US3387239A - Electro-mechanical relays - Google Patents

Description

June 4, 1968 J. s. CHENHALL 3,387,239

ELECTRO-MECHANICAL RELAYS Filed March 23, 1966 2 Sheets-Sheet .1

Invenlor Joan ande, ("Menu/4a..

. 4 wwwm A Home y June 4, 1968 J. 5. CHENHALLY I 3,33 I I ELECTRO -MECHANI CAL RELAYS Filed March 25, 1966 2 Sheets-Sheet 2 I Inventor Jaw! S'nmuu. (min/Ha A Home y United States Patent 3,387,239 ELECTRO-MECHANICAL RELAYS John Samuel Chenhall, Port Hacking, New South Wales,

Australia, assignor to Elevators Pty. Limited, Waterloo, New South Wales, Australia Filed Mar. 23, 1966, Ser. No. 536,786 Claims priority, application Australia, Mar. 30, 1965, 56,989/65 9 Claims. (Cl. 335135) ABSTRACT OF THE DISCLOSURE The contacts in or for an electro-mechanical relay are moulded singly or in pairs into plastic wafers through which a securing screw passes so that the whole stack may be quickly assembled with the parts in their correct relative positions, the wafers preferably interlocking with one another.

This invention relates to improvements in the construction of an electro-mechanical relay, whose function is to perform switching of electrical circuits by means of contact springs when the operating coil of the relay is energised.

One object of the invention is to provide a relay so constructed that the insulation between the spring sets and the frame will withstand high test voltages, such as those of the order of 2,500 volts, 50 cycles, without any special precautions during assembly.

Another object is to provide a relay whose magnet or solenoid when energised is capable of operating a relatively large number of contacts, for example, up to 12 normally open contacts or 12 normally closed contacts or 8 changeover contacts or a combination of contact types involving an equivalent mechanical loading of the relay.

A third object is to greatly reduce the number of component parts in the relay and so reduce cost and time of assembly.

The relays with which the invention is concerned are of the kind in which movement of a p rt when a solenoid or magnetic coil is energised or dc-energised moves simultaneously one or more series of electric contacts arranged one above the other into or out of contact with other stationary contacts interspersed between them.

Such stacks of contacts (or pile-ups) are normally built up from separate contact springs held at one end of each by insulating blocks. Screws pass through such blocks and springs, such screws being insulated from the metal contacts by plastic sleeves or the like.

Usually there will be two such stacks or pile-ups arranged side by side and operated at the same time when the coil is energised. Hitherto the contacts of each such stack have been quite separate from those of the other stack and the whole assembly operation of said contacts and separate spacer block's, including the positioning of a buffer block between said contacts and various projections thereon to hold the fixed contacts in position, has been of a fiddling and time consuming nature which has increased the cost of such relays, as well as sometimes causing unreliability in service.

According to the present invention a contact for installation in an electro-mechanical relay has moulded around it at or near one end a plastic wafer and there is provision for the screw or screws or other securing means to hold said contact in the pile-up to pass through a portion of that wafer and not through the contact itself.

In a preferred form in accordance with the invention the contacts are produced in pairs, one contact of each pair forming part of one of each of two parallel pileups, the said pairs of contacts being held together and in their correct mutually relative position (but insulated ice from one another) by a plastic water moulded around both of them at or near one end, there being provision for securing screw or screws or other securing means to pass through the central portion of the wafer between the two contacts.

Preferably also the wafers are so formed as to interlock with one another so that they automatically position the contacts correctly during assembly.

The wafers are relatively thin sheets or discs of plastic material, their total thickness however being considerably greater than the thickness of the metal contacts themselves.

The preferred material from which the wafers are moulded is nylon but other suitable plastic materials may be employed if preferred.

Further features of this invention will be apparent from the following description of one preferred constructional embodiment thereof, and by reference to the accompanying explanatory drawings which illustrate one example of a two stack electro-mechanical relay constructed in accordance with the invention.

In the said drawings:

FIGURE 1 is a side view of the relay in question; and

FIGURE 2 a plan view thereof, while FIGURE 3 is an end view thereof;

FIGURES 4 and 5 are views of separate assemblies of pairs of movable and fixed contacts respectively, while FIGURES 6 and 7 show the pairs of FIGURES 4 and 5 respectively in end view.

In this construction an electro-mechanical relay comprises a frame 10 for holding a coil magnet 11 having electrical connection lugs 12 and a pivot 13 for an armature or clapper 14. Such pivot 13 is a horizontal rod at one end of the frame 10 which passes through lugs upon the armature 14. The latter is of generally L-shape having a generally nearly vertical portion extending down in front of the electric coil magnet 11 and a generally horizontal portion which extends under each of two stacks or pile-ups of stationary and movable contacts hereinafter described. When the magnet 11 is energised the inner end of the horizontal part of the armature 14 rises and through suitable mechanical arrangements raises all the movable contacts aforesaid into or out of contact with their associated stationary contacts.

The contacts are made in pairs and alternate pairs in vertical sequence differ from one another; being stationary or movable respectively.

One type of pairs of contacts, namely the movable contacts, is illustrated in FIGURES 4 and 6. It comprises two straight contact blade springs 15 arranged parallel to each other and with lugs 16 for connection of wiring by soldering, clip-on connection or otherwise at one end (the rearward end) and silver or other contact points 17 on one face at their other or forward end.

Each said contact has a portion which lies inside a moulded wafer 18 of nylon. This wafer is of rectangular form and lies between the two contact blades 15. The contact blades do not touch each other inside the wafer 18 but are well spaced from one another.

The fixed and movable contact blades 15, 24 do not overlap each other (otherwise than within the thickness of the plastic Wafers 18, 25) except where the contact points 27 are located and thus the risk of accidentally short-circuiting is minimised. The movable contacts 15 themselves are well spaced apart by half the thickness of each of the two wafers 18 which contain them plus the entire thickness of the intervening wafer 25 holding a pair of fixed contacts 24.

The terminal connection tabs 26 for all the fixed contacts lie above each other but well spaced vertically and the terminal contact tabs 16 for all the movable contacts also lie one above the other but well spaced vertically and in addition, because the latter are splayed outwards slightly as seen in FIGURE 4, they are spaced horizontally also from the connection tabs 26 upon the other contacts between them. This minimises the risk of shortcircuit and also facilitates the connection of wiring to such terminal tabs.

The central portion of the wafer 18 is formed with two holes 19 through which securing screws 20 to hold the stack of contacts in position upon the base or frame 18 can pass.

The two flat faces of the wafer 18 are slightly hallowed out in their central portions to reduce the area of contact and thereby ensure that superposed wafers bear snugly against each other.

The wafer 13 is also formed on each face with a pair of projections 22 and a pair of recesses 23 adapted to receive similar projections 22 on another wafer, each pair being towards one for and aft edge of the wafer.

Where there is a pair of projections 22 on one face of the wafer there is a pair of recesses 23 adapted to receive similar projections immediately below them on the other face, and vice versa.

The second type of double contacts namely the stationary contacts is illustrated in FIGURES and 7 and comprises fiat metallic blade springs 24 which extend longitudinally through similar square wafers 25 with contacts 26 for soldered, clip-on or other terminal connections at one end beyond the wafer and at their other ends extending horizontally in an outward direction. Their outward extremities hold silver or other contact points 27. The size and shape of the wafer 25, the holes 28 therethrough the central hollowing of its faces at 29 and the projections 36 and recesses 31 are the same as those for the first described pairs of contacts, respectively corresponding to features 19, 21, 22 and 23 previously described.

The edges of all the wafers 18, 25 are rounded or bevelled off from the centre planes of said wafers all round, thereby increasing the lengths of the leakage paths between superposed contacts.

With this construction it is a simple matter to lay one pair of contacts of one kind (movable or stationary) upon a block 32 at the rear end of the frame containing projections and recesses corresponding to those of the wafers 18, 25 and then another pair of contacts of the other kind upon the first. Another pair of the first kind is then placed upon the second pair and so on until say half a dozen or more pairs of double contacts have been so assembled. All these hold themselves in their correct positions relative to one another because of the interlocking projections and recesses 22, 23, 30, 31. They are all then clamped in position by a cover plate 33 and the bolts which are passed through the said cover plate, the stack of waters 18, the block 32 and into the frame 10 of the relay below such stack.

Secured to each of the movable contact blades 15 is a short push rod 38 of insulating material, which engages with the surface of the movable contact blade 15 above or below it. Other types of mechanical interconnection between the movable contacts and the armature 14 are possible and the present invention is not limited to this particular push rod construction.

At the forward end of the relay (where the armature 14 is located) there is a-bulfer block 35 in the form of a moulding which fits nonrotatably into the frame 10 and extends up between the two pile-ups of contacts. It is held to the frame by a suitable bolt 36 passing through a longitudinal hole in its centre. The armature 14 divides to pass with clearance on each side of this buffer block 35.

This buffer block has integrally moulded projections 37 upon its side faces and the stationary spring contact blades 24 engage against the upper or lower faces of such projections 37, so limiting their downward or upward movement while permitting them some movement in the opposite vertical direction to enable resilient engagement with them of the movable contacts which are not restrained by the buffer block projections 37 since their blades 15 are more widely spaced apart.

According as to whether the movable and stationary contacts are positioned with the one face or the other uppermost and how they are engaged with the projections 37 on the buffer block 35 the relay contacts 17, 27 may be arranged in a wide variety of forms to cover various switching arrangements. For example all may be open normally and closed when the magnet 19 is energised or vice versa or some may be opened and others closed when the magnet is energised. Or all or some of the movable contacts may move to open one circuit and close another by moving from one pair of stationary contacts below them to another pair above them.

Thus there is great flexibility of arrangement possible in this relay and the assembly operations are greatly simplified, while economy is effected not only through some speeding up in assembly but through the absence of many small parts customarily necessary.

The pile-ups are clamped to the relay frame 10 by the bolts 20 which pass through the moulded wafers 18, 25 without passing through the blades 15 or 24, thereby affording a high insulation level between the contacts and the frame 19 without the use of insulating tubes or the like to insulate the blade springs from the clamping screws.

The moulded wafers 18, 25 greatly reduce the number of parts which are assembled to form a pile-up, thereby achieving substantial economies in manufacture and assembly.

The moulded wafers 18, 25 being provided with male and female spigot interconnections 22, 23, 30, 31 clip together in their correct positions during assembly without the use of screws.

Because of the accurate location of the blades 15, 24 in the moulding die, the contact tips thereof are less likely to suffer lateral displacement in relation to each other than when such blades are separately assembled, according to current practice.

Moulding the contacts in pairs further reduces the number of separate parts for final assembly, so reducing assembly cost and time.

The blade springs 15, 24 can be pretensioned two at a time.

Words of position such as above as used in this specification are based upon the assumption that the pile-ups of movable and stationary contacts are arranged vertically above the armature 14. However it will be appreciated that the relay can be mounted in any position and that when the pile-ups are not vertically arranged appropriate changes are to be made at the wording.

I claim:

1. A pair of contacts for installation in an electromechanical relay, one contact of such pair being adapted to form part of one of each of two parallel pile-ups the said pairs of cont-acts being held together and in their correct mutually relative positions but insulated from one another by a plastic wafer moulded around both of them at or near one end, there being at least one hole for securing means to pass through the central portion of the said water between the two contacts.

2. A pair of contacts as claimed in claim 1 in which the wafers are so formed that a plurality of them when mutually superposed will interlock with one another so that they automatically position the contacts correctly during assembly.

3. A contact or pair of contacts as claimed in claim 2 comprising a pair of projections and a pair of recesses adapted to receive similar projections upon each face of said wafer, the projections upon one face coming immediately below the recesses on the other.

4. A contact as claimed in claim 1 in which the fiat faces of the wafer are slightly hollowed out in their central portions.

5. A pair of contacts as claimed in claim 1 comprising also terminal lugs for connection of wiring which are splayed outwards slightly from the centre line of the pair of contacts.

6. A pair of contacts as claimed in claim 1 comprising also terminal lugs for connection of wiring which are parallel to the centre line of the pair of contacts.

7. A contact as claimed in claim 1 in which the edges of the wafer are rounded or beveled from their central plane.

8. An electro-mechanical relay comprising an electromagnet or solenoid, an armature adapted to be moved when said electro-magnet or solenoid is energized and to return to its initial position when said electro-magnet or solenoid is dc-energized, together with a plurality of contacts as claimed in claim 2 secured in position relatively to said relay by means passing through the wafers specified and a mechanical interconnection between said armature and each of the movable contacts specified.

9. An electro-niechanical relay as claimed in claim 8 comprising also a buffer block positioned between pairs of contacts and having projections adapted to engage and limit any travel of the stationary contacts.

References Cited UNITED STATES PATENTS 1,921,430 8/1933 Reynolds et .al. 200-1 2,385,858 10/1945 Horman 200-1 2,838,631 6/1958 Hufnagel 335-428 BERNARD A. GILH'EANY, Primary Examiner.

H. BROOME, Assistant Examiner.

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