US2083532A

US2083532A - Electrically operated snap action modulating valve

Info

Publication number: US2083532A
Authority: US
Inventors: Carl G Kronmiller
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1933-11-11
Filing date: 1933-11-11
Publication date: 1937-06-08
Anticipated expiration: 1954-06-08

Description

June 8, 1937.

c. G. KRONMILLER 2,083,532

ELECTRICALLY OPERATED SNAP ACTION MODULATING VALVE Filed Nov. 11, 1953 2 Sheets-Sheet l 37 43 0 fjfil as an FIG. 2 Q I29 129 I 59 l I; I ae w M i I53 I e I I 20 o a? o o -n' a a I 2 O o J 2 a4 20 l8 l5 l9 25 FIG. 1. w 25 v s u 3| 44 43 awe/MM CARL G. KRONM l LLER June 8, 1937. c. G. KRONMILLER 2,033,532

ELEGTRICALLY OPERATED SNAP ACTION MODULATING' VALVE Filed Nov. 11, 1955 '2 Sheets-Sheet 2 I Illllllum. I

llllllllllllll mxllllllllllllll -'--m|m|l||Ll CARL G. KRONM I LLER Patented June 8, 1937 PATENT oFFicE ELECTRICALLY OPERATED SNAP ACTION MODULATING VALVE Carl G. Kronmiller, Minneapolis, Minn., assignor Minneapolis-Honeywell Regulator Com pany, Minneapolis, Minn, a corporation oi Delaware Application November 11, 1933, Serial No. 697,688

8 Claims.

The present invention relates to the art of positioning an instrumentality in various positions as the result of movement of a control member, usually remotely located, and has particular 5 utility in controlling the flow of fuel to a burner, such for example, as the flow of gas to agas burner.

It is well known in the art of gas burning that most gas burners can be turned down to a relatively low flame fairly efliciently and without much danger of a pop-back into the mixer, but in most cases, these burners require a considerably larger initial flow of gas in order to be successfully ignited.

One of the objects of the present invention is the provision of.electrical control mechanism for a single valve, the control mechanism being so arranged that the valve remains closed until there is a demand for apredetermined supply of 30 fluid at which time the valve is quickly opened and thereafter may be moved to an intermediate flow position if the demand decreases but is still greater than zero demand.

Another object of the invention is the provision of an electrical control system for a single valve, the control system being so arranged that'the valve remains closed until there is a predeter-' mined demand whereupon the valve quickly moves to a partially open position and may theremand increases.

While present day gas burners may be throttled down to a relatively low flame without the flame popping back into the mixer, it is still impossible to throttle such burners to a completely closed position without encountering difficulties before the valve is completely closed. It is therefore desirable to quickly close such a valve when the flow therethrough reaches a predetermined minimum.

A further object of the invention, therefore is the provision of an electrical valve control mechanism for quickly closing a single valve when the demand for fluid flow reaches a predetermined minimum.

Another object of the invention is the provision of an electrical control system for a single valve, the system being so arranged that the demand for fluid flow must reach a predetermined minimum before the valve opens and at which time the valve opens quickly with a snap movement and is thereafter opened more widely or moved to more nearly closed position according to the demands for fluid flow until a minimum flow position is Cil after be opened further automatically if the dereached whereupon the valve is snapped closed or quickly moved to closed position.

In automatic control systems, and particularly in those automatic control systems for controlling heating valves, dampers, and similar instrumentalities, it is often desirable to move the valve in one direction by one motor means and in the other direction by another motor means, the valve remaining stationary when both motor means are deenergized or, in some cases, when both are energized. In such a system, the valve will remain in the position to which it was last moved if the supply of electrical power should fail. Such a situation often gives rise to a dangerous heater condition and it is therefore desirable to include mechanism in such a system whereby the valve will move to one of its extreme positions inthe event there should be a failure of electrical power.

Another object of the present invention, therefore, is the provision of a control system for a valve, damper, or slmilarinstrumentality which moves the valve in one direction upon energization of a first motor means and moves it in another direction upon energization of a second motor means, the arrangement being such that the valve remains stationary when both motor means are equally energized or both deenergized, together with means for moving the valve to one of its extreme positions if the supply of power should be interrupted. In addition, the apparatus of this invention is so arranged that the valve can be manually moved to another position during a power failure together with means for returning the valve to automatic control upon the resumption of power and these features are likewise enrbraced by the objects of my invention.

A. further object of the invention is the provision of an improved adjustable flow proportioning port or valve for general use.

Another object of the invention is the provision of an improved mechanical snap action device of general utility.

Other objects of the invention will become apparent iroin the description, the drawings, and the appended claims.

For a more complete understanding of the invention, reference may be had to the following description and accompanying drawings, in which:

Fig. l is a side view of the apparatus comprising the present invention, there being parts in section and others broken away to show the con struction more clearly,

Fig. 2 is a stretch-out view, in perspective, of my novel flow proportioning port or valve,

Fig. 3 is a front view of the control mechanism shown in Fig. l, certain of the parts being shown in section, and

Fig. 4 is a schematic wiring diagram of the system of my invention.

Referring first to Figs. 1 and 2, a valve casing I6 is provided with an inlet port I I and an outlet port I2, there being a partition wall I3 therebetween which has a valve opening formed therein. The upper side of valve casing I is provided with an upwardly extending cylindrical extension l4 which is provided with exterior screw threads. A circular bracket I5 is provided with a lower flange I6 which is clamped against the end of tubular extension I4 by means of a collar I1. The bracket I5 is further provided with an upper flange I8 which is secured to a circular base I plate I9 by any suitable means such as the screws there being a sealing-off diaphragm 2| clamped between circular base plate l9 and flange I8 of bracket I5. The base plate I9 is provided with a circular opening 22.

A valve stem 23 is provided with an upper threaded portion 24 which passes through sealing-off diaphragm 2|, extends through circular opening 22, and terminates above base plate I9. The diaphragm 2| is secured to the upper portion 24 of valve stem 23 by suitable nuts 25 and washers 26 whereby fluid is prevented from passing to the atmosphere by way of tubular extension l4. The lower end of valve stem 23 is threaded as indicated at 21 and supports a valve disc 28 t which is received within a valve disc retainer 29,

tion 21 of valve stem 23.

the valve disc 28 cooperating with the valve opening in partition I3 to prevent the flow of fluid from the inlet through the valve opening and out the outlet I2. The lower end 21 of valve stem 23 further supports the movable member 36 of an adjustable fluid flow throttling device generally indicated at 3|. A spring retainer 32 is placed upon the lower end of valve stem 21 above the valve disc retainer 29 and these parts are all secured in their proper positions by means of nuts 33 which cooperate with thelower threaded por- A coiled spring 34 has one of its ends abutting spring retainer 32 and its other end abuts a circular disc 35 which in turn is pressed against the lower surface of flange I 6 of bracket I5. In this manner, the valve disc 28 and the movable member 36 of the flow proportioning device are normally biased to the position shown in Fig. 1 of the drawings.

Referring now particularly to Fig. 2, it will be seen that the adjustable flow proportioning device comprises a relatively stationary cylindrical member 36 which is carried by a stud 31 rotatably mounted in a nut 38 which is'threaded into the lower portion of valve casing ID. A portion of the surface of the relatively stationary cylindrical member 36 is cut away as indicated at 39. The movable member 39 of the adjustable flow proportioning device 3| comprises a cylindrical member which-is provided near its upper end with a plurality of openings 40 by means of which fluid may flow within the member 36 whenthe valve disc 28 has been raised from the valve opening in partition wall I3. The member 30 is further provided with a skirt 4| of substantially semi-circular formation. The member 30 is adapted to be received within the cylindrical member 36. By adjusting the relatively stationary cylindrical member 36, the opening 39 therein may be placed so that it will be completely covered by skirt 4| when the movable member 30 is in any of its positions including its highest elevated position and its lowermost position. The cylindrical member 36 may additionally be adjusted so that skirt 4| is located oppositely thereto whereby upon raising of member 30, the portion 42 thereof will gradu ally uncover the opening 39 in cylinder 36 to allow a variable flow of fluid through opening 39. Likewise. the member 36 may be adjusted to any desired intermediate position whereby upon raising of movable member 30, the skirt 4| thereof will maintain only a portion of the opening 39 covered. In this manner, by properly adjusting the cylindrical member 36, the amount of fluid which will flow through the opening 39 thereof for the various vertical positions of member 36 may be adjusted as desired. Stud shaft 31 is provided with screw threads 43 which receive a nut 44 by means of which the cylindrical member 36 may be secured in any desired position of adjustment and preferably a cap 45 cooperates with threads formed on nut 38 to prevent the passage of fluid from within the casing II] to the atmosphere through the hole in the nut 38 which receives the stud 31. The end of stud 31 is preferably slotted as indicated at 46 to facilitate adjusting of cylindrical member 36.

By means of this arrangement, when valve stem 23 is initially elevated, the valve disc 28 uncovers the valve opening in partition wall I3 and upon continued elevation of valve stem 23, a variable amount of fluid flow through the valve casing I0 is permitted, the amount of fluid flow depending upon the adjustment of cylindrical member 36.

Referring particularly now to Figs. 1 and 3, the base plate I9 supports a pair of side plates 50 and 5| which extend upwardly from the base plate I9 and support an upper horizontal frame plate 52. A pair of spaced brackets 54 are secured to the upper surface of frame plate 52 and extend upwardly therefrom. These brackets 54 journal a stud shaft 55 upon which is mounted a pair of links 56 that extend across the frame plate 52. The opposite ends of links 56 are secured together by a pin 51 which extends outwardly to receive one end of a link 58, the other end of link 58 being connected to the upper end of valve stem 23 by means of a nut 59. The pin 51 also journals a roller 69 which is located between the pair of links 56. A vertically movable actuating rod 6| is located between plates 59 and 5| and is provided with a reduced portion 62 whereby a shoulder 63 is formed against which one end of a coiled spring 64 abuts, the other end of coiled spring 64 abutting the under surface of frame plate 52 whereby the actuating rod 6| is normally biased to move downwardly. In the device as built, the rod 6| extends downwardly into engagement with the base plate I9 whereby the amount of downward movement of .rod 6| under the bias of spring 64 is limited so that the extreme lowermost position of the rod 6| corresponds with the position shown in Fig. 3 of the drawings. The reduced portion 62 of rod 6| extends through frame plate 52 and a guiding collar 65 secured thereto, extends upwardly between links 56, and terminates thereabove in a threaded portion'66 which-receives a threaded washer 61 and a locking nut 68. A combination tripping member and spring retainer 69 is adjustably secured to the reduced portion 62 of actuating rod 6| at a point slightly above collar 65 and considerably below the links 56. The lower end of a coiled spring 16 rests upon spring retainer 69 and the upper end thereof holds projections 1| of a collar 12, which is slidably received on reduced portion 62 of actuating rod 6|,

just below suitable notches 13 formed in links 56.

From the construction so far described, it will be apparent that upon upward movement of actuating rod 6|, the links 56 will be rotated in a counter-clockwise direction as viewed in Fig. 3

about the stud 55 whereupon the pin 5'! will raise valve stem 23 by means of connecting link 58 whereby to lift valve disc 28 to uncover the valve 10 opening in partition wall l3 so that the valve disc 28 and movable member 30, in the absence of the mechanism which is to be described hereinafter, will be raised and lowered in ,exact accordance with the upward and downward movements of actuating rod 6|.

The frame plate 52 supports a second pair of brackets 15 which extend upwardly therefrom. A shaft 16 extends through an insulating panel H secured to plate 52 and is journaled in the lower portions of brackets 15. A combined locking and tripping member 18 located between brackets 75 is secured to shaft 16. This locking and tripping member 18 comprises a bell-crank, one arm of which is formed into a hook 19 which is adapted to engage the upper surface of roller and restrains upward movement of the links 56. The other arm of the locking and tripping member it is provided with a surface 80 which is in the path of upward movement of spring retainer and the end of this arm is formed with a concave surface ill for a purpose which will appear hereinafter. A spring 82 which is coiled about shaft 16 has one of its ends engaging one of the brackets 15 and itsother end engaging the latching and tripping member 18 to normally bias the same to the position shown in Fig. 3 of the drawings wherein the hook i9 is engaged with the roller 6!].

Near the upper ends of bracket 15 is journaled a stud shaft 84 on which is pivotally mounted a second latching and tripping member 85 which takes the form of a bell-crank having one of its arms formed in a hook 86 which is adapted, under certain conditions to be hereinafter set forth in detail, to engage the lower surface of roller 60 and prevent clockwise rotation of links 56. The other arm of the bell-crank which comprises the latching and tripping member 85 comprises a trip 8i! which extends beneath the washer 6'! and lies in the path of downward movement thereof. A coiled spring 88 is coiled upon a reduced portion of stud shaft 54 and has one of its ends bent around one of the brackets i5 and its other end bent around the tripping arm M of latching and tripping member 85 whereby this latching and tripping member is normally biased to assume a position wherein its hook 86 engages the under surface of roller 6i}.

An insulating panel 'l'ii supports a pair of flexible switch arms W and iii, the switch arm 96 carrying a contact 92 upon its upper surface and the switch arm 98 carrying a contact 93 upon its lower surface. Contact 92 is normally biased into engagement with a contact 95 which. is carried by a bracket 95 secured to insulating panel ill and in a similar manner, contact 93 is normally biased into engagement with a contact 96 carried by a bracket 57? secured to insulating panel ii. The pin 57 has an extended end which lies between flexible switch arms 96 and .ii and when the links 56 are in valve closing position as shown in Fig. 3 of the drawings, this extended end of pin 5? engages switch arm 96 to move contact at from engagement with conment with its cooperating contact I02.

tact 94. As links 56 are rotated in a counterclockwise direction, the extended end of pin 57 first allows switch arm 90 to move upwardly under its bias whereupon contact 92 engages contact 94. Upon continued rotation of links 56 in a counter-clockwise direction, the extended end of pin 51 moves away from switch arm 90 and when the links 56 have rotated to a position corresponding to a full opening of the valve, the extended end of pin 5'! engages switch arm 9i and raises the same to move contact 93 from engagement with contact 96. The switches 92-414 and 9396 comprise limit switches as will become evident hereinafter.

The insulating panel 11 also supports a second switching mechanism which comprises a switch arm i 00 that carries a contact l0| which normally engages a contact I 02 carried by a bracket I03 secured to panel TI. This switching mechanism also includes a flexible switch arm Hi4 which carries a contact I5 that is normally biased to disengage a contact I06 carried bya flexible switch arm Hi1. Associated with the switch arm I00 and engaging the underside thereof is a strip of insulating material I08. The switch arm I00 is provided with an actuating pin I09. Similarly, a strip of insulating material H0 is associated with switch arm In! and engages the underside thereof. The shaft 16 is provided with an actuating stud III which, upon proper manipulation of shaft 16, engages insulating strip Hi8 and raises switch arm Hill to move contact llli from engage- Such upward movement of switch arm I00 causes its actuating pin Hill to press upwardly upon insulating strip H0 whereupon Switch arm in! is raised to move its contact I06 into engagement with the contact I05 carried by switch arm I04.

Now with the parts shown in Fig. 3, as actuating rod Si is moved upwardly, links 56 are restrained from counterclockwise rotation by reason of engagement of hook 19 with the upper surface of roller 60. The compression. spring H3 is thereby compressed and the spring retainer 69 bears against the surface of latching and tripping member it. As actuating rod 6i continues its upward movement, the hook l9 gradually moves from engagement with roller 65 and after actuating rod M has moved upward- 1y asufiicient amount, the compression spring ill will rotate links 56 in a counterclockwise direction with a snap movement because the same have been released for such movement by hook iii passing ofi the roller 6t. At this time, the coiled spring 86 swings latching and tripping member about stud shaft 86 in a clockwise direction to bring hook 86 underneath roller til. This movement of links 56 has carried the end of extended pin 5i from engagement with switch arm til, whereupon contact 92 engages contact 9 1. It will therefore be seen that the valve remains closed during initial upward movement of actuating rod 6i and when this rod has moved upwardly a predetermined amount, the valve is snapped open to an intermediate position, corresponding to the amount of upward movement of actuating rod 5i. The position of rod (ii at which hook it will disengage roller 66 may be varied by changing the position of spring retainer 69 upon the reduced portion 62 of rod 6i. The valve now having been opened, it will thereafter be moved strictly in accordance with the movements of actuating rod 6i and if the actuating rod 5i moves upwardly sufficiently far to move the valve to full open position, then the extended end of pin 5? will engage switch arm 9I to disengage contact 93 from contact 96. When the actuating rod 6I during downward movement has reached such a position that the valve is placed in aposition wherein the desired minimum flow of fluid is permitted, projection 11 will have moved out of notches 13 and the washer 61 will have engaged trip 81 to begin moving hook 86 from beneath roller 60. Upon further slight downwardly movement of actuating rod 6I, the hook 86 will be moved from beneath roller 60 sufficiently to allow coiled spring 34 to rotate links 56 in a clockwise direction with sufficient force to snap the valve closed and, at this instant, the coiled spring 82 will rotate latch- 15 ing and tripping member 18 to the position shown in Fig. 3 wherein its hook 19 again engages the upper portion of roller 60. The valve is thereby again latched in closed position and can only be reopened after actuating rod 6I has again been 20 raised to a position wherein hook 19 disengages roller 60. The minimum flow position at which the valve is snapped closed by disengagement of hook 86 from roller 60 may be adjusted by adjusting washer 61 and locking nut 68 in respect to the end 66 of actuating rod 6I.

The lower end of actuating rod 6I is provided with teeth II5 which mesh with a pinion II6 secured to a main operating shaft II1 that is journalled in plates 50 and 5I. The main operating shaft II1 carries a balancing contact finger II8 which engages a resistance I I9 and sweeps thereacross upon rotation of main operating shaft H1 in a direction to raise actuating rod 6|. Main operating shaft II1 also carries a gear I20 which is located between side plates 50 and SI and meshes with a pinion I2I. Pinion I2I is secured to a gear I22 which is secured to a shaft I23 journalled in side plates 50 and 5I Gear I22 meshes with a pinion I24 which is formed integral with a sleeve I25 loosely journaled upon a shaft I26 mounted in side plates 50 and SI. Loosely mounted on sleeve I25 is a pinion I21 to which is secured a locking disc I28 that is provided with a plurality of notches I29. Pinion I21 meshes with a pair of pinions I30 which are mounted on stud shafts I3I carried by a gear I32 near the periphery thereof. Secured to the extended hubs of pinions I30 are a pair of similar pinions I33 but the pinions I33 are provided with a slightly smaller number of teeth than the pinions I30, the pinions I30 preferably having one more tooth than the pinions I33. The pinions I33 both mesh with a pinion I34 which is secured to the sleeve I25 whereby pinions I24 and I34 are connected together and a rotate in unison. The pinion I21 has the same number of teeth as the pinions I33 and the pinion I34 has the same number of teeth as the pinion I30 so that in the example herein described, the

pinion I34 has one more tooth than the pinion I21.

The gear I32 meshes with a pinion I35 which .is

secured to a shaft I36 journaled in side plates 50 and 5|. Secured to the shaft I36 is a gear I31 which meshes with a motor pinion I38 carried by the rotor shaft I39 of a motor I40 which has a 65 rotor HI and afield winding I42. Similarly, a

gear I43 which is secured to shaft I36 meshes with a motor pinion I44 which is secured to the rotor shaft I45 of a motor I46 having a rotor I41 and a field winding I48. A magnet I50, mounted upon base plate I9,

is provided with a field winding ISI and a pivoted armature I52. latching member I53 which is adapted to enter any one of the notches I29 in disc I28 to prevent rotation of the same when the field winding I6I Pivoted to the armature I52 is a of magnet I50 is energized. A spring I54 is preferably interposed between armature I52 and latch I53 whereby the same are resiliently connected.

Referring now to Fig- 4 of the drawings, the system is shown as being controlled by a movable member I60 which is adapted to sweep across a resistance I6I. The movable member I60 is herein shown as controlled by a bimetallic element I'62 which preferably responds to the temperature of the space being heated as the result of a flow of fluid through valve casing III but it is to be expressly understood that the movable member I60 may be controlled in accordance with any condition other than temperature or in any other desired manner. Associated with resistances H9 and I6I is a pair of solenoid coils I63 and I64 which are connected in series, their junction being indicated at I65. The solenoid coils I63 and I64 conjointly control the position of a plunger I66 which is connected to a flexible switch arm I61 through a rod I68 and a light coiled spring I69. Switch arm I61 carries con tacts I10 and HI which are adapted to cooperate with relatively stationary contacts I12 and I13.

If the valve of the instant invention is used in connection with a heating or similar device, it is preferred to utilize a limit control of wellknown construction indicated at I14 which opens the circuit when some condition of the heating system becomes excessive. Low voltage electrical power is supplied by the low voltage secondary I 15 of a step-down transformer I16, having a high voltage primary I11 suitably connected to the usual line wires. The relay winding I5I is connected across the secondary I15 through the limit control I14 by means of wires I18, I19, and I whereby the relay winding I5I is normally constantly energized. Similarly, the solenoid coils I63 and I64 are connected in series across transformer secondary I15 through limit control I14 by wires I18, I19, I8I, I82, I83, I84 and I80. Resistances H9 and I'6I are connected in parallel with the series connected solenoid windings I63 and I64 through protective resistances I85 and I86 and through the switch IOII 02 by wires 202, I81, I88 and I89. Balancing contact finger II8, movable member I60, and the junction I65 of solenoid coils I63 and I64 are interconnected by wires I90, I9l and I92. Contact I13 is connected to a small number of turns of solenoid coil I63 by a wire- I93 and contact I12 is connected to a small number of turns of solenoid coil I64 by a wire I94. Switch arm I61 is connected to switch arms and 9I by means of a wire I95. One end of field winding I42 is connected to contact 96 and the other end thereof is connected to one side of secondary I15 by wires I98, I84 and I80. One end of field winding I48 is connected to the other side of secondary I15 through limit switch I14 by wires I99, I8I, I19 and I18. The switch I05-I06, which is normally opened, is connected to shunt the limit control I14 by means of wires 200 and 20I.

Operation With the parts in the position shown in the various figures of the drawings, the temperature equally energized. Plunger I66 is therefore in a central position wherein contacts I10 and I" are disengaged from their respective cooperating contacts I12 and I13. Limit switch 9294 is open and both field windings I42 and I48 are deenergized. The limit control I14 is closed and electrical power is available as indicated by the attraction of armature I52 whereby the latch I53 is positioned in one of the notches I29. As the result, disc I29 and the attached pinion I21 are prevented from rotating.

Since no heat is being supplied to the space to be heated, it is evident that the temperature thereof will soon begin to fall and this fall in temperature will be accompanied by a slow movement of movable member I60 along resistance I6I towards the left hand end thereof. A very small movement of movable member I60 in this direction rearranges the effective resistances connected in circuit with solenoid coils I63 and I64 in such a manner that solenoid coil I64 will become more highly energized than solenoid coil I69. Plunger I66 will therefore move to the right firmly into engagement with contact I12.

tact I12 whereby an energizing circuit forfield winding I42 is established as follows: secondary I15, wire I10, limit control I14, wire I19, wire I8I wire I92, a small number of turns of solenoid coil I64, wire I94, contact I12, contact I10, switch arm I61, wire I95, switch arm 9I, contact 93, contact 96, field winding I42, wire I98, wire I84, and wire I to the other side of secondary I15. The current fiow through the small number of turns of solenoid coil I64 brings contact I10 more gization of field winding I42 causes rotor I M to rotate in a clockwise direction as viewed from the left in Fig. 3 so that the gear I32 is likewise rotated in a clockwise direction. The studs I3I are therefore rotated about shaft I26 in a clockwise direction and carry the pinions I30 and I33 with them in the same direction. Inasmuch as pinion I21 is held stationary and because the pinions I33 have a lesser number of teeth than. the pinions I30, the pinions I34 and I24 will slowly rotate in a clockwise direction. Gear I22 is therefore driven in a counter-clockwise direction and gear I20, pinion M6 and main operating shaft H1 in a clockwise direction whereupon actuating rod III is raised slowly and balancing contact finger M9 slowly moves along balancing resistance IIII toward the right hand end thereof as viewed in Fig. 4. As balancing contact finger II8 moves along balancing resistance II9, the effective resistance connected in circuit with solenoid coils I93 and I94 will be slowly changed until the current flow through solenoid coil I63 is so proportioned in respect to the current flow through solenoid coil I64 and the small number of turns thereof that plunger I55 will be returned to its central position to separate contacts I10 and I12 and deenergize field winding M2. This small upward movement of actuating rod I6I compresses coiled spring 10 slightly inasmuch as links 56 are held stationary by engagement of hook 19 With roller I30.

In this manner, as the space temperature falls, the movable member I50 slowly moves along resistance I91 towards the left end thereof and actuating rod 91 will be slowly raised in small increments. When the space temperature has dropped to a point demanding a flow of fuel which beforehand has been predetermined as being suificient to'properly support combustion, hook 19 will be tripped from roller I50 as heretofore Enerexplained and the valve will snap open to a posi-- from engagement with switch arm 90 and al-' lows contact 92 to move into engagement with contact 94. If contacts I and I12 are still closed, or the next time they are closed as the result of further fall in space temperature, it will be noted that the small number of turns of solenoid coil I64 will be connected in parallel with field winding I 49 and the full flow of current through these parallel circuits will traverse field winding I42. In this manner, after closing of limit switch 92-94-, field winding I42 will be more highly energized than field winding I48 whenever contacts I10and I12 are closed. The torque exerted by rotor MI is therefore greater than the torque exerted by rotor I41 and the actuating rod 6| will be raised. Whenever contact I10 separates from contact I12, the field windings I42 and I48 will be connected in series across transformer secondary I and through limit control I14 by a circuit as follows: secondary and wire I80 to the other side of secondary I15 so that the torques produced by rotors MI and I41 are equal and actuating rod BI remains stationary, it being noted that the drives through the. planetary gearing comprised by gear I32 and the associated pinions is an irreversible drive.

If there is a further drop in the space temperature accompanied by movement of movable member I60 along resistance I6I towards the left end thereof, rod 6| will be moved upwardly a corresponding amount and the valve will be more widely opened. If the space temperature should drop to such a point as to demand a full flow of fuel so that the valve is opened to its wide open position, then the extended end of .pin 51 will engage switch arm III to separate contacts 93 and 99. When this happens, the series circuit throughfield windings I42 and I49 is broken and all circuits for field winding I 42 are broken so that field winding I42 cannot be energized when the, valve. is in wide open position.

Whenever the space temperature rises, the reverse action takes place. In other words, movable member I60 slowly moves along resistance I6I towards the right hand end thereof and such movement changes the eifective resistance connected in circuit with solenoid coils I09 and IM to unbalance the current flows therethrough, but in this instance, the current flow through solenoid coil I63 becomes greater than the current flow through solenoid coil I99. Plunger I99 therefore moves to the left to bring contact I'II into engagement with contact I13. If, at this time, limit switch 0i96 is open, a circuit through field winding 1% will be established as follows: secondary I15, wire limit control I141, wire I19, wire I01, wire' I99, field winding I40, contact 94, contact 92, switch arm 99, wire I95, switch arm I91, contact I11, contact I13, wire I99, a small number of turns of solenoid coil I93, wire I33, wire and wire to the other side of secondary I15. If the vane is not in its full open position so that limit switch 93-915 is closed, the field winding I 42 will be in parallel with the small number of turns of solenoid coil I69 with the result that field winding will be more highly energized than field winding I42. In

either event, rotor I41 will turn in a counterclockwise direction as viewed from the left in Fig. 3 so that gear I32 is likewise rotated in a counter-clockwise direction and actuating rod 6I is moved downwardly at a slow speed. Balancing contact finger H8 is therefore slowly moved along balancing resistance H9 towards the left end thereof. As heretofore explained, the current flow through the small number of turns of solenoid coil I63 will exert an additional pull on plunger I66 so as to hold contact I1I in firm engagement with contact I13.

Movement of balancing contact finger II8 along balancing resistance II9 toward the left end thereof will again change the effective resistances connected in circuit with solenoid coils I63 and I64 to return the plunger I66 to its central position after actuating rod 6| has been moved downwardly sufficiently to position the valve in accordance with the new demand for heat. When plunger I66 returns to its central position, contact I1I will separate from contact I13 so that field windings I42 and I48 will be placed in series across secondary I15 so that they are equally energized and further rotation of rotor I41 ceases.

The valve will now be opened and closed in small increments in accordance with fluctuations in the space temperature and this action will continue until such time as the demand for heat bcomes so low as to cause the valve to be positioned to deliver such a small fiow of fuel that there is danger of a pop-back or of the fires going out at which time trip 81 will be engaged by washer 61 to trip hook 86 from beneath roller 60 and the valve will snap shut, the mechanical parts returning to the position shown in the drawings.

From the foregoing description, it will be ob served that the mechanism of the present in vention provides means whereby a single valve is snapped open to a minimum flow position required for proper ignition upon an initial demand for heat and is thereafter modulated or positioned in small steps in accordance with changes in the demand until the demand becomes so low as to require such a small flow of fuel that there is danger of a pop-back, the fires going out, etc., whereupon the valve automatically snaps closed and cannot again be reopened until there is a demand which corresponds to the minimum initial flow which has been determined as necessary for proper ignition.

In the event that the supply of electrical power should fail while the valve is in any of its open positions, relay winding I5I will be deenergized whereupon armature I52 is no longer attracted to hold latch I53 in one of the notches I29. Disc I28 and associated pinion I21 will be thereupon freed for rotation. This allows the planetary gear mechanism to rotate freely and the combined actions of coiled springs 64 and 34 return the mechanical parts to the position shown in the drawings wherein the valve is latched closed. This same action will occur in the event that some condition in the heating system. to which the limit control I14 responds becomes excessive so as to open limit control I14.

It is often desirable to open the valve and latch it open by manual operation in the event the same closes by reason of a failure in electrical power. Referring to Fig. 1, it will be noted that base plate II9 supports a bracket 205 on which is pivoted a lever 206, the inner end of which embraces valve stem 23. The valve may be opened by deshunts limit control I14.

pressing the outer extended end of lever 206 and may then be latched open by rotating shaft 16 in a clockwise direction as viewed in Fig. 3 so as to move hook 19 from the path of roller 60 and bring concave surface BI of the latching and tripping mechanism 18 underneath roller 60. Such operation of shaft 16 causes actuating stud I II to engage insulating strip I08, as heretofore explained, thereby separating contact IOI from contact I02 and moving contact I06 into engagement with contact I05. Separation of contacts IOI and I02 disconnects the right hand ends of resistances H9 and I6I from the right hand end of solenoid coil I64 and closure of contacts I05 and I06 Therefore, upon the resumption of power and irrespective of the condition of limit control I14, a circuit will be completed through solenoid coil I64, the circuit thereafter branching and parts of it going through solenoid I63, resistance I6I, and resistance I IE! to the other side of secondary I15. The plunger I66 therefore moves to the right and brings contact I10 into engagement with contact I12 to energize field winding I42 as heretofore explained, whereupon the valve will be more widely opened, lifting roller 60 from the concave surface BI and allowing coiled spring 62 to return the latching and tripping arm 18 to move from latching engagement and in so doing rotate shaft 16 at least sufiiciently to allow contacts IOI and I02 to reclose and contacts I04 and I06 to reopen, whereupon the system is returned to automatic control.

It will therefore be additionally noted that the present invention provides for the positioning of an instrumentality such as a valve by oppositely acting motor means, the valve remaining in the position to which it has been moved whenever the motor means are equally energized (or both deenergized) together with means whereby the instrumentality returns to some desired position upon the occurrence of a failure of electrical power and in addition, means are provided whereby the instrumentality may be manually placed in some desired position and upon the resumption of power, the instrumentality will again be automatically placed under automatic control.

While a specific embodiment of the invention has been herein described, it is evident that those skilled in the art can make many changes therein without departing from the invention and I am therefore only to be limited according to the scope of the appended claims.

I claim as my invention:

1. In combination, a flow controlling element, a control member movable back and forth along a predetermined path of travel, reversible motor means, circuits for operatively energizing said motor means, switching mechanism in control of said circuits, connections between said member and switching means for controlling said switching means, an instrumentality to be controlled, connections between said motor means, switching means and instrumentality, electrical means constantlv connected to a source of electrical power for releasing said instrumentality for return to a given position independently of said motor means upon a failure in electrical power, a manual operator for moving said instrumentality to some other position independently of said motor means and latching it therein, and switching means for returning said instrumentality to the control of said motor means upon the resumption of power.

2. In combination-a, flow controlling element, reversible electric motor means in control thereof,

electrical means constantly connected to a source of electrical power for allowing said element to move to a predetermined position independently of said motor means upon an interruption in the supply of electrical power, a manual operator for moving said element to another predetermined position independent of said motor means, and manually operable switching means associated with said motor means for returning said element to the control of said motor means upon the resumption of power.

3. In combination, a single fluid flow controlling element, a member movable back and forth along a predetermined path of travel in response to changes in fluid flow demand, an electrical control system associated with said movable member and fluid flow controlling element for normally gradually moving the latter from closed to open position as the movable member moves from one of its extreme positions to the other of its extreme positions, and means associated with said electrical control system for maintaining said fluid flow controlling element in its closed position until said movable member reaches an intermediate point in its path of travel during movement in opening direction at-which time said element is quickly moved to an open position corresponding to the position of the movable member and for moving said fluid flow controlling element to closed position when said movable member reaches a second position during movement in closing direction, said second position lying between said first position and the extreme position corresponding to closure of said fluid flow controlling element.

4. In combination, a single valve biased to rence of a failure in electrical power, and means for manually moving said valve to an open position and for returning said valve to the control of said electrical means upon the resumption of power irrespective of the position of said movable member.

5. In combination, a valve biased to closed position, a member movable through a predetermined range in response to changes in flow demand, means including an electrical operator for quickly moving said valve from closed position to an intermediate open position only after said movable member has moved to a position requiring a substantial fluid flow and for thereafter opening the valve in small increments as the movable member continues its movement in the same direction, said means allowing the valve to move to closed position upon the occurrence of a power failure, and means for manually latching said valve in an open position during a power failure and for returning the same to the control of said movable member upon the return of power irrespective of the position of said movable member when power returns.

6. In a fluid flow regulating system, a main shut oif valve, throttling means operatively supported and controlled by said shut off valve for graduating said fluid flow supply, actuating being operative upon continuous movement of said element'from one of its extreme positions to cause said actuating means first to move quickly said valve to a predetermined partially open position wherein a minimum amount of fluid flow is permitted and then to move said valve and consequently said throttling means to a position in which said throttling means is effective to permit a flow substantially corresponding to the position of said element, ind means for adjusting the minimum amount of flow permitted when said valve is in its predetermined partially open position without varying said partially open position.

' 7. In a fluid flow regulating system, a main shut off valve, throttling means operatively supported and controlled by said shut off valve for graduating the fluid flow supply, a valve casing housing said main shut off valve and said throttling means, actuating means for actuating said shut off valve, said actuating means being located on said valve casing, and control means for said actuating means, said control means comprising an element variably positioned in accordance with the fluid demand and being operative upon continuous movement of said element from one of its extreme positions to cause said actuating means first to move quickly said valve to a predetermined partially open position wherein a minimum amount of fluid flow is permitted and then to move said valve and consequently said throttling means to a position in which said throttling in response to changes in fluid flow demand, said member being located at a substantial distance from said motor, a control system for said fluid flow controlling element employing said power flow controlling member as a means for controlling said system and said power operated motor as the actuating means for the system, said control system being effective upon movement of said power flow controlling member from one of its extreme positions in one direction to cause said fluid flow controlling element to remain in closed position until said power controlling member reaches a first intermediate position in its path of travel, then to move quickly to an intermediate partially open position, and thereafter to move gradually to a position corresponding to the position of the controlling member, and said system being effective upon movement of said power flow controlling member in the opposite direction to cause said fluid flow controlling element to move gradually towards closed position in accordance with the position of said controlling member until said fluid flow controlling element reaches a predetermined partially closed position and to thereafter move quickly to full closed position, said partially closed position lying between said partially open position and full closed position.

CARL G. KRON MILLER.