US2618717A - Oscillating contact device for periodical variation of electric current conditions - Google Patents

Description

Nov. 18, 1952 J -rm 2,618,717

OSCILLATING CONTACT DEVICE FOR PERIODICAL VARIATION OF ELECTRIC CURRENT CONDITIONS Filed July 30, 1946 2 SHEETS-SHEET 1 CURRENT SOURCE FlG.2b.

INVENTOR J.T. WESTIN ATTORNEYS NOV. 18, 1952 WESTlN 2,618,717

OSCILLATING CONTACT DEVICE FOR PERIODICAL VARIATION OF ELECTRIC CURRENT CONDITIONS Filed July 30, 1946 2 SHEETS-SHEET 2 INVENTOR J. T. WESTI N ATTORNEYS Patented Nov. 18, 1952 .OSCILLATING CONTACT DEVICE FOR PERI- .ODICAL VARIATION OF ELECTRIC CUR- BENT CONDITIONS Johan Torsten Westin, Amal, Sweden, assignor to Aktiebolaget Hakanssons Industrier, Amal, Sweden, a-corpor-ation of Sweden Application July 30, 1946, Serial No. 687,057 In Sweden August 1, 1945 Claims. 1

This invention relates to oscillating contact devices for periodical variation of electric current conditions and more particularly to improvements in a self-acting electromagnetic switch device for providing current impulses spaced by relatively long time intervals, during which the current is broken.

In self-actingswitch devices of the above character it is a well known principle to utilize an oscillating body having a low periodicity. Such devices are used, for instance, for electric fences. In order to attain this action, however, it is necessary for the oscillating body to have a comparatively large mass and for the oscillations to be brought about by means of comparatively light spring means.

This principle involves disadvantages from the points of view of construction and reliability of operation, in that it entails a relatively bulky, heavy, expensive and easily damaged apparatus. Current variations of a frequency less than that of the oscillating body itself cannot possibly be obtained by means of this known apparatus.

Accordingly it is an important object of this invention to make provision for the frequency of the current variation to be to a large extent independent of the number of periods per unit time of the contact device proper, which number can be given a suitable value. With this arrangement the above disadvantages are eliminated. This is highly valuable, particularly in contact devices for such low current pulse numbers as are necessary, for instance, for electric fences, signal lamps, output limiters and similar apparatus.

More specifically it is an object of the invention to provide a contact device including a swinging, preferably oscillating, body, which is actuated by electromagnetic or mechanical means.

The main feature of the invention resides in that the contacts of the apparatus are arranged in such a manner in relation to the oscillating body that the circuit containing said contacts remains open while said body (or pendulum) is oscillating and is closed again as said body comes to rest or nearly so.

Theaforesaid and other objects I attain by the constructional forms shown in the accompanying drawings, wherein, for the purpose .of illustration only, there are shown a number of preferred embodiments of my invention, and wherein:

Figure 1 is a diagrammatic view illustrating in neutral position a contact device comprising a pendulum .body and pendulum contacts arranged adjacent each side thereof.

Figures la, 11), and 10 show the contact device of Fig. 1 in operation.

Figure 2 is a diagrammatic side view, partly in section, illustrating in inoperative position a contact device according to the invention in association with an electromagnet.

Figures 2a and 2b show the contact device of Figure 2 in operative position.

Figure 3 is a side elevation of .a modified form of the contact device of Fig. 2.

Figure 4 illustrates a further modified embodiment of the invention, and Figure 4a shows this embodiment in operation.

Figures '5 and 6 illustrate two further modified embodiments of the invention.

F gs. 1, 1a, lb, .and 1c are intended to illustrate the principle of the invention. The reference numeral 1 designates a central pendulum being, for instance, a metal leaf spring, which is fixedly supported at one end, the other end thereof being free to oscillate. The numerals 2 and 3 respectively, indicate two pendulum members contacting the central pendulum l on opposite sides thereof (Fig. 1), said lateral pendulum members having preferably equal flyweight masses and number of periods in relation to each other but of less values in relation to the central pendulum. The contact pendulum members are connected to a source of current 4, and a load 5 is series connected in the circuit. At the fixed supporting points the pendulum contacts 2, 3 are insulated from each other and from the central pendulum I by mean of insulation pieces 6.

If the central pendulum -l is given an ,electro.- magnetic or mechanical power impulse (indicated by the arrow in Fig. 1a), which it is itself, of course, capable of transferring directly or indirectly if connected as a self-actin switch, the central pendulum will carry the contact p ndulum 2 with it but will separate from the contact pendulum 3. This causes the circuit to be opened. When the central pendulum i has completed a quarter of a period and begins to move in the reverse direction it will separate from the contact pendulum 2 due to the lower periodicity of the latter. As soon as the central pendulum has passed its initial position it will bring with it the contact pendulum 3 without being retarded to such an extent as to permit the contact pendulum 2 to catch up. Thus the circuit will still be open (Fig. 1b). On the next reversal of the central pendulum I it will first separate from contact pendulum 3 and then meet and bring with it contact pendulum 2 (Fig. 1c), whereupon the course of events will be repeated. Thus, with suitably proportioned pendulum members the circuit is maintained open until the oscillations are damped out or substantially damped out. Thereafter the central pendulum will receive a new impulse, begin to oscillate and keep the circuit open until the oscillations are again damped out, etc.

Fig. 2 illustrates a contact device associated with an electromagnet and preferably adapted for application to an electric fence. The electromagnet is provided with double windings I, 8 and thus acts as a transformer. The iron core 9 of the electromagnet is provided with an air gap [8, in the vicinity of which the magnetic lines of force are deflected. The pendulum body or bob ll of the central pendulm l is made of soft iron and acts as an armature forthe electromagnet. In this case only one of the contacts, 20, is placed on a pendulum arm l2, whereas the other, 3a, is secured to the free end is of a spring metal strip Hi, the opposite end of which and the corresponding ends of central pendulum I and contact arm l2 are secured to the iron core 9 by means of a screw l5. Adjacent the gap ID the metal strip I4 is formed with an S-shaped double bend [6, whose portion H to the right of the gap In contacts the core 9. At their fixed ends central pendulum l, pendulum arm [2 and metal strip [4 are insulated from each other by means of insulation pieces 6.

When current is supplied through lead 18, pendulum arm i2, contacts 2a and 31a, metal strip i l, grounded leads i9 and 20, primary winding and lead 2!, the armature H is operated, so that it will powerfully impact the bend l5 (Fig. 2a). Thereupon the free end [3 is moved upwardly throwing the contact 2a of the pendulum arm l2 away from itself resulting in an opening of the circuit at that point. Then the central pendulum i will spring back past its original position to meet the pendulum arm l2 having now a downward movement (Fig. 2b). The continued operation will proceed substantially as described in connection with Figs. 1 to 10. Not until the oscillations of the central pendulum begin to die out the contact 20!. will again abut contact 3a, whereby the circuit is closed again and the operating cycle is repeated. Each time a current impulse passes through the primary winding 8, a higher voltage impulse is induced in the secondary winding which is connected to a fence wire through conductor Reference numeral 23 indicates a capacitor.

The embodiment of Fig. 3 corresponds to a substantial degree to the contact device illustrated in Figs. 2 to 2b and differs therefrom, practically, only in that the contact 3a is changed from the end of the spring metal strip It to the iron core 9, from which it is insulated by means of an insulation piece c.

As the armature H of the central pendulum l is operated and thereupon impacts the bend 16 of metal strip I4 the free end [3 thereof will spring upwardly and impact pendulum arm I 2. Thus the contact 2a is forcibly separated from the contact 3a, whereby the circuit is opened. The continued succession of events will agree with that described above.

Fig. 4 illustrates a contact device which makes it possible to obtain longer time intervals between the current impulses than is the case as regards the arrangements of Figs. 1 to 3, inclusive. In the contact arrangement according to Fig. 4 both contacts 2a and 3a. are secured to pendulum arms Ma and Ma, respectively, said arms being provided with extensions 24 and 25,

respectively, extended past said contacts. A fixed stop 26 insulated from the iron core 9 by means of an insulation piece .3 projects into the space between the extensions. The pendulum arm Me has a magnet armature 2?, and the armature of central pendulum l is divided into two portions Na and Nb.

When current is supplied the magnetic field lines deflected at the gap it! will pass through armature portion Ha, magnet armature 21 and armature portion lib and back to the iron core. This results in a, simultaneous attraction of armatures Ila and Nb, and 2?. Then the deflection of pendulum arm 12a. is limited by extension part 24 being stopped by stop 26 (Fig. ea) The central pendulum I, however, is permitted to perform a greater deflection, in which it carries with it the pendulum arm Ida. When, owing to the fact that contacts 2a and 3a are brought out of engagement with each other, the circuit is opened the central pendulum i will spring back past its initial position carrying with it the pendulum arm 12a. Thereafter the operating cycle will proceed as before.

A further advantageous embodiment of the invention is illustrated in Fig. 5 This arrangement departs from the two foregoing in that the contact spring 13 (Ida) is omitted and the mode of operation aimed at is obtained by providing the central pendulum I with a contact 22) which, as the primary circuit is closed, and, as a result thereof, the armatiu'e ii is operated by the electromagnet 9, closes the secondary circuit momentarily by rapidly impacting a contact 3b connected in that circuit and secured to an insulation piece 6 fixed to the core 9. When the pendulum i is in its neutral position the primary circuit is closed by a contact 2a provided on spring I2a and a contact 30. secured to the core 9 through the medium of an insulation piece 6. The impact of contact 2b on contact 3b causes a slight vibration in the core 9, whereby the primary circuit is opened at the contacts 2a, 3a, which are, in the manner already described, kept apart by the oscillating pendulum i until the oscillations thereof are damped out or nearly damped out.

A further and very advantageous embodiment of the invention is illustrated in Fig. 6. In this figure two braces or other securing means for the spring members are indicated at 28, members 29 being insulation pieces, 33 and 3!, respectively, two leaf springs, 32 a magnet armature secured to leaf spring 39; members 33, 8d and 35, 36, respectively, are two pairs of contacts, 311 a relatively rigid bell crank, 38 a leaf spring supporting the latter, 3% a second armature carried by bell crank 31 and spring 33; 4e and H are connections for the secondary winding, 62 and 53 are connections for the primary winding, id and 45 are terminals for a source of current, and it is a terminal for a load device, such as an electric fence. The elements referred to are interconnected and associated in a manner to operate as follows:

If a source of current is connected across the terminals 64 and 45 the primary circuit is closed. Thereby the core 9 is magnetized and operates the armatures 32 and 39. The motion of armature as is transferred bell crank 37 to contact 34 so that the latter is rapidly moved to the right (acccrding to the figure) until contact 35 engages contact 35 and is instantly stopped. In the course of its movement the contact will press and slide on the contact 33, which is forced upwards due to the inclination of the contact surfaces relative to the direction of movement of contact 34. When the contact 34 is stopped, the contact 33 will continue to move upwards, the contact surfaces will be separated and the primary circuit will be opened. Then the magnetic flux will disappear, whereby a higher voltage impulse is induced in the secondary winding. This impulse is supplied through closed contacts 35 and 36 to terminal 43 and thence to the load device. When the flux vanishes the armatures 32 and 39 are deenergized and the biased springs 30 and 38, respectively, act to move the same in a direction opposite to that caused by the energization thereof. The motion of armature 39 is transferred by bell crank 3'! to the contacts 34 and 35, which are rapidly returned to their original positions. The contacts 35 and 36 are separated and the distance between the contacts 33 and 34 is increased. On account of the butt impact of the bell crank 3'! against transformer core 9 on reaching its initial position the movement of bell crank 31 will cease practically instantaneously. Owing to the freely oscillating pendulum armature 32 the contact 33 is in the manner described prevented from engaging the contact 34 and thereby causing the primary circuit to close until the flyweight energy stored in the pendulum 32 is substantially consumed. The pair of contacts 35, 36 serves to shorten the time during which secondary voltage can be applied to terminal 46.

The embodiments hereinabove described and illustrated in the accompanying drawings are, of course, to be considered merely as examples, and the different parts of the arran eme t a e ceptible of being varied in numerous Ways without departing from the scope of the invention.

What I claim and desire to secure by Letters Patent is:

1. An improved contact device comprising in combination, an oscillatable member, electromagnetic means for periodically actuating said member, a source of electric current, an oscillatably mounted contact, a second fixed contact cooperating therewith, circuit means, and a circuit cut-off means comprising aspringmetal strip, said strip having an S-shaped bend therein at a point opposite said oscillating member and the free outer end of said strip being adapted to be located close to the pendulum arm of said oscillatable contact when the latter is at rest, said bend having a knee thereof engaging a fixed support, said oscillatable member engaging said strip adjacent the knee of said S-shaped bend, and said movable member being adapted during each period of its movement to actuate said contact members in such a manner that said member, once set in motion, will act to open said contacts only after having stored up a predetermined amount of energy, and to thereafter maintain said contacts open until said energy stored up in said member is substantially consumed after having performed a plurality of oscillations.

2. An improved contact device comprising in combination, an electromagnetic means, an oscillatable member forming an armature of said means, an oscillatably mounted contact, a second contact co-operating therewith, circuit means, and a circuit opening means comprising a spring metal strip having an S-shaped bend therein, said bend having a knee thereof engaging a fixed support, said oscillatable member engaging said strip adjacent the knee of said S-shaped bend, said oscillatable member being adapted on energization of said electromagnetic means to open said circuit at said contacts only after hav- 6,. ing stored up a predetermined amount of energy, and to thereafter maintain said contacts ooen until said energy is substantially spent after hav ing performed a plurality of oscillations.

3. An improved contact device comprising in combination, an electromagnetic means having an iron core, an oscillatable member forming an armature of said means, said core having an air gap for deflecting the magnetic lines of force in the vicinity thereof, an cscillatably mounted contact, a second contact co-operating therewith, circuit means, and a circuit cut-off means in the form of a spring metal strip having an S-shaped bend, said cut-off means being located opposite said air gap and said bend having a knee thereof engaging said core, said oscillatable member en gaging said strip adjacent the knee of said 8- shaped bend, said oscillatable member being adapted on energization of said electromagnetic means to open said circuit at said contacts onli after having stored up a predetermined amount of energy, and to thereafter maintain said contacts open until said energy is substantially spent after having performed a plurality of oscillations.

4. An improved contact device comprising in combination, an oscillatable member, electromagnetic means for periodically actuating said member, a pendulum member, a contact mounted on said pendulum member, a second contact cooperating therewith, circuit means, and a circuit cut-off means comprising a spring metal strip carrying said second contact at one end thereof, said strip having an S-shaped bend therein at a position opposite said oscillating member, said oscillatable member engaging said strip'adjacent the knee of said S-shaped bend, said bend having a portion thereof engaging the core of said electromagnetic means, said oscillatable member having a natural frequency of vibration which is greater than the natural frequency of vibration of the contact carrying pendulum member and being adapted during each period of its movement to actuate said contact members in such a manner that the oscillatable member, once set in motion, will act to open said contacts only after having stored up a predetermined amount of energy, and to thereafter maintain said contacts open until said energy stored up in said member is substantially consumed after having performed a plurality of oscillations.

5. In an improved contact device of the type comprising an electromagnet actuator having an iron core and a winding, an air gap in the core, a straight pendulum arm secured to said iron core, a contact adjacent the free end of said arm and mounted thereon, a spring strip secured to said iron core, a contact adjacent the free end of said spring strip and mounted thereon in a position to coact with said contact on said pendulum arm, said contacts being biased to contacting position, said spring strip having an S-shaped bend therein adjacent the air gap in the iron core, an oscillatable pendulum arm secured to said core intermediate said straight; pendulum arm and said spring strip and insulated therefrom, and a soft iron bob on the free end of said oscillatable pendulum arm adjacent said bend in said spring strip and said air gap, said oscillatable pendulum arm having a natural frequency of vibration which is greater than the natural frequency of vibration of the said straight pendulum arm, and comprising an armature for said electromagnet and being actuatable thereby, whereby upon energization of said electromagnet said oscillatable pendulum arm will be actuated 7 and serve to separate said contacts by striking Number said spring strip and said straight pendulum arm 731,056 and to keep said contacts open during the period 768,288 of oscillation of said oscillatable arm. 830,921 J OI-IAN TORSTEN WESTIN. 5 900,320 1,067,823 REFERENCES CITED 1 082,475 The following references are of record in the 1,231,264 file of this patent: 1,324,452 UNITED STATES PATENTS 1854863 2,185,950 Number Name Date 2,210,211 673,376 Bennett May '7, 1901 2,365,733

8 Name Date Jones June 16, 1903 Kelly Aug. 23, 1904 Orr Sept. 11, 1906- Snell Oct. 6, 1908 Von Kramer et al. July 22, 1913 Orswell Dec. 23, 1913 Kettering June 26, 1917 Kaisling Dec. 9, 1919 Roe Apr. 19, 1932 Rose Jan. 2, 1940 Levenburg Aug. 6 1940 Williams Dec. 26, 1944

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