US2921162A - Circuit interrupter - Google Patents

Description

Jan. 12, 1960 C. L' CRADDOCK CIRCUIT INTERRUPTER Filed Sept. 30, 1957 =1 vlllllllvlllllllllli, E

INVENTOR.

C'Hemss 6124000046 f (fi ur ne 6 United States Patent CIRCUIT INTERRUPTER Charles L. Craddock, North Hollywood, Calif. Application September 30, 1957, Serial No. 687,140

' Claims. 01. 200-87) This invention relates generally to interrupters and more particularly to a magnetically operated electric circuit interrupter of the type frequently used in the operation of flashing warning signals or lights.

In recent years the use of warning signal lights of the flashing type has become quite widespread in highway and similar construction work. In general, these signal lights are self-contained, and include a battery, a circuit interrupter of some type, a transformer, and a high voltage gaseous discharge tube. Frequently, the circuit interrupter is combined with the transformer and includes a pair of contacts, one of which is urged toward a gap in the transformer core when the primary circuit to the transformer is completed. Movement of this contact moves the second contact, mounted upon a pivoted arm or wheel, so that the' impulse imparted to the wheel or arm carries the second contact away from the first contact, breaking the circuit to the transformer primary, and releasing the first contact. A spring then returns the second contact to the first contact, thereby completing the electrical circuit to the primary of the transformer, whereupon the cycle is repeated. Each time the contacts separate, a high voltage is induced in the secondary winding of the transformer, and the gaseous conduction'lamp, connected to the secondary of the transformer, is thus briefly illuminated.

While this form of construction is relatively simple, the use of the pivotally-mounted arm or wheel, the bearings'therefor, and the return spring all add complications that result in a somewhat expensive piece of equipm'ent that has a number of points that can cause trouble.

To reduce the drain upon the batteries, it is desirable to have the circuit interrupter make and break the circuit witha frequency in the general range of from one-half to two cycles per second. Occasionally even a slower speed is desired, and the device may be operated once every three or four seconds. With such frequency, the mass of the pivoted arm or wheel becomes greater, and the contacts sometimes fail to separate quickly, causing burning and pitting of the contacts, with consequent faulty operation.

It is'therefore a major object of the present invention to provide an electrical circuit interrupter that overcomes many of the disadvantages and objections of the prior devices. 'Another object of the invention is to provide such a circuit interrupter that is very simple in its construction and 2,921,162 Patented Jan. 12, 1960 tion will become apparent from the following description of a preferred form thereof, and from the drawings illustrating that form in which:

Figure 1 is a side elevational view of a circuit interv rupter constructed in accordance with this invention, with the associated electrical circuitry being indicated;

Figure 2 is a plan view of the interrupter shown in Figure 1; and

Figure 3 is a schematic electrical circuit of the entire system.

Referring now to the drawings and particularly to Figure 1 thereof, the numeral 10 indicates generally the transformer and circuit interrupter, the primary of the transformer being connected to a battery 11, and the secondary of the transformer being connected to a suitable lamp 12. In this respect, the electrical circuit of the circuit interrupter is similar to those of previous devices. However, the mechanical construction of the circuit interrupter, and particularly the timing mechanism thereof, is considerably different. Thus, where previous devices have used spring-biased oscillating arms or wheels, the present device makes use'of a generally cup-shaped disk, here referred to as a suction cup, that is driven against a surface, and then allowed to separate from the surface. Thus, in Figure l, a rubber suction cup 13 is adapted to be driven against a plate 14, driving out some of the air originally trapped between the cup and the plate, and causing the cup to adhere to the plate. Air then gradually leaks between the cup 13 and the plate 14, and after a period of time, a sufficient amount of air has entered into the space within the cup to permit the latter to separate from the plate. By a proper control of the characteristics of the cup 13 andplate 14, the time required for this separation can be adjusted to the desired value.

One method of using such a timing mechanism is illustrated in Figure 1. In this figure, the numeral 15 indicates the customary core of an interrupter and transformer assembly, the core having a magnetic gap 16 that interrups the otherwise complete low-reluctance magnetic path provided by the core. Upon the core 15 is placed transformer winding .17 having a primary winding 20 with leads 21 and 22. A secondary winding 23 has leads 24 and 25 therefrom, and it will be appreciated that the transformer winding 17 may be a so-called autotransformer, in which the secondary winding is a continuation of the primary winding, or may be of the type in which two separate windings are used.

Attached to the core 15 is an insulating block 26 on which are mounted a pair of leaf members 27 and 28. The leaf members 27 and 28 project from the block 26, and at its free end, the upper leaf member 27 carries a contact point 30. The lower leaf member 28 extends a greater distance from the block 26, and carries a contact member 31, aligned with the contact point 30 of the upper member. Continuing on from that contact point 31, the lower leaf member 28 carries an armature plate 32 adapted to bridge the magnetic gap 16, and at its outer end, carries the suction cup 13. The upper leaf member 27 is preferably rather stifli, while the lower leaf member 28 is relatively flexible and may be described as a reed.

In its normal position, with the transformer winding 17 deenergized, the lower reed 28 assumes the position indicated in solid outline in Figure 1, with the contact points 30 and 31 touching each other and completing an electrical circuit. The armature plate 32 is spaced from the core 15 and the magnetic gap 16 therein, while the suction cup 13 is spaced from the plate 14, all as indicated.

The plate 14 preferably takes the form of an angle 33 having one leg, forming the plate 14, extending generally perpendicular from the adjacent edge of the core tion, and other undesirable cup may seal; Most metals have a tendency to react with the material of the suction cup 13, andhence are undesirable. While many different materials will be found suitable, it has been found that hard, smoothsurfaced types of plastics, such as are available under the trade names Synthane, and Teflon, and also nylon, are verysatisfactory. These materials may be extruded, and are available in angle sections, such as section 33. The extruded section may then be cut into short lengths, and one such length applied to thecore in the manner shown.

The electrical circuit is completed by connecting the lead 21 from the primary of the transformer 17 to one of the leaf members, such as the reed 28, and the leaf member 27 is then connected, preferably through a switch 35", to the battery 11. The other terminal of this battery is connected to the remaining terminal 22 of the primary winding. A capacitor 36 is connected between the leafmem'bers 27 and 28 so that arcing between the contact points 30- and 31 is reduced.

With the various parts initially in the position indicated in solid outline in Figure 1, when the. switch35' is closed, a circuit is completed from the battery 11, through the'contacts 30 and 31, and to the primary of the transformer 17'. The energization of the primary produces a magnetic field within the core 15, but in the vicinity of the magnetic gap 16, this magnetic fieldspreads outwardly and passes through the armature plate 32, pulling the plate and the reed 28. toward the core 15; This movement of the reed 28 toward the core 15 drives the suction cup 13 into contact with the plate:14, and separates the contacts 30 and 31 so that the circuit to the primary of the. transformer- 17 is broken. With the. breaking or interruption of the primary circuit, the.mag-- netic field collapses causing the induction of a high voltage in the secondary winding that is applied to the gaseous lamp 12. The lamp thus flashesbrightly, and: then: becomes dark.

After the suction cup 13; has been driven against.

of; the reed 28 and the resilience of thematerial forming the suction cup 13 eventually cause, the cup toseparate. from the plate, whereupon the reed 28, returns. to, its original position, thereby again completing a circuit to the primary of the transformer. winding 17.. The cycle then repeats, and continues to do soas long as power is suppliedv to the circuit including the primary winding: 20 and ,the contacts 30 and 31. For convenience, the: electrical circuit is shown in schematic form in Figure 3.

It, willbev apparent that the.- length of a cycle can be varied over av wide range by a suitable choice of materials and various other parameters. Thus, the stiffness or hardness of the suction cup 13 is a very important factor, since this determines howfar the. center of the cupis driven toward the plate 14, and consequentlyhow much air is forced from between the cup and the plate. Likewise, the size of the cup, 13, the force. with. which it is driven against. the plate, and; they stiffness of, the I reed 28 are all factors that will control the speed: of

circuit interruption, In. each case, however, it. will be, 1 ing; s;aidf movable means from said first'position toward n r er. to. minimize he... possibilities of.-.-t1irt,.oxidai 4 efiects from interferingwith the operation of the circuit interrupter, it is preferable to place the interrupter and transformer assembly 10 in a container that is preferably filled with an inert gas and then sealed. In this way, the interrupter will maintain its original calibration for an extended period of time, and the problem of high voltage flash-over-is greatly reduced. This latter isparticularly important if the device is used athighaltitudes- By way of a specific example, and not as a limitation, a circuit interrupter has been constructed making usev of a suction cup 13 having an external diameter of approximately three-quarters of an inch. The cup is made of the plate 14, is approximately one-fourth inch, and when I the armature plate 32 is" attracted to the core 15,the'- total travel ofthebase of the cup 13 is approximately onefourth inch. The first three-sixteenths of an inch travel of the cup are thus spent in moving the cup into contact with the plate 14, and the last one-sixteenth inch is'spent in pressing the lips of the cup against the plate. With such a device, the frequency of operation of the circuit interrupter is approximately seventy cycles per minute. When the interrupter is enclosed within a pressurized container, the inert gas in the container is preferably nitrogen or helium, and is maintained at a pressure of approximately one and one-half atmospheres.

From the foregoing, it will be seen that there has been provided a device fully capable of achieving the objects and securing the advantages heretofore set forth. It will be apparent to those skilled in the art that modifications may be made therein that do not depart from the broad concept of the invention, and consequently the patent is:

not tobe restricted to the particular form or arrangement of parts herein described and shown, except as limited byv the. following claims.

I claim:

1. An interrupter of the class. described which includes; movable: means: normally urged to a first position; a. pair of electrical contacts, one of said contacts being moved with said movable means and said contacts being: closed when said movable means are in said first position;.meansz actuated by the closure of said contacts for moving. said movable. means from said first position to a second position, wherev said contacts are open; whereby said? movable; means. repetitively moves between said firstandsecond positions; suction cup means connected to: said movable. means for movement therewith; and a member. having; a smooth surface adjacent said suction cup meansand adapted to be engaged thereby when said: movabler'meansi is moved to said second position, said suctionqcupz means. being held to said member for a predetermined; period of. time by reason of the reduced pressure within said; cup means, and. thereafter releasing from: said, member: and releasing said movable means for return to said first position. i

2:...An interruptenof the class described which in eludes: support means; movable means mounted on said support; means; and resiliently urged toward a first posi tion; a pair of electrical contacts, one of said contacts being held substantially immovable with respect to said support means; and the other of said contacts being moved with said; movable means, said. contacts being closed when said movable means: is in said first position; means'actuated by-theclosure ofsaid contacts for drivasecond positiomwhere. said contacts are open, said driving means being active only while said contacts. areand having a smooth surface adjacent said suction cup means, adapted to be engaged thereby when said movable means is moved to said second position, said suction cup means being held to said member for a predetermined period of time by reason of the reduced pressure within said cup means, and thereafter releasing from said member and releasing said movable means for return to said first position, whereupon said contacts are again closed and the cycle is repeated.

3. An interrupter of the class described which includes: a magnetic frame having a magnetic gap therein; means mounted for movement with respect to said magnetic frame and resiliently urged toward a first position with respect thereto; a pair of electrical contacts, one of said contacts being held substantially immovable With respect to said magnetic frame and the other of said contacts being moved with said movable means, said said contacts being closed when said movable means is in said first position; magnetizable means mounted on reed means for movement therewith and aligned to bridge said magnetic gap, said magnetizable means being spaced from said magnetic frame when said movable means is in said first position; coil means on said magnetic frame, adapted to be energized by the closure of said contacts to produce a magnetic field in said magnetic frame, thereby attracting said magnetizable means and moving said movable means from said first position to a second position, where said contacts are open; suction cup means connected to said movable means for movement therewith; and a member substantially immovable with respect to said magnetic frame and having a smooth surface adjacent said suction cup means and substantially parallel to the lip thereof, adapted to be engaged thereby when said movable means is moved to said second posi tion; said suction cup means being held to said member for a predetermined period of time by reason of the reduced pressure Within said cup means, and thereafter releasing from said member and releasing said movable means for return to said first position, whereupon said contacts are again closed and the cycle is repeated.

4. An interrupter of the class described which includes: a magnetic frame having a magnetic gap therein; reed means supported at one end and held thereat against movement with respect to said magnetic frame. the other end of said reed means being movable toward and away from said frame but resiliently biased away from said frame toward a first position; contact support means substantially immovable with respect to said magnetic frame: an aligned pair of electrical contacts, one of said contacts being mounted on said contact support and the other being mounted on said reed means for movement therewith, said contacts being closed when said reed means is in said first position; magnetizable means mounted on reed means for movement therewith and aligned to bridge said magnetic gap, said magnetizable means being spaced from said magnetic frame when said reed means is in said first position; coil means on said magnetic frame, adapted to be energized by the closure of said contacts to produce a magnetic field in said magnetic frame, thereby attracting said magnetizable means and moving said reed means from said first position to a second position, where said contacts are open;

suction cup means mounted on the movable end of said reed means for movement therewith; and a member substantially immovable with respect to said magnetic frame and having a smooth surface adjacent said suction cup means and substantially parallel to the lip thereof, adapted to be engaged thereby when said reed means is moved to said second position, said suction cup means being held to said member for a predetermined period of time by reason of the reduced pressure within said cup means, and thereafter releasing from said member and releasing said reed means for return to said first position, whereupon said contacts are again closed and the cycle is repeated.

5. A circuit interrupter of the class described which includes: a magnetic frame having a magnetic gap therein; an electromagnetic coil mounted on said frame; reedmounted magnetic armature means, said armature means being adapted to bridge said magnetic gap but normally being spaced therefrom, one end of said reed mounting being anchored to said frame at a point remote from said gap, and the other end of said reed being movable with said armature and projecting beyond said frame; a first electrical contact mounted on said reed mounting and movable therewith; a second electrical contact mounted by said frame and substantially immovable with respect thereto, said first and second contacts being so positioned and arranged that said contacts are in closed circuit relationship with each other when said armature is in said normal or first position, and are in open circuit relationship when said armature is in a second position adjacent said gap, said first and second electrical contacts being in series with said coil; suction cup means mounted on said other or movable end of said reed mounting and movable therewith, said suction cup means being mounted on said reed mounting for movement thereby in a direction parallel to the axis of symmetry of said suction cup means; and cooperating means mounted on said frame and having a surface parallel to the lip of said suction cup means, said surface being spaced from said lip when said armature is in said first position; and being engaged by said lip when said armature is in said second position, said coopearting means being mounted for adjustment with respect to said frame, and so positioned that movement of said armature from said first to said second position drives said suction cup means against said cooperating means and distorts said suction cup means to produce a reduced pressure therein, thereby temporarily holding said suction cup to said cooperating means and restraining return movement of said armature to said first position.

References Cited in the file of this patent UNITED STATES PATENTS 2,206,468 Parkinson July 2, 1940 2,248,846 Brewer July 8, 1941 2,341,931 Lloyd Feb. 15, 1944 2,488,024 Mudon Nov. 15, 1949 2,810,797 Gulnick Oct. 22, 1957 FOREIGN PATENTS 42,722 Netherlands Mar. 15, 1938

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