US2343861A - Electromagnetically controlled device - Google Patents

Description

March 14, 1944. 1 c. BIGGLE l 2,343,861

`- ELECTROMAGNETICALLY' CQNTROLLED DEVICE Filed May 27, 1941 I ttorncg NITED STATES 'PATENT OFFICE ELECTROMAGNETICALLY CONTROLLED DEVICE Laurence C. Biggie, Altadena, Calif., assigner to General Controls Co., Glendale, Calif., a corporation o! California Application May 27, 1941, serial No. 395,429 s claims. (ci. fzs-ssc) My present invention relates to electromagnetically controlled devices of the type wherein an amature is magnetically retained in engagement with the energized core of an electromagnet only after they have been moved into such engagement by the operation of mechanical means. Devices of the type indicated are commonly employed for the control of valve closure members, switching means, and the like; energization of the electromagnet being controlled by means responsive to a condition such as temperature, pressure, or the existence of a flame at a pilot burner. Upon abnormal change in the condition, the electromag- Anet is deenergized and the closure member or switch assumes a safe position; manual resetting of the device then being required.

It has been found that, when the armature and core are brought together, the amount of flux initially required for the attraction of the armature is considerably greater than that subsequently necessary for retaining it in its attracted position. In other words, if the amount of current thorugh the` electromagnet coil is gradually increased until the amount of flux produced is' just suiiicient` to hold the amature in engagement with the core against the force of a xed bias, immediately thereafter the amount of the current can be substantially` reduced before the armature is released. Even when magnetic materials having very low retentivity are employed, ordinarily the amount of current can be reduced about 50 per cent before the armature is released. 'I'he reason for this phenomenon is notclear, but it is believed that intermolecular attraction is probably a contributing factor. When the deenergization of the electromagnet, in response to change in the controlling condition, is gradual,

las when a thermoelectric device normally heated by a pilot burner llame is employed as the source of energy and the ilame 'is extinguished, a dangerous delay may' occur before the device reaches its safe position due to the diiierence between the drop-ou and hold-in values of the current. I t is therefore a general object of my present invention to provide mechanical means for so compensating for this diilference that the "hold-in and drop-ou values oi the current are then substantially the same. Electromagnetic means for accomplishing a similar purpose are disclosed iu the copending application of William A. Ray, Serial No. 378,756, vnlecl February 13, i941. Amore specific object of my invention is to pro-- vide, in a device of the character described, mechanical means for producing a force'tending to separate the core and amature, which force is' counter to and asymmetric with respect to the magnetic holding force.

Another object is to provide mechanical means for moving the core and armature into engagement with each other, which means, upon release, applies a, force to one of the electromagnetic members, which force is asymmetric with respect to the other member.

Another object is to provide means connected to the armature for mechanically moving it into engagement with the core, inv which position a force is applied to the armature by the moving means which aids and is symmetric with respect to the magnetic force; the means when released exerting a force on the armaturewhich is counter to and asymmetric with respect to the magnetic holding force.

Another object is to provide means of the type described in the preceding object whereby the armature is normally moved in an arc toward and away from the core.

Other objects an dadvantages of the inven-A tion will be found in the description, lthe drawing, and the appended claims.

For complete understanding of the invention, reference may be had to the following detailed description and accompanying drawing, wherein: Y

' Figure 1 is a diagrammatic -view of a iluid control valve embodying my invention; and

Figures 2 and 3 are diagrammatic views of modified forms oi the invention.

Referring ilrst to Fig. 1 of the drawing, the numeral II indicates a valve casing having an inlet I2 and an outlet port opening I3. Cooperable with a seat I4 provided at the inner end of the port is a closure member I5 carried by a stem I6 which is reciprocably mounted in brackets I1 secured to the casing. Compressed between the closure member I5 and the adjacent bracket is a spring I8 which urges the closure member toward its seat. Provided for the actuation of the closure member is a T-shaped lever I9 which is' pivot'ed on a pin 20 fixed to the casing. The lower end of the verticalportion 2l of lever I9 is bifurcated and providedA on opposite sides of stem I6 with rollers (not shown) mounted on pins 26, which rollers are disposed between. spaced collars 22 provided on the stem I6. A rod 23, extending through an opening in an upper wall of the casing and engageable with the right-hand horizontal portion of member I9, carries on its outer end a push button 24, between which and the casing `is a spring 2i urging the rod 23 out.- wardly.-

Rigidly mounted in the casing is a U-shaped electromagnet core 21, around one arm of which is provided an energizing coil 28, the terminals of which insulatingly extend to the outside oi' the casing. Cooperable with pole faces formed at the lower end of the arms of core 21 is a diskshaped amature III. The armature is loosely connected to the lever I9 by a pin 3i secured to the end of the left-hand horizontal portion of the lever, the reduced end portion 32 of the pin loosely extending through a central opening in the armature and being provided at its extremity with a disk-shaped head 33. The junction between the pin II and its reduced portion 32 is rounded so that it can uniformly engage the lower edge of the opening in the amature when lever I9 is rocked in a clockwise direction.- It will thus be seen that. when push button 2l is depressed, the force applied to armature III through pin 3| is Asymmetric with respect to the arms of core 21.

The parts are shown in the figure in the positions which they assume when push button 24 is manually depressed, closure member I5 being in open position and armature 30 being held firmly in engagement with the pole faces of core 21. When the push button is released, ii' core 21 is unenergized, the lever I9, under the'iniiuence of spring IB, rocks about its pivot in a counterclockwise direction, moving the closure member toward its seat and the armature away from the core. If, however, when the push button is released, the core 21 is sutliciently energized by passage of current through coil 28, the armature will be magnetically retained in engagementwith the core and the parts will thus remain substantially in the positions shown. Since head 33 of pin ll, due to the pivoting of lever I9 on pin 2U, moves in an arc, only its left-hand lower edge will be in engagement with the recessed upper surface of the armature. The force of spring I8 is thus applied to the armature at a point which Referring nowto Fig. 3, the numeral 5I indicates a valve casing having an inlet 52 and an outlet 53, with which outlet a port 54 communicates. Cooperable with the port is a combination closure member and armature 55. reciprocable in a guide 55, and normally movable between valve-opening and closing positions respectively toward and away from the pole faces of p a U-shaped electromagnet core 51 by manual opthe core, its other end bearing upon a portion of the member 55 adjacent one of the arms of the core. Upon reduction or holding iiux, the member 55 is iirst tilted away from the right-hand arm of the core and then falls by gravity into portclosing position, in which position it is out of engagement with spring 60, the normal position of which is shown in broken lines.

It will thus be seen that in each of the embodiments of the invention shown in the various figures, when the resetting means is retracted, the force then tending to disengage the armature from the core is more effective to perform that function than a force applied symmetrically with respect to the core, with the result that the arma ture tends to drop-out at approximately the same value of flux as that required to initially hold it.

While, by way of illustration, I have shown and described specific embodiments of my invention applied to the control of a fluid control valve, the invention is obviously not so limited and modifications may be made Without departing from the spirit of the invention. I intend therefore to be is asymmetric with respect to the core, so that when the current in coil 2B is sufficiently reduced the armature will be tilted away from the core. Such a tilting force is obviously elective to disengage the armature at a higher value of holding flux than would aforce applied at a point symmetric with respect to the core, so that the armature is promptly released upon gradual deenersization of the core, as when a thermoelectric device nonnally heated by a pilot burner flame is employed as the source of energy and the flame is extinguished.

In the somewhat modified form oi' the invention shown in Fig. 2, lever I9 (corresponding to lever I9 of Fig. 1) is provided with a bent-up lefthand end portion III for engagement with the central portion of a disk-shaped armature 4I which is cooperable with the pole faces ofa U- shaped core I2 having an energizing cc-il 43. In this modification, the core is shown rotated through 90 with respect to the position of the core shown in Fig. l. Connecting lever I9 with the armature is a pin 44 which extends through an eccentric opening in the armature and is pivoted at its lower end to the lever. The pin is Provided with a head 45 which is received in a conical recess formed in the upper end of the opening. By the arrangement described, it will be seen ti'at in resetting, the armature is forced symmetrically into engagement with the pole faces of the core, and upon release' of the reset button a force is applied to the armature through the pin head 45 which tends to tilt the armature away from the core.

limited only by the scope of the appended claims.

I claim as my invention:

1. In combination: an electromagnet comprising an armature member and a core member, said core member being adapted when energized to retain said amature member in engagement therewith only when the members are rst mechanically broughttogether, means for mechanically moving one of said members into engagement with the other and for then applying a force to said one of the members which is assistant to and substantially symmetric with respect to the magnetic holding force, and means connected to said mechanical means and effective when the same is retracted for continuously applying a force to said one of the members which is counter to and asymmetric with respect to the magnetic holding force so that said one of the members is tilted away from the other when the energization of the electromagnet is reduced.

2. In combination: a relatively fixed electromagnetic core, a mor-'able armature cooperable with said core, said core being adapted when energized to magnetically retain said armature in engagement therewith only when it is rst me chanically moved to that position, and pivoted means for normally mechanically moving the armature in opposite directions in an arc toward and away from the core and biased in 'the latter direction, said mechanical means being so connected to the armature that when the armature is moved thereby into engagement with the core force is applied thereby to a portion ofthe armature which is substantially symmetric with respect able'in one direction and biased in an opposite direction; said movable means being adapted in its movement in said one direction to move one of said members into engagement with the other and to then exert a force thereon which is assistant to and substantially symmetric with respect to the magnetic retaining force; said movable means, in its subsequent movement in said other` direction under the iorce of said bias, exerting a force on said one of the members which is counter Yto and asymmetric with respect to the magnetic retaining force so that said one of the members is tilted away from the other of the members when the energization of the electromagnet is reduced. i

4. In combination: an electromagnetl comprising an armature member and a core member; said core member "being adapted when energized to retain said armature member in engagement therewith only when the members are first mechanil cally brought together; and means manually movable in one direction to move one of said members into engagement with the other, and biased in an opposite directio said means having one portion engageable. in the movement of the means in said one direction, with said one of the members at a point thereon which is substantially symmetric' with respect to the magnetic retaining force when the members are in interengagement; said means also having another portion for engagement with said one of the members but which is out of engagement therewith when the members are manually held in interengagement by the means; said other portion, in the subsequent movement of the means in said opposite direction under the force of said bias, engaging said one of the members at a point thereon which is asymmetric with respectv to the magnetic retaining force sothat said one of the members is tilted away from the other of the members when the energization of the elecv tromagnet is reduced.

5. In combination: an electromagnet comprising an armature member and a core member; said core member providing a pole face in engagement with which said armature memberl is magnetically retained when the core member -is energized and the members are first mechanically brought into interengagement; means for mechanically moving the armature member into engagement with said pole face and for then applying avforce to the armature member which is assistant to and substantially symmetric with respect to the magnetic retaining force; and means effective when said mechanical means is retracted for continuously applying a force to the armature member while it is in engagement with said pole face ,tending to disengage it therefrom, said force being applied at a point on the armature member such that the armature member forms a lever having a fulcrum at an edge of said pole face.

LAURENCE C. BIGGLE.

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