US2325103A - Fluid-pressure-actuated regulating system - Google Patents

Description

July.27,-1943. c. w. BRISTOL FLUID-PRESSURE-ACTUATED REGULA'IING SYSTEM med Nov; 15, 1937 3 Sheets-Shut 1 7 INVENT OR. 624 RL To/vWBR/s TOL ATTORNEY.

y 1943- c. w. BRISTOL I 2,325,103

FLUID-PRESSURE-ACTUATED REGULATING SYSTEM Filed Nov. 15, 1937 5 Sheets-Sheet 2 INVENTOR. CARL 701v WBms TOL July 27, 1943.

5 c. w. BRISTOL FLUID-PRESSURE-ACTUATED REGULATING SYSTEM Filed Nova 15, 1937 3 Sheets-Sheet 3 1N VENT OR. CARLTONWBmsroz.

Patented July 27, 1943- MTED STATES PATEar o FLUm-PaEssoaE-Ac'rm'ran nncumrme srs'rEM Carlton W. Bristol, Naugatuck, Conn., asslgnor to The Bristol Company, Waterbury, Conn., a corporation or Connecticut Application November 15,1931, Serial No. 174,609 '5 Claims. (Cl. 236-82) the basic controland subsequently be gradually withdrawn, until, under steady-state conditions, the basic control alone is effective. A control of this nature is well exemplified in U. S. Letters Patent No. 2,005,773, issued June 25, 1935, to Luis de Florez. Herein, the basic control is effected by means of a principal bellows member, and the auxiliary control by means of a pair of mechanically opposed bellows members, one of which responds simultaneously with the principal bellows, and the other is subject to a time delay, as determined by a constriction in a conduit supplying fluid pressure thereto. A regulating valve is made subject to the joint influence of these two elements of the control system by means of a floating lever,

In constructions of this nature, where the 0pposed motor members are in communication with the pressure fluid by which control is effected, the pressure must usually be above atmospheric, with the result that any leak which may develop in the system will result in the escape of pressure fluid and a consequent disturbance of the control function. In other forms, in which the opposed motor members are tightly sealed, it is necessary to provide special compensating means to eliminate the effects of changes in temperature of the sealed-in fluid.

In any case wherein bellows membersare utilized in direct opposition the arrangement does not make for flexibility in design nor for ready adjustment; and the stresses set up under operating conditions necessitate the use of stifi and heavy parts quite incompatible with the required delicacy of performance.

It is an object of this inventionto provide for 1 readily to the utilization of either an elastic fluid or an incompressible fluid in the auxiliary control means.

A still further object lies in the provision of auxiliary control means of this class, which shall be readily adaptable to electrical, as well as to pneumatic, basiccontrol.

The invention has for another object to facilitate flexibility in the design and operation of regulating systems of this class.

Still another object lies in the provision of a design which shall be at once simple, light in weight, and inexpensive to construct and-adjust, and which shall be readily adaptable to quantity production methods.

In the proposed control system, the time-delay element makes use of a fluid normally at atmospheric pressure. This may be atmospheric air, or it may be an incompressible fluid in communication with the atmosphere. Actual operation of the auxiliary control is effected by a single bellows member which first responds simultaneously with the basic control action, and then gradually withdraws its effect at a rate depending upon the extent of the initial response. The internal system, being in communication with the atmosphere, is not subject to adverse nating the undesirable effects of stiflness and inertia inseparable from bellows members having relatively thick metal walls.

The nature of the invention, be understood when described in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation or a pneumatic control system embodying the invention, and particularly adapted tothe regulation of temperature in an enclosed space by the control of the flow of a heating agent, such as steam, thereto.

Fig. 2 shows to an enlarged scale a section oi a three-way valve adapted to use in such a system.

Fig. 3 is a diagrammatic view of an alternative form of pneumatic control system embodying the invention.

Fig. 4 is a detail view of an element of mechanism adaptable to use in such a system.

however, will best Fig. 5 is a view of a portion of a control sys-' tem embodying the invention, the system being particularly-adapted to the use of a non-elastic fluid in certain elements of the mechanism.

Fig. 6 is a detail sectional view of a part of an alternative mechanism incorporating the invention.

Fig. 7 is a view of an element of mechanism particularly adapted to use in conjunction with the embodiment shown in Fig. 6.

Fig. 8 illustrates a simplified form of the invention.

Fig. 9 illustrates the adaptation of electrical motion-transmitting means to a pneumatic control embodying the invention.

Fig. 10 shows diagrammatically an electrical temperature-regulating system incorporating the invention.

-Fig. 11 shows a simplified form of the electrical embodiment of the invention.

Referring to Fig. l of the drawings, iii desig= nates a closed vessel or chamber in which it is desired to maintain by the admission of a suitable heating agent, such as steam, through a pneumatically-operated direct-acting regulating valve ii, a predetermined constant temperature, as determined by a sensitive bulb ii. The latter contains an expansible or volatile fluid and forms a part of a closed system including a capillary tube i3 and a Bourdon spring It carried by a mounting plate E5. The regulating system of which the above-mentioned elements comprise coacting units may be of the class set forth in U. S. Letters Patent No. 1,880,247, granted October 4, 1932, and is subject to certain modifications hereinafter to be set forth.

A three-way valve iii of the supply-and-waste type, fixed to the base or mounting plate iii, is adapted to receive fluid under pressure, such as air, from a constant pressure source it, and to control the outgoing pressure of the same. To this end, the valve i8 is arranged to be opera= tively actuated by a bellows member t8, also aihxed to the base iii, in such a sense that in crease of fluid pressure within said bellows memher will cause the valve to lower the pressure or" air delivered by the same, and vice versa. .Bei-= lows member I8 is placed in communication the constant pressure source by a conduit having therein a constricted portion Connected to the conduit it is a stationary orifice member 26, having double-opposed jets, substantially as set forth in the above-mentioned Letters Patent No. 1,880,247. A vane member is adapted to swing through a limited angle 1 tached to an extension or the vane member 22 is the mid-point of a floating lever 26; and the up per extremity of this lever, as shown in the diagram, is attached by a linl: to the Bourdon spring it.

Communicating with the outlet side of the three-way valve it is a conduit 2%, providing a resilient collapsible bellows member 29, the space within the chamber and exterior to the bellows being directly in communication with the conduit 26. A resilient bellows member 38 fixed at one end to the base-plate I5 has its interior space in free communication with the interior space of the bellows member 29 by means of a conduit 3i. The free end of bellows member 31) is attached by means of a link 32 to the lower end of the floating lever 24, the relative disposition of these parts being such that the line of actionof the link 32 passes through the axis 23, and with the bellows member iii! in a state of repose, the point of attachment of the link 32 to the floating lever 26 will lie upon said. axis. Tapped ofi the conduit 8i is a bleeder or vent 33 to the atmosphere, the same having interposed therein a constricted portion, which may take the form of a throttling valve 35. There may also be connected to the conduit 35 a stationary chamber 35 having its internal volume adjustable, as by a piston 35 adapted to be positloned by a manually operable screw member 87?.

The internal arrangement of the three-way valve i6 is shown diagrammatically in Zlg. 2. A body member 38 has internally located therein two opposed conical seating surfaces and Mi, either of which may be engaged by a bah direct connection to the diaphragm top of the any conduit or associated apparatus connected to the outlet port, and, being well known in the art of pneumatic control, here demands no further elucidation. i

Operation of the control system as shown in Fig. i. may be described as follows: Assume there first to exist a steady-state condition, in which the supply of heating'agent through the valve it is exactly equal to the demand in order to maintain the temperature at the predetermined value. The Bourdon spring E 3 will serve to position the upper end of the lever 26 in accord ance with this value. The system. being equilibrium, the pressure in conduit 26 xvi; 2 steady, and the interiors of bellows members and 3d will assume the pressure or the 812E phere, with which they in communication through the conduit 3i and the vent Bellows member at will assume a position of repose as determined by its resiliency, and, through the link 32, will position the lower end of the lever 28, so that the point of attach; 532 to the lever 25 will lie on the a about which swings the vane member The vane wili thus be given in relation to the orifice M a definite optimum position corresponding to a stead -state condition in control system.

Consider now a condition which the tern perature under regulation manifests a tendency to rise. This will be refiecmd in an increase in fluid pressure within the bulb it? and the Bourdo'; spring i l, and a consequent deflection of upper end of the floating lever 2% toward the right, whereby the vane 22 will be deflected away," from the orifice member 25, permitting an im creased escape of air from the same and causing the pressure of air in the conduit it], as limited by flow through the constriction 226i, to be lowered, with a corresponding axial shortening of the bellows member l8 and a movement of the valve it in a sense to increase air pressure in the conduit 28 and all members communicating therewith, The immediate result of the increased pressure in conduit 25 is to cause the valve II to close and decrease the flow of heating agent to the space within the chamber In, thus tending to compensate for the original tendency toward rising temperature. During this part of the cycle, the lever 24 may be considered as swinging about the point of attachment to the link 32 as a fulcrum; and, this point of attachment'lying in the axis 23, the deflection of said vane member will be exactly proportional to that 'of the Bourdon spring I.

A further result of the increase of pressure in the conduit 26, and therefore in the chamber 28, is an immediate compression of the bellows member 29, and a consequent expulsion of air therefrom, which air tends to pass freely through the conduit 3| to the bellows member 30, expandagain at atmospheric pressure, the bellows member 30 restored to its normal position of repose,

and the vane to its original deflected position subject solely to the Bourdon spring l4.

Similarly, it will be seen that upon a decrease in temperature in the chamber iii, the vane 22 will be deflected by the Bourdon spring M toward the right, which action will be followed by cation with the conduit 58.

and adapted to control the pressure of air from a constant-pressure source 55, as exerted through .a conduit 56 on the operating element of the The three-way valve 54 is and subject to regulation of its internal pressure by the rate of escape of air through a doubleopposed orifice member Gil having juxtaposed thereto a vane member 6! rotatable through a small angle about a pivotal support or axis 82 on the base ,53. A'floating lever 63, pivoted at its mid-point upon the structure of the vane member 6 I, has one of its extremities operatively attached by a link 54 to the free end of the Bourdon spring 5|.

Mounted on the base 531s a bellows assembly 65 consisting of a closed chamber 86 having therein a resilient collapsible bellows member 81', the annular space withinsaid chamber'and exterior to the bellows being directly in communi- Mounted upon a plate 68, angularly adjustable about an axis 68 and carried by the base 53 is a resilient bellows member 10, having its interior space directly in the bellows member Iii carried thereby. Formed in the plate 68 is an arcuate slot 13, whereby the adjusted position of the plate may be definitely fixed by means of a screw H threadedly engaging a momentary deflection toward the left as the bellows member 30 temporarily contracts, after which the equalization of interior and exterior pressures in the bellows member 30 will cause the vane to move gradually toward the right until the bellows member 30 resumes its normal position of repose. This action of momentarily opposing the control efiect, and subsequently and gradually withdrawing the opposition, has been found under many types of operating conditions to minimize any tendency toward fhunting" and to produce a stable control.

Adjustment of the rate of response of the bel-. lows member 30 to movement of bellows member 29, and of its subsequent return to normal dimensions, may be effected both by varying the amount of opening of the valve 34, and by adjusting the internal volume of the chamber 3U b positioning the'piston 38 through manipulation of the screw 31. Compensation may thus be the base plate. Tapped oil the conduit II is a bleeder or vent 15, having interposed therein a constricted portion, which may take the form V member 10, whereby the latter may be caused to move angularly the member 11 in adlrection depending upon which of its opposed extremities is selected for attachment of the link 18, and to an extent governed by the radial distance of the selected hole from the center of rotation. A

lever arm '80 forming a part of the bell-crank member 1'! is operatively attached to the free extremity of the floating lever 63 by means or a made for different thermal inertia characteristics as manifested in different types of apparatus to be made subject to automatic temperature regulation.

In Fig. 3 is shown a control system embodying- Mounted on a suitable supporting base 53 is a three-way valve 54 of the form shown in Fig. 2,

link 8|, whereby such motion as the bell-crank member may receive from the resilient bellows member I0 will be imparted to the said floating lever, and will thereby be combined with the movements of the Bourdon spring ill in positioning the vane member 6!. The proportioning and location of the floating lever 63 are made such that the pivot point of attachment of the link 8| to the floating lever may in its travel 1 pass through the axis 62, and the length of the link Bi is made such that when the bell-crank"mem'- ber 1'! lies with the are upon. which are located the holes 78 concentric with the axis 69, the said pivot point will coincide with the axis 62.

The operation of the primary control elements of the embodiment shown in Fig. 3 is identical with that set forth in connection with the form shown in Fig; l, the valve 52 tending to be auto matically positioned by the control mechanism I to admit to the chamber 48 a flow of heating agentsufllcient to maintain or restore thermal equilibrium at the predetermined temperature Variations in the control pressure in the impose a stabilizing movement on the floating lever 63 and modify the positioning of the vane 6| inv a sense to damp out oscillations otherwise inherent to the system of control. The intensity of the secondary action may be adjusted to existing conditions by a suitable selection'among the pivot locations 18, the bellows member 18 being subjected to a corresponding angular displacement by setting of the plate 68.

Connecting the link 18 to the member 11 alternatively on one side or the other of the latter's axis of rotation effects a reversal of thesecondary control action, and makes possible the selection between two methods, each of which is especially applicable in particular cases. The proportioning and adjustment of parts is such that with the elements of the control mechanism brought to th neutral position, as shown in Fig. 3, where the center of the arc of location of the holes 18 coincides with the axis 68, the plate 68 carrying the bellows 18 may be set in any desired position in its range of adjustment without disturbing other adjustments of the mechanism.

In the event of there being desired a higher degree of resiliency to restore the bellows member 18 to its normal position of repose, resort may be had to means such as set forth in Fig. 4. A bell-crank member 82, corresponding to the bell-crank 11 in Fig. 3, is provided with a radial projection 83, from which a tension spring 84 is connected to an abutment 85 afllxed to the frame of the mechanism. The tendency of this spring will be to maintain the bell-crank 82 in a position where the point of pivoting of the same will lie on a straight line with the points of attachment of the spring 84 to the projection 83 and the abutment 85, which position may be made to correspond to the neutral point or position of repose of the bellows member 18.

In Fig. 5.15 shown an alternative form of the invention, particularly suited to the utilization of a non-elastic fluid in the auxiliary control. The function and arrangement of the floating lever 86 and the main regulating valve 81 shown in this figure are identical with those of the lever 24 and the valve H shown in Fig. 1; and the general method of basic control is in all respects identical with that hereinabove set forth. A conduit 88, serving to convey pressure fluid to the valve 81 for the purpose of controlling the same 'in a manner identical with that above set forth,

communicates also with a bellows member 88, making the same responsive in all its movements to the pressure of the fluid in the conduit 88, and tending at all times to take up a position corresponding to that of the valve 81. Mechanically attached to the bellows member 88, but having no interior communication therewith is a bellows member 88 flxed to the frame of the instrument. Also fixed to the frame of the instrument is a bellows member 82, communicating freely with bellows member 88 through a. conduit 88 and operatively connected by means of a link 84 to the extremity of floating lever 88 in a manner similar to the attachment of link 82 to lever 24 in Fig. 1.

Communicating with conduit 83 is a conduit 88 having therein a constricted portion, as, for example, a throttling valve 86, and entering a tank or open reservoir 91. The system comprising bellows members 88 and 82 and conduits 93 and is normally filled with an inelastic fluid, such as thin oil, the reservoir 81 also containing sufflcient of the same fluid that under no conditions may air obtainentry to the conduit 85 or any other part of the auxiliary control system.

' Operation of the invention as shown in Fig. 5 is similar to that of the elastic-fluid-filled types shown in Figs. 1 and 3; but the incompressibility of the liquid content of the bellows members 88 and 82 will render definite and positive the response of the latter to movements of the formenexcept as the combined resiliencies of the said members may cause liquid to pass through th conduit and the constriction 86 into or out of the tank 81', thus providing the time element of ultimate ,response which characterizes the performance of the invention.

A further alternative form is shown in Fig. 6, wherein the several elements of the mechanism are nested in a manner to efl'ect compactness of construction. A hollow cylindrical shell 88 has concentrically positioned within it an outer and an inner resilient bellows member 99.and I88, respectively, the interior of the inner member I88 being open and in free communication with the atmosphere. One of the two annular chambers, for example the outer chamber I 8|, is connected in a manner similar to chamber 28 in Fig. '1 to the three-way valve and pressure-actuated regulating valve of a basic control system of the type hereinabove set forth; The other (innet) chamber I82 is vented to the atmosphere through a conduit I83 having a constricted portion, as a throttling valve I84. The interior of bellows member I88 is operatively attached by means of a link I85 to an extremity of a floating lever I86 in a manner exactly similar to, and with the same function in view, as the connection between link 32 and lever 24 in Fig. 1.

The performance of the combination will be such that a change in fluid pressure, as communicated from the control system to the chamber I8I, will act on the exterior of bellows member 88 to compress the same, which action will at first immediately be communicated through the air contained within the annular chamber I 82 to the bellows member I88, producing motion of the link I85 and of the extremity of the floating lever I88, efiecting a compensating action similar to that set forth in connection with the previously described embodiments of the invention. Subsequently and gradually, as permitted by the equalization of fluid pressure through the constriction I84 to or from the atmosphere, the resiliency of the bellows member 88 will cause it to assume its normal position of repose with its exterior surface at atmospheric pressure, thus restoring the lower extremity of the lever I86 to its original position, and effecting the secondary and delayed action of the auxiliary control.

In the event of its being desired to augmentthe normal resiliency oi bellows member I88, resort may be had-to a spring combination similar to that shown in .Flg. '1. Asv shown, there are pivotally mounted on a base plate I81 two opposed lever arms I88 and I88 normally maintained by a tension spring H8 in engagement with stops III and H2, forming parts of the plate I81. A pin H3, carried by the lower end of the floating lever I86 rests in the space between the lever arms in such a manner as to be maintained thereby in the neutral or normal position of repose.- Upon deflection of the lever I in either direction by action of the link I05, one or other of the lever arms will yield in opposition to the tension'of the spring H0, which will act to restore the moving parts associated therewith to their normal position of repose, as the pressure or the fluid within the chamber I02 becomes equalized with atmospheric pressure due to delayed flow through the constriction I04.

In Fig. 8 is shown a form of the invention in which the auxiliary control having a time-delay characteristic is derived directly from motion of the main regulating valve, rather than, from changes in air pressure governing said valve. A regulating valve I I5 in a pipe line H5 is adapted to be operatively controlled by pressure of the carrying a heating agent or the like to be regulated, is adapted to have its degree of opening controlled by a pressure fluid in a conduit I33 connecting the operating element ofvalve I31 with a three-way valve (not shown and identical in connection and function with those hereinabove set forth).

Carried on a stationary support I40 is a posi tion motor I4I- similar to motor I34 and having its moving element operatively associated with the, stem of valve I31, as by a crank-arm I42 attached to the moving element of the motor and having therein a slot I43 engaging a pin I44.

' carried by the valve stem. The internal windings fluid in a conduit III leading from a three-way valve (not shown and similar in construction and arrangement to those hereinabove fully 'set forth and described) I ried by a bracket II9 fixed to the body of the valve I I5 is adapted to have its length, and therefore its internal volume, varied in response to movements of the valve II5 by means of an arm I carried by the stem of said valve.- A second bellows member I2 I, carried on a stationary support I22 is attached by a link I23 to a floating lever I24, adapted to function as ,an element of a control mechanism in a manner identical with the several similar floating levers hereinabove set forth. A conduit I provides free communication between the interior spaces of bellows members I I8 and I2I, and also communicates with the atmosphere through the throttling valve I25.

The operation of the embodiment shown mm. 8 is similar to those hereinabove set forth, the action of th auxiliary control system being derived from motion of the bellows member H8, as derived from movement of the valve I I5 through the arm i20. Upon a change in position of this valve, the corresponding change in dimension of the bellows H8 will cause a change inpressure of the air in conduit I25 and bellows member I2 I, whereby the lower extremity of the floating lever I24 will be moved, and the control modified as in the embodiments hereinabove set forth. As the pressure within the conduit I25 becomes equalized with that of the ambient atmosphere by seepage through the constricted valve I25, the bellows member I2I will be restored to its normal dimension, and the lower extremity of the floating lever to its position of repose, thus retracting the original auxiliary control action.

In Fig. 9 is shown a i'orm oi the invention, in which the movement of the auxiliary control elements is derived from that 0! the regulating A bellows member I I3 carlies the essence of the invention.

valve through the medium of an electrical telemetering system of the instantaneous type. Mounted upon a common support I21 are two re-' silient bellows members I23 and I29, communicating freely with-each other by means or a conduit I30 and restrictedly with the atmosphere through a throttling valve I3I. Bellows member I23 is attached by means of a link I52 to the lower extremity-oi a floating leveria whose function in control is identical with thatof the floating levers hereinabove set forth Carried by the support I 21 is a position motor I34 (such as the well-known "Selsyn type), having its moving element connected through a crank-arm I35 and a link I35, to the bellows member I23, whereby movement of the moving element of said position motor will be communicated to the said bellows member, eflecting a change in its internal volume. A regulating valve I31 in a pipe line I55 75 The contact I53 is carried by'an arm I50, swi

of-the position motors I34 and MI are connected together by a three-conductor circuit M5, and to synchronous sources of alternatingcurrent I46 and I4I,respectively, whereupon, in accordance with principles well known in the artoi autothe bellows member I28 to change its internal volume and produce in bellows member I29 an immediate response and a corresponding movement of the lower extremity qt floating lever I35,

with an auxiliary effect on the elements governing the pressure applied to the main regulating valve as hereinabove setforth. As the pressure within the conduit I30 becomes-equalized with that of the ambient atmosphere by seepage through the constricted valve I3I, the resilient bellows member I29 will be restored to its normal dimension, and the'lower extremity of the floating lever I33 to-its position of repose, thus retracting the auxiliary control action.

Fig. 10 shows an embodiment of the invention in which the primary or basic control, instead of being pneumatic, as hereinabove set forth, is electrical, the only utilization of fluid pressure in the controlsystem being in the bellows members, communicating freely with each other and restrictedly with the atmosphere, in which feature A Bourdon spring I50 connected by a capillary tube iii to a bulb I52 containing an expansive or volatile fluid, forms an element responsive to changes in temperature to which the bulb may be exposed. The bulb I52 is located in a chamber or enclosed space (not shown in the drawings, but similar in all respects to chamber I0 in Fig. 1) whose temperature is to be regulated to a constant and predetermined value by the control 01' a heating agent, such as steam, admitted to said chamber through a pipe I53 having therein a regulating valve I54, adapted for operation in either direction by a reversible electric motor I55. Operation of the motor l55'is eiiected by means of an electriccircuit includinga source of, supply m. stationary contacts urbane use, with either otwhich may coact a movable contact i53, together with such interconnecting conductors that when contact I53 engages contact I58 the motor will be operated in a direction to closethe valve I54. and when contact I53 engages contact I51, the motor will be operated in a sense t'o'open the valve, this system of control being standard practice and well known in the practice of automatic regulation of temperatures and the like.

axi I6I, and bearing a pivot upon which is mounted at its intermediate point a floating lever I62. One extremity of the floating lever I62 is a connected by a link I63 to the Bourdon spring I56. The remote extremity of the floating lever I62 is provided with a pivot point I64, which may be brought into alignment with the axis I6I. A resilient bellows member I65 mounted on a stationary support I66 is operatively connected by means of a link I 61 to the pivot point I64 on the lever I62, so that the position taken by the intermediate fulcrum of said lever, and hence of the contact I59, will be subject to the joint influence of the Bourdon spring I56 and the bellows member I65. Alsomounted on support I66 is a regilient bellows member I61. The interior spaces of said bellows members communicate freely with each other by means of a conduit I68 and restrictedly with the atmosphere through a' throttling valve I69.

A position motor I14 is carried by the support I66, and has its movable member operatively connected by means of an arm "I and a link I12 to the bellows member I61. A position motor I18, adapted for electrical coaction with motor I16, is fixed in relation to the body of the regulating valve I54, and has its moving element adapted for positioning in correspondence with the valve I54, as by a gear sector I14 mounted on the moving element of the position motor and meshing with a pinion I15 forming a part of the motor I and definitely associated with movements of the valve I54. The internal windings of the position motors I16 and I13 are connected together by a three-conductor circuit I16, and to synchronous sources I of alternating current (which may be embodied in the common source I56 as shown) by two two-conductor circuits I11 and I16, whereupon, in accordance with principles well known inthe art of automatic electrical control, the moving elements of the two position motors will tend to take up corresponding positions in space.

For the purpose of explaining the operation of this apparatus, conditions may first be considered in which the pivot I64 lies on the axis I6I, which corresponds to the normal position of repose of the system. Basic or primary regulation of the valve I54 in response to variations of temperature at the bulb I521 will then be effected as hereinbefore set forth, with a resulting tendency to maintain the said temperature at adefinite and predetermined value. Any movement of the motor I55 in a sense to change the setting of the valve I54 will at the same time be communicated through the pinion I15 and the sector I14 to the position motor I18, and thence to the position motor I16 and bellows member I61, changing its internal volume and thereby varying the pressure of the contained air, with a resultant immediate response of bellows member I65 and a movement of the upper extremity of the floating lever I62 away from its position of repose, giving a resultant secondary movement of the contact I59. The secondary movement of the contact I59 may be in a sense to increase the original movement due to deflection of the Bourdon spring or to decrease said movement. according to the requirements of the system to be regulated, selection between these two relative actions being dependent upon the relative directional action of the position motors I18 and I16, and this, in turn, depending upon the electrical connections. As the pressure within the conduit able through a small angle about a stationary I66 becomes equalized with that of the ambient atmosphere by seepage through the constricted valve I69, the resilient bellows member I 65 will be restored to its normal dimension, and the pivot point I64 on the floating lever I62 will resume its normal position of repose lying on the axis I6I, thus retracting the secondary control action introduced by the auxiliary mechanism, including the position motors and the bellows members.

In Fig. 11 is shown a form of the invention in which an electric-motor-operated valve is caused to actuate directlythe auxiliary control having a time-delaycharacteristic, without the interposition of a telemetering system or its equivalent. In this embodiment a regulating valve I86 is adapted for operation in either direction by a reversible electric motor I 8|, actuated through a three-conductor circuit I62 in a manner identical with the motor I55 shown in Fig. 10. A bellows member I66 carried by a bracket I84 fixed to the body of the valve is adapted to have its length, and therefore its internal volume, varied in response to movements of the valve I86 by means of an arm I85 carried by the stem of said valve.

A second bellows member I86 carried on a stationary support I81, is attached by a link I88 to a floating lever I89 adapted to function as an element of an electrical control mechanism in a manner identical with the floating lever 62 in Fig. 10. A conduit I66 provides free communication between the interior spaces of bellows members I86 and I86, and also communicates with the atmosphere through the throttling valve I9I.

Operation of the embodiment shown in Fig. 11 is similar to those hereinabove set forth, the electrical control being identical with that explained in connection with the embodiment shown in Fig. 10, and the auxiliary time-delay control identical with that explained in connection with the embodiment shown in Fig. 8, so that upon the motor I8I moving in response to the action of electrical contacts I92, the resulting motion of the stem of valve I86, acting through the arm I85, will change the dimensions of bellows member I88, thus causing the pressure within the conduit I96 and the bellows member I86 to be varied, with a corresponding movement of one extremity of the floating lever I69. The reaction upon the electrical contacts I92 is identical in manner with the performance of the embodiment shown in Fig. 10; after which, as the pressure in the bellows member I66 becomes equalized with that of the ambient atmosphere by seepage of air through the constricted valve I9I, the bellows member I86 will be restored to its normal While the several embodiments of the invention as hereinabove disclosed and illustrated have been shown as directed to thecontrol of a valve for regulating the passage of a flowing fluid, it will be obvious to those versed in the art that the principles are equally applicable to the positioning of an electrical contactor or a rheostat, or other type of regulator for controlling the flow of electric current to a heating device or other means for affecting the magnitude of a condition to be controlled, such, for example, as disclosed in U. 8. Letters Patent No. 1,685,995 issued 00- tober 2, 1928.

Iclaim:

1. In a system for automatically regulating a variable condition to a predetermined value, including power-operated means for controlling the flow of an agent to affect said condition, a memasaaros ber sensitive to changes in the value of said condition, relay means for governing the application of power to said power-operated means, and means rotatable through a limited angle about an axis for commanding the application of power through said relay means to said regulating means for operating the same; a resilient fluidpressure-responsive member subjected only to a substantially constant external pressure and having an inside closed spaceadapted to receive fluid under pressure in immediate correspondence with and in exact proportion to changes in said regulating means, and means for gradually equalizing inside and outside fluid pressures on said member, a floating lever intermediately pivoted on said commanding means and having pivot means on its respective extremities operatively and respectively connected to said sensitive member and to said resilient member, whereby the said commanding means may partake of the resultant motion of both said members.

2. In a system for automatically regulating a a variable condition to a predetermined value, in-

cluding' power-operated means for controlling the flow of an agent to afiect said condition, a member sensitive to changes in the value of said condition, relay means for governing the application of power to said power-operated means, and means rotatable through a limited angle about an axis for commanding the application of power through said relay means to said regulating means for operating the same: a resilient fluid-pressure-responsive member exteriorly subjected only to a substantially constant fluid pressure, and having an inside closed space adapted to receive fluidunder pressure in immediate correspondence with and in exact proportion to changes insaid regulating means, and means for gradually equalizing inside and outside fluid pressures on said member, a floating lever intermediately pivoted on said commanding means and having pivot means on its respective extremities operatively and-respectively connected to said sensitive member and to said resilient member, whereby the said commanding means may partake of the resultant motion of both said members, the pivoted connection of said resilient member to said floating .lever being adapted at a point in its excursion to coincide with the axis of rotation of said commanding element, said point corresponding to a condition of equality of inside and outside pressures onsaid resilient member.

3. In an automatic control system: a fluidpressure-actuated valve device for controlling a condition, mechanism responsive to changes in the condition for regulating the same, and adjustment means for the responsive mechanism, comprising a bellows affected by the valve device in accordance with the condition under control, movable fluidpressure-actuated means connected with the said bellows and with the responsive mechanism, and having restricted communication with an external atmosphere.

4. In an automatic control system: valve means responsive to a variable force for regulating a flow of energy, a first resilient member having an internal space of variable volume and adapted to be actuated to vary said volume simultaneously and in direct proportion to movement of said valve means, a second resilient member having an internal space of variable volume in free communication with that or said first member and subjected only to the difierence be-.

tween the fluid pressure therein and atmospheric pressure, and a constricted bleeder vent permitting a gradual equalization of pressures internal and external to said second resilient member, the said second member aflecting the variable force to which the responsive means is subjected.

5. In a control system having a fluid-pressure- I actuated regulating member and a device for commanding the action of said member through control of the pressure applied thereto: variablevolume means communicating directly with the sure-responsive means responding only to the diflerence in pressure within the variable-volume means and atmospheric'pressure.

CARLTON W. BRISTOL.

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