US3284735A - Magnetic series flasher having two electromagnetic coils and a magnetically reversible armature - Google Patents

Description

Nov. 8, 1966 H. e. SIIBERG 3,234,735

MAGNETIC SERIES FLASHER HAVING TWO ELECTROMAGNETIC GOILS AND A MAGNETICALLY REVERSIBLE ARMATURE Filed July 12. 1965 \LAAA ATTORNEYS United States Patent MAGNETIC SERIES FLASHER HAVING TWO ELECTROMAGNETIC COILS AND A MAG- NETICALLY REVERSIBLE ARMATURE Hamming G. Siiberg, Union, N.J., assignor to Tung-Sol Electric Inc., a corporation of Delaware Filed July 12, 1965, Ser. No. 471,120 Claims. (Cl. 33591) The present invention relates to intermittently operating thermoresponsive switches and more particularly to a switch which can be employed for flashing automobile directional signal lamps. The new device is relatively insensitive to changes in operating voltage, is of simple construction, provides good contact life at high loads and has but a single moving part.

The device employs as the moving element a metal having a low Curie point, such as the various nickel iron alloys which are magnetic at low temperatures and lose their magnetic properties when heated to or above a predetermined higher temperature. By using the low Curie point metal for the spring biased armature of a relay, the armature when cold will be attracted by a magnetic field and when heated by current passing through the armature will lose its magnetic attractability and move to its retracted position under its spring bias. In prior thermomagnetic relays utilizing the Curie point effect, permanent magnets were employed which made the device very sensitive to change in voltage since the higher the voltage the more rapid'heating of the armature with the result of a decrease in the period of attraction and conversely at lower voltages the period of attraction of the armature would increase.

In the device of the present invention two electromagnets are employed to act on a single armature so that the magnetic density of the cores will compensate for any occurring voltage changes in the system.

The winding of one electromagnet provides the necessary force to pull the armature into the circuit and also connects the power source in series with the load, which for example, can be directional lamps to be flashed. The winding of this electromagnet has a high electrical resistance so as to prevent the lamps from lighting.

The winding of the second electromagnet is of low electrical resistance and shunts the winding of the first electromagnet when the armature is attracted, thereby providing a low resistance path to the lamp permitting the lamps to light. The second electromagnet has sufiicient force to hold the armature in attracted position so that the armature will heat up to its Curie point temperature and lose its magnetic attractability. When the armature loses its magnetic permeability, the spring bias therein causes retraction of the armature to open the circuit of the second electromagnet and thereby remove the shunt about the winding of the first electromagnet.

In this arrangement, when the operating voltage increases, both the pull-in and hold-in forces increase, However, at the same time the current through the armature, when the winding of the second magnet is energized, increases and thereby raises the temperature of the armature more rapidly so that the Curie temperature is reached more quickly causing the armature to be retracted sooner. Thus the increased voltage is compensated for in the system. In the same way, when the operating voltage decreases, the windings of the first and second electromagnets will provide less attraction for the armature, but the armature when held will heat more slowly, thus lengthen ing the time before the armature is released to compensate for the weaker forces applied by the electromagnets.

Further, the present invention has the advantage of permitting different design parameters for the two elec- 3,284,735 Patented Nov. 8, 1966 vdesired speed and ratio when used as a flasher as will be explained below.

For a better understanding of the invention and of the advantages thereof, reference may be made to the accompanying drawing of which:

FIG. 1 is a flasher representing one embodiment of the invention and shown with the armature in the retracted position; and

FIG. 2 is the flasher of FIG. 1 shown with the armature in the attracted position.

The flasher shown in the drawing includes a base 2 of insulating material such as a phenolic resin carrying two terminals 4 and 6 which are molded therethrough. Terminal 4 above the base 2 supports a conductor 8 to which one of the ends of each of the windings 10 and 12 is electrically connected. Winding 10, which is of low resistance having relatively few turns, encircles a U-shaped core 14. Winding 12 which is of relatively high resistance and has a relatively large number of turns, encircles a larger U-shaped core 18. An armature 22 constructed of a metal having a relatively low Curie temperature, for example, a nickel-iron alloy available under the trade name Nilvar or a nickel steel alloy available under the trade name Invar, is fulcrumly mounted at its lower end on a bracket 24 supported from terminal 6. The armature 22 has a spring bias therein tending to maintain the armature in the retracted position shown in FIG. 1. When the armature is attracted contact 26 carried thereby engages a fixed contact 28 supported on a post 30. Post 30 is insulatedly mounted on the 'base 2.

The other end of winding 10 is electrically connected to contact 28 by way of post 30 and the other end of winding 12 is connected to core 18 which is in conductive contact with bracket 24.

The operation of the above described device will be clear from the following description. When one terminal of a source of energy is connected to terminal 4 and a lamp load is connected between terminal 6 and the other terminal of the source, current flows from terminal 4, post 8, winding 12, core 18, to bracket 24, terminal 6 and to the load. This current, because of the inclusion of the relatively high resistance winding 12, will be insuflicient to light the lamps of the load.

The current in winding 12 develops a magnetic force in the U-shaped core 18 which attracts armature 22 and brings the contact 26 carried thereby into engagement with contact 28 as seen in FIG. 2. Current thereupon flows from terminal 4 and post 8 through winding 10, post 30, contacts 28 and 26, armature 22, terminal 6 and the load. The winding 10 provides a low resistance shunt for winding 12. The current through winding 10 and the armature 22 is suflicient to heat the armature and thereby raise its temperature to the Curie point. This current is also sufficient to cause illumination of the lamps of the load.

When the magnet properties of the armature 22 are reduced at the raised temperature to a point where the spring bias in the armature overcomes the magnetic pull on the armature from U-shaped core 14, the armature snaps back into the position shown in FIG. 1, opening the circuit and opening the shunt about the winding 12. Accordingly, the coil 12 is again energized developing a magnetic force in the U-shaped core 18 which in turn attracts the armature when it has cooled sufficiently to regain its magnetic properties. In this manner the cycle will repeat itself.

Thus, in the new device, the magnetic forces are supported by two separate magnetic circuits working alter- "nately. The invention has the advantage, as heretofore explained, of permitting different design parameters for I hold-in force and pull-in force and of providing autotact, by varying the spring force in the armature necessary to open the shunt circuit or by variation in the relative number of turns of the windings.

It will be clear from the foregoing description that the invention provides a single rugged voltage compensated flasher or the like which requires a single moving part and which lends itself to ready adjustment. Obviously, various changes in the illustrated construction could be made without departing from the spirit of the invention or the scope of the accompanying claims as will be apparent to those skilled in the art.

The following is claimed:

1. An intermittently operating thermoresponsive switch comprising:

(i) an armature fulcrumed at one end thereof and composed of material which loses its magnetic permeability upon heating,

(ii) a first electromagnet having a high electrical resistance winding and a second electromagnet having a low electrical resistance winding,

(iii) means connecting said first electromagnet so that when energized it attracts said armature to said second electromagnet to be held thereby in the attracted position in which position the Winding of the first electromagnet is shunted until said armature moves from said attracted position because of loss of its magnetic permeability.

2. An intermittently operating thermoresponsive switch comprising:

(i) an armature fulcrumed at one end thereof and having a first contact at the other end thereof, said armature composed of material which loses its magnetic permeability upon heating by current passing therethrough,

(ii) a first electromagnet having a high electrical resistance winding and a second electromagnet having a low electrical resistance winding,

(iii) the winding of said second electromagnet having one of its ends terminating at a second contact,

(iv) and said armature when magnetically attracted by said first electromagnet, carries said first contact into engagement with said second contact to shunt the coil of said first electromagnet and to heat said armature.

3. An automobile flasher switch comprising:

(i) a base of electrically insulating material having at least two terminals passing therethrough,

(ii) an armature fixed in contact with a first one of said terminals and having a first contact at its free end, said armature composed of material which loses its magnetic permeability upon heating by current passing therethrough,

(iii) a first electromagnet having a high electrical resistance coil and a second electromagnet having a low electrical resistance coil.

(iv) the coil of said first electromagnet having its ends connected across said terminals,

(v) the coil of said second electromagnet having one of its ends connected to the second one of said terminals and its other end connected to a fixed second contact, 7

(vi) said armature when magnetically attracted by said first electromagnet carries said first contact into engagement with said second contact to shunt the coil of said first electromagnet by the coil of the second electromagnet and to heat the armature.

4. The flasher of claim 3 wherein said armature is spring biased to retracted position in which said contacts are separated.

5. The flasher of claim 3 wherein the magnetic force from said first electromagnet is sufiicient to pull the armature towards it and said second electromagnet has a sufficient magnetic force to hold the armature after the coil of said first electromagnet is shunted and before the armature loses its magnetic permeability.

No references cited.

BERNARD A. GILHEANY, Primary Examiner. R. N. ENVALL, JR., Assistant Examiner.

Claims (1)

1. AN INTERMITTENTLY OPERATING THERMORESPONSIVE SWITCH COMPRISING: (I) AN ARMATURE FULCRUMED AT ONE END THEREOF AND COMPOSED OF MATERIAL WHICH LOSES ITS MAGNETIC PERMEABILITY UPON HEATING, (II) A FIRST ELECTROMAGNET HAVING A HIGH ELECTRICAL RESISTANCE WINDING AND A SECOND ELECTROMAGNET HAVING A LOW ELECTRICAL RESISTANCE WINDING, (III) MEANS CONNECTING SAID FIRST ELECTROMAGNET SO THAT WHEN ENERGIZED IT ATTRACTS SAID ARMATURE TO SAID SECOND ELECTROMAGNET TO BE HELD THEREBY IN THE ATTRACTED POSITION IN WHICH POSITION THE WINDING OF THE FIRST ELECTROMAGNET IS SHUNTED UNTIL SAID ARMATURE MOVES FROM SAID ATTRACTED POSITION BECAUSE OF LOSS OF ITS MAGNETIC PERMEABILITY.

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