US3182232A

US3182232A - Electromagnetic relays

Info

Publication number: US3182232A
Application number: US186100A
Authority: US
Inventors: Yule William Henry Drury
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1961-06-12
Filing date: 1962-04-09
Publication date: 1965-05-04
Anticipated expiration: 1982-05-04
Also published as: BE618768R; CH399591A; DE279333C; NL279333A; GB974085A; GB915019A

Description

May 4, 1965 w. H. D. YULE ELECTROMAGNETIC RELAYS 4 Sheets-Sheet 1 Filed April 9, 1962 .lll I l l l I l l I I I l I l I I l I I I l l I I l I I l I IQIAII) \|||\\i|| llllllll 4 4. f \Lll' N I II III! III. l

Inventor WILLIAM H- a. raw

A Home y W. H. D. YULE ELECTROMAGNETIC RELAYS May 4, 1965 Filed April 9, 1962 4 Sheets-Sheet 2 III/III I nvenlor W/LL/AM M D. Yl/Lf y 2 M Attorney y 4, 1965 I w. H. D. YULE 3,182,232

ELECTROMAGNETI C RELAYS Filed April 9, 1962 4 Sheets-Sheet 3 lnvenlor WILL/AM H. D- YULE Bywgf;

A Home y ELECTROMAGNETIC RELAYS Filed April 9, 1962 4 Sheets-Sheet 4 v Inventor WILL/AM h. 0. YULE Attorney United States Patent 3,182,232 ELECTROMAGNETIC RELAYS William Henry Drury Yule, London, England, assignor to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 9, 1962, Ser. No. 186,100 Claims priority, application Great Britain, June 12, 1961, 21,134/ 61 6 Claims. (Cl. 317-471) This invention relates to electromagnetic relays and in particular to means for reducing contact bounce, or chatter, in such relays.

According to the invention there is provided an electromagnetic relay in which contact bounce is reduced by providing permanent magnetic means for holding back the armature of the relay in the unoperated position, the armature being primarily biased back by other means.

An embodiment of the invention as applied to a nonpolarized light-current electromagnetic relay of the balanced armature type will hereinafter be described with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of the relay, sectioned through a sealing cover,

FIG. 2 is a left hand end elevation of FIG. 1, sectioned through the cover.

FIG. 3 is a part sectional end elevation along the line AA' of FIG. 1,

FIG. 4 is a partly sectioned plan view of the armature and movable contact springs assembly.

FIG. 5 shows schematically the main magnetic circuit and arrangement of the armature and stationary contacts;

FIGS. 6, 7, and 8 show the plan view, right hand end elevation, and side elevation respectively of a magnetic backstop for the relay.

The problem of contact bounce is general to electromagnetic relays. It has been found to be particularly acute when caused by the resonance of a critically balanced relay armature. Such a relay is described in British Patent No. 811,262, and our invention will be illustrated as applied to this relay.

Referring to FIGS. 1 and 2, the relay is enclosed in a metal cover 1 soldered to a stamped metal base 2 and in known manner subsequently sealed to avoid adverse effects of humidity and low air pressure on the relay.

The main magnetic circuit includes a bar-shaped core 3 of rectangular cross section and centrally recessed at each end. In the left-hand recess is attached a rightangled or L-shaped pole-piece 4, and in the right-hand recess is attached a right-angled or L-shaped polepiece 5, the polepieces 4 and 5 facing inwardly and being of different lengths.

Also attached in the right hand recess is a right-angled or L-shaped non-magnetic supporting piece 6. The portions of the longer polepiece 4 and of the supporting piece 6 parallel to and spaced from the core 3 are rigidly attached to the base 2 by non-magnetic screws or

studs

7 and 8 respectively, so that resonant vibration of the assembly is reduced to a minimum.

Alternatively the supporting piece 6 may extend along the whole of the base 2, with the longer polepiece 4 resting on the support piece 6 and the screw 7 passing through both the polepiece 4 and the support 6.

Referring now to FIGS. 1, 6, 7 and 8 together, the magnetic backstop 28 is positioned in the angle of the supporting piece 6. The view of the magnetic backstop 28 shown in FIG. 1 corresponds to that shown in FIG. 8, and the line B-B on FIG. 7 corresponds to the width of the Supporting piece 6.

The magnetic backstop 28 consists of a block of magnetic iron 29 in which are set two small permanent mag- 3,182,232 Patented May 4, 1965 ICC nets 30. The magnets 36 are made of the material known by the registered trademark Platinax.

The screw 8 passes through the base 2, the supporting piece 6, and into the threaded hole 31 in the magnetic backstop 28, thus securing the magnetic backstop 28 in position.

Referring back, now to FIGS. 1 and 2 only, a Winding 9 may be wound directly onto the core 3, or prewound on a spool which is then slipped onto the core 3. External electrical connections for the winding 9 are provided by connecting, as by soldering, the ends 10 of the winding 9 to separate terminating pins 11 sealed through and insulated from the base 2.

A flat armature 12 is pivoted about its central transverse axis on a pivot pin 13 between supports 14 formed by bent-up side extensions at the end of the longer polepiece 4. Alternatively, the armature supports may be bent down from side extensions at the end of the shorter polepiece 5. The pin 13 is slightly bowed before insertion so that it holds itself in position after insertion through the armature and its supports.

The armature 12 thus lies in a plane substantially parallel to the base 2, inside the longer polepiece 4 and outside the shorter polepiece 5.

The main magnetic flux path is along the longer polepiece 4, the armature supports 14, the pivot pin 13, the armature 12 and the shorter polepiece 5. There is negligible flux leakage across the relatively large air gap between the polepiece 4 and the armature 12.

Thus, as shown in FIG. 5, the main magnetic circuit is in the shape of a C with its free ends oil-set in two spaced parallel planes and the centrally pivoted armature 12 in a parallel plane intermediate the two spaced planes.

To prevent sticking between the sides of the armature and the inner sides of the armature supports where relative movement occurs on operation of the relay, washers 15 of non-magnetic material, e.g., nickel silver, may be inserted therebetween.

The relay is provided with two sets of changeover contacts. As shown in FIGS. 3 and 4, two movable contact springs 16 are rigidly attached to the top face of the armature 12 by screws 17, or by rivets, and are sandwiched between

insulating blocks

18 and 19 so as to be insulated from the armature 12 and from each other. The screws 17 bear on a clamp plate 20. Thus it will be seen that the armature and moving contact assembly is substantially symmetrical about the central pivot of the armature.

FIG. 4 is sectioned so as to clearly indicate the shape of the contact springs 16. At each end of the portion of the springs 16 which are attached to the armature 12, extension pieces 21 are bent up and locate in a corresponding recess in the insulating block 19, thus preventing any longitudinal movement of the contact springs 16.

Semi-circular recesses 22 in the inner edge of the contact springs 16 allow clearance for the shank of the screws 17, or rivets if used.

Returning to FIGS. 1 and 2, stationary contacts for co-operation with the movable contact springs 16 are provided by terminating pins 23 sealed through and insulated from the base 2, and made from contact material or capped at one end with suitable contact metal to form the stationary contacts 24.

The movable contact springs 16 may be bent down in the form shown in FIG. 1 or alternatively may be straight, in which case the terminating pins 23 must be extended upwards.

The resilience of the springs 16 is chosen to give satisfactory contact pressure and freedom from excessive bounce. In a miniature relay no separate contacts are provided on the springs 16 which are themselves made ansaaea 3 of a suitable resilient contact material. Separate contacts may of course, be provided if required.

In the unoperated position, the right hand (FIG. 1) contacts are closed, and the armature 12 is urged away from the shorter polepiece 5 by suitably formed restoring springs 25', each attached at one end to a terminating pin 26 sealed through and insulated from the base 2, and each attached at the other end to an angled extension piece 27 of a movable contact spring 16 at the centre of the armatrue 12.

The restoring springs 25 are made of a suitable resilient conducting material, such as Phosphor bronze, and thus function in addition as electrical connecting means to the movable contact springs 16.

As stated in the above description the armature 12 is biased back in the unoperated position by the restoring springs 25, and the resilience of the contact springs 16 is chosen to give freedom from excessive contact bounce. These two features were present in the earlier disclosed relay disclosed in British Patent No. 811,262. In this embodiment which is a modification of the earlier relay, the magnetic backstop 28, provides a small additional holding force on the armature and is the main means of reducing contact bounce.

This is a non-polarized relay. The small magnets 30 (FIGS. 6, 7, and 8) are positioned so that one has its N-pole, and the other has its S-pole, facing the underside of the armature 12'. The block of magnetic iron 29 acts as a magnetic flux carrier so that the magnetic backstop 28 effectively constitutes a horseshoe permanent magnet.

The holding force on the armature is due to a magnetic flux path around the horseshoe magnet and across the width of the armature 12. This magnetic flux path is substantially at right angles to the main magnetic flux path, through the armature which operates the relay. Thus, although the magnetic backstop 23 results in slight increase in the necessary operating current, it does not aifect the non-polarity of the relay.

It is not essential tothe invention that the horseshoe magnet used to reduce contact bounce should be in the form of a backstop for the armature relay, as in the above described embodiment; a separate backstop might, of course, be used. Also the form of the horseshoe magnet in the above described embodiment is specifically for use in a non-polarized electromagnetic relay. Clearly,

permanent magnets or magnetic backstops of different forms, having only one type of magnetic pole acting on the armature, could be used in polarized electromagnetic relays for reducing contact bounce.

What I claim is:

l. In a non-polarized electromagnetic relay, a magnetic structure comprising a pair of salient poles, flux generating means associated with said structure, a balanced armature positioned between said poles in flux linking relationship therewith and operable between an operated and unoperated position in response to variations in magnetic flu generated by said flux generating means traversing the said armature, and magnetic damping apparatus disposed adjacent one end of said armature to urge the armature in its unoperated position by a second magnetic flux traversing said armature in a direction normal to the direction of the first said magnetic flux.

2. A non-polarized electromagnetic relay as set forth in claim 1 wherein said magnetic damping means comprises a permanent magnet having its poles positioned adjacent the same end of said armature.

3. A non-polarized electromagnetic relay as set forth in claim 1 wherein the said magnetic damping means comprises backstop means limiting the movement of said armature in its unoperated position.

4. A non-polarized electromagentic relay as set forth in claim 1 wherein one of said salient poles is flux-linked with an intermediate portion of said armature.

5. A non-polarized electromagnetic relay as set forth in claim 1 wherein the flux of the magnetic fields generated by said flux generating means and by said magnetic damping means are substantially independent of each other.

6. A non-polarized electromagnetic relay as set forth in claim 1 wherein said armature includes biasing means urging one end of said armature from its operated position to its unoperated position into flux linking relationship with said magnetic damping means.

References Cited by the Examiner UNITED STATES PATENTS 2,915,681 12/59 Troy 317 -171 3,013,136 12/61 De Fringue 317-l71 JOHN F. BURNS, Primary Examiner. E. JAMES SAX, Examiner.

Claims

1. IN A NON-POLARIZED ELECTROMAGNETIC RELAY, A MAGNETIC STRUCTURE COMPRISING A PAIR OF SALIENT POLES, FLUX GENERATING MEANS ASSOCIATED WITH SAID STRUCTURE, A BALANCED ARMATURE POSITIONED BETWEEN SAID POLES IN FLUX LINKING RELATIONSHIP THEREWITH AND OPERABLE BETWEEN AN OPERATED AND UNOPERATED POSITION IN RESPONSE TO VARIATIONS IN MAGNETIC FLUX GENERATED BY SAID FLUX GENERATING MEANS TRAVERSING THE SAID ARMATURE, AND MAGNETIC DAMPING APPARATUS DISPOSED ADJACENT ONE END OF SAID ARMATURE TO URGE THE ARMATURE IN ITS UNOPERATED POSITION BY A SECOND MAGNETIC FLUX TRAVERSING SAID ARMATURE IN A DIRECTION NORMAL TO THE DIRECTION OF THE FIRST SAID MAGNETIC FLUX.