US2364917A

US2364917A - Hysteresis compensator

Info

Publication number: US2364917A
Application number: US421179A
Authority: US
Inventors: William A Ray
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-12-01
Filing date: 1941-12-01
Publication date: 1944-12-12
Anticipated expiration: 1961-12-12

Description

Dec. 12, 1944. w A, RAY 2,364,917

V nyswsm asis COMP'ENSATOR Filed Dec. 1, 1941 4 1 I Zinventor: W/u/AM A. RAY,

(Ittorneg Patented Dec. 12, 1944 2,364,917 nrs'reassrs comrnmsa'roa William A. Ray, Los Angeles, Calif;

Application December 1, 1941', Serial No. 421,179

7 Claims.

My present invention relates to hysteresiscompensating means and particularly to such means of the type adaptedto reduce delay in drop-out" of an armature upon deenergization of its electromagnet.

In electromagneticaliy controlled devices in which an armature is attracted through a distance against a biasing force, the electromagnetic force required to move the armature through space is much greater than that then required to hold the armature in its attracted position. Thus there necessarily is a large differential between the electromagnetic force and the opposing biasing force during the attracted movement of the armature.

In control systems employing a thermoelectric generator for energization of the electromagnet,

upon failure of the means for heating the gen-- erator, current continues to flow, in a gradually decreasing amount, which current, until the' differential between the electromagnetic force and the biasing force is overcome, will be eflfective to retain the armature in its attracted posi-- tion. With such a gradual deenergization of the electromagnet, and with a large differential be-' is in its attracted position, while maintaining a It is therefore an object of this invenwill be found in the description, the drawing and the appended claims; and for complete understanding of the invention, reference may be had to the following detailed description and accompanying drawing, wherein;

Figure. 1 is adiagrammatic representation of a controlsystem embodying my invention; and

Figure 2 is a similar representation of a system embodying amodifled form of my invention.

In the drawing, the numeral Ii indicates a valve casing having an inlet l2 and an outlet I3 separated by a ported partition l4 providing a main valve seat l5. Cooperable with the seat I! is a closure member is carried by a diaphragm I! which is arranged to cover an opening in the top of the casing. The diaphragm is held at its margin between flanged portions of casing Ii and of a housing l8, secured to the casing to provide a pressure chamber l9 above the diaphragm.

For controlling the fl-uid pressure in chamber IS, .a three-way valve is provided which comprises a pair of jet members 20 and 2i. Jet member 20 is connected with the inlet l2 by a pipe 22, and jet 2! communicates with the atmosphere through a pipe 23 extending through a side wall of the housing. Cooperabie with jets 20 large differential between the forces when in its ture toward the electromagnet for increasing the armature-biasing force.

Another object is to provide, in a device of the and 2| is an armature 24, fulcrumed at a point intermediate its length'on one leg of a U-shaped electromagnet core 25 and urged by a compression spring 26 to a position wherein jet 2| is closed.

thermostat 29 to a thermoelectric generating device 30, adapted to be heated by a flame 3i of a burner 32. When the thermostat 29 is in circuit-open position, the electromagnet is unenergized and spring 26 holds armature 24 in engagetype indicated, means actuated in response to the movement of the armature toward the electromagnet for decreasing the electromagnetic.

such that-a relatively large amount of flux is employed for attraction of the armature, as when a large air gap initially exists between the armature and electromagnet, the residual magnetism may then be so great that there is a tendency for the armature to hang-up" even when the electromagnetic circuit is, abruptly opened.

Other objects and advantages of my invention the diaphragm; the parts being in the positions shown in Fig. 1.

Upon closing of the energizing circuit by the thermostat 29, the electromagnet will attract the armature 24 and move it, against the force of spring 26, to a position wherein jet 2| is open and Jet 20 is closed. The parts are so positioned that the armature closely approachesbut never actually contacts the. upper leg of the core 25, so that proper engagement of the armature with the let 2| is assured. With the armature in its attracted mitting the pressure below it to raise the dia-.

phragm against the weight of disk 33. The closure I6 is thus moved to its open position, allowing fluid to pass from the inlet I 2 to the outlet l2. Subsequent deenergization of the electromagnet will permit spring 26 to move armature 24 to the position wherein jet 2| is again closed, whereby fluid may enter chamber I! through pipe 22. As the pressures above and below the diaphragm equalize, weight I2 again forces closure member it'into engagement with its seat.

A bucking coil 34 is connected by wires 4. in parallel with the main coil 21 through a mercurytube switch 35, and is reversely wound on the core 25 to produce, when energized, a magnetic flux opposing that of the main coil but of lesser magnitude. The switch is secured on an arm 38 which is pivoted at one of its ends on a portion of the housing It, the arm being connected toward its other end with the disk 33 by a link 21.

when the closure member i6 is in engagement with its seat i 5, the arm 28, on which the switch is secured, is at such an angle that the mercury 28 is separated from the contacts 38. Thus, when the main coil 21 is initially energized, the bucking coil 34 is not energized, and the maximum force of the electromagnet is available to attract the armature 24. However, after the armature is in its attracted position, the diaphragm l1 starts to rise, as previously described, and causes the switch 35 to tilt to such an angle that the mercury flows toward the contacts and bridges the same. This causes energization of the bucking coil 34, and the magnetic flux tending to hold the armature in its attracted position is thereby reduced, but is still of suillcient magnitude to hold the armature in its attracted position against the opposing force of spring 26. It

will be seen that by thus decreasing the difleren-- tial between the electromagnetic force and the spring force, less decrease in the electromagnetic flux is required to allow the armature to dropout than would be the case with a large diilerential between these forces. The undesirable holdin" effects, produced by residual magnetism or gradual deenergization of the electromagnet, are thus overcome.

In Fig. 2 of the drawing is shown an embodiment oi my invention in which mechanical means are employed to vary the effective, or resultant, force tending to hold the armature in its attracted position. Compressed between the armature 24 and one arm of a pivotally mounted bell-crank 4| is a spring 42, constantly urging the armature away from the electromagnet. The other arm of the bell-crank is connected by a link 43 to an arm 44 which is pivotally mounted at one of its ends on a portion f the housing It. The other end of the arm 44 is in slidable engagement with the top surface of the disk 33. When the closure member I6 is in engagement with the seat i5, upon initial energization of the electromagnet the armature is moved toward the core 25 against the force of spring 42. This results in upward movement of the diaphragm, as previously described, and similar movement of the free end of pivoted arm 44. The movement of this arm is transmitted through link 43 to the bell-crank 4i which turns in an anticlockwise direction to further compress spring 42, whereby the differential between the magnetic holding force and the opposing spring force is reduced.

While I have herein shown and described, by way of illustration, specific embodiments of my invention, I wish it to be understood that modiilcations may be made without departing from the spirit of the invention, and that I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a control system: a motor movable between limiting positions; an electromagnet; an armature movable toward the electromagnet, when the same is energized, to a position wherein the reluctance of the magnetic circuit, formed by the electromagnet and the armature, is reduced; means constantly urging the armature away from the electromagnet; means actuated by the movement of the armature for so controlling the operation of said motor that it moves directly from one of its limiting positions to the other; and means for facilitating movement of the armature away from the electromagnet when the same is deenerglzed comprising means independent of the armature and controlled by the movement of the motor, in response to the movement of the armature toward the electromagnet, for decreasing the resultant force thentending to retain the armature in its attracted position.

2. In a control system': a motor, and electro magnetic means for controlling the operation of said motor; said electromagnetic means comprising an electromagnet and an armature cooperable therewith, said armature being movable toward said electromagnet when the same is energized to a position wherein the reluctance of the electromagnetic circuit is reduced, means urging the armature away from the electromagnet, and means controlled by the movement of said motor in response to the movement of the armature toward the electromagnet for decreasing the force applied to the armature by the electromagnet.

3. In a control system: a fluid pressure operated motor and electromagnetic means for controlling the operation of said motor; said electromagnetic means comprising an electromagnet and an armature cooperable therewith, said electromagnet said main coil, said armature being movable toward said electromagnet when said main coil is energized to a position wherein the reluctance of the electromagnetic circuit is reduced, means constantly urging the armature away from the electromagnet, and switching means controlled by the movement of said motor in response to the movement of said armature toward the electromagnet for connecting said bucking coil to a source of electrical energy.

4. A control system as defined in claim 1: wherein said armature-urging means is a spring; and the'means, controlled by'the movement of the motor for decreasing the resultant force tending to retain the armature in its attracted position, consists of means for increasing the-force of said spring. I

5. A control system as defined in claim 1: wherein said armature-urging means is a spring; and the means, controlled by the movement of the motor for decreasing the resultant force tending to retain the armature in its attracted position, consists of a lever mechanism so interconnecting said motor and said spring that the force of the same is increased.

. 6. In a control system: an electromagnet having a main energizing coil and a bucking coil,

said bucking coil being effective when energized to oppose and partially overcome the effect of said main coil, a thermoelectric generator for energizing said main coil, means for heating said generator, an armature movable toward said electromagnet when said main coil is energized, means urging said armature away from the electromagnet, a motor controlled by the movement of the armature, and means controlled by the movement of said motor in response to the movement 10 of the armature towards the electromagnet for assuring prompt release of the armature upon failure of said heating means, said motor-com trolled means comprising means for connecting said bucking ooil to a source of electrical energy. 7. A control system as defined in claim 1: whereinsaid motor is of the fluid pressure oper-' ated type, and the means actuated by the movement of the armature is a pilot valve.

WILLIAM A. RAY.