US3005936A - Electromagnetic timing device - Google Patents

Description

Oct. 24, 1961 w. H. BERGMANN ELECTROMAGNETIC TIMING DEVICE 2 Sheets-Sheet 1 Filed July 10, 1958 Fig.3.

INVENTOR Wilfried H. Bergmonn wnnassas BY M6.

ATTORN EY Oct. 24, 1961 w. H. BERGMANN ELECTROMAGNETIC TIMING DEVICE 2 Sheets-Sheet 2 Filed July 10, 1958 I I I1lllll g F m me O .C 0 am S O O 0 0 0 O 0 0 5 llllll I29 ffrr-rr O mwmwmw d manna -m obcdet F bm f c e m H E 5 O O 0 0 0 O 5 O 5 0 5 2 2 II I- United States Patent 3,005,936 ELECTROMAGNETIC TIMING DEVICE Wilfried H. Bergmann, Irwin, Pa., assignor t0 Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed July 10, 1958, Ser. No. 747,770 7 Claims. (Cl. 317-178) This invent-ion relates generally to electromagnetic devices and, more particularly, to time limit contactors.

In the design and construction of electromagnetic devices, or contactors, it is often desirable to provide for a long and definite delay in the operation of a device. Heretofore, the interval of time obtained by the use of such devices has been too short in many instances and, as a result, additional and auxiliary devices had to be used to provide the necessary time delay.

One broad object of this invention is the provision of a magnetic circuit for an electromagnetic device that includes in the circuit ferromagnetic material with special magnetic characteristics.

It is also a broad object of this invention to utilize the magnetic after-effect of the material Ni Mn for timing purposes in an electromagnetic device by including this material in the magnetic circuit of such electromagnetic device.

One object of this invention is the provision of a time limit contactor that shall be simple in structure and design, efficient in operation, and which may be readily and economically manufactured.

A further object of this invention is to provide for an adjustable time constant in the operation of electromagnetic devices.

It is a more specific object of this invention to include in the magnetic circuit of an electromagnetic device a portion thereof of Ni Mn, utilizing the magnetic aftereffeot of this materail for time delay in the operation of the device.

Other broad, as well as more specific, objects of this invention will become more apparent from a study of the following specification when considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a view in side elevation, partly in section, of a time limit electromagnetic contactor constructed in accordance with this invention;

FIG. 2 is a front elevational view of the contactor illustrated in FIG. 1;

FIG. 3 is a perspective view of the arrangement of the contact members on the electromagnetic time limit device;

FIG. 4 is a diagram showing an accelerating contactor embodying the features of this invention, associated with a starting control system; and

FIGS. 5 and 6 each show a number of curves which demonstrate the characteristics possessed by the electromagnetic time limit device constructed in accordance with this invention.

Referring .now to the drawings, the electromagnetic time limit device TL illustrated, comprises a frame 30 to which a core 31 is secured. The core member 31 may be secured to the frame in any suitable manner. In this particular showing, a bolt 32 cooperating with the frame 30 and having threaded engagement with the core, is utilized. A support 33 of magnetic material, as of soft iron, and in the shape of an inverted L. is also rigidly secured to the frame 30 by the bolt 32. The support 33 has the horizontal leg of the L disposed substantially parallel to the core member 31.

An armature 34 of magnetic material as soft iron is mounted on the support 33 and is disposed in alignment with the core 31. To mount the armature for oscillatory movement, a notch 36 is provided at the end of the sup- 3,005,936 Patented Oct. 24., 1961 "ice porting member 33. In the construction illustrated, the notch 36 is provided at the junction of the end portion of support 33 and a plate 35 mounted on top of the support and extending a short distance beyond the end of the support.

The simplest type of armature that is suitable for this electromagnetic time limit device is a metal plate of magnetic material, as soft iron, which is cut square at the end, or preferably cut by planes forming an acute angle at one edge of the end of the armature adjacent the end of the support 33. Further, to provide for a free pivotal movement of the armature when mounted in the notch 36, the walls defining the notch should be spaced at an angle greater than a right angle. The size of the angle of the notch as well as the size of the acute angle at the upper end of the armature will be determined by the desired angle of swing of the armature. In this embodiment of this invention, to make the notch of the desirable angular extent, the plate 35 is bent upwardly at a point near the upper right-hand end of the support 33.

It will be readily understood that a sufficient and free angular motion of the armature may be obtained if the angle of the notch 36 is made slightly greater than the sum of the angle of movement and the acute angle at the knife edge of the armature coacting with the notch 36.

In order that the armature may be readily mounted, removed, and replaced, a rectangular notch 38 is cut in the projecting bent portion of the plate 35. In cutting the notch, the plate 35 is cut at two places to form a tongue 39 which is bent upwardly much more than the end portion of plate 35 forming, in part, the notch 36. As shown, a bracket 40 is mounted on the armature and provided with an extension or tongue 41 which extends through the notch 38.

The upper tongue 39, which is integral with plate 35, is provided with a slot 42, extending inwardly from the end, for receiving a bolt 43, while the tongue 41 has an opening through which the bolt extends. A spring 45 is mounted on the bolt 43 and is disposed to bias the armature 34 counterclockwise about the knife edge 37. In this manner, the armature is retained in position, the tongue 41 engages the two sides of the notch 38 to prevent lateral movement, while the spring 45 biases it upwardly into the notch 36.

The armature may be readily removed by compressing the spring 45 and forcing the bolt 43 upwardly and out of slot 42.

As shown, the bolt 43 is provided with an adjustable nut 46 whereby any desired spring tension may be applied to the armature. The armature is provided with one main contact member 26 pivotally' mounted at 47 on a lever 48. A spring 49 biases the contact member in such a direction as to firmly press the upper end of the lever 48 against the bracket 40.

In the showing in FIG. 1, the coil 2 is assumed to be energized thus holding the armature firmly against the armature receiving surface 60 to substantially eliminate the air gap between the armature 34 and core 31 and to hold contacts 26 and 27 open.

To actuate the armature 34, a magnetizing coil 2 is mounted on the core 31. As will be readily understood, this coil 2 may be constructed to have any desired number of turns of suitable conductors, which will depend on operating conditions to be met. The core 31 may also carry two or more coils, depending on operating needs.

The type of electromagnetic contactor herein disclosed is merely representative. The invention resides, broadly stated, in the combination of an electronmagnetic device and the particular alloy heat treated to manifest certain magnetic characteristics especially useful in obtaining time delays. This combination is very useful when it is desirable from a primary electrical circuit, to control the change in the current or in the voltage, or any other characteristic, of a secondary circuit as a function of the time elapsed since a certain change in the primary circuit. In the prior art, such control involves quite complicated intermediate circuitry or timing devices.

The novel and simple approach for achieving the useful and desirable results mentioned is to functionally and to an extent structurally link both circuits by a magnetic core of NIgMl'l, utilizing the magnetic after-effect in this material. The magnetic properties of this alloy were investigated extensively in Japan and Russia and to some extent in this country. This investigation established that this alloy is magnetic and can exhibit, according to the prevailing state of atomic order in the alloy, a magnetic after-effect from a few seconds up to a maximum of 30 hours. The prevailing state of atomic order in the material depends merely on a relatively simple heat treatment.

In FIG. 6, the curves show the time eflfect for a 500 C. quenched specimen. By plotting the magnetization against time, other curves are obtained showing some of the desirable characteristics of this Ni Mn alloy.

In FIG. the curves C1, C2, C3, C4 and C5 show various magnetic after-effects this alloy may be made to manifest.

The magnetizing curves shown in FIG. 6 show, for a particular sample of Ni Mn having had a particular heat treatment, how the flux density varied with time for difierent magnitudes of magnetomotive force being applied to the sample.

If after magnetization of this alloy to saturation, the magnetomotive force is removed, the flux in the material will decay. The speed of decay may be changed to almost any slope desired. For one heat treatment, a sample of the alloy will manifest a flux decay as indicated by curve C1, another sample having a different history of heat treatment will manifest a flux decay as shown by curve C2. Similarly, the characteristics of curves C3, C4, C5, and so on, may be obtained.

A contactor as herein disclosed may be adjusted to drop out at flux densities as D1, D2, D3, or any other value.

From the foregoing, it is apparent that a contactor as herein disclosed, if provided with a magnetic circuit having a section thereof made of the alloy Ni Mn, which is heat treated for any selected flux decay, can be made into a time limit device having any time constant from a few seconds to hours if necessary.

In the particular contactor herein disclosed, it sufiices to make the core 31 of the alloy Ni Mn and heat treated to requirements.

A clearer picture of the advantages and novel features of thisinvention can probably be had from a discussion of the operation of the time limit contactor in conjunction with the system of control shown in FIG. 4.

Assuming that leads 1 and 6 are energized and leads and are energized. Since the leads 1 and 6 supply the main circuitry, these leads are preferably energized at a constant relative high value of direct-current voltage, and leads 10 and 15, serving certain of the control circuitry only, are energized at a constant direct-current voltage of lower value. Assuming further that the main switches MSl and M82 are closed, the control switches CS1 and CS2 are closed, and that the selector switch SS is in the position indicated, then two energized circuits are immediately established.

One circuit may be traced from lead 1 through the main switch MSl to bus 2, the shunt field winding 3 of motor M, conductor 4, bus 5, main switch MS2 to lead 6. A second circuit is established from bus 2, through adjustable resistor R1, through contacts 7 of the selector switch SS, the actuating coil 3 of the time limit contactor TL, the back contacts 9 of the main contactor MC to bus 5. The first circuit etfects the energization of the held winding 3 of the motor M. The second circuit effects the energization of the actuating coil 8 at a selected value within a certain range depending on the adjustment of resistor R1. Since coil 8 is energized with a selected relatively high voltage and is otherwise also designed to produce many ampere turns, it rather rapidly, in spite of the normally slow magnetic build-up characteristics of Ni Mn, increases the flux density in the magnetic circuit of the time limit contactor to a maximum. The time limit contactor thus, for the type of energization assumed, has no appreciable time constant on pickup. The contacts 26 are thus opened rather rapidly and contacts 25 closed rather rapidly. The closing of contacts '25 produces a desired result hereinafter discussed. The opening of contacts 26 places the accelerating resistor 18 in the motor armature circuit to protect the motor and produce proper acceleration when the motor armature is energized.

To eifect motor operation, the starting switch 13 is closed, whereupon a circuit is established from lead 10 through the control switch CS1, to bus 11, actuating coil 12 of the main contactor MC, starting switch 13, bus 14, control switch CS2, to lead 15. The operation of the main contactor MC effects the closing of contacts 16, 19 and 23 and the opening of contacts 9. The closing of contacts 16 establishes a holding circuit for coil 12 through the contacts 16 and stop switch 17. Starting switch 13 may thus be released. The closing of contacts 19 establishes a circuit from bus 2 through the armature of the motor M, the starting, or accelerating, resistor 18, thecontacts 19, to bus 5. The motor thus starts accelerating. Since contacts 9 are opened the time limit contactor begins to time out.

If the core 31 is selected to have a magnetic afteretiect following the curve C1 and the contactor spring 45, by means of the nut 46 on bolt 43, is adjusted to cause the contactor to drop out when the flux density is at D1 then the contactor will drop out, after deenergization of winding 8, at point CD1, or twenty units of time later. The units of time may be seconds, or minutes, but could also be hours depending on the selection of the core material for core 31.

When the time limit contactor has timed out, that is, drops out, the contacts 26 and 27 close and since contacts 20 are closed, a shunt circuit is established for resistor 18 through contacts 24 26 and 27 and full voltage is thus applied to the motor M.

The opening of contacts 9 deenergizes winding 8 of the time limit contactor TL. This means the instant the motor starts accelerating while drawing its energy through the starting resistor 18, the relay or contactor TL, begins to count time, so to speak. Twenty units of time, for example, later contacts 26 bridge the contacts 27 to thus apply full voltage to the motor. The starting cycle is thus completed.

When it is desired to obtain a timing effect from the time limit contactor TL during pick-up, then the time limit contactor may be provided with a second coil 22 on the core which second coil is arranged to be energized at any selected value within a given range depending on the adjustment of resistor R2 from the lower control voltage of leads 1t and 15, and it is otherwise designed to produce fewer ampere turns. Further, the selector switch SS is positioned to open contacts 7 and 2t and to close contacts 21 and 24. The opening of contacts 7 prevents the use of coil 8 since the circuit for this coil is now open, and the opening of contacts 20 prevents the establishment of a shunt circuit for resistor 18 by the closure of contacts 26 and 27.

For this alternate system of starting starting switch 13 is operated and the main contactor MC operates as hereinbefore discussed, and the motor starts with resistor 18 in the armature circuit, but now the closing of contacts 23 establishes a circuit from bus 11 through adjustable resistor R2, through contacts 21 of the selector switch S5, the actuating coil 22 of the the motor, the

time limit contactor TL and contacts 23 to bus 14. Since the coil 22 has few ampere turns the contactor TL begins to build up its flux rather slowly. If the build-up follows curve C3 from lower right to upper left, the contactor will not pick up until the flux has reached the point CD3. The time interval will thus be determined by the time it takes the flux to buildup from T to T with T corresponding to point CD3.

At T contacts 25 close and since contacts 24 are closed the resistor 18 is removed from the motorarmature circuit and full voltage is supplied to the motor.

Since certain changes may be made in the construction shown without departing from the scope and spirit of this invention, it is apparent that the claims hereto appended should be given the broadest interpretation. Certain changes that may be made are, for example, the selection of the entire magnetic circuit of elements of the alloy Ni Mn, or any one or combination of elements of the mentioned alloy or selecting any one of the many characteristics as C1, C2, C3, etc., for any one of the elements of the magnetic circuit.

I claim as my invention:

1. In an electromagnetic time limit device, in combination, a magnetic circuit including in the circuit the magnetic alloy Ni Mn possessing the property of a magnetic after-effect extending over a relatively long period of time, and including in the magnetic circuit a movable armature biased to an unactuated position, means for producing a magnetic flux in said circuit for a time interval to move the armature to its actuated position, whereby, after ter mination of said time inteival by reason of the magnetic after-effect the flux slowly decays in the circuit to thus release the armature to its biased unactuated position after the expiration of a selected relatively long time period after the expiration of the mentioned time interval.

2. In an electromagnetic time limit device, in combination, a magnetic circuit including in the magnetic circuit the magnetic alloy Ni Mn possessing the property of slowly decaying magnetic after-eifect after removal of a magnetizing force and including in the magnetic circuit a movable armature biased to an unaotuated position to produce an air gap in the magnetic circuit, a pair of energized electric terminals, a coil for magnetizing the magnetic circuit to eifect operation of the armature to an actuated position to substantially eliminate the air gap in the magnetic circuit, means for connecting the coil to the terminals and for disconnecting the coil from the terminals, whereby, after disconnection of the coil from the terminals the flux in the magnetic circuit slowly decays so as to release the armature to its biased unactuated position after a selected relatively long period of time.

3. In an electromagnetic time limit device, in combination, a movably mounted armature, biasing means for biasing the armature to a predetermined position, means for adjusting the biasing means, an electromagnet, including in its magnetic circuit the magnetic alloy Ni Mn heat treated to have a selected magnetic after-effect, for actuating the armature against the action of said biasing means, whereby, upon deenergization of the electromagnet, the flux in the magnetic circuit decays in accordance with the characteristics of the magnetic after-efiect to eflect positive operation of the armature to its biased position a predetermined relatively long time after deenergization of the electromagnet depending on the force of adjustment of the biasing means.

4. In an electromagnetic time limit device, in combination, an electromagnet including in its magnetic circuit the alloy Ni Mn heat treated to have a selected magnetic after-effect of certain relatively slow decay characteristics, a movably mounted armature, adjustable spring means for biasing the armature by any selected biasing force to a predetermined position, said armature being disposed to move against the biasing force of said spring to a second predetermined position upon application of a magnetomotive force to the electromagnet, whereby the armature, upon removal of the magnetomotive force from the electromagnet, will move to its biased position in a selected relatively long period of time dependent on the adjusted force of the biasing spring means and the flux decay characteristics of the magnetic circuit of the electromagnet.

5. In an electromagnetic time limit device, in combination, a magnetic circuit including a core member and an armature disposed to coact with said core member, means for biasing said armature away from said core member, a coil for producing a magnetizing force in the core member, said core member being made of the magnetic alloy Ni Mn heat treated to have a selected magnetic after-effect of a selected relatively slow flux decay characteristic, whereby said armature, upon removal of the magnetizing force from the armature moves to its biased position a selected relatively long interval of time after removal of the magnetizing force from the core, the interval of time depending on the biasing force acting on the armature and the said relatively slow flux decay characteristic selected. k v I 6. in an electromagnetic time limit device, in combina tion, a magnetic circuit including in the circuit the material N i Mn that has been heat treated to have a selected rela tiv'ely long magnetic after-effect characteristic, said mag= netic circuit also including a magnetizable movable arma ture having two operative positions, which positions may be designated an actuated position and an u'nactuated position, means for subjecting the magnetic circuit to a magnetizing effect having a magnetomotive force that may be varied from zero to any other appropriate mag nitude, whereby the armature is caused to move from one operative position to its other operative position as the flux density in the magnetic circuit, a selected time interval after a change in the magnitude of the magnetomotive force, passes through a selected fiux density.

7. In an electromagnetic time limit device, in combination, a magnetic circuit including in the circuit the mate rial Ni Mn that has been heat treated to have a selected relatively long magnetic after-effect characteristic, said magnetic circuit also including a magnetizable movable armature having two operative positions, which positions may be designated an actuated position and an unactuated position, means for subjecting the magnetic circuit to a magnetizing effect having a magnetomotive force of a relatively low magnitude, whereby the armature is caused to move from its unactuated position to its actuated position a selected time interval after application of the mag netizing efiect, the time interval being determined by the said relatively long magnetic after-effect characteristic of the material to allow the buildup of a selected flux density in the magnetic circuit to elfect the actuation of the armature.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Ferromagnetism (Bozorth), published by a NOSF' rand, 1951; pages 315-320 relied on..

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