US 2611063 A
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Description (OCR text may contain errors)
Sept- 15 1952 R. E. H. CARPENTER 2,611,063
ELECTROMAGNETIC RELAY Filed Aug. 28, 1950 2 SHEETS-SHEET 1 Attorney Sept. 16, 1952 R. E. H. CARPENTER ELECTROMAGNETIC RELAY 2 SHEETS-SHEET 2 Filed Aug. 28, 1950 atentec Sept. 16, 19512 ELECTROMAGNETIC RELAY Rupert Evan Howard Carpenter, South Croydon, England VApplication August 28, 1950, Serial No. 181,903 In Great Britain September 2, 1949 v K 14 Claims.
This invention relates to the mounting and control of the contacts of electrical .circuit- 1 controlling apparatus such as electrical switches and circuit-breakers of all kinds but it has particular reference to the contacts of electromagnetic relays, and is more particularly concerned with the construction and control of the vibratory armature and the mounting and sup- ;port of the passive or side contacts of such relays. A fundamental problem encountered in the design of electromagnetic relays is that of pre- Wenting Ibouncing orchattering of the contacts, .and this problem becomes more difficult of solution as the contact travel, and hence the velocity of the moving contact at the instant of impact, is increased.
, Two types of bouncing may be observed, one
. of comparatively low frequency in which typically the first bounce occurs some one to two milli- 1 seconds afterthe first impact, the duration of theiirst break being a substantial fraction of a millisecond, and another of much higher frequency in which the contacts separate, for ex- ,ample, some thirty to fifty microseconds after wear may be quite serious.
The present invention aims at eliminating both these forms of contact bouncing, and it is especially useful in relays having long contact .traveL although not, of course, limited to electromagnetic relays of any kind.
In accordance with the present invention, this -is attained by providing a mass mounted on one or both'of the supports of the pair of contacts to be controlled in such a Way as to be able to move relatively to that support due to the inertia ofthe mass. operating at the instant of change of velocity caused by the closing of the pair of contacts and the relative movement is restrained mainly or largely by the action of forces set up by friction occurring between bearing surfaces shaped to slide smoothly one upon another or by fluid friction or by friction occurring Within a -deformable body. In the case of an electro- Vmagnetic relay with a vibratory armature, the
inertia mass may thus be mounted on the arma- 'ture -or on the support or supports of the passive contact or contacts or both. The frictional v'ffc'irces may be exerted on` a surface of the mass or within a body of deformable material coupling the mass to the respective contact support so that a drag is applied to the contact support and the contacts are maintained closed in spite of any tendency to bouncing due to the elasticity of the parts. l
By an electrical analogy, the frictional coupling of the inertia mass to its contact support is of the nature of resistance coupling rather than capacity coupling and the restraining force operates immediately deceleration of the contact and its support begins. The system is unlike that of a mass mounted on a compliant support and the latter would not result in the desired reduction or elimination of contact chatter.
If the frictional drag is exerted through an external surface of the mass, in the case of the armature contact of a relay, it may be applied to the end surface or a side surface of the armature or of a member fixed to the armature. The force holding the frictional surfaces in engagement may be provided either by a spring pressing the sliding mass against the armature or, by making the sliding mass of magnetic material, when magnetic attraction, due, for example, to stray flux from the armature, may provide the necessary force. The sliding surfaces may bear directly upon one another, or an interposed layer, such as a washer, having the desired frictional and wear-resisting characteristics may be employed, a synthetic resin impregnated with graphite or some soft metal having been found suitable. When the mass is springheld, the spring may be made adjustable so as to control the frictional force.
In cases in which the velocity of transit of the armature is highly Variable, and especially when it is different in the forward and return directions of its movement as in single-current working, there is some danger of the sliding mass hitting its stop, and this impact being transmitted to the armature and hence to the contacts, may itself tend to cause bouncing. In order to reduce this effect, a spring or springs may be employed tending to centralise the sliding mass with respect to its stop or stops, or the latter may be springy. Thus, for example, the spring may be a cylindrical coiled compression spring housed within the inertia mass and bearing on a seating in the mass at one end and constrained by a fixed member at the other end. Then, when the mass slides relatively to the armature, the spring is deformed and in recovering,'tends to centralise the mass. The fixed stop engaging one end of the spring may comprise the head of a stem projecting vfrom the armaf pads.
ture and also passing through a clearance hole in the inertia mass and thereby acting as a limit stop for the sliding movement. Of course, other centralising means suificiently gentle in action to permit the necessary sliding can be adopted, such as a coiled compression spring of conical conguration.
If the frictional dragy is exerted within a body of rubber-like material which should exhibit considerable hysteresis, the latter is deformed on the mass tending to overshoot the armaturev and thereby energy is expended yinthematerialv` The body may due to its mechanical hysteresis. then consist for example of `a pad of soft material, such as felt or natural or artiiicial rubber* cemented to the armature and surmounted by a metal weight forming the inertia.'V mass and clamped between the said pad of material and a second similar outer pad of soft material. A stem may project up from the armature through Ythe adjacent pad and passes through a clearing holle in.` the metal mass so that the latter overfthe armature face. The frictional drag or damping may be provided by employing a'ring of 'felt or other'rubber-like material encircling an extension of the said outer 4part ofthe arm sothat'as vibration' is impartedA to the` cantilever arm, the said ring is deformed in compression- Figure 4 is a plan of Figure 3;
Figure 5 is an elevation; and
Figure 6 is a plan corresponding respectively' to Figures 3 and 4 but showing a modified form of the armature damping member;
Figure 7 is a sectional edge elevation of the upper part of an armature showing another form or" the anti-bouncing device; Y
Figure 8 is a sectional elevation on the line VIII- VIII in Figure 9; and
Figure 9 a plan of another form of damping member employing an inertia mass including A' deformable rubber;
tension or shear Vand provides the 'damping -`action. y
Q'Again Va pin may'extend from the said ex- -tension vof the outer part of the arm towards vthe relay frame and may itself be encircled by vajring of the deformable material enclosed in ramletal ring which forms the inertia mass. VIn l'another form, the spring arm bearing the ycon- A tact isextended and inclined inwards towards the relay frame at an angle and is straddled r"bya vstrip of; deformable material which isencased ina metal strip which forms the inertia `mass. Yet again the outer part of the ,contact spring arm may be shaped with a'friction surface and vbe looped intoV a spring bearing the iertia'mass and pressing it into'contact with thesaid frictionjsurface. Then on impact-of the armature against the passive 'contact,jt`he inertia mass is restrained by the frictional force applied to it' and acts to prevent the passiveV y accordance with the invention will now be more fully described with reference to the accompanying drawings, in whichn Figure 1 is a side elevation ofthe upper part cfa relay Vfitted withanV armature damping lmemberaccording to the invention;
Figure 2 is a plan of the same; y
' Figure 3 isv an venlarged elevational, partly in section, of the upper part of the armature and its damping member; l
Figure 10 is a side elevation; and vFigure 11 a section on the lneXI-XI in Figure 10 of one form of the improved stationary orA passive contact; Y
Figure 12 is a side elevation; and Figure 13 a section on the line XIII-XIII in Figure 12 of another form of stationary contact;
VFigureli'is a side elevation; and Y Figure '15 aV section on the line XVLXVr-in Figure 14 of'yetel third form of stationaryfcontact; while i vFigure 16is a side elevation; and Figure V17a plan of 'still'another formofestationary contact.
Referring'firstto Figures A'l to 4 rof therdrawings, lthe invention is applied to an electromagnetic relay as described in the specificationof my United States Patent No. 2,559,399. Ini Figures l`4 and 2, `the permanent magnets are seen at I, the armature "2 bears thecontacts 3 vwhich 'engage the stationary Ycontacts il supportedon the frame members 5. l v Y The'inertia mass't lcarried by the "armature is shown in more vdetail in Figures 3`and"4"and 'is in the jformof a'hollow cylinder.
y A Y'screwthreaded `stemfi is adjustably tapped rinto the upperend of the'armature 2 andis secured by a lock-nut 8 of Duralumin which consists 'fof-fa hexagonal shank 9- and a at circular` platform I0. On Athe top Vof the'latter is --supportedfa washer II which, in 'this vexe'miple,'consists r`of the phenol-formaldehyde resin'knownas Catalifn and is impregnated with graphite. The cylindrical mass Sjrests on the washer II yand'fsur- 1 rounds the stemAI which passes through aclearinghole I2 in the base vof the massfj Afccnidal Ycoiled compression spring Iisjhoused'- in'the Lcylinder E and abuts at the botto'mon the vupper 'surface of vthe vbase Vof the'jcylinderV 6 andf'fat "the-top against the* head Illfoftheste'm 7. vThe spring I3 thus pressesthejmassv r6fagainstthe washer II and 'the' latter againstwtheplatfrm I il fixed' to the armature 2 with an adjustable pressure. "In order-'to adjust'this pressurefthe `lock-'nut 8 is loosenedfby'grippingithehexagonal vshank 9 and the stem I screwed up rdown'and then lockedI by' tightening `the lock-nut "8.
In'operation, when the' armaturel "i'sfdecelrated by one of its contacts @striking-the coacting passive contact'ii, the mass 6 tends to'continue its movement thus exertingfa'frictional vdrag on theV platform I3' andthe armature-2,
thereby resisting any tendencyA for thel armature `2 to bounce away from the contacta. During this time, the spring I3 is distorted? but-when the parts come to rest; it recovers and centralises the mass B again. p t
'The mountings 0f the passive por 'sidev contacts Aare asshown in more Vdetail-Vin Figures lean/d '11. Each Contact,l 4 carriedA on a stm; iiat cantilever spring I5 rivetted `to one of fthe? relay `15 frame members'S at. I6.. The spring I5.has;parts I1; and I8l at either endV parallel tolthexfaces of the armature 2 and `of theframe member 51 and an intermediate-part I9 extendingat-.anangle to the parts I1 and I8 such that the line-between the contact 4v and the effective hinge` at'the bottom end of the part I9 is at about 45 degrees to the face of the frame member 5. The Vpart I8 carries the stationary contact 4. The partl I8 is extended and turned over at 2| towards the frame member 5. A strip of neopreneA 22 is bent to embrace thepart 2| and is. retained in position by an encircling strip 23 of metal which serves as the inertia ,mass vand when the passive contact 4 is struck,k deforms thenneoprene 22 isothat the energy of any-vibration -offlthe spring I6 y is absorbed as hysteresis` in the Arubber strip 22 andthe vibration is limmediatelyl damped out.`v v- -1 In Figures and 6, a modified device isshcwn which may replace lthe inertiamass 6 shown in Figures 1 to 4. Again a Vscrew-threaded stem 1 is adjustably tapped into the end of the armature I and is surrounded by a washer 24 seated on the end of the armature 2, a synthetic resin washer 25, the boss of a bracket arm 26, anda further synthetic resin washer. 21. This pack is adjustably pressed together by va cylindrical coiled spring 28 abutting at its lower end against a cup 29 and at its upper end against an enclosing cap 30; the wholerbeing held down by a nut 3I screwed on to the stem 1 and enabling the pressure to be adjusted., The bracket arm 26 supports the inertia mass`32 which is a cylinder threaded over a second stem 33 and held by nuts 34.
In this case, when the armature 2 is decelerated, the mass 32 tends to continue its movement and, as a result, the bracket arm 26 exerts a frictional drag on the armature 2 through the washers 24, 25 and 21 with a similar result as in Figures 1 to 4. The actual movement of the bracket arm 26 relatively to the armature 2 in either direction is limited by a pair of stops consisting of resilient arms 35 which are secured by a further nut 36 and yield under the force of the mass 32 but recover to centralise that mass when the parts come to rest.
It is obvious that the device shown in Figures 5 and 6 could be attached to either edge surface of the armature 2 instead of to its end surface.
In the further form shown in Figure '1, a small entirely closed cylinder 53 is xed to the top surface of the armature 2 and contains a looselyfitting slidable piston 54 which forms the inertia mass. The spaces 55 on either side of the piston 54 are filled with light oil which provides the frictional force restraining the movement of the piston 54. Conical springs 56 at either end of the cylinder 53 serve as stops for the piston 54 and assist in centralizingr the latter.
Yet another variant is shown in Figures 8 and 9 in which a stem 'I is again screw-threaded andV tapped into the end of the armature 2. A circular pad 31 of felt encircles the stem 1 and rests on a washer 4I seated on the end of the armature 2. On the pad 31 rests a metal weight 38 which forms the main inertia mass and has a clearing hole 39 through which the stem 1 passes. A second pad 40 of felt rests on the weight 38 and the three members 31, 38 and 40 are pressed on to the end of the armature by a top washer 4Ia and nuts 42, the pad 31 being preferably cemented to the Washer 4I and to the weight 38 and the pad 40 also being cemented to the weight 38. In this case, when the armature is decelerated, the Vweight 38 continues itsumovenient-.but there is no frictional sliding of one member on another,^- AOn the other hand,V the pads 31 and .40 are deformed withinternal friction which restrains the motionyof the weight 38.and-thus prevents bouncing. of the contacts.
In Figures l2 and '13, a variant of the mount,- ing for the stationary contacts is shown. 'Ifhe contact 4 is mounted on a cantilever spring I5 as in Figure 10 but the part I8 of the spring is extended and is encircled by a relatively massive ring 43 4of felt. The effect, however, is similar to that of the form shown in Figures 10 and 1,1. In Figures 14 and 15, the mounting for the stationary contacts Vis yet again varied. In this case, the part I8 of the cantilever spring I5 yhas a headed pin 44 extending at right angles to wards the relay frame member 5. A ring of felt 45 encircles the pin 44 to which it is fixed by adhesive and thering 45 is encased in a metal ring 46 which acts as the inertia mass. Otherwise, the operation is the same as in the case of Figures 10 and 11. l
Finally, in Figures 16 and 17, the part I8 of the cantilever spring i5 which bears the station-l ary contact 4 is turned at right angles at 41 into thevertical plane and vbroadened into a platform 48. A narrow extension 49 is looped tothe side at 50 and turned over into contact with the platform 48 at 5I. At that point, it carries the inertia mass 52 which is a cylindrical weight. The spring loop 50 is set so that it causes the mass 52 to be frictionally coupled to the contact 4 throughl the platform 48 on the supporting arm I8.
What I claim is:
1. In an electric switch having a pair of cooperating contacts, one of which is mounted upon a movable support, the combination of an inertia member mounted upon said movable support and being movable with respect to said support under the impact of a sudden engagement of said contacts, means providing a frictional coupling between said inertia member and said support for applying frictional drag on said support by the relative movement of said inertia member upon sudden closing of said contacts, and resilient means interposed between said inertia member and said support and tending to limit said relative movement.
2. A switch according to claim 1 wherein said movable support comprises an armature member carrying the movable contact.
3. A switch structure according to claim 1 wherein said movable support comprises a yieldable member carrying a passive contact.
4. A switch structure according to claim l wherein said frictional coupling is provided by sliding contact between a surface of said inertia member and a surface on said movable support, and including spring means for holding said surfaces in contact under pressure.
5. A switch structure according to claim 4 and including a graphite-impregnated washer interposed between said surfaces.
6.. A switch structure according to claim 1 wherein said frictional coupling means comprises a body of deformable material connecting said inertia member with said movable support and having appreciable internal resistance.
7. A switch structure according to claim 1 wherein said inertia member comprises a body of deformable material mounted upon said movable support and being connected with said support by a resilient portion thereof having an apprecif ableinternalfresistance, whereby..zsaid.resilient :portion forms: alIrietiona-l Y couplings beimveens'aid body-.andsaidsupport and opposesrelativefmov ment-betweenssaid bodyaand saidsupport.`
-fAnl electric switch structure .A accordingVV V.to claiin'lband" includingA a` fixed stop for. limiting relative movement ofV said inertia.V member with respectftof-said supportf and-wherein said. resilientmeansfactsl upon said-inertiamember inl a direction to oppose movement of` said member towards saidstop.v l A y 9.In an electric switchrhavlng armovable contactbarriedby a movablevarmatureranda passive contact supported upon` a cantilever'spring- `and being-yieldably movable upon engagement-by said movable contact; thecombination-o aninertia member supported" upon said cantilever spring and vbeingA movable' withA respect 1 to saidv spring under'the-impact of sudden engagement oflsaid contacts, and *means` providing a frictional coupling between -said inertiav member and Asaid springV for applying a frictional-dragfon said springby the relativemovement of said inertia m"ember. y
'lOA switch sinfuctureV according to `claim 9 wherein saidinertia member comprises aV body of resilient'deformablematerial mounted Aon an extension' of said spring:
` Y 'T111' Aj switchr structure'according to vclaim 10 andfincluding a metal member surrounding said looliy'cjzf` Vdeformable material. i' j 1.2i" 'Ag 'swit'chj structure. according tov `claim' 9 y i in 'said' inertia. member isY carried byarr. ex-
tension arm' .offthe cantilev'efs'ringturned .back
' sowthatithe inertiamembertis pressed to: bear l frctionally, on.. the .cantilever spring.
alever arm carrying''saidinertia member on'one of said arm to 'saidimovable supportV for lpivotal movement about an axis arranged transversely c BEYFERENCESQITED. The"` ollowing;V references'. are. of record `inthe file of this -patent:Y .c i A ,ly
vUNITED STATES PATENTS Nilmber v Name v y' Date v L 2,540,854VV Woestemeyer Feb. 6, 1951 Number Country D'r/ itel f 376.5112" Germani June-Salm