US2337205A - Electrical relay - Google Patents

Description

Dec. 21, 1943. v H 2,337,205

ELECTRICAL RELAY Filed July 23, 1942 2 Sheets-Sheet l m'wmae N {g Aw AI'TORIVIY' Ja /Wm MM IYQWI Patented Dec. 21, 1943 UNITED STATES i rc'iEN'l' OFFICE (@l. coo -9c) 11 Claims.

My invention relates to electrical relays, and has particular reference to relays of the flasher class arranged to operate contacts in such a manner to open close such contacts alternately. More particularly, my invention relates to a flasher relay of the pendulum type, such, for example, as is disclosed in Letters Patent of the United States No. 2,156.684, granted to Arthur W. Fisher and myself on May 2, 1939, for Electrical relays.

In a type flasher relay, two sets of contacts are cperatively connected with the pendulum in such a manner that one set of contacts is closed in one portion of the pendulum stroke and the other set of contacts is closed in another portion of the stro :e. Such a relay incorporates means for causing the pendulum to oscillate at substantially its natural period. thereby causing the contacts to become alternately opened and closed at a rate dependent upon the period of the pendulum.

In certain applications of such relays, as for example in the control of the lamps of flashing light signals at railway-hi hway intersections, it is desire. is to close one set and open the other set of contacts when the relay is deenergized and the pendulum assumes its pendant or gravity biased position. contact arrangement must be attained without producing a limping operation of the contacts, that is. the times during which the two sets or" contacts are respectively opened closed when the relay is energized should remain substantially equal. It has been proposed heretofore to provide means for obtainthe desired closure of contacts in the doom- Zed position of the relay while maintaining a substantially eves time interval of operation of the two sets of contacts. Such means are for Letters Patent of the States No. 2,156.685, granted on May 2, to Noble C. Shaw, which discloses means eiiective when the relay is decnergized for exerting a f on the p duluh'i to move it away from gravity biased position to a position wherein t of two sets of contacts is closed. t also discloses for exerting a force s pendulum to resist movement of the penduring a portion or" its stroke so as to shor n or the stroke and thus to c or an unsymmetrical arrangement the two sets of contacts operated by the pendulurn.

fin object of hivention is to provide novel and improved means for obtaing in a pen ulum t pe flasher relay substantially equal tire;

vals of operation of two so of which is closed in l of the relay.

Another object is to provide. a relay of the class described, novel and improved means for obtaining substantially equal time intervals of operation. of two sets of contacts which are arranged unsy.o-....etrically so that one set is closed in the deenergized condition of the relay.

A further object is to provide a novel and i111- proved pendulum combination having one 11.0- ment of inertia in one portion of the stroke and having a different moment i inertia in another portion of the stroke.

An additional object is to provide novel and improved mans for varying the time that a pendulum requires to swing through a portion of its strolze as compared to the time of the swing of the pendulum in another portion of the stroke.

A still further object is to provide novel improved flasher relays of the pendulum type.

The above-mentioned and other important objects and characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with the invention by providing in a flasher relay a pendulum combination comprising a pendulum and an auxiliary mass associated with the pendulum in such a manner as to provide two different resultant moments of inertia, one for each of two different portions of the stroke or cycle of the pendulum combination.

I shall describe two forms of enibodyirig my invention, shall then p nt out the novel features thereof =1 claims.

In the accompanying drawings, .l is a View partially i front elevation and partially in section, showing one form of relay embodying my inve Fig. 2 is a view partially in end elevation and partially in sec the relay shown in l. 3 a top showing in more detail the contact arre ..nent of relay shown in Figs. 1 and 2. 4 is a View showing in more detail the pendulum combination, embodying my inventio of i 5 shcu Figs. 1, 2 and 3. Figs. 5 show pendu um coin -nation of Fig. in different operating positions. Figs. 7, 8 and 9 are views showing a modifled form of the pendulum combination of Fig. i, also embodying my irive tion, and for use wi h the relay she in Figs. 1, 2 In each of the several views, similar reference charactors have been employed to designate corresponding parts.

Referring to the ts of contacts, one set -e deenergized condition 4.. one

drawings, the reference character R designates as a whole a pendulum type flasher relay of the class shown for example in the aforesaid Patent No. 2,156,684. In view of the disclosure in this patent, only those portions of the relay essential to an understanding of my present invention will be described herein.

Relay R, in general, comprises an insulating top plate A from which is suspended by means of hangers I a suitable rectangular frame 2. A rockshaft i journaled at its ends in bearings 3 (see Fig. 3) suitably secured to frame 2, is biased to one position by a pendulum combination arranged to be oscillated at a predetermined frequency which depends upon the proportioning and adjustment of the parts, the oscillation being effected by means of a suitable motor device M hereinafter described.

The pendulum combination includes a compound pendulum which I shall term the main pendulum and which may have any suitable form but inthe form here shown comprises a U- shaped bracket 1 having upwardly extending arms la pinned intermediate their ends to rockshaft and provided at their upper ends with enlarged portions lb to provide a desired mass for this portion of the pendulum. A depending threaded post secured to the underside of yoke le of bracket l carries a counterweight if which is mounted eccentrically to the post To, and which serves both as a means for regulating the period of oscillation of the rockshaft within certain limits, and also as a means for varying the position to which the rockshaft is biased by means of the pendulum combination.

The pendulum combination also includes means operative to vary the resultant moment of inertia of the combination in certain portions of its stroke. These means comprise a movable mass so arranged that its center of gravity can be displaced from the rotational axis of the combination in one portion but not in another portion of the pendulum stroke, whereby to alter the moment of inertia or period of the pendulum combination in this one portion of the stroke.

In the form of the invention which is shown in Figs. 1 to 6, inclusive, this movable mass comprises an auxiliary pendulum 35 pivoted on a jackshaft 3| secured to one of the upwardly extending arms la at a point above the axis of rockshaft 4. The shafts 4 and iii are arranged so as to be substantially in vertical alignment when the combination is at rest and assumes its gravity biased pendant position represented in Figs. 1 and 2. In this condition of the apparatus, the centers of mass of the main and auxiliary pendulums will lie very close to or within a common vertical axis.

A stop 32 is provided on leg lo of the main pendulum and engages one side of the auxiliary pendulum 39 when the pendulum combination is in its gravity biased position. Stop 32 functions to prevent swinging movement of pendulum 3G to one side of the vertical axis of the combination while freely permitting the auxiliary pendulum to swing about its pivot to the other side of the vertical axis.

The previously referred to motor device M for oscillating the rockshaft d comprises an armature 8 which is pinned to the rockshaft at one side of bracket 1, and an electromagnet which cooperates with armature 8. This electromagnet may have any preferred construction, but in the form here shown comprises a winding 9 mounted on a backstrap l9 secured to the short arms lid of two L-shaped pole pieces ii, the long arms (ill Ilb of which extend upwardly past the opposite sides of armature 8 and are secured to depending lugs 21) formed on frame 2. The angular disposition of armature 8 with respect to rockshaft 5 is such that, when the rockshaft occupies the position to which it is biased by the pendulum combination, the longer axis of the armature will be inclined from the vertical at an acute angle with a horizontal line joining the two pole pieces lib, through the center of shaft as best seen in Fig. 2. This acute angle may be varied through relatively wide limits, but I have found that the best operating characteristics are ob tained for most conditions of operation when this angle is approximately 40.

The relay also comprises a plurality of contacts, here shown as six in number and designated by the reference characters 52, 53, ii, l5, l8 and ll, respectively. These contacts are of the well-known mercury type, and each comprises (see Figs. 2 and 3) a pair of electrodes 58 and is disposed in an evacuated bulb containing a quantity of mercury 253 which flows into or out of engagement with the electrodes to make or break a circuit passing therethrough. Contacts l2, 3 and it are mounted in spring clips 2!, 22 and 23, respectively, which are suitably secured to yoke 'lc of bracket l, and the contacts 55, it and H are mounted in spring clips 25, 26 and 2?, respectively, which spring clips are likewise suitably secured to yoke 5c of bracket 1.

Certain of the contacts such, as for example, as the two contacts l2 and i5, may be employed to control the supply of energy to winding 9 of the motor device lVl in such a manner that wind ing 9 will be supplied with current when the contacts l2 and [5 are both closed, but when either one of these contacts becomes opened due to the motion of the rockshaft, the supply or current to winding 3 will be interrupted. This result is accomplished by a series connection of the two contacts [2 and it. The position of rockshaft 4 at which the contacts I? and i5 are adjusted to open will depend upon the angular position of the armature with respect to the roclzshait and on the proportioning of the parts, but when the armature is secured to the rcckshaft in about the position shown, contact will preferably be so adjusted that it will break the operating cir cuit when the rockshait swings approximately T" in a clockwise direction as viewed in Fig. 2 from the position to which it is biased. Also, contact i2 will preferably be so adjusted that it will break the operating circuit when the rockshaft swings approximately 10 in a counterclockwise direction as viewed in Fig. 2 from the position to which it is biased. It should be particularly pointed out, however, that satisfactory operation of the pendulum can be obtained with a variation of several degrees in either direction from the above described adjustment of the contacts i2 and 55. The remaining contacts it, i l, it and 5? may be used for controlling the flashing lights of a highway crossing signal or other device, and are so adjusted that oscillation of the rockshaft with its intended amplitude will cause these contacts to become alternately opened and closed.

The operating mechanism of the relay is enclosed within a suitable casing 63 held in position against the underside of the top plate A by means of screws which pass through clearance holes provided in the bottom of the casing, and are screwed into tapped holes provided in the lower ends of depending lugs 66, the upper ends of which are secured to the underside of frame 2.

The operation of the relay as a whole is as follows: l hen winding 9 of the electromagnet is clcenergizetl, the roclzshaft 4 will occupy the posi t cn to which it is biased by the pendulum comnation and under these conditions the relay controlling c ntacts 52 and 15 will hoth be closed; one set or such as contacts 53 and. i i, will he closed while the other set, comprising contacts l3 and i i, will he opened. lhis arrangement i readily effected by suitably positioning t e evacuated bulbs so that in tie deenergized position of the armature, the terminals of the contacts i5, It and ll are bridged by the mercury herein while the terminals of c ntacts l and. are not so bridged. When, wever, current supplied to winding 3, a magnetic field is established between the pole pieces ii oi the electroinagnet, which field causes armature it to turn in a clockwise direction as viewed in Fig. 2

order to assume a position of minimum reluctance. This rotation of the armature will, of course, be transmitted to the rockshaft, and as as the rockshait begins to rotate, contacts and i l will close contacts it and El will o; During this portion of the 5 he,

auxiliary pendulum to will swing away ir stop so that the two p nclulums and 38 iter this monientu; is expended, shaft will start to rot in the $101]. due to the action of J remain awav liom the portion of the clockwise strcl soon as the pendulum comh'i. tic ret position in which contact l5 heoo winding s will again become one cause a reta force to be excited or arrna Tl s retarding force will no small, however, because the effective air set the respective pole pieces and the armature will it sub -tan and will be rapidly. Just prior to the tir e pendulum 7 es its normal penoa .t or biased position, contacts i3 and l will open and contacts iii and Jill close. When pendulum l swings past its rial pendant position, the a" xiliary pendulum so all come to rest against 3 an thus he d with pendulum o; iainder of the counterclockwise swing: or one from. As soon as armature it re a which contact opens, winding 2;

ed. end of may he a roll reached at the ous clockwise pendulum lee direction, ise to be exerted on the shalt, and as soon as aft is rotated in the clockwise direction to the position in which contact 32 winding will again become energized and will subse n see as the out in the co all till

quently remain energized until the rockshaft has swung past its biased position to the position in which contact it opens. The energization of winding it during this portion of the movement will cause a pulse of energy to be exerted on the rockshait which assists the clockwise rotation of the shaft, and t e parts are so proportioned that this pulse at normal operating voltages will be sufficient to supply to the shaft '16 loss of energy during each cycle caused by i ction and the retarding force on the magnet during the previous counterclockwise rotation of t e rochshait. It follows, therefore, that when the circuit of magnet l is closed, the rocks'nait will oscillate at substan i lly the natural period of the pendulum combination as determined by the esultant moment of inertia of the i auxiliary pendulums. This oscillation will cause the contacts l3, ll alternately to open and close in an obvious manner, and will be apparent that oy connecting these contacts in suitable control circuits they may be used alternately to energize and deenergize the flashing lights of a highway crossing signal of the welllmoun type, or to control any other apparatus requiring alternate energization and cleenergization at a predetermined substantially constant frequency.

It should he noted that my invention provides novel and improved means for obtaining substantially equal intervals of operation of the two sets of asymmetrically arranged contacts. That is to say, a compound pendulum relay having one set of contacts normally closed and another set of contacts normally open in the pendant position of the pendulum, ordinarily will operate when the relay is energized to cause the normally closed set of contacts to he closed for a time interval greater than the time interval of closure of the normally open contacts. This is due to he fact that the contacts of the said one set are closed during the portion oi the pendulum stroke that extends from one extreme position to a given point beyond the ravity biased intermediate position, while the contacts or" the other set are closed in the portion of the pendulum stroke that extends extreme "rorn the other position to the given point which is intermediate the said other extrene position and the gravity biased pendant position of the pendulum. It thus follows that the contacts of the two sets are closed throughout unequal portions of the pendulum stroke, hence if the pendulum combination operates at a constant frequency or rate, the contacts of the two sets will then be closed for unequal periods of time. This will result in a limping operation of th contacts. This uneven operation of the contacts is undesirable in many applications of the relay, particularly in the control of highway crossing signals and the pendulum combination which I have provided corrects this defect.

It will now apparent that the combination of the two penduluros and is arranged so that when rockshait l performs the counterclockwise portion of its stroke (as viewed in Fig. 2) from its normal biased position, the auxiliary pendulum 225 is carried along with pendulum 'a' and the time interval required for the pendulum combination to travel from this position to its extreme counterclockwise position and back to the biased position is a function of the moment of inertia of the two pendulums considered as a unitary structure. Accordingly, the moment of inertia for this portion of the stroke will have a given value. When, however, the main pendulum l swings from its normally biased position in the clockwise direction and return, the auxiliary pendulum then swings away from pendulum l in a manner to increase the distance between its center of gravity and the rotational axis of pendulum I, so that the moment of inertia of the resulting combination is caused to have a value larger than the said given value. Accordingly, the period of the pendulum during this clockwise portion of the stroke is increased so that a greater time is consumed by the pendulum for completing this portion of the stroke than would be the case ii the auxiliary pendulum (it were not provided. It follows that by properly proportioning the parts, time interval required for the pendulum combination to travel from the given position at which the contacts make and break (which position is slightly beyond the pendant position), to either of its extreme positions can be made substantially equal, thereby causing the two sets of contacts to be closed for substantially equal intervals or" time.

An alternative form of the pendulum combination that may be employed in relay R is represented in Figs. 7, 8 and 9. This alternative form comprises an evacuated bulb or envelope partially filled either with a liquid 3? of rela tively heavy mass, such as mercury or with some other readily shiftable The tube is secured to pendulum l at a preselected point either above or below its axis of rotation but the tube is adjusted as shown in Fig. 7 to cause the mercury to gather at one end of the tube when the pendulum combination is in its pendant position. When pendulum l is in the counterclockwise porticn of its stroke, the mercury mass remains substantially unshifted from this position with respect to the vertical axis of the combination (see Fig. 8), hence the moment of inertia of such ombination will remain substantially constant during this portion of the pendulum stroke. When, however, pendulum l swings in the opposite or clockwise direction, tube will tilt in such a manner as to cause the mercury contained therein to flow in the other end of the tube away from the vertical axis of the combination (see Fig. 9,), thereby altering the moment of inertia and hence the period of the pendulum combination. This arrangement obviously may be suitably proportioned by the proper selection of masses and distances to cause the pendulum combination to require substantially equal intervals of time to swing from just past its dead center position, at the point where the one set of contacts will break and the other set of contacts will make, to either extreme position. It follows that this arrangement will be efiective to prevent a limpoperation of the two sets of contacts that are asymmetrically arranged.

Although I have herein shown and described only two forms of apparatus 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. In combination, a pendulum, means for causing said pendulum to oscillate between two extreme positions, and a movable mass secured to said pendulum for displacement of its center (ill of gravity with respect to the rotational axis of said pendulum when it is intermediate its gravity biased position and one extreme position but not the other, thereby to provide a pendulum combination having a moment of inertia in one portion of its stroke that difiers from the moment of inertia in another portion of the stroke.

2. In combination, a pendulum, means for causing said pendulum to oscillate at substantially its natural period, and means for varying said natural period in a selected portion of said pendulum stroke, said means comprising a weight mounted on said pendulum for displacement of its center of gravity with respect to the rotational axis thereof in said selected pendulum stroke portion.

3. In combination, a pendulum, motor means for causing said pendulum to oscillate with a predetermined amplitude at a preselected freuency, a second pendulum secured to the first pendulum for swinging movement relative thereto at a point removed from the axis of rotation of said first pendulum, and a stop on said first pendulum for limiting the swinging movement of said second pendulum to a selected portion only of the stroke of said first pendulum.

4.. In combination, a pendulum, motor means for causing said pendulum to oscillate with a predetermined amplitude at a preselected frequency, two contacts operated by said pendulum and adjusted so that one contact is closed in one portion and the other contact is closed another portion of the pendulum stroke, a movable weight secured to said pendulum at a point removed from its axis of rotation, and means for limiting movement of said movable weight in said one portion but not said other portion of the pendulum stroke.

5. In combination, a pendulum, motor means for causing said pendulum to oscillate with a predetermined amplitude at a preselected frequency, two contacts operated by said pendulum and adjusted so that one contact is closed in one portion and the other contact is closed in another portion of the pendulum stroke, an auxiliary pendulum journaled on said first pendulum at a point removed from the axis of rotation of said first pendulum, and a stop secured to said first pendulum for restraining movement of said auxiliary pendulum in a selected one of the portions of said first pendulum stroke.

6. In combination, a pendulum, motor means for causing said pendulum to oscillate with a predetermined amplitude at a preselected frequency, two contacts operated by said pendulum and adjusted so that one contact is closed in one portion and the other contact is closed in another portion of the pendulum stroke, and an envelope partially filled with a relatively heavy liquid secured to said pendulum at a point removed from its axis of rotation and adjusted to cause said liquid to fiow away from the vertical aXis of said pendulum in but a selected one of said portions of said pendulum stroke.

7. In a flasher relay comprising a pendulum, motor means for causing said pendulum to oscillate with a predetermined amplitude, and contacts operatively connected with said pendulum for closure of certain contacts in one portion and other contacts in another portion of the stroke of said pendulum, the combination with said pendulum of a shiftable weight operatively connected with said pendulum for displacement of the center of gravity of said weight with respect to the axis of rotation of said pendulum in a selected one of said portions of the pendulum stroke to provide difi'erent moments of inertia of said pendulum-Weight combination in said two portions of said pendulum stroke.

8. In a flasher relay comprising a pendulum, motor means for causing oscillation of said pendulum with a predetermined amplitude, two contacts operatively associated with said pendulum, one of which is closed during the portion oi said pendulum stroke that extends from one extreme pendulum position to a given position which is beyond the gravity biased position and the other of which is closed during the remaining portion of said pendulum stroke that extends from the other extreme pendulum position to said given position; the combination with said pendulum of a shiftable Weight operatively connected with said pendulum at a point removed from its axis of rotation for displacement of the center of gravity of said weight with respect to said axis in but said remaining portion of said pendulum stroke, whereby to provide a greater moment of inertia for said pendulum-weight combination in said remaining portion of said stroke as compared with the moment of inertia of said pendulum- Weight combination in said one portion of said stroke.

9. A flasher relay comprising a pendulum, motor means for causing oscillation of said pendulum with a predetermined amplitude, two contacts operatively connected with said pendulum and asymmetrically adjusted so that one contact is closed in the portion of the pendulum stroke that extends from one extreme position to a given position beyond the gravity biased position and the other contact is closed in the remaining portion of said stroke, and a shiftable weight operated by said pendulum in such manner as to provide a moment of inertia for said penduiumweight combination in said remaining stroke portion which is greater than the moment of inertia of said pendulum-weight combination in said first-mentioned portion of said stroke.

10. A flasher relay comprising a pendulum,

motor means for causing oscillation of said pendulum with a predetermined amplitude, asymmetrically adjusted contacts operatively connected with said pendulum and comprising a contact closed in a selected portion of the pendulum stroke that extends between one of the extreme positions of said pendulum to a given point beyond the gravity biased pendulum position and another contact closed in the remaining portion of said stroke, an auxiliary pendulum journaled to said first pendulum at a point removed from the axis of rotation of said first pendulum, and means for limiting the swinging movement of said auxiliary pendulum to the one portion of said pendulum stroke that extends between the other of said extreme pendulum positions and said gravity biased position, thereby to provide a resultant moment of inertia for said pendulum combination having a greater value in said one portion than in the remainder of the pendulum stroke.

11. A flasher relay comprising a pendulum, motor means for causing oscillation of said pendulum with a predetermined amplitude, asymmetrically adjusted contaots operatively connected with said pendulum and comprising a contact closed in a selected portion of the pendulum stroke that extends between one of the extreme positions of said pendulum to a given point beyond the gravity biased pendulum position and another contact closed in the remaining portion of said stroke, a container secured to said pendulum, and a movable weight partially filling said container, said container being adjusted to limit the movement of said weight to the one portion of said pendulum stroke that extends between the other of said extreme pendulum positions and said gravity biased position, thereby to provide a resultant moment of inertia for said pendulum combination having a greater value in said one portion than in the remainder of the pendulum stroke.

BENJAMIN MISHELEVICH.

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