Electromagnetic relay

T. BAKER

2,369,331

ELECTROMAGNETIC RELAY

Filed June 30, 1941

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INVENTOR

GEORGE THOMAS BAKER

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ATTORNEY

Patented Feb. 13, 1945

2,369,331

UNITED STATES PATENT OFFICE

2,369,331

ELECTROMAGNETIC RELAY

George Thomas Baker, Liverpool, England, assignor, by mesne assignments, to Automatic Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware

Application June 30, 1941, Serial No. 400,519 In Great Britain July 18,1949

Claims. (Cl. 200—104)

The present invention relates to electromagnetic relays particularly of the kind which are .used in telephone and like signalling systems. Such relays usually consist of an electromagnet consisting of a straight core with winding, a heel piece and an armature pivoted with respect to the heel piece and a bank of contact springs mounted on the back of the heel piece and arranged in various combinations depending upon the use to which the relay is to be put, which contact springs are operated by the movement of the armature. Such a construction of relay has certain disadvantages. From the manufacturing point of view it is necessary to assemble a large variety of contact spring combinations to cater for the different uses to which the relays are put and the number and nature of spring combinations required. Furthermore the various contact springs require to be individually adjusted which due to the bank formation is liable to affect the adjustment of other contact springs so that the greater the number of contact springs the more is the adjustment required. A further disadvantage is the irregular shape of the relay which does not conveniently lend itself to protection from dust by a cover and in particular by a cover which can be hermetically sealed, so that the contacts may operate in an enclosed chamber and in a non-oxidising atmosphere. Another disadvantage of the present construction is that the assembly involves a number of operations which result in individual adjustments being required to every relay, such adjustments being dependent upon the degree of tightness with which screws are forced home as well as upon variations in thickness of the insulating members and the springs themselves. This necessitates considerable skill in the assembly of the relay to do this in a cheap and reliable manner.

The object of the present invention is to provide a construction of relay which enables the above defects to be largely overcome and to this end according to one feature of the invention the component contact springs of each spring combination used in a relay are secured in position in separately detachable units preferably by moulding so that it is only necessary to stock a limited variety of spring combination units such as “makes,” “breaks,” changeovers,” which can be combined in any order and number within the capacity of the relay.

According to a second feature of the invention which is particularly advantageous but is not exclusively limited to relays having a plu rality of detachable spring combination units a novel method of assembly is employed in which an embracing member or casing co-operates with the component parts of the relay to secure 5 the parts together and complete the structure of the relay, for instance the component parts may be placed in succession in the embracing member or casing and finally secured in their correct relative positions by a final securing 10 operation thereby reducing the securing operations, of which quite a number are required in the known type of relay, to a single operation and in particular to an operation which does not call for further adjustment of the contact 15 springs.

A further feature of the invention which while particularly advantageous for use in conjunction with a relay is not exclusively limited to having a plurality of moulded spring com20 bination units and assembled within an embracing member or casing so as to reduce the securing operations required consists of arranging that the operating member or members of the contact spring combination moves in the same 25 direction as and in line with movement of the armature. By this means it is possible for the spring combinations to be mounted in line with the core of the relay and secured in a tubular casing.

³⁰ The protection of the contact from dust according to a subsidiary feature of the invention is effected either by moulding the individual spring combinations in capsules having flexible sides or moulding the spring combinations with35 in a fixed annular member having flexible ends but including all the spring combinations required or providing a moulded cover for the relay, its armature and operating parts as well as for the spring combinations.

These and other features of the invention will be better understood from the following description of one method of carrying the invention into effect described with reference to the accompanying drawing comprising Figures 1 to 7.

⁴⁵ Of these figures Figs. 1-4 show various views of one form of relay embodying the various features of the invention although it will be understood that the invention is not limited to such a construction but extends to any relay 50 construction falling within the scope of the appended claims, Fig. 1 showing a part sectional longitudinal view of the heel end of the relay assembled inside a moulded insulating case of tubular form each spring combination unit such as “makes,” “breaks,” “change-overs,” etc. being

2,361 in the form of an individual capsule. Fig. 2 shows a sectional view through the line VW in Fig. 1.

Fig. 3 shows a sectional view of the armature end of the relay, which view is taken at t right angles to that of Fig. 1, that is to say, looking in the direction designated X in Fig. 1, while Fig. 4 shows a sectional view through the line YZ in Fig. 3.

Fig. 5 shows an enlarged semi-diagrammatic 1' representation of a sectional elevation of a typical one of the capsules of the relay, while Fig. 6 shows a plan view of such a capsule in which for the purpose of showing the shape of. the contact springs therein the upper flexible 1 face or diaphragm is assumed to have been removed.

Fig. 7 shows a spider spring arrangement for enabling the relay armature to be centered without having to rely on the sides of the moulded 2 case, so enabling friction to be reduced.

Referring now to Figs. 1-4, the .main body of the relay comprises a moulded insulating tube &lt;0 which is closed at the left-hand end in Fig. 1, and which has a cap 11 (Fig. 3) which when se- 2 cured in position closes the other end. The case may be moulded of suitable material such as in any of the known synthetic resin materials and if preferred a transparent insulating plastic material may be employed instead so that the opera- 2 tion of the relay after assembly and sealing may be observed at any time.

The whole re’ay including the operating winding, heel-piece, armature and capsule spring combination units are assembled inside this tube ³which forms part of the structure of the relay and which serves to support the various components thereof in the correct relationship to each other.

Before consideration is given to the mode of · assembly of the relay, an examination will be made of the contact spring combination units which when assembled within the case together form the spring-set build-up.

It will be understood that the various units are ⁴built-up as different standard items such as makes, breaks,” change-overs,” “make before break change-overs,” so-called “Y break” or “break last” units and so on. These items are , stocked in the individual forms and are the same ' for all general purpose relays, the production of any such relay consisting of taking the appropriate contact units out of stock and assembling them as will be described later in the description. _r

As shown the units are in the form of capsules ° which can be individually sealed the interior being either exhausted or filled with an inert gas but if the tube 10 is sealed, there is no necessity for the individual contacts to be sealed and so the unit can consist of a structure without an enclosed ⁶chamber as will be readily appreciated. Alternatively the springs only may be kept in stock and the particular combinations required moulded in position as a whole. ₆

Considering now the construction of a typical capsule make” contact unit such as is shown in Figs. 5 and 6, it will be seen that this comprises an outer annulus ί 2 which may be moulded from the same material as the relay case 10, and 7 two flexible end faces or diaphragms 13 and 14 which may be also of the same material but of sufficient thinness to enable such movement as is required to close or to open the contacts, as the case may be, to be obtained with a minimum 7

J,331 effort. Carried by the flexible end faces 13 and 14 is a cylindrical central pillar IS which is also of moulded insulating material and which is provided with a small projecting tongue 16 (Fig. 6) > by means of which it supports the lower contact spring 17. The two contact springs II and 18 extend through and are sealed in the annulus 12 at a proper distance from each other and curve round on either side of the pillar 15, while they ⁰ terminate in winding tags which are bent at right angles to the plane of the capsule. Bota springs are downwardly tensioned, spring 18 engaging with a moulded tongue in the annulus 12 and spring 17 engaging with the projection on the central pillar 15. Preferably the contact springs are moulded in position and can be individually adjusted. By suitably dimensioning the pillar or operating member 15 with respect to tne annular or fixed supporting member 12 for inθ stance by making the thicknesses exactly equal the adjustment of the contact springs of each unit will be substantially independent of the adjustment of other secondary units on either side thereof.

⁵ When the pillar 15 is caused to commence to move upwardly the diaphragms 13 and 14 distort and so allow this movement to take place and in so doing the pillar carries the spring 17 into contact with contact spring 18, the move³ ment prior to contact being determined by the relative positions of the projector 16 on the pillar and the projection on the annulus ring 12. Similarly, when the upward pressure is removed from the pillar the tension on the springs assisted by ⁵ any force which may be exerted by the distorted diaphragms causes the pillar to restore to the position shown in Fig. 5 when the contacts are opened.

In the case of a changeover combination the ” third contact spring required will be located below the spring 17 and will be tensioned upwardly against a second tongue which will be provided in the annulus 12. Other types of spring combina_ tions will be dealt with in whichever manner proves most convenient.

The assembly and construction of the different types of capsule units it is proposed to effect by machine from the component mouldings and con_n tact springs. In particular the thickness of the outer annulus and central pillar in each case will be made as closely alike as possible so that if a number of capsules are laid together as shown in Fig. 1, then the outer rings will form a virtually - continuous tuoe and the pillars will form a continuous column. This ensures that all spring combinations are interchangeable with one another in the pile without the necessity for readjustment, and further ensures that spring combinations after having been taken from stock, can ⁿ be assembled in a pile without there being any need for adjustment thereof.

Considering now the assembling together of the relay components, it will be noted from Fig. 5 ₅ that the connecting tags of the contact springs in the capsule which may be in rod or strip form are bent at right angles to the plane thereof, and the first part of the assembly is to drop the capsule contact units required into the tube 0 10 so that the connecting tags which locate in different longitudinal recesses in the walls of the case project through radially displaced holes around the circumference of the base of the case. Conveniently the tags would be of uniform length 5 and could be cut when in position so that all tags

2.369.331 project the same distance. As the space in the tube allocated for the capsule units is constant if the full number of capsule units is not required the vacant space can be taken up by a blank or blanks consisting of an outer annulus only and which will be inserted into the tube case prior to the insertion of the capsule units.

A circular operating plate 19 (Figs. 1 and 3) and the operating rods 20 and 21 (Figs. 1 and 3) are next dropped into position. These comprise simple resinous mouldings, the former transmitting the pressure of the operating rods in response to an operation of the relay armature to the central pillars 15 of the capsules and being held in place simply by this pressure and by location within the outer case Ϊ0. The operating rods are passed through holes in inwardly projecting members of the moulded case shown in Fig. 4.

The electromagnetic operating element is now inserted in position. This comprises a winding 22 wound on a core 23 screwed or otherwise secured to or integral with a U shaped heel-piece 24. This element is kept in place as shown in Fig. 3 by an abutment of the moulded shell case which engages with the closed end of the U shaped heel-piece, while the top ends of the U limbs are each provided with a projecting lip which engages in recesses in the case 10. When the heel-piece is pushed into position in the moulded shed it will be understood that the shell will be slightly distorted by pressing on the sides until it forms a slightly oval shape so as to enable the projecting lips to enter and position themselves opposite the recessed holes therein. When this has been done and the pressure is released, the heel-piece, and the winding core will remain locked in position substantially as shown in Fig. 3.

The magnetic disc-shaped armature 25 is now dropped in being supported by the rods 20 and 21 at a predetermined distance from the end of the core and the top cap 11 is pressed home to complete the assembly in which position it is secured by suitable sealing means; a centering spider. 26 or its equivalent is interposed between these two items to hold the armature against the rods 20 and 21. When the winding is energised the armature is attracted to the heel-piece and winding core and in so doing displaces the operating rods 20 and 21 to the left as seen in Fig. 3. This movement is communicated via the pressure plate 19 to the central pillars of the group of capsules, and when these are moved relative to the outer rings the various spring combinations will be operated.

On de-energisation of the winding the pressure exerted by the displaced contact springs in the various capsules together with the pressure exerted by the distorted diaphragms operate to restore the operating rods and in turn the armature to the normal position shown in Fig. 3.

In a preferred construction, the members IS are provided with recesses on one side and bosses on the other, the boss of one member fitting neatly into the recess of the other member whereby the capsules are centrally located with respect to each other, the face of the disc 15 opposite the end capsule is fitted with a recess or boss to engage with the boss or recess of the pillar 15 of the end capsule. On the opposite face are two recesses into which the ends of the rods 25 and 21 are adapted to be fitted preferably in such a way that the rods are supported during assembly in an upright position independently of any support from the wall of the casing so that after the electromagnet is placed in position, and the armature, the other ends of the rods 20 and 21 will readily enter into recesses in S the face of the armature. The armature in turn is supported centrally by the spider and consequently the whole movement of the armature and connecting rods and pillars 15 can be effected without any sliding or rubbing action.

Although a method of electrical connection to the winding is not shown it will be understood that this can be effected in a similar manner to that involved in making connection to the capsules by providing contact tags supported and U insulated in the U shaped heel-piece and passing through one pair of slots in the casing 10 as shown in Fig. 2'. It will be moreover noted from reference to Fig. 1 that two threaded holes are provided, which extend part way through the £0 closed end of the container, these holes being provided for the purpose of securing the relay to the mounting plate. Alternatively the tags could be arranged to engage springs in a holder so as to permit of ready interchange.

It will have been noted that no screws are required in the relay assembly, and this operation is therefore rendered very simple. The provision of an over-all cover on the relay for all component parts thereof provides immunity from dust gQ troubles and obviates the necessity for provision of separate covers either on an individual or group basis. The use of a moulded tube form of exterior case enables a number of relays when mounted on a base plate to present a very neat Iff appearance owing to the absence of projecting parts. The metallic parts on the relay are small in number and are simple in construction; the main bulk of the relay, which comprises insulated moulding materials, can be produced in quantity at a very low cost making the relay cheap to manufacture.

An advantageous feature of the relay is that when It is to operate under straightforward nonmarginal conditions no adjustment whatever 45 should be necessary after assembly. In the cases where the relay has to meet reasonably widely spaced operate and non-operate current values, or where it has to have controlled slow-to-operate or slow-to-release times in which case a cop50 per slug will be provided, then any of the known forms of air gap control can be incorporated on the armature plate.

While it is expected that the relay will meet most of the present day circuit requirements it 55 is appreciated that some special consideration will have to be given to special requirements such as obtain in the case of impulsing relays, marginal relays, polarised relays, and so on.

The relay as already outlined provides a com40 pletely dust-proof construction, but in circumstances where the contacts have to operate under onerous circuit conditions it may prove desirable to evacuate one or more of the capsules or even to evacuate such capsules and afterwards ¢5 inject into them an inert gas. A further alternative to which the design according to the invention particularly lends itself, is to seal the connecting wires in the bottom of the tube and to seal the top cap in position and it would then 70 be possible to evacuate the whole relay and then to inject an inert gas, instead of dealing with the separate capsules.

This would give two advantages in addition to simplifying the capsule construction, firstly, that no plating or other protection would be required

4· 2,3 on the metallic parts of the relay as these parts would be completely protected from adverse climatic conditions, while the capsules themselves need not be made closed units as described and in fact could be provided with one diaphragm ® only thereby simplifying manufacture thereof.

If the central pillar members of the capsules are arranged to interlock with one another as described above by providing bosses on one side and recesses on the other the operating efficiency 1® Is further increased by assuring the formation of a continuous operating pillar when the capsules are assembled within the relay case. Again if a simple metal spider spring such as is shown in Fig. 7 be interposed between the armature 25 15 (Fig. 3) and top cap II, and designated 26 in this figure, the armature could be held central without rubbing on the sides of the tube and thereby introducing friction during its operating movement. Referring to Fig. 7, tongues “a” could 20 be bent forward to seat in recesses in the armature and tongues “b” could be bent backwards to seat into recesses in the top cap, the ends of the tongues have a sharp bend into the recesses so as to restrict lateral movement of the armature. 25

If a casing is provided for the whole relay the construction of the separately detachable units of the contact springs or a single unit should not be of cylindrical form but only approximately so, such as of horse-shoe shape so as to leave ;io a gap in the periphery through which the actual contacts of the springs and their movement could be observed. The contacts springs may themselves be so shaped as to bring the contacts into the gap and therefore nearer the pe- :v> riphery.

It should also be understood that it is not essential although highly desirable that the tube should be cylindrical. A hexagonal, octagonal or even a square section may be satisfactory for a 40 range of relays but the cylindrical shape with freedom to insert the contact spring combinations at a large variety of angles would seem to be the best for general use unless of course special provision is made for dealing with the leading in 45 tags.