US2579673A - Circuit breaker - Google Patents

Description

CIRCUIT BREAKERS Filed Sepf. 27, .1947

@WiWi/ma Patented Dec. 25, 1951 CIRCUIT BREAKER John G. Jackson, Detroit, Mich., signor to Square D Company, Detroit, Mich., a corporation of Michigan Application September 27, 1947, Serial No. 776,528

l 22 Claims.

This invention relates to automatic electric circuit breakers and more particularly to eurrent responsive tripping means for effecting the automatic opening of such circuit breakers upon current overload.

One object of the invention is to provide a simple and economical but eii'ective combined thermal and magnetic tripping means for an automatic electric .circuit breaker.

vAnother object lot the invention is to provide tripping means for an automatic electric circuit breaker including a current responsive bimetallic member adapted to iiex upon moderate current *overload to eilect opening of the circuit breaker, with relatively stationary and movable magnetic elements for eiecting magnetic tripping of the .circuit breaker on heavy current overloads and `short circuits and with the magnetic elements bodily supported upon the bimetallic member.

Another object oi' the invention is to provide tripping means in accordance with the preceding object in which the movable magnetic member moves a resilient latching tip which is also mounted upon the bimetallic member so as to be bodily movable therewith upon thermal trip as well as movable relative thereto upon magnetic trip.

Another object of the invention is to provide a tripping means in accordance with the immediately preceding object in which an integral extension of the resilient latching tip serves to mount the movable magnetic member upon the bimetallic member.

Another object o1' the invention is to provide tripping means for an automatic electriccircuit breaker having relatively stationary and movable magnetic members in which the movable magnetc member rotates about an edge on the stationary Amagnetic member to effect the magnetic tripping of the circuit breaker and in which the movable magnetic member is maintained in contact with the stationary magnetic member edge to minimize the l reluctance of the flux path thereat.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specication and appended drawings illustrating certain preferred embodiments in which:

Figure 1 is a front elevational view of a circuit breaker according to the present invention with the front cover broken away over the current responsive tripping means.

Figure 2 is a vertical sectional view on the line II-II of Figure 1 and showing the breaker mechanisin in the oir position.

Figure 3 is a bottom plan view of the current responsive tripping means when in the position of Figure l but with the movable armature removed.

Figure 4 is a detail sectional view on the line IV-IV of Figure 3.

Figure 5 is a sectional view through the current responsive tripping means taken on the line V-V of Figure 3.

Figure 6 .is a view of the armature member alone taken in bottom plan from the position of Figure l.

The current responsive tripping means of this invention has been illustrated in connection with a circuit breaker mechanism which will be but briefly described, with more particular reference to Figure 2, and which comprises an insulating base I having a conducting strap 2 mounted on an end ledge of the base by means of a hollow spun over rivet 3 in which is threaded a terminal stud l. The conducting strap 2 extends within the hollow portion of the base I through an end opening which is closed by means of an insulating plate 5, the interior end of conducting strap 2 carrying a stationary contact i3. Guided within the base for rectilinear movement toward and away from the back of the base is a generally U-shaped member 6 having a iiat forward surface 'I which cooperates with an interior camming surface upon a manually operable handle 8 mounted for pivotal movement upon integral shaft 9. Upon the longer leg of the element 6 is pivotally mounted, by interengaging notches, a contact bar Il carrying at one end a movable contact I2 cooperating with the stationary contact I3. A `compression spring I4 is disposed between the bottom of the base and the contact bar I I so as to bias the bar away from the bottom of the base and for rotation about its engagement with the element i.

Upon an end ledge at the end of the base opposite to the conducting strap 2 is mounted a second conducting strap I5 by means of a hollow spun over rivet li into which is threaded a terminal screw I2. The conducting strap I5 extends within the base I through an end opening closed by an insulating plate I8 and has a pressed out central portion I9 at its interior end upon which is mounted a bimetallic member 2I. Between the pressed out portion I9 of the conducting strap I5 and the normal legs 22 thereof is disposed an element 23 within which is threaded a stud 24 which is movable to bend the pressed out portion I 9 to effect thermal calibration of the breaker. Sealing material to prevent access to the stud 24 after calibration is indicated at 25.

The current responsive tripping means according to the present invention will be described more in detail inl connection with the other figures of the drawing. andwill be herein referred to only briefly as comprising a stationary magnetic yoke 26, a magnetic armature 21 and a resilient latching tip 28 mounted upon the bimetallic member 2l and movable bodily therewith and relative thereto. A conducting flexible lead 30 interconnects the bimetallic member 2l and the contact bar II.

In the operation of the breaker mechanism of Figure 2 the parts are shown in manually disengaged position. If the handle 8 is rotated in a counterclockwise direction, a cam surface of lesser diameter will be presentid to the surface 1 of the rectilinearly movable element 6 so that this element will be moved forwardly of the breaker under the action of spring i4. In this movement, the contact bar I I will pivot about its engagement with the latching ltip 28 until contact I2 engages contact I3 to complete the circuit through the breaker. For return to the manu ally off position, the handle is rotated in a clockwise direction and the parts then reassume the position of Figure 2.

With the contacts engaged, upon the occurrence of a moderate overload through the circuit breaker the-bimetallic member 2I will be heated by the passage of current therethrough and will iex in a clockwise direction to bodily move the latching tip 28 oi of the latching end of the contact bar II which then rotates about its pivotal mounting upon the longer leg of the element 6, under the bias of spring I4 and in a clockwise direction, to move contact I2 to disengaged position. To reset the parts after an automatic operation, the handle 8 is rotated in a clockwise direction beyond the off position whereupon the element 6 in moving toward the back of the breaker will effect rotation of the contact bar I I, as well as movement bodily thereof, so that the contact bar rotates in a counterclockwise direction to again place its latching end in back of the latching tip 28. After resetting, movement of the operating handle in a counterclockwise direction will again engage the contacts to close the circuit through the breaker.

The tripping magnetically is effected upon the occurrence of heavy overloads or short circuits wherein the armature is attracted to the yoke 26 in a shorter time than would be required for the heating and flexing of the bimetallic member 2i. In magnetic tripping the armature 21. when attracted to the yoke 26, engages the resilient latching tip 28 to move it relative to the bimetallic member 2| to eiect unlatching of the contact bar II and hence rotation thereof to the contacts disengaged position.

The construction of applicants new current responsive tripping means is shown more particularly with reference to Figures 3 through 6. The resilient latching tip 28 is formed on a spring member 29 having an upper hook portion 3I which extends through a slot 32 in the armature 21 to mount the armature upon the bimetallic member 2 I. The latching tip 28 is provided with a projecting nose as shown and has a flange 33 at its back end which engages the bimetal 2| to limit the position of latching tip 28. The magnetic yoke 26 has a portion thereof formed with a U-shaped cross section at 34 and at the ends of the U there are provided a pair of elongated pole faces 35 which the armature 21 contacts in its attracted position. The yoke 26 and the 'spring strip 29 are mounted upon the bimetallic member 2l by means of a rivet 36 so that the legs of the U-shaped portion 34 embrace the bimetallic member so that the yoke 26 is energized magnetically by the current flowing through the bimetallic member 2| which then, in effect, becomes a single turn about the yoke. The armature 21 is mounted by means of the hook end 3I of the spring piece 29 and is disposed with its upper end as viewed in Figure 5, engaging the upper edges of the pole faces 35 of the yoke 2t. When the magnetic flux within the yoke is sufficient to attract the armature 21 for movement thereto the armature rotates about its engagement with the edges of the pole face and against the small bias provided by the resilient hook 3|. The lower air gap between the armature 2| and the pole faces 35 is determined by a rib 31 within the base (Figure 2) which limits the movement of the armature away from the yoke 2.

In the arrangement herein shown it is seen that for thermal tripping the latching tip 28 moves bodily with the bimetal 2l as it flexes under the heating action of the current passing therethrough. Upon magnetic trip, the latching tip'28 is moved relative to the bimetal 2I by the engagement of the armature 2l with the latching tip to cause movement thereof against its resilient bias. By mounting the armature 21 in engagement with the pole faces 35 of the yoke 26 so as to pivot thereabout, there is provided a small path of low magnetic reluctance which increases the sensitivity of the magnetic trip and lowers the current value at which the armature 21v is attracted to the pole faces of the yoke. With the resilient latching tip only a small magnetic force is required to effect the unlatching movement compared to what would be required to eiect movement bodily of the relatively stiff bimetal 2l.

While certain preferred embodiments of the invention have been speciflcfly disclosed, it is understood that the invention, is not limited thereto, as many variations will be readily apparent to those skilled'in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

I claim:

1. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for effecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a magnetic yoke supported upon said bimetallic member and energized in response to the flow of current through the breaker, an armature member also supported upon said bimetallic member and adapted to be attracted to said yoke upon the occurrence of an overload current of sufficient value, and means on said bimetallic member engaging said releasable means and adapted to be moved bodily by said bimetallic member upon flexing thereof in response to the passage of moderate overload currents, said engaging means being movable relative to the bimetallic member by said armature as it is attracted in response to heavy overloads and short circuit currents.

2. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current reu sponsive means for effecting the release of said yreleasable means upon the passage c! an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a magnetic yoke supported upon said bimetallic member and energized in response to the flow of current through the breaker, an amature member also supported upon said bimetallic member in engagement'with an edge of said yoke and pivoting about said edge into engagement with the yoke as the armature is attracted upon the occurrence of overload currents of suicient value, and means on said bimetallic member engaging said releasable means and adapted to be moved bodily by said bimetallic member upon flexing thereof in response to the passage of moderate overload currents, said engaging means being movable relative to the bimetallic member by said armature as it is attracted in response to heavy overloads and short circuit currents.

3. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for effecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a magnetic yoke supported upon said bimetallic member and energized in response to the flow of current through the bimetallic member, an armature member also supported upon said bimetallic member and adapted to be attracted to said yoke upon the occurrence of an overload current of suilicient value, and means able means to normally latch the same in operative position, said engageable means being moved by said bimetallic member in response to the occurrence of moderate overloads and being moved by said armature member upon the occurrence of heavy overloads and short circuit currents.

` 4. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for effecting the release of said l releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a resilient spring strip mounted on said bimetallic member with one end formed as a latching tip to engage said releasable means, a magnetic yoke mounted upon said bimetallic member, an armature member mounted on said bimetallic member for pivotal movement by the opposite end of said resilient strip and maintained thereby in contact with one edge of the magnetic yoke about which edge the armature pivots in moving to attracted position, said yoke and armature engagement providing a path of low magnetic reluctance thereat, the bimetallic member flexing under the action of moderate overloads to bodily move said latching tip out of engagement with said releasable means, said armature moving said latching tip relative to the bimetallic member into releasing position upon the occurrence of heavy overloads and short circuit currents.

5. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for effecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the ilow of current through the breaker, a reengageable with said releassilient spring strip mounted on said bimetallic member with one end formed as a latching tip to engage said releasable means, a magnetic yoke mounted upon said bimetallic member, an armature member mounted on said bimetallic member for pivotal movement by the opposite end o! said resilient strip and maintained thereby in contact with one edge of the magnetic yoke about which edge the armature pivots in moving to attracted position, said yoke and armature engagement providing a path of low magnetic reluctance thereat, the resilient spring strip biasing the armature toward unattracted position, and means limiting the extreme unattracted position of the armature, the bimetallic member flexing under the action of moderate overload currents to bodily move said latching tip out of engagement with said releasable means, said armature moving said latching tip relative to the bimetallic member into releasing position upon the occurrence of heavy overload and short circuit currents.

6. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for eecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a magnetic yoke, a resilient spring strip, common means positively supporting said yoke and a midpoint on said strip upon the bimetallic member, one end of said resilient strip being formed as a latching tip engaging said releasable member, an armature member, the opposite end of said resilient strip extending through a slot in said armature member to mount the same upon said bimetallic member with the armature in engagement with an edge of said magnetic yoke about which edge it pivots to rotate to attracted position, the bimetallic member flexing under the action of moderate overload currents to bodily move the latching tip out of engagement with said releasable means, said armature being attracted to the yoke upon the occurrence of heavy overload and short circuit currents and effecting movement of said latching tip relative to the bimetallic member to releasing position.

7. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responsive means for effecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the flow of current through the breaker, a magnetic yoke, a resilient spring strip, common means positively supporting said yoke and a midpoint on said strip upon the bimetallic member, one end of said resilient strip being formed as a latching tip engaging said releasable member, an armature member, the opposite end of said resilient strip extending through a slot in said armature member to mount the same upon said bimetallic member with the armature in engagement with an edge of said magnetic yoke about which edge it pivots to rotate to attracted position, said opposite end of the resilient strip biasing the armature against the edge of the yoke and into its unattracted position, and means limiting the extreme unattracted position of said armature, the bimetallic member flexing under the action of modernate overload currents to bodily move the latching tip out of engagement with said .re-

leasable means, said armature being attracted to l the yoke upon the occurrence of heavy overload and short circuit currents and eecting movement of said latching tip relative to the bimetallic member to releasing position.

8. In an automatic electric circuit breaker having separable contacts and means releasable to effect separation of said contacts, current responslve means for effecting the release of said releasable means upon the ypassage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the ilow of current through the breaker, a magnetic yoke supported upon said bimetallic member and energized in response to the flow of current 'through the breaker, an armature member also supported upon said 'bimetallic member and adapted to be attracted to said yoke upon the occurrence of an overload current of suiiicient value, a resilient strip carrying a latching surface engageable by said releasable means, a main portion of said strip being disposed on the high expansion side of the bimetallic member and having an abutment as the low expansion side of the bimetallic member so that the latching surface and resilient strip are moved bodily by the bimetallic member as it engages the abutment upon flexing in response to the passage of moderate overload currents, said armature moving the latching surface and strip relative to the bimetallic member as the armature is attracted in response to heavy overload and short circuit currents.

9. In an automatic electric circuit breaker having separable contacts and means releasable to eect separation of said contacts, current responsive means for effecting the release of said releasable means upon the passage of an overload current through the circuit breaker comprising a bimetallic member heated in response to the iiow of current through the breaker, a magnetic yoke supported upon said bimetallic member and energized in response to the flow of current through the breaker, an armature member also supported upon said bimetallic member and adapted to be attracted to said yoke upon the occurrence of an overload current of suflicient value, and a resilient metallic strip mounted on said bimetallic member and carrying a latching surface engageable by said releasable means, said latching surface and resilient strip being bodily movable by the bimetallic member by flexing thereof in re' sponse to the passage of moderate overload currents, said latching surface and strip being movable relative to the bimetallic member by said armature as it is attracted to the yoke in response to heavy overloads and short circuit currents.

10. A circuit breaker including relatively movable contacts, a releasable member operable when released to effect opening of said contacts, trip means including a bimetal element electrically connected to be traversed by current, electroresponsive means comprising a pair of magnetic members on opposite sides of said bimetal element and energized by the current fiow therethrough, both of said magnetic members being movable, resilient means movable upon occurrence of overload current flow by said trip means one of said magnetic members being engaged by said resilient means and biased thereby away from said bimetal element but being movable magnetically relative to said bimetal against the bias of said resilient means to effect release of said releasable member upon the occurrence of a heavy overload, and the other magnetic member i 8 being iixedly mounted ment and movable thereby upon bending of said bimetal element to effect release of said releasable member upon the occurrence of a smaller overload.

element, resilient means movable upon the occurrence of overload current flow by said trip means, said resilient means engaging said armature and biasing said armature away from said bimetal element, said core member being mounted 'to be moved by said bimetal element, said bimetal element flexing when heated a predetermined amount to move said core member of the eletcroresponsive means and effect release of said releasable member, and said electroresponsive means being operable to move the armature relative to the core member in response to overload current above a predetermined value to instantaneously effect release of said releasable member. v

12. In a circuit breaker comprising relatively movable contacts and a member releasable to effect opening of said contacts, a bimetallic member heated by the current of the circuit of the breaker, an electromagnet supported on said bimetallic member, said electromagnet comprising a core member energized by the current iow through said bimetallic member and a movable armature, said bimetallic member flexing when heated a predetermined amount to bodily move said electromagnet and eiect release of said releasable member, and said electromagnet being operable in response to overload currents above a predetermined value to instantaneously release the releaseable member without substantially moving said bimetallic member.

13. In a circuit breaker comprising relatively movable contacts and means releasable to effect opening of said contacts, trip means operable to release said releasable means in response to overload currents comprising an electromagnet having a magnetic core member and a movable armature operable to release said releasable means, a current responsive bimetal element forming the sole support for said core and said armature. said bimetal element flexing when heated a predetermined amount to bodily move said core member and said armature without substantially increasing the gap` therebetween to release said releasable means.

14. In a circuit breaker comprising relatively movable contacts and operating means therefor. trip means operable in response to overload currents to effect contact opening operation of said operating means, said trip means comprising an electromagnet having a magnetic core member. an armature operable to effect opening operation of said operating means, and a bimetal element connected in the circuit of the breaker to be heated by the current of the circuit and operable when heated a predetermined amount to bodily move said core member and said armature to ei'- fect opening operation of said operating means. said bimetal element constituting the sole supporting means for said core member and said armature and being connected to move both said core member and said armature when the bimetal upon said bimetal elebends without substantially increasing the gap between the core member and the armature.

15. In a circuit breaker comprising relatively movable contacts and means releasable to eiect opening of said contacts, trip means operable in response to overload currents to release said releasable means, said trip means comprising a bimetal element traversed and heated by the current of the circuit, an electromagnetic core member mounted for movement by said bimetal element and extending around three sides of said bimetal element to be energized by current traversing said bimetal element, a movable armature pivotally supported on said electromagnetic core member, said electromagnetic core member being operable in response to overload currents above a predetermined valueto attract said armature and effect instantaneous release of said releasable means, and said bimetal element flexing when heated a predermined amount in response to overload currents below said predetermined value to move said electromagnetic core member and effect release of said releasable means.

16. In a circuit breaker comprising relatively movable contacts and means releasable to effect opening of said contacts, trip means operable to release said releasable means in response to overload currents comprising an electromagnet having a magnetic core and a movable armature operable to release said releasable means, a current responsive bimetal element forming the sole support for said electromagnet and said armature, said bimetal element flexing when heated a predetermined amount to bodily move said electromagnet and said armature while the magnetic air gap remains substantially the same to release said releasable means, and means for adjusting said bimetal element while the magnetic airgap remains the same.

17. A circuit breaker including relatively movable contacts, a releasable member operable when released to effect opening of said contacts, trip means including a bimetal element electrically connected to be traversed by current, electroresponsive means comprising a core member and an armature surrounding said bimetal element and energized by the current flow therethrough, said core member being mounted for movement by said bimetal element upon heating thereof due to overloads and said movement of the bimetal element and core member causing release of said releasable member, and said core member having said armature pivotally mounted on the core member for movement relative thereto magnetically upon the occurrence of heavy overloads to also cause release of said releasable member and opening of said contacts.

18. A circuit breaker including relatively movable contacts, a releasable member operable when released to eifect opening of said contacts, trip means including a bimetal element electrically connected to be traversed by current, electroresponsive means comprising a pair of magnetic members on opposite sides of said bimetal element and energized by the current flow therethrough, both of said magnetic members being movable, one of said magnetic members being pivotally mounted on the other magnetic member, a spring biasing said pivotally mounted magnetic member away from the other magnetic member and said pivotally mounted magnetic member being magnetically movable about its pivot against the bias of said spring without bending said bimetal element to effect release of said releasable member upon the ow of a predetermined heavy current, and the other magnetic member being movable upon bending of said bimetal member to effect release of said releasable member upon the occurrence of a predetermined smaller current.

19. A circuit breaker including relatively movable contacts. a releasable member operable when released to effect opening of said contacts, a terminal strip, a bimetal element mounted and electrically connected at its upper end to said terminal strip, a flexible conductor connected to the lower end of the bimetal element and electrically connecting it in series with said contacts, a core member having a U-shaped section of magnetic material extending around the bimetal element, an armature extending across and pivote`d on the ends oi the U of the core member, said core member being movable upon bending of the bimetal element to cause release of said releasable member upcn the flow of a predetermined current through the bimetal element, a spring biasing said armature against pivotal movement toward the ends of the U of the core member, and said armature being movable about its pivot against the bias of said spring by the magnetic flux caused in the U-shaped core member and armature by the current flow in the bimetal element to cause release of the releasable member upon the flow of a higher predetermined current through the bimetal element.

20. A circuit breaker including relatively movable contacts, a releasable member operable when released to effect opening of said contacts, trip means including a bimetal element electrically connected to be traversed by current, electroresponsive means comprising a pair of magnetic members mounted on opposite sides of said bimetal element and energized by the current flow therethrough, both of said magnetic members being movable, a strip of spring material having a portion thereof movable to effect release of said releasable member, one of said magnetic members being movable magnetically toward the other magnetic member and causing bending movement of the spring strip against its normal bias to the point where said portion of the spring strip causes release of the releasable member, said other magnetic member being movable upon thermal bending of the bimetal element and said bending of the bimetal element also causing movement of said portion of the spring strip to eifect release of the releasable member.

@21. In a circuit breaker having relatively movable contacts and means releasable to effect opening of said contacts, current responsive means for effecting release of said releasable means in response to overload currents below a predetermined value comprising a bimetal element, a magnetic member mounted on said bimetal element, a second magnetic member adapted to be attracted by the first said magnetic member in response to overload currents above said predetermined value, a biasing member extending along said bimetal element for supporting said second magnetic member, said bimetal element operating'said biasing member in response to overload currents below said predetermined value to effect release of the releasable means and both of said magnetic members being movable upon movement of the bimetal element with the air gap between the two magnetic members remaining` substantially constant, and said magnetic members being attracted in response to overload currents above said predetermined value to actul l ate said biasing member and effect instantaneous release of said releasable means.

22. In a circuit breaker having terminals and contacts, at least one of which contacts is movable, and a spring-actuated trip arm releasable by thermal and magnetic means to cause opening of said circuit contacts, the combination of a bimetal member connected at one point to one of said terminals and at another point to one of said relatively movable contacts so as to carry current therethrough and a magnet and armature mounted on said bimetal member at opposite sides thereof so as to partially surround said/ bimetal member. spring means pressing said magnet and armature apart so as to' establish a magnet air-gap, said armature being movable by and with said bimetal member on the occurrence of relatively small overloads, and movable by said magnet independently of and relative to said bimetal member on the occurrence of relatively large overloads to cause release of said trip arm, said magnet air-gap remaining substantially unaltered during movement of said armature by and with said bimetal member.

JOHN G. JACKSON.

wams

12 REFERENCES crrrm The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,812,847 Sachs June 30, 1931 2,027,238 Lindstrom Jan. 7, 1936 2,035,743 Frank et al. Mar. 3l, 1936 2,089,716 Smith Aug. 10, 1937 2,184,372 Von Hoorn Dec. 26, 1939 2,265,030 Dorfman Dec. 2, 1941 2,300,884 Gano Nov. 3, 1942 2,312,167 Jackson Feb. 23, 1943 2,312,168 Jackson Feb. 23, 1943 2,312,169 Jackson Feb, 23, 1943 2,328,458 Jackson et al Aug. 31, 1943 2,360,684 Jennings Oct. 17, 1944 2,376,759 Dyer et al May 22, 1945 2,424,909 Adam July 29, 1947 FOREIGN PA'I'ENTS Number Country Date 597,445 Germany May 25, 1934 616,133' Germany July 20, 1935

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