US2321710A - Relay - Google Patents

Description

June 15, 1943. H M STOLLER 2,321,710

RELAY Filed Sept. 26, 1941 f-/a T /M/E/VTOR T H M; S TOLLE l? A TTOR/VE V Patented June 15, 1943 RELAY Hugh M. Stoller, Mountain Lakes, N. J assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application September 26. 1941, Serial No. 412,360

Claims.

This invention relates to relays and more particularly to a combined line and cut-off relay assembly for use on subscribers lines of telephone systems.

In telephone systems and particularly in systems of the step-by-step type, each subscribers line is provided with a line relay and a cut-off relay, the two windings of the line relay being energizable in a circuit extending from the terminals of the centra-l oflice battery over two pairs of normally closed contact springs comprising a part of the cut-olf relay and the calling line loop when the calling subscriber closes the line loop at his substation to initiate a call. The line relay upon energizing is instrumental in closing two pairs of contact springs, over one pair of which a circuit is established to start an idle` line finder in search of the calling line and over the other pair of which the winding of the cutoff relay is connected to the test or sleeve conductor of the calling line terminating in multiple bank terminals of all line finders having access to the calling line. When the started line finder nds the calling line and its test brush encounters the test multiple of such line, the circuit prepared by the operated line relay for the cut-off relay is completed and the cut-off relay operates to open its two pairs of normally closed contacts to thereby disconnect the windings of the line relay from the calling line loop. It also closes a third pair of contacts whereby the cut-off relay locks itself to the circuit completed over the test brush of the line finder and is thus maintained operated following the release of the line relay resulting from the disconnection of the windings thereof from the calling line loop.

Some suggestions have heretofore been made for combining line and cut-off relays into a single unit to effect savings in manufacturing and installation costs andtto effect a ysaving in i mounting space on the apparatus rack at the central office. Since several thousand of both line and cut-off relays are required each year, to meet the normal expansion of installed telephone omces and to meet the normal demand for new office installations, it is apparent that a relay structure that would perform all of the functions of both the usual line and cut-off relays in a reliable manner and which could be simplified to such an extent as to effect material manufacturing, installation and maintenance costs would be of great value.

It is therefore the object of the present invention to simplify the structural details of a combined line and cut-off relay assembly, to

reduce thereby the cost of manufacture, installation and maintenance and to effect more reliable operation.

To attain this object and in accordance with one feature of the present invention, the magnetic circuit of the assembly comprises a channel-shaped field piece having two cores extending from the base of the channel forwardly between the flanges thereof upon-one of which is supported a two-winding line relay coil and upon the other of which is supported a cut-off relay coil. To complete the magnetic circuit, two armatures are provided which are pivoted on axes extending at right angles to the flanges of the channel and which are attractable toward the forward edges of the channel flanges and toward the pole face ends of the cores. Supported on the upper flange of the field piece are two spring pile-ups associated respectively with the two armatures. For actuating the springs of the associated spring pile-up, each armature is provided with a forwardly extending arm having a spring operating stud of insulating material secured therein.

In accordance with a further feature of the invention, a short-circuited winding in the form of a copper sleeve surrounds each core and is interposed between the core and the coil supported on the core. The copper sleeve on the line relay core is provided to render the line relay slightly slow to release its armature to thereby insure that the cut-off relay will have suflicient time to close its holding circuit before the line relay releases its armature in response to the opening of the loop circuit over the subscribers line by the attraction of the cut-off relay armature. The copper sleeve on the cutoff relay core permits the current to build up quickly in the test circuit established through the winding cf the cut-off relay and the winding of the test relay of the line finder at the instant the line finder finds the terminals of the calling line. Heretofore the quick building up of current throughthe winding of the` cut-off relay has been accomplished by the connection of a resistance of approximately 2800 ohms in shunt of the cut-off relay winding and by mounting Such resistance as a non-inductive third winding of the line relay coil. The provision of the copper sleeve on the cut-off relay core permits the quick building up of current through the cut-off relay coil by inductive instead of conductive coupling and avoids the more expensive non-inductive winding and the consequent necessity for dissipating the heat therefrom. An additional advantage attained by the omission of the shunt resistance is that all of the current then passes through the cut-off relay coil and the required ampere turns can be developed with a lower resistance, cheaper winding.

Other features of the invention will be apparent from the detailed description taken in connection with the accompanying drawing in which:

Fig. 1 is a perspective view of av relay assembly in accordance with the present invention with the spring pile-ups, one armature and one backstop arm omitted and one of the relay coils shown partly in cross section to more clearly illustrate a novel feature of the invention;

Fig. 2 is a perspective view of the upper portion of the relay assembly illustrating the mounting of one of the spring pile-ups; and

Fig. 3 illustrates diagrammatically a circuitv application of the improved -relay assembly.

Ihe relay assembly is provided with a channelshaped field piece member I` which is bent into the shape best disclosed in Fig. 1 from a blank punched from a sheet of magnetic iron. The member I has a base portion 2, an upper flange 3 and a lower flange 4. The upperilange 3 is provided with two portions 5 and 6 bent upwardly from its opposite ends to form brackets to which the spring pile-ups are secured. The base portion 2 of the field piece member I is provided with two holes (not shown) in which the rear ends of two cores I are secured. After the cores are secured in place, thev forward edges of the flanges 3 and 4 and the forward ends of the cores I are ground or machined to be in good alignment.

Each core 'I is surrounded by a tubular copper sleeve 8 the rear end of which is knurled to hold the rear spoolhead of a coil, the core being knurled near the rear end thereof to hold the sleeve thereon. The coil 9 mounted on the lefthand core I as viewed in Fig. 1 is a cut-olf relay coil having a single winding secured as by pyroX- ylin cement to the rear spoolhead I which may be of suitable insulating material,l such as phenol bre, and which may have two-winding terminal lugs (not shown) secured thereto in the usual manner and extending rearwardly through an opening provided therefor in the base 2 of the eld piece member I. The coil I'I mounted on the right-hand core 'I is a line relay coil having two equal windings secured to a rear spoolhead similar to the spoolhead I0 and having fourwinding terminal lugs secured thereto and extending rearwardly through the opening in the base 2.

Associated with the forward ends of the core 'I are two armatures I2 and I3 stamped from magnetic iron. The armature I3 has been omitted from Fig. 1 to enable a clearer disclosure of the structural details ofthe cut-off relay coil 9. Each armature is provided at its upper and lower outside cornersy with cut-away portions to form two aligned and vertically extending pintles I 4k and I5 and with an arm I6 extending forwardly at right angles therefrom to serve as a member for operating certain springs of an associated spring pile-up. The arm I6 has a portion I'I which extends above the plane of the upper flange 2 in the outer end of which is secured a spring operating stud I8 of insulating material, such as hard rubber. The two armatures I2 and I3 are similar except that they are reversely stamped and bent. The lower pintles I5 of the two armatures are seated in holes I9 in the forwardly extending arms of a U-shaped pivot plate which may be welded or otherwise secured by its base to the inner face of the lower flange 4. In welding the plate 20 to the flange, the ends of its arms are permitted to extend suiliciently beyond the forward edge of the lower flange 4 so that when the pintles I5 of the armatures are inserted through the holes I9, they will be permitted to turn freely but will be held against undue separation from the edge of the lower flange. The upper pintles I4 of the two armatures are seated in holes ZI' in the forwardly extending arms of an upper U-shaped pivot plate 22. The plate 22 is secured by its base to the outer face of the upper flange 3 by screws 23, in such a position that when the pintles I4 of the armatures are inserted through the holes 2|, they will be permitted to turn freely but will be held against undue separation from the edge of the upper flange. The plate 22 is provided at each end thereof with a forwardly extending arm 24 bent to lie in a plane at right angles to the base portion of the plate and serving as al backstop for the associated armature.

A spring pile-up is secured to each of the upwardly extending brackets 5 and 6 of the member I.V The spring pile-up associated with the line relay armature I2 comprises two fixed springs 25 and 26 and two cooperating, movable or armature springs 2'I and 28. These springs are clamped to the bracket 5 by screws 29 which extend through aligned holes in an outer clamping plate 3l), in the springs, in the spacers 3l, 32, 33 and 34 of insulating material, such as phenol fibre, which are interposed between the springs and between the outer spring 26 and the outer clamping plate 39, in the metal spacer 35 and into threadedy holes 36 in. the bracket 5. The pairs of springs 25 and 21 and 26 and 28 have their cooperating contacts normally disengaged. The screws 29V where they extend through holes in the springs may be insulated therefrom by the usual sleeves of insulating material which surround the shanks of the screws. The other spring pile-up associated with the cut-off relay armature |3comprises three xed springs 3l, 38 and 39 and three associated movable or armature springs 45|, 4I and 42 as disclosed in Fig. 3. These springs are insulatedly secured to the bracket 6 in the same manner as the springs of the other pile-up. 'I'he pairs of springs 3l and 40 and 3B and` 4I have their cooperating contacts normally engaged and the pair of springs 39 and 42 have their cooperating contacts normally disengaged. Each spring terminates at its rear end in a soldering terminal to enable external Wiring conductors to be connected therewith and each movable or armature spring has its contact end bifurcated with a contact welded to each section thus formed, the pair of contacts on each spring cooperating with a pair of contacts welded to the associated xed spring.

As best disclosed in Fig. 3, the insulating stud 53 secured to the arm of the line relay armature I2, engages against the outer face of the armature spring 2'I. Aligned with this stud and secured to the other armature spring 28 as by ring staking, is an insulating stud 43 which extends freely through a hole in the fixed spring 25 with its outer end engaged against the spring 2l. Thus by the attraction of the armature I2 assoelated with the une relay C011 ll, the studs ls and 43 cause the movement of the armature springs 21 and 28 to engage their contacts with the contacS Of the associated xed springs 25 and 26.

The insulating stud I8 secured to the arm of the cut-off relay armature I3, passes freely through a hole in the xed spring 31 with its free end engaged against the outer face of the armature spring 49. Aligned with the stud I8 and ring staked or otherwise secured to the armature spring 4I is an insulating stud 44, the outer end of which passes freely through ahole in the xed spring 38 into engagement with the inner face of armature spring 40 and the other end of which is engaged against the outer face of the armature spring 42. Thus by the attraction of the armature I3 associated with the cut-01T relay coil 9, the studs I8 and 44 cause the movement of the armature springs 40 and 4I to disengage their contacts from the contacts of the associated xed springs 31 and 38 and to engage the contacts of armature spring 42 with the contacts of fixed spring 39. The armature springs are all so pretensioned that through the insulating studs I8, 43 and 44, they normally press the arms of the two armatures I2 and I3 against the backstop arms 24 in which position, the inner edges of the armatures are separated from the front edges of the flanges 3 and 4 by suitable air-gaps.

3 illustrates the application of the improved relay assembly to a subscribers line of a dial switching system served by a line nder. In this figure, the relay assembly has been schematically disclosed to better illustrate its operation. A subscribers substation is illustrated by the circle 45, the line finder by the brush set 46 and the test relay of the line finder by the rectangle 41. In the installation of the relay assembly, two terminals of the line relay coil II are connected respectively to the battery and ground busbars of the central office battery and the other two terminals are connected to the armature springs 40 and 4I. One terminal of the cut-off relay coil 9 is connected to the battery bus-bar and the other terminal is connected to the two armature springs 28 and 42 and to the sleeve multiples 48 of the subscribers line appearing in the banks of all connector switches having access to such line. The springs 31 and 38 are connected to the ring and tip conductors 49 and 58 of the line, the springs 26 and 39 are connected to the sleeve or test multiples I of the line in the banks of all line-finder switches having access to such line, such for example as the switch 46, and the springs 25 and 21 are connected to the line-finder start circuit 52 and to ground respectively.

With the relay assembly thus connected, when the subscriber at substation 45 removes his receiver from the switchhook to initiate a call, a circuit is established from ground through the right winding of line relay coil II, over the normally closed contacts of springs 38 and 4I, tip conductor 59 of the calling line, over the line loop through the substation 45, and thence returning over the ring conductor 49, over the normally closed contacts of springs 31 and 4I) to battery through the left winding of line relay coil II. Coil I I thus becomes energized to attract the associated armature I2 to thereby move armature springs 21 and 28 to engage their contacts with the contacts of the fixed springs 25 and 26, respectively. The engagement of the contacts of springs 25 and 21 closes the line-finder start circuit 52 to start an idle line nder in search of the calling line and the engagement of the contacts of springs 26 and 28 prepares an operating circuit for the cut-off relay coil 9 which may be traced from battery through such coil, over the contacts of springs 28 and 26 to the sleeve or test terminal 5I thereby placing potential on such terminal and the multiples thereof to indicate to a started line finder that the line is in a calling condition.

It will be assumed that the line finder indicated by the brush set 46 is started to hunt for the terminals of the calling line. As soon as the test brush 53 engages the test terminal 5I of the line, the previously traced circuit through the out-off relay coil 9 is completed through the Winding of the line-finder test relay 41 to ground. Coil 9 thereupon energizes, the copper sleeve 8 on its core permitting a quick build-up of current through its winding whereby the test relay 41 is enabled to operate quickly. With the coil 9 energized, the associated armature I3 is attracted to disengage the contacts of springs 4U and 4I from the contacts of springs 31 and 38, respectively, to thereby disconnect the windings of the line relay coil II from the calling line loop and to engage the contacts of spring 42 with the contacts of spring 39. With the contacts of these latter springs now engaged, a holding circuit for the cut-oir relay coil is established from battery through such coil over the contacts of springs 42 and 39, test terminal 5I, brush 53, to ground at the line nder to hold the cut-01T relay energized after its initial operating circuit is opened at the contacts of springs 26 and 28 by the retraction of the line relay armature I2. Since the core of the line relay is provided with a copper sleeve, the retraction of the line relay armature, whereby the contacts of springs 26 and 28 become opened, is delayed for a suiiicient interval to insure that the holding circuit for the cut-off relay coil 9 has been established by the engagement of the contacts of springs 39 and 42. Cut-off relay coil 9 is now maintained energized over its holding circuit until the line finder becomes released following the restoration of the receiver to the switchhook at the calling line substation.

While the relay assembly has been disclosed as applied to a subscribers line terminating in the bank of a line nder, it will be apparent that a change in the arrangement of the springs of the spring pile-ups would enable the relay to be used in other types of dial switching or manual systems.

What is claimed is:

l. In combination, a line relay having a magnetic circuit including a core and an armature attractable thereto, Contact springs operable by said armature and a cut-off relay having a magnetic circuit including a core and an armature attractable thereto, contact springs operable by said armature, and a copper sleeve on the cut-off relay core to enable a quick build-up of current in the cut-off relay coil.

2. A combined line and cut-off relay assembly comprising a field piece, two cores secured thereto, a line relay coil supported on one of said cores, a cut-01T relay coil supported on the other of said cores, armatures attractable to the ends of the respective cores, contact springs supported on said eld piece, certain of which springs are operable by the cut-off relay armature and others of which are operable by the line relay armature and a copper sleeve on the cut-ofi relay core to enable a quick build-up of current in the cut-01T relay coil.

3. A combined line and cut-off relay assembly comprising a channel-shaped iield piece, two cores secured to the base thereof and extending forwardly between the anges thereof, a line relay coil supported on one of said cores, a cut- OIT relay coil supported on the other of said cores, armatures attractable to the forward pole-piece edges of the flanges of said channel and to the ends of the respective cores, contact springs supported on one of said flanges, certain of which springs are operable by the cut-off relay armature and others of which are operable by the line relay armature and a copper sleeve on the cut-01T relay core to enable a quick build-up of current in the cut-off relay coil.

4. A relay having a magnetic circuit including a core and an armature attractable thereto, contact springs operable by said armature, an operating coil supported on said core and energizable in a circuit including another relay and a copper sleeve on said core interposed between said core and said coil to provide a quick build-up of current in the circuit of said coil.

5. A relay having a magnetic circuit including a core and an armature attractable thereto, contact springs operable by said armature, an operating coil supported on said core and energizable by the entire current applied thereto over a circuit including another relay and a copper sleeve on said core interposed between said core and said coil to provide a quick build-up of current in the circuit of said coil.

HUGH M. STOLLER.

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