US2117047A - Circuit controlling device - Google Patents

Description

y 1938/ J. H. WHEELOCK 2,117,047

CIRCUIT CONTROLLING DEVICE Filed D80. 26, 1931 3 Sheets-Sheet l a i B, h i i l 5ai P 6 v 7\\ l k i 5 l ill 1 4 Fig.1.

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Inventor";

Attorneu May 10, 1938. J, WHEELOCK 2,117,047

CIRCUIT CONTROLLING DEVI CE Filed Dec. 26, 1931 3 Sheets-Sheet 2 lnu'en tov; I

john H. LUheelock Bu A tcorneg y 1938. .1. H. WHEELOCK CIRCUIT CONTROLLING DEVICE 5 Sheets-Sheet 3 Filed Dec. 26, 1931 Inuenior john H. wheelock Atior ne Patented May 10, 1938 UNITED STATES PATENT OFFICE Signal Engineering & Manufacturing Com pany, New York, N. Y., a corporation of Massaohusetts Application December 26, 1931, Serial No. 583,319

2 Claims.

The present invention relates to circuit controlling devices, and has for its object to provide a device of this character that is adapted to interrupt the flow of electrical currents without destructive arcing between the contacts thereof.

The device of the present invention relates particularly to a circuit controller, of the type employing a pivoted magnetic armature, adapted by its movement to carry contacts into and out of engagement, the device in its operation being characterized by the substantial elimination of destructive arcing between its contacts, due to an improved manner of breaking the arc in the travel of the contact carrying armature.

Other results obtained by the invention are reduction of the operating current required, as well as reduction in size of parts, as compared to prior devices of the same current carrying capacity. The above and other advantageous features of the invention will hereinafter more fully appear from the following description with reference to the accompanying drawings, in which:-

Fig. 1 is a view in side elevation of a circuit controlling device embodying the invention, with its contacts closed.

2 is a view in front elevation of the device shown in Fig. 1.

Fig. 3 is a View similar to Fig. 1, showing the contacts of the device partially open.

Fig. 4 is a View similar to Fig. 1, showing the contacts of the device entirely open, with the circuit broken.

Fig. 5 is a view in front elevation showing a modified form of the device.

Fig. 6 is a view in side elevation of the device shown in Fig. 5.

Fig. 7 is a view in front elevation showing a further modification of the device particularly adapted to handle heavy currents.

Fig. 8 is a view in side elevation of the device shown in Fig. '7.

Like reference characters refer to like parts in the different figures.

Referring first to Figs. 1 and 2, the invention is shown, for purposes of illustration, as being embodied in a relay, the essential elements of which comprise an insulating base I carrying a U-shaped magnetic core 2, the shorter leg of which is surrounded by an energizing winding 3 with a magnetic armature 4 pivotally supported by the lower end of the longer core leg. With the structure shown, energization of the winding 3 is adapted to attract the armature A and hold it in the position of Fig. 1, deenergization of the winding 3 permitting the armature 4 to fall back into the position of Fig. 4, under the influence of gravity.

The armature A carries upwardly extending contact arms 5 and B, terminating in contact tips 5a and 6a, and the insulating base I carries stationary contacts I and 8 spaced apart substantially the same distance as the contact tips 5a and 6a, respectively. As indicated in Fig. 2, current from a suitable source 9 is supplied to the stationary contacts 1 and 8 through conductors Ta and 8a, respectively, an electrical load 10, represented by any current consuming device being connected in one of the conductors la or 8a. The terminals of the energizing winding 3 are also shown as being connected to the source 9 through conductors 3a, a control switch ll being provided in one of the conductors 3a whereby the winding 3 may be energized, or deenergized, at will.

Assuming that the parts occupy the position of Fig. 4, that is with the winding 3 deenergizecl due to the switch I! being open, it is to be noted that the flexible contact arms 5 and 6 are so formed that the contact tip 5a. is considerably nearer to the stationary Contact '1 than the upper contact tip 6a is to the stationary contact 8. Therefore, when energization of the winding 3 by closure of the switch I 1 causes the armature 4 to be swung upwardly toward the shorter core leg, the contact 5a first engages the stationary contact I, while the contact tip 6a is still separated from the contact 8, as indicated in Fig. 3, this sequence of operation being of importance, as will hereinafter appear. In this position of parts, no current from the source 9 is flowing through the load l0, although both of the contact tips 511 and 6a are under voltage from one side of the source 9, through the series connection of the contact arms 5 and 6. As the armature 4 completes its upward movement, as indicated in Fig. 1, the contact tip 5a slides somewhat on the stationary contact I, the accompanying flexure of the arm 5 maintaining the contact pressure. Therefore, when the upper contact tip 6a. engages the stationary contact 8, with some flexure of the arm 6, the connection of the load In to the other side of the source 9 is completed and current flows through the load while the winding 3 remains energized.

Upon deenergization of the winding 3, as by opening the switch H, the armature 4 is free to move downwardly, under the influence of gravity, aided to some extent by the tendency of the deflected contact arms 5 and 6 to resume their normal unflexed condition. As the armature t starts its downward movement, the contacts are disengaged in the reverse order of their closing, so that the contact tip to leaves the stationary contact 8 while the contact tip 5a still remains in engagement with the stationary contact 'i, as indicated in Fig. 3. Under conditions of current flow through the load Iii, there always exists a tendency for an arc to be drawn between the contact tip E; and the stationary contact 8, as the tip 6a leaves the contact 3, but with the device of the present invention this arc is quickly extinguished before it attains sufii cient intensity to be destructive to the contact surfaces, owing to the separation of the contact tip a from the other stationary contact I, as indicated in Fig. i. In considering the operation of the device as described above, it has been found that the breaking of heavy currents can be accomplished without destructive arcing between the contacts, because of certain inherent characteristics of the device, which may be briefly summarized as follows. In the first place, when the contact tip 6a first starts to leave the stationary contact 8, upon deenergization of the Winding, the rate of downward movement of the armature is at a minimum, with the armature speed increasing rapidly from zero as it falls. Therefore, it follows that any arc between contact tip 6a and contact 8 is formed at the time of their first separation, when the armature starts to drop and the air gap in the circuit is small. But before any such are can reach a destructive intensity, the air gap is suddenly increased at another point in the circuit by the separation of the contact tip 5a from the contact I, at a speed very much greater than the initial speed of separation of the contact tip 6a from the contact 8. In other words, by the time the contact tip 5a leaves the contact the freely falling armature has accelerated to the point where the separation between these contact surfaces occurs at relatively high speed, and this accelerated increase in the air gap breaks the load circuit.

Another factor entering into the separation of the contact tip 5a from contact i, without appreciable arcing, resides in that any arc initially drawn between the contact tip to and contact 8 reduces the voltage at which the circuit is subsequently broken between contact tip 5a and contact 1. Furthermore, the provision of separate contact arms on the armature 4 cooperating with separate stationary contacts connected to opposite sides of the source 9 makes it possible to control the circuit without the utilization of flexible conductors leading to the movable contacts, and this general arrangement is applicable to meet a Wide variety of circuit conditions. As shown in Fig. 2, the armature 4 carries two pairs of similar contact arms 5 and 6, each connected to the armature by a bar l2 insulated therefrom at I3, and since the opposed ends of the contact carrying bars l2 are separated by an interposed insulating spacer It, the circuits controlled by the respective pairs of arms 5 and 6 are electrically inde pendent of each other.

Referring now to Figs. 5 and 6, there is shown a modification of the device for controlling a number of separate load circuits in parallel, with both positions of the armature 4 being utilized to cause the engagement of different contacts. As best shown in Fig. 6, a number of pairs of contact arms l5 and I6 are mounted on the upper side of a common bus bar I? carried by the armature 4 and insulated therefrom at Hi. In addition, other pairs of contact arms is and 29 extend below the bus bar H with the arms l9 the same length as the upper contact arms l5 and with the arms slightly longer than the arms l6. With the armature 4 in an open position as shown, the contact arms l5 and I9 are in engagement with two sets of spaced stationary contacts 2| and 22 located on opposite sides of the pivotal axis of the armature 4. At the same time, the lower set of contact arms 26 are in engagement with a series. of spaced stationary contacts 23, all connected to a bus bar 24 carried by the insulating base Ia. With the bus bar 24 connected to one side of the source 9, obviously current will be distributed to separate circuits leading from the contacts 2| and 22.

Upward movement of the armature 4 upon energization of the winding 3 will first cause partial opening of the different load circuits as the longer arms l5 and i9 separate from the stationary contacts 2| and 22, respectively, after which separation of the shorter contact arms 20 from the stationary contacts 23 causes breaking of all the circuits with an accelerated increase of air gaps. As the armature 4 completes its closing movement, immediately following disengagement of the contacts 20 from the contacts 23 as described above, the contact arms |6 on the upper side of bus bar I! engage a series of spaced stationary contacts 23a connected by a bus bar 24a, which is connected to the same side of the source 9 as the bus bar 2 This places all of the longer contact arms l5 and I9 under voltage, so that when these arms engage the second series of spaced contacts 2|a and 22a current will be distributed to the separate circuits leading from these contacts. Obviously, downward movement of the armature 4, upon deenergization of the winding 3, will first cause disengagement of arms l5 and I9 from contacts 2 la and 2211, followed by the disengagement of arms Hi from contacts 23a. Thus, the device of Figs. 5 and 6 is adapted to break a multiplicity of circuits without destructive arcing, due to the accelerated increase in air gaps in all the circuits being broken, in either direction of movement of the armature.

Referring now to Figs. '7 and 8, there is shown a further modification of the device for controlling a large number of separate load circuits, this form of the device being particularly adapted to handle heavy currents in a single piece of apparatus. As best shown in Fig. 7, the device employs a pair of energizing windings 3a, 3a with corresponding armatures 4a, 4a supporting between them a common bus bar 25 insulated therefrom at 26. The bus bar 25 carries a series of short contact arms 21 adapted to engage a series of stationary contacts 28 connected by a bus bar 29, the bus bar 29 being in turn connected to one side of the source 9, as indicated. The movable bus bar 25 also carries two series of oppositely extending long contact arms 36 and 3| of equal length with respect to the pivotal axis of the armatures 4a, the upper arms cooperating with spaced stationary contacts 32 mounted on the insulating base la. The lower set of arms 3| cooperates with a series of stationary contacts 33 mounted on separate brackets 34 supported by the base la, the air gaps between the contact arms and 3| and the stationary contacts 32 and 33 respectively, being the same.

As will be evident from a comparison between i and 8, the air gaps between the short con tact arms 21 and the stationary contacts 28 are substantially the same as the air gap between an arm 5 and contact J, so that the operation of the device of Fig. 8 is the same as the operation of the device of Fig. 4, with respect to the making and breaking of the circuit, without destructive arcing. As indicated in Fig. 7, all the stationary contacts 32 and 33 are connected separately and in parallel to the other side of the source 9 through electrical loads 35, so that pulling up of the armatures 4a in response to energization of the windings 3a results in first energizing the bus bar 25 from one side of the source as the contact arms 2! engage contacts 28, and then completing the circuit simultaneously through all of the loads 35 as the arms 30 and 3| engage the stationary contacts 32 and 33, respectively. Obviously, upon deenergization of the windings 3a, the dropping back of the armatures 4a will result in breaking the large number of load circuits without destructive arcing, due to the accelerated increase in air gaps between the arms 21 and contacts 28, which air gaps are in parallel with all of the load circuits.

From the foregoing, it is apparent that by the present invention there is provided an improved circuit controlling device characterized by the substantial elimination of destructive arcing between its contacts, due to the provision of means for successively creating gaps in the load circuits at an increasing rate. As a result, a device embodying the present invention is adapted to handle heavier currents than prior devices of the same rating, with a reduction in the current required for energizing the operating Winding. This latter advantage is due to the fact that the device may operate with a smaller air gap between armature and core when employing the principle of an accelerated increase of air gap in the circuit being broken.

I claim:

1. Apparatus for controlling the flow of current in an electrical circuit comprising, in combination, a source of electrical energy, a current consuming device connected to one side of said source, and a circuit controlling device providing a pair of spaced stationary terminals insulated from each other and connected to the other side of said source and to said current consuming device, respectively, said circuit controlling device further providing a pivoted member free to fall in one direction of movement and electrically connected contacts movable with said pivoted member co-operating with said stationary terminals for creating a gap in said circuit at one terminal at one speed, and for increasing the gap in said circuit at the other terminal at an accelerated speed determined by the rate of falling of said pivoted member.

2. Apparatus for controlling the flow of current in an electrical circuit comprising, in combination, a source of electrical energy, a current consuming device connected to one side of said source, and a circuit controlling device providing a pair of spaced stationary terminals insulated from each other and connected to the other side of said source and to said current consuming device, respectively, said circuit controlling device further providing a pivoted member carrying electrically connected flexible contact arms for engagement with said terminals to establish said circuit therebetween, said contact arms being adapted to successively disengage said terminals at different rates of contact separation, in response to free movement of said pivoted member under the influence of gravity.

JOHN H. WHEELOCK.

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