US2359728A - Arc prevention circuit - Google Patents

Description

Oct. 3, 1944. o. CLEVEN 2,359,728

ARC PREVENTION CIRCUIT Original Filed Sept. 20, 1941 2 Sheets-Sheet 2 2/5 2 5 2%; 25 25d AM/ 3/ 22/ l ze W WWWW 0L UF L CL EVE N Patented Oct. 3, 1944 ARC PREVENTION CIRCUIT I 0111! L. Cleven, Washington, D. 0.

Original application September 20, 1941, Serial No. 411,768, now Patent No. 2,275,421, dated March 10, 1942. Divided and this application January 20, 1942, Serial No. 427,428

3 Claims. (Cl. 175-294) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to an electric circuit. The invention herein described, if patented, may be manufactured andused by or for the Government for governmental purposes Without payment to me of any royalty thereon.

This application is a division of my application Serial No. 411,768, filed September 20, 1941, patented March 10, 1 942., Number 2,275,421, for improvements in Combined punching and verifying machines, in which the circuit about to be described was shown.

In electric organizations of machines of the character shown and described, in the above mentioned application, much trouble is caused and much expense entailed in keeping certain of the electric contacts from burning out, caus d by the frequent making and breaking of the circult.

There are devices for diminishing the destructive efiect of arcing wherein the current is called upon to furnish very considerable power, such as condensers, etc., but as indicated, these merely reduce the burning of the contacts. Therefore, the main object of this invention is to provide an electric circuit involving a main circuit and branch circuits, including magnets or mot rs, or their equivalents, which will furnish suflicient power to perform the work required wherein there is frequent and continuous making and breaking of the circuit when in operation. The circuit about to be described is never broken in operation, but merely shifted from one branch circuit to another without breaking the main circuit, the amount of current in the main circuit being held equal to the amount required to' do the work in any of the branch circuits.

In the drawings illustrating the invention, certain of the figures of the parent case have been reproduced, and to connect this invention more intimately with the parent case, the same reference characters have been employed.

Fig. 1 is a detailed sectional view of a Port on of the punching and verifying machine in connection with which the circuit may be used, showing a punch key depressed and also showing the upper contacts still closed but released and about to open;'

Fig. 2 is a fragmentary sectional view taken transversely to Fig. 1 through the lower portion of the machine, illustrating the contacts and c ntact strips used in connection with a card punch-' his machine of the class described and showing the relative arrangement of the parts with the upper contacts separated before a punch key has been depressed;

' punch actuating bars shown in m application hereinbefore referred to. This bar in operation has a sliding movement. It is provided with a recess 64 to receive the end 63 of the bell crank 58, whose other arm extends into recess 56 in the shank of the punch key 5|, so that when the key is depressed the punch actuator bar is moved forward. The underside of this bar is provided with a recess 69 into which extends the upper portion of a bail 13 extending across the similarly constructed punch actuating bars. To this bail is attached one arm of a bell crank 12, pivoted at 10, to a plate 35 forming a part of the machine. The other arm of the bell crank is pivoted at 15 to the upper end of'a rod 16 which extends downwardly through a suitable opening in table 5, where below the table it is provided with a shoulder 11 for controlling the contacts that control the circuit to the motors or magnets 49 and 50. The rod 16 has an extension 18 adapted to be engaged by a stud 19 on link 44 to aid in the control of the magnets. A spring 19' attached to the head of the rod 1-6 and to an ear on the machine base, tends to hold the rod in position to engage the contact piece being supported by the blocks 8| and 82.

The contact strip 88 carries on its underside a contact point 92 shown in contact with contact point 83 carried by the lowermost contact strip 94 which is hinged at 95 to a continuation 96 of said strip. Thi continuation 95 is supported, together with a limiting piece 91, between the insulating blocks 82 and 83. The limiting pieces 84 and 9| are so arranged, as shown, that they limit the downward movement of the upper contact strips 85 and 88, whereas the lower strip 94 is limited in its upward movement by piece 01, and in its. downward movement by stud 98 on the inner side of the machine base. The outer end of the strip 88 is let into a block 99 of insulating material and firmly held thereon. Also let into the block is a metallic piece I positioned to be engaged by a shoulder I1 on the rod I6 to make contact between the contact point 89 and '81. To the underside of the piece I00 is attached a spring IOI, whose outer end is secured to a piece I02 of insulating material securely fastened to the lowermost contact strip 94. To the underside of piece 802 is attached a spring I03, weaker than the spring I05, whose lower end is attached to a pin I04 in the side of the machine base.

When a key, for instance like 5!, is depressed, the bar 29 (Fig. 1) through the instrumentality of hell crank 58, is moved to the left causing the bail I3 (which is shown in its engaged position) to rock bell crank 12 and consequently lift the rod I6 causing the shoulder 11 to engage and lift the contact strip 88, and the spring IOI' being stronger than the spring I03, causes both the lower contact strips to move upward while in contact, until the strip 94 is arrested by the limiting piece 9'! v(Fig. 2). In this upward movement of the strips, the contact point 81 makes contact with contact 86 before the contacts 92 and 93 are broken. In the further upward movement of the shoulder 11, the lower contacts 92 and 93 are broken, thus momentarily both contacts are made, the contacts 92 and 93 controlling the magnet 50, and the contacts 86 and 8! controlling the magnet 49, thus for a moment both sets of magnets are energized, but upon the further upward movement of the shoulder I1 the lower contacts are broken, shifting the current solely to magnets 49 which furnish the power to do the work required, whatever that may be, but'in the present embodiment, the power for perforating a card. When armature 45 reaches the magnets 49, the stud 19 on link 44 will have engaged the rod I8 and rocked the shoulder 11 out of engagement with the piece I00, thereby releasing the contact strip 80 and again causing both sets of magnets to be momentarily energized, but upon a still further downward movement of the lower contact strips under the influence of springs IM and I03, the contacts 92 and 93 are again closed, and contacts 06 and 81 are broken, thus shifting the current into the magnets 50 until another forward movement of the actuator bar 29 is effected. The shoulder 11 remains in its raised position opposite metallic piece I00 until the actuator bar 29 is released and restored to normal position which, in the present instance, is effected by the spring 65. Meanwhile, due to the influence of spring I9, the rod I6 is moved downward and the shoulder I1 is again brought beneath the metallic piece I00 for another operation. As we have seen, for a moment both sets of magnets are energized, but it is important that the resistance employed in the main circuit shall be such as to limit the amount of current available for either of the branch circuits, sufficient to do the work in either one of said branch circuits, after the current has been shifted from one branch circuit to another.

Fig. 3 illustrates a diagram showing the electric circuits for the magnets 49 and 50, whereby at times both sets of magnets simultaneously and momentarily are energized, and at others, one or the other set is energized. There is a switch 2I3 employed between the source of current 2| 4 and the contacts, and-when the switch is closed, the circuit which is never broken in the performance of the work is shifted from one set of magnets to the other. From the source 2 l4, the current flows through resistance 2I4' substantially the same as the resistance in each of the branch circuits over wire 2 I 5 to magnets 50, and thence over wire 2 H to contact strip 94, which carries contact point 93 in contact with contact point 92 of the contact strip 88, and over wire 2 I8 back to source.

When the rod I6 is actuated to lift the metallic piece I00, and before the contacts 92 and 93 are broken, the contacts 86 and 81 will be closed.

When the rod 16 moves further upward, the contacts 92 and 93 are broken so that the current will pass from the source over wire 2I5 to magnets 49 and from thence over wire 2 I 9, to contact strip 85 through contact points 86 and 81 which are now closed, to contact strip 88, and thence over wire 2I8 back to source.

The magnets 49 and 50 may be and preferably are of equal resistance and hence when the current is shifted from the branch circuit including one set of magnets to the branch circuit including the other, the fact that both branch circuits are momentarily closed reduces the current in each and therefore substantially reduces, if not entirely eliminates, the tendency for sparking or arcing at the contacts which are separated so that in a device of the class described no ob- Jectionable sparking or arcing occurs.

Referring to the modification in Figs. 4 to 9, the numeral 2I9' designates a commutator which will usually be mounted upon a shaft like 220, either revolving on the shaft or with it, accordingly as which will be more convenient in the organization in which it is used. The commutator comprises a body 22I of insulating material. In the periphery of the body is a metallic conducting insert 222 which entirely surrounds the body and is connected with a shorter insert 223 by a connector 224. The numeral 225 designates another metallic insert which extends around the periphery of the body to points where it is connected with the insert 223 by shorter connectors 226 and 221. The inserts 223 and 225 may be of any suitable length, and connected by connectors of any suitable length.

Numerals 228, 229 and 230 designate resilient contact strips which are, in the embodiment illustrated, mounted on a block 23I of insulating material.

The numeral 232 designates a source of electrical energy. A wire 233 leads uninterruptedly from the source to contact strip 228 which connects with insert 222 and, as illustrated, connects this insert through connector 224 with insert 223 and through connector 226 connects with insert 225 which is in contact with the contact strip 230, and from thence the current passes over wire 234 through resistance 235, and through a second resistance 236 and switch 231, back to source. The circuit thus described is the first branch circuit. Leading from wire 234 at 238 is a wire 239 which leads to any device diagrammatically shown at 240, which may require for its operation frequent intermittent electrical energy and, as shown, this wire enters said device at 24I. From the device, after performing the work required, the current passes over wire 243 to contact strip 229. As illustrated this circuit is now open, but upon rotation of the commutator the strip 229 will contact with the insert 223 and the current will pass over the connector 224 to the insert 222 and over contact strip 228 and wire 233, back to source.

Shortly after the contact strip 229 makes contact with the insert 223, the strip 230 breaks contact with insert 225, but momentarily during the rotation of the commutator, the contact strips 229 and 230 are in contact with inserts 223 and 225 at point :1 of insert 225, both branch circuits are active. The point i of the insert 225 makes contact with strip 230 to permit current to flow through the initial circuit before the connector 226 breaks contact with the contact strip 229 and thereby provides a path of less resistance than through an air gap formed as contact is broken between the connector 226 and the strip 229. The amount of current available in the main or battery circuit is controlled by resistance 236 substantially the same as the resistance in each of the branch circuits and as the resistance 235 in one branch circuit is made the same as the resistance of the device 240 in the other branch circuit, it will be seen that when both of these branch circuits are momentarily closed and then only one of them is opened, the tendency for sparking at the contacts of the switch in the latter circuit is thereby substantially reduced to such an extent that with a device of the class described there is no objectionable tendency for sparking as the current is shifted from one branch circuit to the other.

From the foregoing it will be seen that means are provided for controlling the amount of current in the main or feeder circuit, and the arrangement is such that there is just so much current available for use in one or another of the branch circuits that may be shifted from one of said circuits to another without disturbing the main or feeder circuit. When, momentarily, both branch circuits are closed, there is still only a controlled amount of current available suflicient to operate either one or another of the branch circuits, and this is the amount that is shifted from one branch circuit to another.

I claim:

1. Apparatus oi the class described, comprising the combination of parallel circuits, a common source of potential therefor, similarly disposed movable contact strips, engageable contacts carried thereby for controlling said circuits, means for moving said strips in one direction to efiect momentary engagement of all of said contacts to complete all of said circuits, and means for arresting said movement of one of said strips and the contact carried thereby for opening one of said circuits, whereby the tendency for sparking asthe latter circuit is opened is reduced.

2. Apparatus of the class described, comprising the combination of parallel circuits, a common source of potential therefor, movable contact strips normally disposed in substantially parallel relation, engageable contacts disposed between and carried by said strips for controlling said circuits, means tending to hold one pair of said contacts in engagement for completing one of said circuits, means for moving said strips in one direction to effect momentary engagement of all of said contacts to complete all of said circuits, and means for arresting said movement of one of said contact strips for separating said one pair of contacts, whereby the tendency for sparking at said one pair of contacts is reduced.

3. Apparatus of the class described, comprising the combination of parallel circuits, a common source of potential therefor, upper, intermediate and lower contact strips, a pair of normally separated contacts carried by said upper and intermediate contact strips for controlling one of said circuits, a pair of normally engaged contacts carried by said intermediate and said lower contact strips for controlling the other of said circuits, means for limiting downward movement of said upper and said intermediate contact strips, yieldable means for tending to effect engagement of the contacts carried by said intermediate and said lower contact strips, means for moving said intermediate and said lower strips upwardly for eflecting engagement of said normally separated contacts, and means for arresting said upward movement of said lower contact strip after said normally separated contacts have been engaged and thereby separating said normally engaged contacts.

OLIJTE L. CLEVEN.

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