US2379772A - Electromagnetic relay - Google Patents

Description

July 3, 1945. Y A. wELLMAN 2,379,772

ELECTROMAGNETIC RELAY F'1ed Sept. 2, 1943 Inventor: Albert, Wellman,

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Patented July 3, 1945 issn 2,379,772 .ELECTRDMAGNETIC RELAY Albert Wellman, Scotia, N. Y., assignorto General Electric Company, Ya corporation of New York Application September 2, 1943, Serial No. 500,992l (Cl. 20G- 111) fi Claims.

My invention relates to electromagnetic relays, particularly to totally enclosed solenoid type relays, and has for its object the provision of a new and improved relay of thistype characterized particularly by reliability in operation and simplicity of assembly and disassembly. Such a relay is low in cost and adapted for quick, easy and inexpensive manufacture in large quantities.

According to my invention, all the parts of both the magnetic and electrical circuits are held in operative relation solelyby the closure members of an outer insulating` casing.

The novel features which are characteristic of my invention will be set forth with particularity in the claims appended hereto. The invention will be better understood, however, and its objects and advantages more fully appreciated by referring first to the following detailed specification taken in conjunction with the accompanying drawing in which Fig. 1 is a plan view of one end of a relay embodying my invention; Fig. 2 is a cross-sectional view taken along the line 2-2 of Fig. k1; Fig. V3 is a plan view of the opposite end of the relay with the enclosing cover removed; and Fig. 4 is an exploded perspective view of the entire relay.

Referring now to the drawing, I have shown an electromagnetic relay comprising a cylindrical venclosing casing I 0, preferably formed of a suitable non-magnetic electrically insulating material, vand having an external peripheral shoulder I I slightly spaced from one end thereof. Between the peripheral shoulder II and the adjacent end of the .casing I0, thel casing I0 is of somewhat reduced external and internal diamevter thereby to providel an internal peripheral shoulder II a in substantially l the same plane as the shoulder II, 'I'he reduced section of the casing Ill is provided with two pairs of diametrically disposed longitudinal slots I2 and I3. As shown at Fig. 2, the internal shoulder IIa is cut away above the slots I2 and I3 to provide internal longitudinal recesses I Ib for a purpose which will appear more fully hereinafter. The peripheral shoulder II is cut away at diametrically oppo' site points I5.

I8 is provided internally with a hollow cylindrical boss I9 for a purpose which will be more fully described hereinafter.

Removably disposed within the casing Ill is a metallic liner 20 of magnetizable material having at one end a pair of diametrically disposed longitudinal slots 2 If A pair of diametrically op..

posite bosses 20a, on the liner 20 are 'arranged for at diametrically opposite points, ya pair of off-set terminal connectors 23.` In the assembled position shown at Fig. 2, the terminal connectors are so arranged that their off-set portions overlie the shoulders is at the bases of the slots I4 in the casing I0. In this position, the terminal connectors 23 do not interfere with the threaded engagement of the end cap I1 within the casing I0, but their radially extending outer ends are firmly clamped between the end cap I1 andthe shoulders I6.

Between the upper end of the energizing coil 22, as viewed in the drawing, and the upper e'nd cap. I1 is disposed a metallic disk 24 of magnetizable material having at the center thereof a hollow cylindrical boss 26 arranged to exten-d a short distance longitudinally into the coil 22. The hollow boss 26 is lined With a cup-shaped liner 21, preferably formed of a non-magnetizable metal characterized by long wearing qualities. The vcup-shaped liner 21 provides a permanent air gap and` also serves slidably to supporta magnetizable plunger 28 which extends into the coil 22 andis provided with a conical face 29. To prevent the formation of an air cushion between the plunger 28 and liner 2J, the base of the liner 21 is apertured at 21a and the end cap I 1 is formed witha circular linternal boss I1a thereby.

AThe opposite endAof the casing is provided with one pairof diametrically disposed longitudinal slots I4. The slots I4 extend farther longitudinally on the outer surface of the casing than on the inner surface, thereby to provide a pair of shoulders I6 at the bases .0f theseslots. Opposite ends of the cylindrical casing yIl) are threaded to receive apair of end caps I1 and I8, preferably formed of the samemon-magnetic electrically in; suhting material as the casing I0. l'I'he end caps Il and I8 are generallycupfshped and thecat'4 to provide a small air -space I1b between the disk 24A` and the end cap I1. Since the liner 2" constitutes. a necessary and permanent air sali or'break in the magnetic circuit, its reluctance' is minimized byforming the liner to present .a large area for the .passage of magnetic iiux` be-V tween the plunger. 28 and the end cap 24.

It will be noted that the portion of the plungerv 28 Vwhich slides within the liner 21 is of smaller diameter than the plunger head.` This reduction of the plunger diameter makes possible the large flux area through the hner 21. It should be notedl B5' that leakage :dux between the lower end of the' cylindrical .has 26 and the plunger head provides a hold-out force which must be minimised.

' ing portions for these strips.

Such forceis satisfactorily reduced by making the minimum length of this leakage flux path at least two or three times the length of the air gap through the liner 21.

Extending into lthe coil 22 from the opposite end thereof I provide a magnetizable core member 30 having a reentrant conical face 3| for co operation with the conical face 29 of the plunger 28. The core 3D is mounted at its other end upon a magnetizable disk 32 which extends across the lower end of the coil 22 between the stationary core portion 3D and the magnetizable liner 20, thereby to complete a magnetizable frame for the relay.

The stationary core 30 and the magnetizable end disk 32 are centrally bored along the longitudinal axis of the core 30 slidably to receive an actuating pin 33 which is preferably formed of non-magnetizable material. The pin 33 extends beyond both ends of the magnetizable core 30, the upper end of the pin having a reduced end portion 34 iitting into a bore in the end of the movable plunger 28. The lower end of the pin 33 has a reduced end portion 35 which fits snugly into a knob 36 having a peripheral shoulder 31 at the upper end thereof. Beneath the magnetic disk 32, and seated upon the internal shoulder Ila of the casing Ill, I provide an insulating disk or washer 3B. the casing into an upper coil compartment and a lower contact compartment. The parts thus far described in the coil compartment are all clamped in operative relation between the shoulder Ila and the upper end cap |1. The actuating pin 33 passes slidably through the washer 33 so that the knob 36 lies in the lower or contact compartment.

Referring now to the lower end of the relay, as viewed in the drawing, there are radially disposed within the pairs of diametrical slots l2 and I3 two pairs of contact strips 39 and 40. Each contact strip 39 is ilat and is provided internally and externally with keying portions to prevent radial displacement of the strip with respect to the casing, l0. The strips 39 are enlarged both internally and externally to key the strips against radial displacement, the internal enlargements serving as xed contact surfaces and the external enlargements serving as terminal connectors. The Contact strips 40 are ofi`- set so that their inner and outer portions lie in different planes. The outer portions only of the contact strips 4|) are enlarged to provide terminal connections and keying connection with the slots I2. These outer portions of the strips 40 lie against the lower surface ofthe external peripheral shoulder on the casing and in the same plane as the outer portions of the contact strips 39. Within the slots |2, however, the contact strips 40 are off-set and extend a small distance longitudinally of the casing i0. The oif-set in the contact strips 40 serves both to dispose the inner ends of the contact strips 40 in a plane displaced from the plane of the inner ends of the contact strips 39, and also as a key to prevent outward radial displacement of the contact strips 40 with respect to the casing |IJ. Because of the ofl-set in the contact strips 40, it is unnecessary to provide enlarged inner key- The contact strips 40, like the contact strips 39, serve the dual pur`- pose of providing at their inner ends xed contact surfaces and at their outerends terminal connectors. Both pairs of contact strips 39 and 40 are clamped firmly in place, in the assembled The washer 38 eiectively divides position of the relay, between the end cap IB.

and the lower surface of the external peripheral shoulder on the casing l0.

Referring now particularly to Figs. 2 and 3, it may be observed that4 I provide between the planes of the contact strips 39 and the inner ends of the contact strips 4D an S-shaped movable contact element 4|. The contact element 4| is preferably formed of electrically conducting spring material and comprises a diametrical member having a hole at the center thereof and arcuate portions extending oppositely from the ends thereof. vIt will be observed from Figs. 2 and 3 that the movable contact member 4| is mounted upon the collar 36 in such a position that the diametrical body portion of the contact member serves as a bridging contact between the fixed contact strips 39 and the arcuate extensions of the member 4| are disposed to engage the fixed contact strips 40. To opposite ends of the, movable contact member 4| are attached a pair of moving contacts 4|a and lib, which, in operative position, extend a small distance into the internal recesses lib to limit rotation of the contact member 4| with respect to the casing l0 thereby to maintain the moving contacts in proper alignment with the xed contacts.

The movable contact member 4| is biased upwardly and into engagement with the shoulder 3T on the knob 36 by means of a helical compression spring 42 which is seated at one end inthe hollow cylindrical boss i9 of the end cap |8 and the other end of which holds the Contact member 4| against the shoulder 31. The spring 42 biases the moving contact member 4| and actuating pin 33 upwardly, as viewed in the drawing, so that the member 4| normally engages the fixed contact strips 40. In this position the movable plunger 28 is also held spaced from the magnetizable core 3U.

In operation, the movable bridging Contact 4l normally completes a circuit `between the fixed contact members 40. The contact 4| is movable between the xed contacts 40 and the xed contacts 39, the fixed contacts 39 being shown in the drawing below the movable contact mem ber. Thus, when the actuating coil 22 is energized, the movable plunger 28 is drawn downwardly into engagement with the magnetizable core 30 and presses the actuating pin 33 downwardly against the bias of the compression engagement with the normally open xed contacts 39.

To facilitate mounting of my relay upon any suitable base, which may be a vertical or horizontal surface, I provide a mounting bracket 43 encircling the casing I0 and having a pair ol attachment feet extending through the cutaway portions |5 of the shoulder The bracket 43 is formed of spring material and is slightly bent diametrically at 43a to provide some resilience in the mounting.

In View of the foregoing detailed explanation of the structure and arrangement of the various parts of my relay, it will now be evident that all parts of my relay are readily accessible and that the whole is simply and easily assembled or disits legs passed through the cutaway sections I of the shoulder Il. The insulating disk 38' is then slipped intothe casing from the upper en'd and placed against the internal peripheral shoulder ila in the casing. The connected'disk 32 and core 3| are lthen slipped into thcasing on top of the insulating disk 38.

` upside down, the actuating pin 33, with the knob attached, may be placed in the core and the movable contact member 4| slipped over the end of the knobI 36 and against the shoulder lll'. 'lhe pairs of stationary contacts 39 and W are now slipped longitudinally into their respective pairs oi slots I3 and I2, the inner ends of the contactsu 40 being placed under the contact member di 4and `the inner ends of the contacts d@ being placed over the member Il. Finally, the helical compression spring I2 is placed in the boss i9, where it is frctionally held sufilciently to permit it to be inverted over the end oi the lrnob 36, and the end cap I8 is screwed in place to clamp the iixed contacts 39 and 40 Next, the liner 2@ may be placed in the casingand the slots magnetic insulating material attached to opposite ends of said casing to close said compartments and to hold the parts of said relay in fixed operative relation, and a compression spring interposed between the contact compartment closure cap and said movable contact member, said contact compartment closure cap clamping said iixed contacts in fixed position against said external casing shoulder.

2.11m electromagnetic relay comprising an open-ended cylindrical casing of non-magnetic insulating material having a peripheral shoulder axially spaced from one lend thereof, said casing being slotted longitudinally between said peripheral .shoulder and said one end, an energizing coil disposed within said casing, a plunger movable axially of said casing within said coil, a movable contact member operatively connected to rsaid plunger, a contact strip extending radially through said slot and having keying portions internally and externally of said casing,

and an end cap of non-magnetic insulating material -threadedly engaging said one end of said in their operative positions. The relay is now totally enclosed, substantially dustproof and waterproof, and may if desired be hermetically sealed. Finally, the relay may be mounted upon any suitable base by means of the mounting bracket 43.

While l have described only one preferred embodiment of my invention by way of illustration, many modications will occur to those skilled in the art and I therefore wish to have it understood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire Ito secure by Letters'Patent `of the United States is:

1. An electromagnetic relay comprising an open-ended cylindrical casing of non-magnetic insulating material provided with internal and external peripheral shoulders adjacent one end, said casing being slotted longitudinally at diametrically opposite points between said one end and said shoulders, an insulating washer seated on said internal shoulder to divide said casing into coil and contact compartments, a removable cylindrical liner of magnetizable material disposed within said coil compartment, a removable cylindrical energizing coil disposed within said liner, a magnetizable core centrally positioned in said coil and extending from said washer partially through said coil, a magnetizable plunger within said coil movable longitudinally into and out of engagement with said core, a pair of magnetizable disk-s disposed at opposite ends of said coil to complete a magnetic frame for said relay, one of said disks being attached to one end of said core and the other of said disks slidably receiving one end of said plunger, a pair of iixed contacts extending radially through the longitudinal slots of said casing into said contact compartment, a sldable actuating rod extending from said plunger through said core and into said contact compartment, n. movable contact member mounted upon the extending end of said rod, a pair of end caps of noncasing lto close said casing and to clamp said contact strip between said cap and said shoul-A der, whereby the inner end of said strip provides a fixed contact surface and the outer end lof said.

strip provides a terminal connector.

3. An electromagnetic relay comprising an open-ended cylindrical casing of non-magnetic insulating material having a peripheral shoulder axially spaced from one end thereof, said casing being slotted longitudinally at diametrically opposite points between said peripheral shoulder and said one end, an energizing coil disposed within said casing, a plunger movable axially of said casing within said coil, a movable bridging contact operatively connected to said plunger, a contact strip extending radially through each of said slots and having keying portions internally and externally of said casing, and an end cap of non-magnetic insulating material threadedly engaging said one end of said casing to close said casing and to clamp said contact strips between said cap and said shoulder, whereby the innerends of said strips provide xed contact surfaces and the outer ends of said strips provide terminal connectors.

4. An electromagnetic relay comprising an open-ended cylindrical casing of non-magnetic insulating material having internal and external peripheral shoulders axially spaced from one end thereof, said casing being slotted longitudinally at diametrically opposite points between said shoulders and said one end, an insulating washer] seated upon said internal shoulder to divide said casing into separate coil and contact compartments, an energizing coil disposed within said coil compartment, a plunger movable axially of said casing within said coil, a movable bridging contact positioned in said contact compartment and operatively connected to said plunger, a pair oi' contact strips extending radially through said slots and having keying portions internally and externally of said casing, anend cap o! nonmagnetic insulating material threadedly engaging said one end of said casing to close said. contact compartment and to clamp said contact strips between said cap and said external shoulder, and a compression spring seated ailainst said cap and engaging said bridging contact to bias said bridging contact to a normal position with respect Ito said xed contacts.

ALBERT wmmn,

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