US2304783A - Pressure responsive ratio relay - Google Patents

Description

Dec. 15, 1942. R. R. DONALDSON PRESSURE RESPONSIVE RATIO RELAY Filed June 10, 1940 2 Sheets-Sheet l Dec. 15, 1942. R. R. DONALDSON 2,304,783

PRESSURE RESPONSIVE RATIO RELAY Filed June 10, 1940 2 Sheets-Sheet 2 llll Patented Dec. 15, 1942 UNITED STATES PATENT: orrice rnnssunn nnsronsrvn aa'no RELAY j 7 Robert a. Donaldson, Pittsburgh, Pa., mime" to John M. Hopwood, Mount Lebanon, Pa-

Application June 10, 1940, Serial No. 339,692

5 Claims.

This invention relates to relay devices and more particularly toratio relays adapted to respond to an actuating force or impulse and to send out another force or impulse that bears a definite predetermined relationship to the actuating force.

The device'embodying the invention herein illustrated and described is of the type shown in United States Patent Number 2,016,824 granted to G. W. Smith on October 8, 1935, and adapted to perform the same functions and to be used for the same purposes as the ratio relay of said patent.

An object of this invention is to provide a ratio relay that shall represent a distinct improvement over the relay device of Patent 2,016,824 in the construction and arrangement of parts and particularly in the form and construction of the force or impulse-responsive element and the sending valve mechanism.

Another object of the invention is to provide an improved nonsticl'zing valve mechanism that shall be more positive-and sensitive in its performance.

A further object of the invention is to provide a means for eliminating vibration of the valve assembly and force-responsive actuating element. i I g The above and other objects of the invention will be apparent to those skilled in this art from the following description taken in conjunction with the accompanying drawings in which:

Figure 1 is a view in section taken on line I-I of Fig. 2 of the ratio relay device embodying the improvements constituting the invention;

Fig. 2 is a top plan view of the device; Fig. 3 is a bottom view of the device; and Figs. 4, 5, and 6 are views in section taken on .line IV-IV, V-V, and VIVI of Fig. 1, showing details of construction in their assembled relationship.

Throughout the drawings and the specification like reference characters indicate like parts.

'The operation and general arrangement of the device shown in the drawings for the purpose of illustrating the principles of my improved ratio relay or ratioing device, will first be described with reference'to Fig. 1', followed by detailed description of the construction, arrangement, and assembly of the various parts or elements of the device.

- Therelay device comprisesin general a body i having at its'opposite ends'chambers 2 and 3 formed in the under side thereof. These cham- -bers are'clo'sed by means ofdiaphragms and 5 which; as v will be described hereinafter-fare 2,016,824) to be actuated by and in accordance with this sending line pressure.

A beam I0 is supported at its opposite ends from the diaphragms 4' and 5 respectively, the ends thereof being rigidly secured to the diaphragms at their-centeral portions. Compression springs ii and I2 are-disposed attheends oi the beam and are mounted to exert upward forces on the beam, as seen in Fig. 1, in opposition to' the forces produced by the pressure media chambers 2 and 3 and acting on respective diaphragms 6 and 5. e

"A fulcrum I3 is adjustably supportedabove beam l0 and serves as a point about which the beam may tilt or rock.-

Springs H and I: may be of such size 'and stiffness and the compression thereof so adjusted that they will exert an upward. force atv each endof the beam of any predetermined value, say ninety pounds, or sixty pounds, oreany other value desired or that may be required by the range of pressures received from pipe 6 and tolbe sent or transmitted through pipe 9. The specific values mentioned above are merely suggestive, as the value of the forces exerted by springs Ii and I2 may be expressed in general terms A (spring Ii) 'andB (spring l2).

The forces' exerted by'diaphragms 4 and 5 as the result of the pressure existing in chambers 2 and} respectively will ofcourse be proportional to the pressure expressed'in lb./sq. in. multiplied by the area of the diaphragms.- For convenience the force exerted by the pressure in chamber 2 on diaphragm I and the force exerted on diaphragm 5 by the pressure in chamber 3', may be given the general values]; and '11 respectively. Therefore the, resultant forces B and R acting on the ends of beam l0 may be expressed as folforces Aand' Bare greater that forces ':i: ,and y,

"designate them these resultant forces R1 andIRz will act the direction of the arrows employed in Fig to acting on diaphragm 4.

Since the resultant force R1 tends to turn beam Ill clockwise, and resultant force R2 tends to turn it counter-clockwise, beam ll will be in balance only when the moments of these forces are equal. The turning moments are in balance when R1'L1=R2-L2. But R1L1=(A-2)Li and R2L2= (B-y) L2; therefore (A-z) =La/L1(B-u) k(B-u), It being the value of Lz/L1. When L1 equals L2, k=1, therefore the relay beam is in balance/when (A :c) (3-11) As s ted above, the value of a: is determined by the pr ssure per unit area received by chamber and t area of diaphragm 4, and the value of y is dete 'ned by the pressure per unit of area (as madam.) sent out from chamber a and the area of diaphragm 5. Therefore, the value of pressure sent out and the value of y will be determined by the values of A, B, :r, and the value of k. If the areas of diaphragms 4 and 5 exposed td the received and sending pressures are unity, say one sq. in., the values of a: and y will be the same as the received and sending pressures. If it be assumed that the areas of diaphragms 4 and 5 are equal to one sq. in. and that forces of springs and I 2 are equal, in which case forces A and B are equal, and that k=1, and if it be assumed that A and B are, for purposes of explanation, adjusted to ninety lb. each then the relay will operate to maintain the relation (A:c)=(B-y) as shown by Table I in which values of x, (A-z), R1, 1 (3-1!) and R2 are given.

Table I (A-n-m -11) =12;

From the above it will be seen that as the received pressures or forces a: increase from zero to ninety the sending pressure for forces 1 increase from zero to ninety in the same increments and are equal to the values of :c at all points, and that the resultant forces R1 and R: are equal and decrease by the same amounts from ninety lb. to zero. Thus the resultant forces R1 and R2 will decrease from values ranging from the maximum value of forces A and B depending on the spring tension for which springs Ii and I2 are set, down to zero provided the forces a: and 1/ respectively are increased from zero to a value equal to the forces of the springs, namely forces A and B. Thus it follows that a change in the value of R1 unbalances the beam so that the valve 8 will be operated to establish a pressure in chamber 3 that will restore R: to a value that balances the beam against the resultant force R1. Likewise if there is a change in pressure in chamber 3 withouta corresponding change in chamber 2, diaphragm 5 will act to so operate valve 8 that the pressure in chamber 3 will be maintained constant at the value required by the pressure existing in chamber 2 and The above-described operation of the relay is the same when the value of a: is decreased from-a higher to a lower value, because valve 8 will be operated to lower the pressure in chamher 4 until the value of 3: equals the value of z.

If the same values of A and B are assumedas in the above table of values, but the value of k is changed'by changing the ratio of Lz/Li, the" relay will operate to maintain a definite relation between the values of a; and y and the equation (4-3:) =k(B-y) will be satisfied. The values given in Table II below are obtained where I: has been given a value of for convenience in dividing the expression (B-y).

By selecting a value of k=L2/L1= the received. pressures will vary from forty-five to ninety and the sending pressures will vary from zero to ninety but the values of R1 and R: are always equal and vary from forty-live to zero, thereby satisfying e equation (A-x) =Ic(Biv).

if k or L2/L1=2 the following Table III of values show what the relation of the received pressures to the sending pressures will be.

Table III Value of: (4-2) =12; Value of u I:(B1 )-R c The above table of values show the relation of pressures received to pressures sent where the value of k is equal to one, is less thanone, and greater than one.

The relation of the pressures received, that is pressures 2:, to the pressures sent, that is pressures 1 may be varied from the equal and corresponding values shown in Table I where k is equal to one, by adjusting either spring II or spring I! to a higher degree of tension than the other. Thus if spring I2 is adjusted to provide a value of B equal to say one hundred ten 1b., the values of x, (4-3:), R1, (B-y), and R: will be as shown in Table IV below.

Table IV I Value of a:

110-60) 50 110-80) 30 (1io-10o)-1o (110-110) i 0 From the above values it is seen'that when equals zero 1/ equals twenty, that R1 and R: both equal ninety and that the values of a: range from zero to ninety and the values of 1 range from twenty to one hundred ten. For all values, however, R1 and R2 are equal and vary from ninety down to zero.

If A is made equal to one hundred ten, for example, and B is made equal to ninety, the values of a: will range from twenty to one hundred ten Qsoik'as nae same vanes hands are'assumedas in the preceding tablesubut thevalue of lcl is changedby llchangingithe ratio 9114 27141} the re: mam t me t m memau me lat on between" values m, may and the equation (4+1) k('l3 -'1'/ will" e sausnea as shown by Table v.1 lnconnectionwith Table V, k-is given the a value, or; convenience got computation.

- R: will be always equal.

' If the value'of k-ortheratib L'z/Ll is made equal to two, the followin g'Table VI of values show what the relation'of received and sending pressures will bef i 1" J VI! If k is made'equal totwo-then-the' values of m will range from zero to-ninety,but the values of .y "will range from sixty flve to one hundred and vary fromninetyto-zero.

"-It will be apparentthat the v'alues A and -B may: be. adjusted as desired over a wide range andthat for'allvalue's of A and B (both being greater than zero) the-relative values may be changed by making k 1 equal to one or greater or less than-one, and that the values'A or :B may be made equal or unequal, and thata value of k may be chosen which is equal to, greater than,-

or-lessthanflone. .o Y a l Description of elements or-tne" 'relay Body l of the relay is substantially rectangular in transverseljsectionfandis preferably cast in onepiece. v Incasingthebody, cores are employed to form a hollow pressure ti'ght volume-chamber 15 having communication. withdiap'hra gm ehame her 3 through which a passage ay [6, which is drilled fromrchamber Lon a'n'fangle as shown. 'Ifhischamber'acts as a da'mping device toprevent vibration of valve and. diaphragm '5'. g The valve and diaphragm shown are sensitive and are subject to sustainedvibrations of different frequencies and amplitudes dependingfon such factors: as stillness of ;springs II and. I2, and diaphragm '5; the area of the inlet and exhaust gertslb'rjviaiv 'a; "said s nd n ine-8- No single one or cto s has 'been v i r c e bi i t sh rei ti ezo e et rsi ut ate er-,ihes eci ecause: may, e-I

haves-found that a volume chamber placed elose to. diaphragm chamber 3 will eliminate these sus tained vibrations. The pressure in chamberl 5,

of course, .;varies with the sending pressuresprm,

duping forces a: and there is suflicient volume. in chambers" to;exer-t, a stabilizing effect n-dia: phragmland its cesoperating elements,-';-= a

-,In casting body l-. ,a core isalso employed, to form a. substantially LL-shaped hollow space, I! one leg of: which is located :below chamber; and substantially parallel to beam 10; the other leg of this hollow portion'extends vertically to theetop o1 body; from a point adjacent to-but above diaphragm chamber 2. hollowrortion accommodates ascrew l8 one'end of which is joumaled in the :end of thebody which valve chamber l is formed and vthe other end'extends through a bushing 19., in the opposite end of the body and has aiiixed thereto a handwheel for turningthe screw. .Bushing ISisthreaded to receive a'clamping nut 21 :wherebythe relay device maybe supported from apanelboard 22, asshown'; A collar is fitted on the shaft of screw l3 and placed against the inner endof bushing l9'and' fastened to. theshaft with a pin 24, whereby longitudinal movement of shafti8 is prevented.- z r 1 A carriage, hasthreaded engagement with screw l3 and-supports fulcruml3. Fulcrum vl3. is"preferably circular or wheel-like in form and is mounted on a pincor shaft 26. which extends transverselyithrough the carriage; "The-bottom face of body I is provided with a window or slot 21 along-which the carriage slides As may be seen more clearly in Figs. 3 and-'5,.-.the carriage is' formed with flanges 28 that-extend under and across body I and serve. to guid'e'the carriage andto maintain roller fulcrum .l3-in itshp'roper position with respect to the upper face of beam Ill.

In order that the ratio of Lax/L1 'or the value of: k may be made visible on a gauge or indicating device, a chain 29 having one end'hooked to the carriage, (as shown in Figs. "1, 2 and -3) "its middle portion running under apulley 30 secured to the receivingend of the relay'and having-its'other .end connected to the indicating device 3|. 1 Thus as carriage and its'fulcrum I3 are moved along screw l8 as the screw isturned; the indicator wouldshow whether the fulcrum was at the midpoint of be'amlli or to the left or-the'right of this point and the position of the fulcrum can be ex pressed-in terms of 'Lz/Li or konitheindicator.

Chamber 2 is'formed by machining a recess in:

. tothe bottom of body I to the required depth;

The side of the bodyis drilledand tapped so that receiving pipei may be fittedto the body an'd have communication with the interiorof cham- 'At the other end of-body 'l", r'ecess'3 is formedby machiningfor otherwise to the required depth:

In verticalalignment with the center-of Challi ber 3, a hole 32 is drilled-and tapped that extends from the top of extension 33 of" body l*down-- wardly into chamber 3. Valveass'e'mbly 8 is threaded into thisholeto the distance required in order 't0 have the proper operation" of the valve, and locked-in place by means of a lock nut As stated previouslyherei'n, diaphragms l and 5 are secured rigidlytobeam l0.

Diaphragm 4 comprises preferably a circular.

flexible, disc-like element which is shaped as shown by the transverse section in Figs. 1 and 4. The central portion of this diaphragm is apertured to receive a bolt 3!, the head of which bears on the top side of the diaphragm. me shank of the bolt extends through a bushing 34 disposed on the under side of the diaphragm but which rests on the top side of a flat end portion 31 of beam ill, and thence through the beam. The

bolt is provided with a lock washer I! positioned on the under side of the end portion 31 and a nut 39 which is drawn up tightly to insure that a pressure-tight joint is established at the point 'where the bolt passes through the diaphragm and also to lock the diaphragm tightly and securely to the beam.

The outer edge of diaphragm 4 is clamped tightly to body I around the edge of diaphragm chamber 2 by means of a clamping ring 40 which is substantially rectangular in shape at its outer perifery and which is provided with a substantially circular openin to receive the active por- I: may be adjusted to any degree of tension to produce the desired value of force B. Y

- In the construction of the relay it is preferred tomakediaphragmslandlofthesamesize, yokes 43 and '4 with their respectiveilanges 4| and II of thesamesireandshapesothat these parts of the relay device may be interchangeable end of which rests against the lower end of valve 1 with a spring cap 45 on which the lower end of spring II is supported. The upper end of spring il encloses bolt and bears against the flat end portion 31 of beam It. By turning adjustment screw 44 upwardly through the lower end of yoke 43 any desired degree of compression may be imposed on spring II in order to obtain the desired or required value of force A.

Acourateoperation of the relay device requires that beam Ill be rigid and stiff so that it will not deflect as the result of the forces R1 and R: acting on the ends thereof. Beam I l is therefore preferably made in one piece by casting of steel or other suitable material with T-shaped section and thereby make manufacture, assembly. re-- pairs and replacements more convenient and less expensive.

Bolt 41 forms a part of valve mechanism 8. As shown in Fig. 6 the bolt is Provided with a central bore orpassage I1 through the body thereof which terminates in a tapered valveport II in the head of the bolt. when the valve port it is uncovered, pressure medium escapes from chamber 3 through e 51 to the atmosphere. The pressure medium supplied to chamber I flows into sending pipe 0 through a port SI which is drilled through one side 0! extension 33 of the relay body into valve bore 12.

Valve assembly I includes a valve body Ii provided with a central bore 02 extending from one end to the other of the body. At the upper end of bore 62 a port 83 is formed having a tapered seat 84 that co-operates with a valve element adapted to close or open .this port. The valve element is carried at the upper end of a valve stem I that extends through .the bore of the body intoichamber 3 with. its lower end nesting in the exhaust port 58. The valve stem is urged downwardly by means of a spring 81, the upper body II and the lower end of which is'carried on a flanged collar is mounted on the valve stem and supported on a shoulder 39 thereon. Lower end portion 10 of the valve stem is made larger than the upper portion so that it may be shaped and fitted to properly control exhaust port I8. Spring 41 tends to urge valve stem 42 in, a direction to maintain the inlet port closed and the throughout the major portion of its length. Thus the leg of the T forms a web 45 on the under side of the beam which gives stillness and resistance to bending and the upper'portion 46 provides a wide, fiat face or trackway for the roller fulcrum I 3.

Diaphragm 5 may be made of the same size and shape as diaphragm 4 and may be secured to the right-hand end of beam Iii by means of a bolt 41, the head 48 of which bears on the top side of the diaphragm. The shank or body of bolt 41 passes through the central portion of the diaphragm, a bushing 49 disposed on the under side of the diaphragm, and end portion 50 of the beam. The bolt is drawn up tightly to hold the diaphragm and bushing securely to the beam by means of a lock washer ii and nut 52. Diaphragm 5 is clamped to body I by means 01' a clamping flange or ring 53 of substantially the same shape and size as flange 40. A substantially U-shaped yoke 54 of the same form and construction as yoke 43 is made as an integral part of flange 53 and serves as a support for spring it. The upper end of spring 12 is disposed about bolt 41 and bears against the under side of beam Iii and the lower end of this spring is supported on a spring cap 55 carried on the end of an adjusting screw 56. Screw 56 is threaded upwardly through the lower end of yoke 54 whereby spring lower end 10 thereof in contact with the seat of exhaust port 54.

From the description of the valve assembly, ex cluding the part which diaphragm I and valve bolt 41 with the valve port-SI formed therein play in the assembly and the operation of the valve mechanism, it will be apparent that the valve is easily repaired because by disconnecting pipe I from the valve body, the .valve body and valve stem 88 may be removed as a unit for inspection and repair. Alsoit will be apparent that the valve is a nonsticking type of valve and requires a very small travel in order to open fully or close fully its inlet and exhaust ports respectively. Further, the complete valve may .be inspected and repaired readily because the valve seat 58 is quickly accessible by merely disconnecting yoke ring 54 from the relay body i, the

diaphragm 5 and the valve bolt 41 may bereadily inspected and repaired or replaced if necessary. I

To adjust the device for operation it is preferable to position fulcrum is at the mid-point of beam III so that the ratio of In to L1 is equal to one. Springs ii and I 2 are then adjusted to produce the required forces A and B, say either sixty, seventy, eighty, or ninety pounds, at the ends of the beam. when making the spring adjustments there should be no pressure in chamher 2 and valve body I should be turned upwardly to a position where inlet port 63 is closed and the exhaust port is uncovered. When springs I i and II have been adjusted to the required tension so that values A and B are equal then valve body Iii is turned downwardly gradually until the end of portion of valve stem seats on the exhaust port 58 and closes it. This point will be readily determined because if the valve body is turned too far into bore 32 valve stem 68 will be moved upwardly and the inlet port opened, allowing air or pressure medium to flow into chamber 3. A gauge could be connected to pipe 9 and by means of this gauge the correct setting of the valve body would be determined because if the gauge shows pressure in chamber 3 the valve body should be backed out until the gauge shows zero pressure. The valve body would then be locked in place with lock nut H.

The device is now ready for operation. By introducing pressures into the receiving chamber 2 the resultant force R1 will be made less than force A whereby force B will cause beam III to turn counter-clockwise and lift valve element 65 oil the inlet port and allow pressure medium to how into chamber 3 until resultant force R: is made equal to resultant force R1 whereupon beam ill will assume a level or balanced position, in which position inlet and exhaust ports 63 and 58 will be closed and there will be no further change in pressure in chamber 3. If the pressure is further increased in chamber 2 the above-described operation will be repeated and a pressure will be built up in chamber 3 until the resultant force R2 is equal to resultant force R1. The opposite action takes place if the pressures received in chamber 2 are decreasing. If these pressures are decreasing then resultant force R1 will exceed resultant force R: and beam II) will tend to turn clockwise about fulcrum 13 whereby valve element 65 will be seated on and close the inlet port and the valve port 58 will be opened by its being moved away from the lower end of the valve stem portion 10, allowing pressure to escape through passage 51 to the atmosphere until resultant force R: is increased to a value equal to resultant force R1.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

i. A relay for ratioing received and sending pressures comprising a rigid relay body, a fulcrum, a lever positioned to rock on said fulcrum, yokes secured to said body adjacent the ends of said lever, a spring carried by each of said yokes and yieldingly engaging said lever, said springs being in compression, one acting to turn the beam in one direction about said fulcrum and the other tending to turn the beam in the opposite direction, a pressure-receiving chamber in said body adjacent one end of said lever and having an inlet to which a pressure impulse line may be connected, a pressure-sensitive member secured at its edge portion to said body and extending across said chamber and having its middle portion connected to the end of the beam adjacent thereto, the forces of pressure actin on the pressure-sensitive member of said receiving chamber opposing the force of the spring acting on the end of the beam adjacent thereto, a sending pressure chamber formed in said body adjacent the other end of said beam, at pressuresensitive member disposed across said chamber and secured at its edges to said body, the middle portion thereoi being secured to the adjacent end of the beam, said sending pressure sensitive member being with a member having an exhaust port for exhausting pressure medium from the sending chamber, a valve body supported on the relay body and extending into said receiving chamsource of supply of sending pressure may be connected, a valve stem within said valve body and having one end disposed to seat in the exhaust port and having a portion disposed to close the inlet port, the valve stem closing both ports when the resultant forces exerted by said springs and pressure-sensitive members on said beam are in balance about the fulcrum, the valve stem closing the exhaust port and being moved with it to open the valve when the resultant force acting on the beam adjacent the receiving chamber exceeds that at the opposite end of the beam. and the valve stem moving to close the inlet port when the exhaust port moves away from the valve stem, and a volume chamber formed in said relay body and having communication with said sending chamber.

2. A relay device comprising a rigid body. a beam having a fulcrum, springs supported from said body and connected to said beam, one on each side of the fulcrum and acting in opposition to each other, a pressure-responsive device associated with one of said springs and connected to the beam so as to oppose the force exerted by such spring on the beam, and a pressure-sending means associated with the other of said springs, comprising a chamber located between said rigid body, a pressure-sensitive member extending across said chamber and connected to the beam and adapted to exert a force thereon opposing the force of the spring associated therewith, said pressure-sensitive member having an element carried thereby and provided wth an exhaust valve port, a valve body associated with said chamber and provided with an inlet port to which a source of supply of sending pressure may be connected. and a valve stem within said valve body and provided with means for closing the inlet port, said stem extending into said chamber and having its inner. end portion disposed to seat in the exhaust port, and means yieldingly urging the valve stem in a direction to close the inlet port, the stem being moved by the pressure-sensitive member with the exhaust port closed when moving in a direction to open the inlet port, the sensitive member moving the exhaust port away from the valve stem to open the exhaust port after closing the inlet port, and an outlet from said chamber to which a sending line may be connected.

3. A device according to claim 2 characterized by the fact that the rigid body is provided with a volume chamber, the interior of which is connected to the interior of the chamber of the pressure-sending means, said volume chamber acting to prevent vibration of the pressure-sending means.

4. A device according to claim 2 characterized by the fact that the pressure-responsive and the pressure-sending means each comprise a chamber formed in said rigid body, that each of said chambers is closed by a diaphragm the edges 01 which are clamped in a pressure-tight relationship to the rigid body and that the middle portions of such diaphragms are secured to the beam.

5. A device according to claim 2 characterized by the fact that the rigid body has a pressuretight volume chamber therein which is connected by a passageway providing unobstructed communication between the sending. chamber I and volume chamber. which volume chamberpreber and provided with an inlet port to which a 7 vents vibration of the valve stem and pressuresensitive member associated therewith.

ROBERT R. DONALDSON.

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