US2666443A

US2666443A - Multiple stage fluid relay

Info

Publication number: US2666443A
Authority: US
Inventors: Eckman Donald Preston
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1947-09-11
Filing date: 1947-09-11
Publication date: 1954-01-19
Anticipated expiration: 1971-01-19

Description

Jan. 19, 1954 D. PJECKMAN 2,666,443

MULTIPLE STAGE FLUID RELAY Filed Sept. 11. 1947 FlG.l

INVENTOR.

DONALD P. ECK MAN ATTORNEY.

Patented Jan. 19, 1954 Ill-LED fS PATENT OFFICE I accents 7 STAGE FLUID RELAY Donald Preston Eclrman, Ithaca, N. Y., assignor,

by mesn'e assignments, to Minneapolis-Honeywell Regulator Gomp'anypMinneapolis, Minn a corporation t Delaware.

" Application September 11, 1.9457, Serial'No. 713.3971

f The present invention relates to air control apparatus of the widelyused type iii-which a change in the value of a controlling condition adjusts a bleed valve unit to vary a primary control air pressure in accordance with the change in the controlling condition, and in which the change in the primary 'c0ntr0If air pressure causes a pilot valveunit to produce a corresponding change a relay control pressure, and in which means areineludedfor producing fol low-up and reset actions.

A general object of the present invention is to provide novel air control apparatus of the forced balance type in which the pilot valve adjustments resulting from the changes in the primary control pressura'an'd the follow up and reset actions are directly effected by mechanical elements which are pneumatic relay or servomotor elements of the Bourdon tube type.

A more specific object of the invention is to provide apparatus of the type specified in which the adjustable elements of 'the'bleed valve unit are rotary elements.

The various features of'novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. Fora better under standing of the invention, however; its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of the invention.

.Of the drawings:

' Fig. 1 is a diagrammatic perspective'view *of an embodiment of the invention;

Fig. 2 is an enlarged section through and transverse to the axis 'of the casing shown in Fig. 1; and

Figs. 3, 4 and 5 are sectional elevations each illustrating a modification or a different portion g; the apparatus 'shown' diagrammatically in Fig. 1 I havediagrammaticallyillustrated an embodiment of the present invention" com-'- prising a rotatable indicating or iron shaft I. The shaft I is associated with means for rotatingthe shaft as required to make-its angular ad- ,justznent a. measure ofthe value of a controlling quantity which may be some. physical condition such as a temperature rate of'fi'o'w orhead'of water, or may be'the output pressure of a so-.- called pneumatic transmitter which maintains an air pressure varying with some variable quan tity or condition to which the transmitter 'is-"re spons'ive. In the form shown by way of: example in'Fig. 1, the shaft is angularly adjusted, by a Beurdentube 2 in the form of a spiral and having-its inner end connected at 3, to the. shaft. l, and having its outer end anchored at 4.. The outer end of the spiral 2 is connected to a then in'ometer bulb 5.

The shaft carries and angularly adjusts a vane-or bafile 6 which forms the valve element of a bleed valve unit of which the other element is a bleed nozzle 1.

-The baille' s is angularly adjustable about the shaft I, but is normally held against rotation relative to the shaft by a pneumatic adjusting element 8, shown as 'a Bourdon tube of helical form'which surrounds the shaft 1 and has one end '9 attached to said shaft, and which. has. its other end I0 attached to the baffle 6. The bleed nozzle 1' is shown as parallel to the shaft I and is arranged to discharge a jet of air which is obstructed and minimized more or less by the baffle 6 when more or less of the baffle extends into the path of said jet. The plane of' 'the face or the baflle 6 adjacent the nozzle! is separated from the end of that nozzle by a very small distance, which may be of the order of two or three thousandths of an inch. Thus, when air under pressure is supplied to the nozzle through a pipe including a restricted orifice, the nozzle pressure may be varied in a definite predetermined man= ner by a relative angular adjustment of the bat fle 6 and nozzle 1 about the axis of the shaft I. With the edge 6' of the bafile 6 extending into the path of the jet discharged by the nozzle 1, the extent to which the nozzle discharge is throttled by the baffle 6 may be varied significantly by a minute angular adjustment of the bafile in either direction.

The position of the discharge end of the nozzle I may be adjusted by means of a'control point adjustment member H. The latter-is shown as journalled to turn about the'sh'aft l. The memher [I may be secured in its difierent angular adjustments by a clamping screw 12 which extends through an arc shaped'slot formed in the.

member II and is threaded into a stationary member I3 against which the slotted portion of the member H is clamped. The nozzle Tls con ne'etedto apipe I 4 supplying air under an approximately constant pressure, which maybe twenty pounds per square inch. The connection between the nozzle 1 and'supply pipe 14 comprises a pipe I5 having one endconnected to the 'pipe l4 and including a restricted portion l5, and a flexible pipe l6 connecting the sec- 3 ond end of the pipe I5 to the nozzle I. The pipe I6 is sufficiently flexible to readily permit the desired control point adjustments of the member II and nozzle I. The path of flow through the restricted portion I5 is made sufficiently small, and the maximum throttling action of the baffle 6 on the nozzle 1 is made sufficiently large to permit a suitably wide range of pressure variation in the nozzle. In practice the range of variation of the nozzle pressure obtainable by the adjustment of the bleed valve unit, may well be from minimum of about two pounds per square inch to a maximum of about eighteen pounds per square inch, when the supply pressure is twenty pounds per square inch.

The nozzle pressure is transmitted to the helical pneumatic element 8 through a second flexible pipe extension I! of the pipe I5. The pipe I1 is shown as connected to the element 8 adjacent the end 9 of the latter which is secured to the shaft I. The purpose and effect of the transmission of the nozzle pressure to the connection 8 between the shaft I and the baffle 63, is to produce a follow-up action which, on a change in the temperature of the thermometer bulb 5, prevents the corresponding angular adjustment given to the baflle 6 from being as great as the angular adjustment given to the shaft I.

Thus, for example, on an increase in the bulb temperature and resultant increase in the fluid pressure transmitted from the bulb 5 to the Bourdon tube 2, the shaft I is given a counterclockwise adjustment, as seen in Fig. l, which is proportional in extent to the change in the bulb temperature. The angular adjustment of the shaft I would produce 'a corresponding angular adjustment of the baflle 6 if the pressure in the helical tube 8 connecting the shaft I and bafile 6 remained constant. However, the decrease in the nozzle pressure produced by the initial movement of the bafile 6 relative to the nozzle I, is transmitted from the pipe I4 through the pipe I1 to the tubular element 8. The resultant pressure decrease in the helical tube 8 results in partial winding up of that tube, and thus gives the bafile 6 a clockwise adjustment, so that the ultimate counterclockwise adjustment, of the baffle 6 produced by the bulb temperature change is smaller than the ultimate adjustment given the shaft I as a result of said change. Conversely, a decrease in the thermometer bulb temperature and pressure produces a corresponding clockwise adjustment of the shaft I and a somewhat smaller clockwise adjustment of the baflle 6.

In the form of the invention shown in Fig. 1, the variations in the pressure in the nozzle I produces control actions by effecting angular adjustments of a baflle or vane I8 which forms the movable valve element of a pilot valve mechanism. The latter comprises a chambered casing I9 in which the vane I8 is supported and rotated by a valve shaft 20 which extends into the casing I9 through a stuffing box 2| carried by the casing wall. Associated with the baflle I8 is a bleed nozzle 22 and an exhaust nozzle 23, each of which is supported by and extends through the end wall of the casing I9. External to the casing I9, the exhaust nozzle 23 opens to the atmosphere, and the bleed nozzle 22 is connected to the pipe I4 through which air under pressure is supplied to the apparatus.

The vane I8 and

nozzles

22 and 23 are so relajet discharged by the nozzle 22 and thus exerts a maximum throttling action on said discharge. In this condition of the apparatus, the baffle I8 is out of register with the adjacent end of the exhaust nozzle 23 so that the relatively small amount of air then entering the casing I9 can escape through the exhaust nozzle 23 at the same rate at which it enters through the nozzle 22, without requiring the pressure in the casing to be above more than about two pounds above the pressure of the atmosphere. When the bafiie I8 is at the opposite limit of its effective range of oscillation, it has a portion in register with the exhaust port 23 and is entirely out of the direct path of the jet discharged by the nozzle 22, and the pressure in the casing I9 then builds up to about eighteen pounds per square inch.

In intermediate positions of the baffle I8, the latter subjects each of the

nozzles

22 and 23 to a throttling action which is smaller than the above mentioned maximum throttling action of that nozzle. In the central position of the baflle shown in Fig. 2, the baffle IB similarly throttles the two

nozzles

22 and 23. The diameters of the cores of the

nozzles

22, 23 and I, and the distance between each nozzle and the plane of the adjacent face of the corresponding baffle valve may be in accord. with the usual practices of the air controller art. It is to be noted that in Fig. 2, the diameters of the orifices of the

nozzles

22 and 23 adjacent the baflle I8 are exaggerated for illustration purposes. The diameters of the nozzle bores, or at least of the orifices at the ends of the passage adjacent the corresponding baflle portions. are quite small in the case of each of the

nozzles

22 and 23, and may be even smaller in the case of the previously mentioned nozzle 1. While the pilot valve pressure range may well be about the same as the range of the pressure in the nozzle 1, the maximum rate of air flow through the pilot valve nozzle 22 will be substantially greater than the maximum rate of air flow through the nozzle 1. The varying control pressure maintained in the casing I9 is transmitted through an outlet pipe 24 from the casing I9 to a control device 25. The latter, as shown diagrammatically in Fig. l, is a diaphragm control valve. The valve 25 may be employed, for example, to regulate the supply of fuel to a furnace to the temperature of which the bulb 5 responds.

With the particular apparatus shown in Fig. 1, increases and decreases in the pressure in the nozzle I produce clockwise and counter-clockwise angular adjustments respectively, of the shaft 20. Those adjustments of the shaft 20 are produced by a pneumatic element 26 in the form of a Bourdon tube extending helically around the shaft 29 and having one end connected to that shaft at the point 21, and having its other end connected by a stationary tube section 23 to the stationary pip'e I4. The'pneumatic element 26 operates 'on an increase or decrease in the pressure in the nozzle 1 to produce a clockwise or counter-clockwise adjustment respectively of the valve shaft 29.

The extent of the angular adjustment given action of a pneumatic element 32. As shown in Fig. l, eachof the'elements 29 and 32 is a helical Bourdon tube surrounding the shaft 29.- The pneumatic element 29 has one end 30 con- 1 icected-to the shaft 20, andhas its opposite end ates-m.

om the pipe... tosa i elem nt t tend togixe i. he sham? 2.0. elockwise and e untenaclockwisel djustments. respect ve y-1 pneumatic Eels,

meat .32 has. one end 3.3;closed. and connec ed. to the sha t fraud as. its. other. end. .connmted. o the-o tlet pipe 5. thr u h. a tnmttlme valve.

4.- In a m and amnaement the elementi 13.2.

u like the elem nts;.2.-

2.9....t iat an inreas or ecrease he nleseure=-transmitted to the element 3.2 immithe pe. .24. pitodu es a c u -c w se clockwise inmvemeh t aespeetivelaei the h flftfll; The. valve Malay-he Q-iusted 5.0 that the full" efi ct. Jot-a P e hange in the outletp pei 2.41s. not transmithesi 0 the pneumetioel me tfl. exc pt latter. a d layn... rod wh ch be a ifew seconds... or may e tow minutes. depending enthe eh raeter of t e regula ion required;

Fro thetores ing. it will-he appa ent. tothose killed n t e art that-the n gulation obtaina le with the apparatus shown diagrammatically in.

Fig- 1 may .be simi ar in-type. to that. obta nabl ith th usual types o .air' ontrol annanatus. havin .iollioweup and reset 'proviisions now e al use In air control" apparatus including a bleed valve unit adjusted in accordance with changes in a. controlling condition and including a pilot valve adjusted in accordance with variations in the nozzle pressure of said unit, the rotary mode of adjusting the. elements which must be adl just'ed to effect pilot valve adjustments and "to effect follow-up and reset; 'aotiqns," is; the ideal diu t nt m e Th u -oi heli a rerepiral Bourdon tube elements inheu of the bellows or a r m elem nts heretoio e oustomaxilvused to e e t ot valve a justments. and to effect ll w nn and reset actions, reduc s th inherent ulk, wei ht and con truct on of th apparatus. It also eliminates the necessity for pivoted'link andv lever elements, and'eliminates the friction, wear and risk of-l ost-motion'inci dent to'the use of such elements.

To obtain greater overall compactness the three helical elements 2 6 2e and '32 curved atout the'valve shaft'zn iniFig. lfmay bearranged concentrically; as show-11in; Fig-i. 3;. The. helienl. elements 26; 2:2: andgaz; shown. Fig, 1 he replaced by spi a fi urdont eesztn 29c nd a eini erte tne ir ubez and eur ec about e shaf 29 with tneinnere d oiweachp ral.

eeu d shaft, and ran ed. side by side, as h -in Fig. i. h pres nt invention may b6 used with advantage on. concentric indicating pneumatic re ei er in truments; and con ni indi ating otentiomet rs, s me ca es, e 'pn uinati lielicar or pi a e ments: of on n t um n m hem nted n he us ru t pen shaft with a corresponding simplification of thecontrol system.

The rotary pilot valve shown in" Fig; I may take other forms one of which is illustrated in Fig; 5. In Fig; 5, the pilotvalveshown com-i prises a casing 18a into which the rotary valve shaft '29- and nozzles 23; and 23'-=oxtend,f yas in Figs. 1-" and 2'. InFig. 5,. however ,a-the singlarigid baffle I 3 of Fig..1'is replaced by" ilfirapper valve '36 and" a flapper valve al' pivotedf at 3B. and 31; respectively. The valves '36 and sub ject the

nozzles

22 and 23 respectively, to inverse throttling 'efiects which variably throttle 6" the-rnozales -33; tans" oecillatesh shown; he

" hop are. sub ect. to, neflection awai are 22.. and; .23....by projections 35 carried a. ever .451 se- 11 and each, radially disnohsling. nozz es. and; 33,; nespect ve curled to the she.

placed" iromsaidi .As. Shown, each of the by a..bias..spriz.1g.j 41. As shown, each flapp r valvlei-isl pivotallv connected; to and. .supponte by the casing 19.

mile, in accondance. with. the? provisions of the. statutes; have lliietxeted 1 and described. the best forms of embodiment of my invention now. known tame it. w ll.v be apparent to those skill dein thejart; that-changes may b mad in'the forms 'ofthe apparatus disclosed without without. departing. .fmm-tholspirit f my inv nticn' as .setl ..forth .inlftho-appended cla ms, ns that some; cases certain vention a r beiusedito advantage. without a. cor.- respoiiding. use. of other .featur s- .ing. new; QQ Q ZibEQ. my invention, what I laim 'as'niew and" desire. to secure} by Letter atentJs:

1'. Air. control apparatus. c mpr s ng; a blee valve unit. including nozzle" and. at le elem relatively adju table 'ab utan. axis to. ofi ct in the bleed valve nozzle pressure n. a the value. of. a control. quant ty, a pilot. hamsmiiineluding an. element. ansuliar -y dju tabl about. an axisi ogvarv alfcontlt l. pr sure; and. a Bcurdcn. tube, element. curved about.

aid axis and; through: which the last men ion d.

element isan julariv adjusted about, said; a s in response o. changes the'bleed. nozzle; pressure.

Air c ntto appali'atus. comprisin a bleed. valve: unit. including. nozzle andbaffle. element relatively adjustable; about an axis to. effect a hange. injthe, bl ed valve nozzle? pres ure on. a hange in hevalue at a. control quanti y, and a pilot valve m h nisin. includin anelem nt ngularlv adjustable ab ut a. s con axi to v ry elatively adjustable. about an. axis to effect a change in the bleed" valve nozzle pressure on a chan e in the value of a control quantity, and a pilot valve mechanism/includin an e m t ns'u arlv adjustable about a. s cond ax s to vary a control presu..r.e a Bczurdon tube elem urved ab ut-said seeei'zuifaXis and. through whi h he' lastmen ioned element is adjusted in re.- snom to changesin-the bl ed nozzle Pressure, :1 second Board r: tube. curv d about sa d. s nd axi iv ng the last mentioned element a follow up adjustment on; a'changie-in said control pressureiancla third Beur n tube cu v d about said seen (1' a 81- 'nath st mentioned lement aiseset d uetment-cnagchangein said. ontrol measure I 4-; am eon ml apparatus; includin a l ed valve unit in luding 11 1e and. 4 bafil elements.

relatively adjustable togjefiect a change in th bleedvalve nozzlo piressuro on a. chan e in the valua ion a 'controlwvariahle; a pilot-valve 1116.011:

e; valve-shaft; 2.

e unes of my in- 7 control. apparatus c mprisi g" a bleed anlsm including a pilot valve element 'angularly adjustable about an axis to vary a control pressure, two Bourdon tubes "each curvedabout said axis and having one end secured to said pilot valve element and having its other end stationary, a conduit connecting said nozzle to one of said. Bourdon tubes for transmitting the nozzle pressure to actuate the tube 'andthereby vary the pilot valve outlet pressure, and a conduit connecting said pilot valve to the other of the Bourdon tubes for transmitting the outlet pressure of the pilot valve thereto.

5. Air control apparatus as specified in claim 4. in which said Bourdon tubes are concentric helices.

6. Air control apparatus as specified in claim l, in which said Bourdon tubes are side-by-side coaxial spirals. I p

"7. A compact air control apparatus inc uding, a shaft mounted for angular movement about its longitudinal axis, a measuring element having a spiral portion coiled about said axis and having a fixed end and a free end connected to said shaft and movable in a curved path in response to the changes in a controlling condition so as to give angular adjustment to said shaft/a nozzle adapted for connection to a source of fluid pressure, a conduit connected to said nozzle, a balile freely rotatable on said shaft and cooperating with said nozzle to control the fiow of fluid therethrough, and an expansible element mechanically connected at one end to said shaft and at the other end to said bafiie and having its interior pneumatically connected to said conduit so that 35 the pressure of the fluid flowing through said nozzle gives follow-up adjustment to said baffle.

8. A compact fluid-pressure-operated control- I ler including, a bleed valve including a segment mounted for rotation about an axis perpendicular to the plane of said segment in response to changes in the value of a controlling condition, a

bleed nozzle cooperating with said bleed valve so that the flow of fluid through said nozzle is controlled by said bleed valve, a pilot valve including a second segment mounted for rotation about an axis perpendicular to the plane of said second segment, a pilot nozzle adapted for connection to a source of fluid pressure and cooperatingwith said pilot valve so that the flow of fluid through said pilot nozzle is controlled by said pilot valve, and an expansible spiral having one end fixed and one end attached to said pilot valve and encircl ing the axis of said pilot valve and connected to said bleed nozze so that the flow of fluid through said bleed nozzle causes said spiral to rotate said pilot valve.

9. A fluid-operated controller including, a pair of relatively movable bleed valve elements, a pair of relatively movable pilot valve elements, one

for angular adjustment about an axis, a measurelement of each pair ofelements being mounted ing element having a spiral portion coiled about the axis of the bleed valve elements and responsive to the changes in value of a controlling condition and having a free end connected to the movable one of said bleed valve elements to move it, a spiral 'expansible element connected under the fluid control of the other of said bleed valve elements and having mechanical connection with the movable pilot valve element and responsive to the iluid'pressure controlled by said bleed valve elements to rotate the movable one of said pilot valve elements.

10. Fuid-pressure-operated control apparatus including, a pair of cooperating relatively movable bleed valve elements, the movable one of said bleed valve elements being rotatable in response to the variations of a controlling condition, a pair of cooperating pilot valve elements relatively rotatable about an axis, a spiral expansible element responsive to the pressure controlled by said bleed valve e ements and coiled about said axis and mechanically connected to the movable one of said pilot valve elements to give it a primary rotary adjustment, and a second expansible spiral coiled about said axis and mechanically connected to the movab e one of said pilot valve elements to rotate it in the opposite direction to said first spiral in res onse to changes in pressure controlled by said pilot valve elements.

l1. Fluid-pressure-operated control apparatus according to claim 10 having, a third expansible spiral coiled about said axis and mechanical y connected to the movable one of said pilot valve elements to rotate it in the same direction as said first spiral. a conduit connecting said third spiral to the pressure controlled by said pilot valve e ements, and a restriction in said conduit to delay the flow of pressure therethrough to said third spiral.

12. Air control apparatus comprising a pair of relatively movable bleed valve elements and a pair of re atively movable pilot valve elements one of each pair of elements mounted for angular adjustment about an axis and cooperating collectively to vary a control pressure in accordance with the variations in the value of a control quantity, a spiral expansible element curved about the axis of one of said pairs of valve elements and having a fixed end and a free end fastened to the movab e one of one of said pairs of valve elements to rotate it, a conduit for applying to said spiral expansible element air pressure varied by the movements of one of said pairs of valve elements, a second spiral expansible element curved about the axis of the other of said pairs of valve elements and having a fixed end and a free end fastened to the movable one of said other of said pairs of valve e ements to rotate itv and a second conduit for appl ing to said second spiral expansib e element air pressure varied by the movements of said other of said pairs of valve elements.

13. Air control apparatus including, a bleed valve unit including nozzle and baiiie elements relatively adjustable to eilect a change in the bleed valve nozzle pressure on a change in the value of a control variable, a pilot valve mechanism including a pilot valve element angularly valve thereto, and a throttling valve interposed in said conduit between said pilot valve and one of said other Bourdontubes for causing said Bourdon tubes to actuate said pilot valve element with a reset mode of operation.

14. Air control apparatus as specified in claim 13, in which said Bourdon tubes are concentric helices.

15. Air control apparatus as specified in claim 13, in which said Bourdon tubes are side-by-side Number coaxial spirals. 2,347,344 DONALD PRESTON ECKMAN. 2,3 82,853 2,461,026 References Cited in the file of this patent 5 2,512,561 UNITED STATES PATENTS 2,518,67 Number Name Date 1,897,135 Mason Feb. 14, 1933 Number 1,987,200 Mabey Jan. 8, 1935 10 546,981 2,052,764 Harrison Sept. 1, 1936 5 8 634 2,212,085 Tate Aug. 20, 1940 73 2 2,240,243 Mason Apr. 29, 1941 2,327,898 Hubley Aug. 24, 1943 Name Date Waidleigh Apr. 25, 1944 Brammer et a1 Aug. 14, 1945 Bilyeu Feb. 8, 1949 Ziegler June 20, 1950 Fischer et a1 Aug. 15, 1950 FOREIGN PATENTS Country Date Germany Mar. 31, 1932 Great Britain Apr. 13, 1945 France Jan. 15, 1943