thereof to close said timing contact, a main armature, an auxiliary winding effective when energized in conjunction with one of said operating windings to cause said main armature to move from a retracted position to an attracted position, an energizing circuit for said auxiliary Winding including said timing contact. a plurality of contact fingers operated by said main armature, backl and front contacts associated with one of said plurality of ngers, said one finger being effective when engaging its back contact to complete a shunt for said holding winding and said auxiliary winding energizing circuit and when engaging its front contact to complete a shunt for said auxiliary winding and an energizing circuit for said holding winding independent of said timing contact, and a back contact associated with a second of said plurality of lingers, said second nger being effective when engaging its back contact to complete the energizing circuit for said one operating winding.

4. A time element relay comprising two operating windings and a holding winding, a timing armature oscillatable by alternate energization of said operating windings, energizing circuits for said operating windings including-a doublethrow contact iinger operated by said timing armature and effective to alternately close said circuits. a timing contact, timing means operated by oscillation of said timing armature and eiective after a predetermined number of oscillations lthereof to close said timing contact, a main armature, an auxiliary winding effective when energized in conjunction with one of said operating windings to cause said main armature to move from a retracted position to an attracted position, an energizing circuit for said auxiliary winding including said timing conl REFERENCES CITED tact a plurality 0f Contact fingers Operated by The following references are of record in the said main armature, and backand front conle of this patent.

tacts associated with one of said plurality of fingers, said one nger being effective when en- 5 UNITED STATES PATENTS gaging its back contact to complete a shunt for Number Name Date said holding winding and said auxiliary winding 2,057,384 Lamb Oct. 13, 1936 energizing circuit and when engaging its front 2,111,635 Lazich Mar, 22, 1938 contact to complete a shunt for said auxiliary 2,454,161 Ha11 Nov. 16, 1948 winding and an energizing circuit for said holdl0 ing winding independent of said timing contact.

HARRY E. ASHWORTH.

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