US1316984A - Magnetic time element - Google Patents

Description

L. W. THOMPSON. MAGNETIC TIME ELEMENT.

APPLICATION FILED m. 16. 121's.

1 ,3 1 6,984. I Patented Sept. 23, 1919.

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His JTttorheg UNITED STATES PATENT OFFICE.

LOUIS W. THOMPSON,

or scnmmcmnr, new Yomlc, ASSIGNOR 'ro GENERAL nmc'rmc comm, A oonrom'non' or NEW YORK.

MAGNETIC TIME ELEMIHVT.

To all whom it may concern:

Be it known that I, LOUIS W. THOMPSON, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Magnetic Time Elements, of which the following is a specification.

My invention relates to devices of the character in which a time element is interposed between the initiation of-an action and its completion and more specifically it relates to electro-magnetic switches in which an interval of time elapses between the act which initials and the final act which completes. Various means have been devised for efiecting such a time element, one of the commonest being the. dash-pot. Electromagnetic switches provided with a dash-pot for delaying the action of a switch member are very commonly employed but because of inherent defects in the dash-pot they have not uniforml been regarded with favor. One of the ob ects of my invention is to provide a time element device which is free from the difliculties experienced in the use of dash-pots and similar devices, and which is mechanically simple and uniformly effective.

In carrying out my invention I employ, as controlling elements, a magnet which is preferably a permanent magnet and an armature arranged so that it will normally be in contact with the magnet. One of these members (in the form which I have shown as the magnet) is arranged to vibrate through its normal position and as it vibrates freely the amplitude will gradually decrease. During the vibration attractive forces will not be sufficiently great to cause the movement into contact but as the amplitude decreases the attractive force increases as it approaches the normal position until finally the movement takes place. I have found that if the vibratory member is mounted to move freely and it is always given the same initial deflection that the time limit will always be a perfectly definite one.

The device which I have shown is an electromagnetic switch in which the deflection of the pivoted magnet is controlled by an electromagnet, the deflection being maintained until the condition of the electromagnet is reversed. The armature, which is Specification of Letters Patent. Patented Sept. 23, 1919. Application filed February 16, 1918. Serial No. 217,849.-

' attracted by the permanent magnet, is arranged to operate a switch so that there will be a definite time interval between the reversal of the condition of the electromagnet and the operation of the switch.

In the accompanying drawing illustrating 'one form of my invention, Figure 1 is an elevation of a complete device; Fig. 2 is an end view of the same, and Fig. 3' shows one system of electrically connecting my improved switch.

Referring to Figs. 1 and 2, 10 represents a permanent magnet which I have shown as of the horseshoe type mounted in a bracket 11. This bracket 11 is secured to shaft 12 which is mounted in bearings 13. These bearings are preferably of the antifriction type, as, for instance, ball bearings, so. as to permit the magnet to vibrate with a minimum amount of friction. Cooperating with the permanent magnet is an armature arm 14 which is pivoted at 15 in a bracket 15 so as to rest against a stop screw 16 when it is not attracted by the magnet. As shown, the armature comprises an arm which may be of non-magnetic material and amagnetic portion 17 of magnetic material which "is attracted by the magnet. As shown", this magnetic portion is cylindrical in form and secured to the arm b a clamp 17 so as to project on both si es of the arm opposite the pole pieces of the magnet. Thin non-magnetic sleeves 16' around the magnetic ortion 17 prevent the latter from freezing to the magnet. The switch, which is operated by the armature, comprises a bell crank member 18 pivoted. at 19, provided with a contact member 20 cooperating with a stationary contact 21. The contacts 20 and 21 are held in engagement by a spring arm 22 which engages the end of the bell crank lever. An electromagnet 23 acts on the spring arm and by pulling it downward forces the arm 14 downward slightly so as to assist in releasing the arm 14 from the magnet 10.

The vibratory 0r reciprocatory movement of the magnet 10 is initiated by electromagnet 24 having an armature 25 pivoted at 2'6. Attached to the armature 25 is a finger 27 which engages a projection 28 on the bracket 11 which supports the magnet. The pivot of the magnet 10 is vertically above the armature portion 17 so that normally. the magnet will hang vertically as shown in Fig. 1 with its pole pieces directly over the magnetic portion 17 of the armature. Wlth the magnet in this position, the armature 14 will be drawn up by the magnet as shown in Fig, 1. If, however, the electromagnet 24 is energized the magnet 10 will be deflected to the right as shown in Fi 3, and the armature will be released and rop into engagement with the stopscrew 16 as shown in Fig. 3. Since the armature of the electromagnet 24 acts ,on the magnet 10 w th a leverage which is short as compared with the leverage at which the magnet 10 is held by its armature, I utilize the magnet 23 for assistin the magnet 24. The magnet 23, b 2% orces the arm 14 away from the magnet thereby reducing the effort requlred of the magnet 24. I may, therefore, make the magnet 24 smaller than would otherwise be the case. Assuming that the parts are 1n the pos1- tion shown in Fig. 3, if the magnet is released it will vibrate on its pivot, swinging back and forth through its normal posltion. Each time the pole pieces of the magnet pass the magnetic portion 17 there is a tendency for the armature to be lifted but the force is not applied sufliciently long to lift it. As the arm continues to vlbrate,

' however, the amplitude of the movement gradually decreases until a point is reached where the force is sufiicient to attract the armature arm. .At this point the armature arm will be lifted into contact with the magnet which will thereupon stop vibrating and the switch 18 controlled by the armature will be operated.)

In Fig. 3 I have shown my devlce ut1l1zed as a time-limit overload relay for controlling the low voltage coil 29 of the c1rouit breaker 30. The winding of the electromagnet 24 is connected in series with thewinding 23 and the circuit of these two magnets is controlled by an overload relay 31. Under normal conditions, the electromagnet 24 being energized, will hold the pivoted member 27 in a deflected posltion as shown in Fig. 3 and the switch contacts 20 and 21 will be held in firm contact by the spring member 22 assisted by electromagnet 23. On the occurrenceof an overload, however, electromagnets 23 and 24 will both be deenergized. The effect of the deenergization of the magnet 24 is to release the pivoted magnet and allow it to swing freely on its pivot but the deenergization of the ma net 23 has no-practical eflect. If the over oad should only continue for a short time, the overload relay will dropand restore the original conditions, but if the overload persists beyond the time which is predetermined, the magnet 10 which is swinging and all the tlme approaching a stop, will reach a point where the armature 14 pul ing downward on the spring armbreaker. When norma conditions are restored to the line, the electromagnet 23 be- I ing energized, forces the arm 14 slightly away from the magnet 10 and at the same t1me the energization of electromagnet 24 deflects the magnet 10 so as to be in readi- 4 ness for the next overload. I find that the operation of the device is improved b reducmg the width of the pole faces 0 the magnet 10 and of the armature as much a possible in the direction of vibration,

thereby reducin the length of the interval during which t 0 full force of the magnet is efl'ective in the armature. As shown, I do this by rounding the pole ends of the magnet and using a cylindrical member for an armature. It will be seen that I have provided a very simple device for giving a very definite,timeinterval and while I have described the principle of operation of my mvention, together with the ap aratus which I now consider to represent t e best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative, andthat the invention can be carried out by any other means.

What I claim as new and desire to. secure by Letters Patent of the United States, is

1. A time element device comprising a magnet and an armature normally attracted into contact with each other and means for causing one of said parts to reciprocate with reference to the other through the normal position at a gradually decreasing amplitude until the magnetic. attraction causes movement into contact.

2. A time element device comprising a magnet, a movable armature normally attracted thereby, means for causing .one of said parts to reciprocate through the normal position at a gradually decreasing amplitude until the magnetic attraction causes the armature to move into contact with the magnet.

3. A time element device comprising a pivoted magnet, an armature normally attracted thereby, means for causing the magnet to reciprocate through its normal tion at a gradually decreasing amplitude until the magnetic attraction causes the ar--- mature to be attracted into contact with the osipivoted magnet, an armature normally attracted thereby and electromagnetic means for initialing a reciprocatory'movement of the magnet on its pivot through its initial position at a gradually decreasing amplitude until the magnetic attraction causes the armature to be attracted into contact with the magnet.

6. A time element switch comprising a magnet and an armature normally attracted into contact with each other, means for causing one of said parts to reciprocate with reference to the other through the normal position at a gradually decreasing amplitude until the magnetic attraction causes movement into contact, and a switch actuated by said movement.

7 A time element switch comprising a magnet and an armature normally attracted into contact with each other, means for causing one of said parts to reciprocate through the normal osition at a gradually decreasing amplitu e until the magnetic attraction causes movement of the other part, and a switch actuated by said movement.

8. A time element switch comprising a pivoted magnet, an armature normally attracted thereby, means for causin the magnet to reciprocate on its pivot t rough its normal position at a gradually decreasing amplitude until the magnetic attraction causes the armature to be attracted into contact with the magnet, and a switch operated by the armature.

9 A time element switch comprising'a pivoted magnet, an armature normally at: tracted thereby, electromagnetic means for initialing a reciprocatory movement of the magnet on its pivot through its normal position at a gradually decreasingamplitude until the magnetic attraction causes the armature to-be attracted into contact with the magnet, and a switch operated by the armature.

10. A time element switch comprising a magnet and an armature, one of which is pivoted, normally attracted into contact with each other, an electromagnet for deflecting the pivoted part from normal and subsequently releasing it so that it will reciprocate through-its normal position at a gradually decreasing amplitude until the magnetic attraction causes the armature to be attracted into contact with the magnet, and a switch operated by the armature.

11. A time element switch comprising a permanent magnet pivoted to vibrate freely, a movable armature normally attracted by said magnet, and an electromagnet arranged to deflect the permanent magnet from its normal position and release it when the condition of the magnet is reversed so that the permanent magnet will vibrate through its normal position at a gradually decreasing amplitude until the magnetic attraction causes the armature to be attracted into contact with the magnet.

12. A time element switch'comprising a pivoted magnet an armature normally attracted thereby, an electromagnet arranged to deflect the permanent magnet from its normal position and release it when the condition of the magnet is reversed so that the permanentmagnet willvibrate through its normal position at a gradually decreasing amplitude until the magnetic attraction causes the armature to be attracted into contact with the magnet, a switch operated by the armature and an electromagnet energized simultaneously with the deflecting electromagnet for controlling the armature.

In witness whereof, I have hereunto set my hand this 15th day of February, 1918. LOUIS THOMPSON.

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