US2474279A - Follow-up servomotor - Google Patents

Description

W. A. RAY

FOLLOW-.UP SERVOMOTOR June 28, 1949. 2,474,279

Original Filed May 5, 1942 3 Sheets-Sheet 1 June 28, 1949. w. A. RAY

FOLLOW-UP SERVOMOTOR v Original Filed May 5, 1942 3 Sheets-Sheet 2 Patented June 28, 179949Y FOLLOW-UP SERVOMQTOR A. Ray, Los Angeles, Calif., asslgnor to Y' General Controls Co., a corporation Original application May 5, 1942, Serial No.

V' 441,773, now Patent No. 2,364,659, December 12,

Y 1944. Divided and this application November 7, 1944, Serial No. 562,337

7 Claims.

This invention relates to control devices and more particularlyto means'for controlling the operation of a reversible motor iorpositioning a member inaccordance with variations in a controlling condition; the present application being a division of my copending application Serial No. 441,773, led May 5, 1942; .now Patent No. 2,364,659, granted December 12, 1944.

An object of this invention is to' provide means for so controlling such a motor, which are simple and compact and which comprise essentially a pair of pivoted levers, one of which is pivoted on the other at a point thereon spaced from its pivot.

Another object is the provisionV of a novel valve arrangement, for controlling a reversible iluid \pressure motor, which is`particularly adapted for actuation by the control means mentioned in the preceding object.

-Another object is Vthe provision of a valve structure, for controlling uidilowto and from a iluid pressuremotorjwherein means are provided for conducting the return iluid around the valve operating means to cool and/or lubricate thesame. Y-

.Another object is the'provision of means for preventing the building-up of :Iluid pressure between the interconnecting surfaces of parts of a valve, between which surfaces there is a connectionfor a passage for pressure fluid, in the event of leakage at or rupture of said connection.

Another object Vis the provision, in apparatus of the character described in the -frst abovestated object, of independentmeans for overriding the operation of the lever system in case of emergency.

Other objects and advantages of my invention will be found in the description, the drawing, and the appended claims; and for complete understanding of the invention, reference should be had to the following detailed description, and accompanying drawing, wherein Y y Figure 1 is a view, mainly in central vertical section, of a valve. embodying my invention;

Figure la is a fragmentary sectional view of the upper portion of the valve illustrated in Fig. 1, showing details of my'improved thermostatic uIi'it; y

Figure 1b is a view, similar to-that of Fig. 1a, showing a modified -form of thermostatic unit; Figure 2 is a transverse section taken along the line 2-2 of Fig.1`;

Figures 3 and 4 are vfragmentary vertical sections taken along the lines v3:--3 and 4 4, respectively, of Fig.2; Y y v Y the-other gures, in

5 housing I1, attached toLthe top of the base Il,`

Figure 5 is a fragmentary vertical section taken along the line 5-5 of Fig. 1

Figure 6'is a lower transverse section talen along the line 6 6 of Figs. 1 and 4;

,Figure 7 is a view, in perspective, of the valve illustrated in the other igures, the valve being shown connected in a conventional uid .pressure motor system, illustrated more-or-less diagrammatlcally; and

Figure 8 is a diagram for facilitating explanation of the operation of the valve, illustrated in the control of a uid pressure motor.

In the drawing, the numeral Ii indicates the main base portion of the valve, below which is a sub-base sectionv I2 which includes supplemental means for operating the valve, which means will hereinafter be described and need not now be considered in connection with the description of the main, or automatically-operated, parts of the valve, since these supplemental means constitute an overriding control system which is operated only incase of emergency.

The valve base I I has an inlet opening i3 (Figs.

5 and. 6) for connection to a source of uid under pressure, and a pair of openings I Il and I5 (Figs. l3 and 4, respectively) through each of which the fluid can pass to and from chambers of the fluid pressure motor under control; the low-pressure uid discharged from the motor nally passing -through an opening I6 (Figs. 1 and 2) in a valve in a manner to be described hereinafter.

As seen in Fig. 6, the high-pressure inlet opening I3 communicates with a passage i8 which extends horizontally across the base, breaking into a vertical opening I9 (see also Fig. 4), and

terminating at another vertical opening 20. Threaded in the opening I9, above the intersection of passage I8,is a valve-seat member 2i (Fig. 4); and similarly located in the opening 20 is another valve-seat member 22 (Fig. 3). Cooperable respectively with seats formed at the inner upper ends of these members are balls 23 and 24, which are respectively urged toward seating position by springs 25 and 26 compressed against caps 2l and 26 closing the respective bottom ends of the openings I9 and 20. The outlet of the seat member 2I leads into a horizontal-passage 29 (Fig. 4) terminating at the opening I5, and the outlet of seat member 22 similarly leads into another horizontal passage l30 (Fig. 3) terminating at opening I4. Branching respectively from the passages 29 and 30 are'vertical openings 3i and 32 (Fig. 6) in the upper endsof which are respectively threaded valve- seat members 33 and 34.

having, each respectively, ball-shaped closure members 35 and 36 which are urged into seating position by springs 31 and 38 compressed against plug fittings 39 and 40 which close the respective bottom ends of the openings II and 32 below the horizontal passages 29 and 80.

For actuation of the ball closures 23 and 24. which control passage of the pressure iiuid, reciprocable valve stems 4I and 42 are provided which are closely guided in ilttings 43 and 44 threaded in the ends of openings I9 and 20 above . passages 29 and 38, each respectively. In a similar manner, the ball closures 35 and 38, which control passage of the exhaust iiuid, are arranged to be actuated respectively by valve stems 45 and 46, guided in the extreme upper reduced portions of the bores of their respective seat members 33 and 34. The stems 45 and 46 are clearanced from the lower walls of the bores so that, when the closures are opened, iiuid can e pass around the stems and through branch passages 41Aand 48, respectively, which lead from the bores to the area 49 above the base member I I within the housing I1. As so far described, it will be seen that when closure 23 only is open, pressure fluid can pass from the inlet I3 to the opening I5, and that when closure 35 only is open, exhaust fluid can pass from opening I to the area-49. Similarly, when closure 24 is open, pressure fluid can pass from the inlet I3 member II which extend from its top surface at the front and rear as viewed in Fig. 1. As best seen in Fig. 2, the upper surface of the lever 60 is centrally channelled in the direction of its length, there being a rectangular opening downward through the middle of the chan` nelled portion 69. Extending medially from opposite sides of the lever are portions 63 and 64, through which are threaded screws 65, 66, 61 and 68, the bottom ends of which are adapted to engage the top -ends of the valve stems 4I, 46, and 42, respectively, when the lever is rocked; the screws being so adjusted that there is a minute clearance between each of them and its respective valve stem when the lever is in its neutral position, as shown.

Pivotally mounted in the vchannel of lever B9, by a pin 18 which extendsinto openings in the walls on either side of the channelled portion 69 and at the right of pin 6I, is another lever 1I. This lever, as is best seen in Fig. 1, has at its opposite ends upwardly extending bosses 12 and 13 which are recessed to freely receive the pin portions 14 and 15, respectively, of means for automatically operating the lever system. The upper portion of pin 14 extends freely into an axial recess 16 formed in the cylindrical bottom end portion of a screw 11 which is threaded in an elongated nut member 18, which in turn is threaded in an openingthrough a top wall of the housing l1. The pin 14 serves as a stop, adjustable in position by screw 11, for limiting counterclockwise rotation of lever 1I. Leakage around the cylindrical upper end portionof screw 11 is prevented by a gland nut 19; and lostmotion between the screw and its nutmember 18 is prevented by a still spring 89 compressed between the nut and a ball-bearing abutment 8i secured to the lower end portion of the screw 'I'he other pin 15 is attached to means for rock-- ing the lever system in response to changes in a controlling condition-the condition in the example illustrated being that of temperature. Threadedly mounted in an opening in an upper extension of the housing I1 is a tubular member 86, within which is an expansible-contractible metallic bellows 81 which is sealingly secured at its bottom end to the member 88 through the medium of a shell 88, and at its top end to a head 89 (Fig. la). The end of the tubular member 86 above the head 89 is closed, by a wall 99, to constitute the space between it and .the bellows a pressure chamber.

Extending from the wall 90 is a thermostatic unit, of the liquid-charged type. which comprises an elongated hollow cylinder 9|, integrally joined at its lower end to the wall 90 and having a relatively thick circumferential wall which is machined or otherwise formed to provide a plurality of spaced iins 92 and end plates 93 and -94. Surrounding the cylinder, and sealingly secured as by solder to the end plates 93 andl 94, is a barrel 95, the ns 92 being preferably in close engagement with the barrel at their peripheries. As shown in Fig. 1a of the drawing, the ins are formed as a continuous helix so that the space between the cylinder and the barrel is divided by them into an elongated helical passage. However, if preferred, there may be provided instead (andv as shown in Fig. 1b, wherein the numerals assigned to the parts corresponding to those of Fig. la are primed) a series of individual ns 92" which divide the space within the thermostatic unit into spaced annular compartments, the iins then being provided with small openings I 10 through which the liquid, with which the unit is charged, can pass between the compartments. It will be seen that, by the arrangements described, there is very effective transfer of heat to the liquid, both from the inside and from the outside of the unit, through the iinsthe parts, of course, being made of metal having good heat-conducting properties. In the lower portion of the cylinder 9|, below the plate 94, are openings 96-whereby the fluid circumambient to the unit can circulate through its central passageway. The interior of the thermostatic unit is connected with the pressure chamber above the bellows 81 by a pipe 91 sealed at its ends in openings through the plate 94 and the wall 90. Clamped to an enlargement 98 formed on the tubular member 86 at itsupper end is a ange 99 whereby the valve may be mounted on a supporting wall, for instance, that of the liquid tank or reservoir of a liquid-cooled airplane engine, the thermal unit then extending through an opening in the wall of the tank so that it is subjected to the temperature of the liquid therein. l

Threaded in the thickened bottom end portion of the bellows head 89 is a stem |09 having an enlarged and elongated lower end portion IUI which is a free iit within a hollow cylinder |02. The shoulder at the top of the enlarged stem portion IBI is normally retained in engagement with the top end wall of the cylinder I|l2 by a 5. spring |03 encircling the cylinder and compressed between the enlarged bottom lend portion of the cylinder and the underside of the anged bottom end portion of asleeve |04, which surrounds an upper portion of the stem and abuts the head 80. Threaded in the bottom'end of the cylinder,

and locked in adjusted position by a pin |05, is v with the lever 50,7by a compression spring H0 acting on the underside of the right-hand channelledfend portion 59 of lever 50. It will thus be seen that upward or downward movement of the pin rocks lever 50 about its pivot 5| (pin 14 acting as a fulcrum for lever 1|) thereby eiecting actuation of the valve closures 24, 35 and 23, 35. When the movement of pin 15 is upward,

closures 24 and 35 are opened, and when its m'ovement is downward, the other pair of closures 23 and 35 are opened. It will be noted that if pins 14 and 15 were positively connected to lever Il (instead of merely being in one-sided engagement therewith) spring -l'lli would not be essential. However, the arrangement illustrated is prefen-ed, since thereby the possibility of lost-motion between the parts is eliminated.'

As was mentioned' at the beginning of the description, the sub-base section I2 includes supplemental means, under manual control, for overriding the automatic operation of the valve in case of emergency. as, for instance, in case for some reason the thermal unit ceased to function properly. These supplemental means serve to control duid-pressure operable means provided in base |2 'and which comp ||3 and-l |4, respectively, formed in the top surface of base I'2. The piston provides a lower abutment for the lever spring ||0, that .spring also normally serving -to retain the pistonin its depressed position. The piston l|2 is similarly downwardly urged by a spring I5 which at its upper end abuts a bushing ||5 threaded in the |21 and |23 of apair or electromagnetically operated valves |23 and |30, each respectively. These vaivesare preferably, and as illustrated, of the type disclosed and claimed in my copending application, Serial No. 429,983, led February 9, 1942, now Patent No. 2,321,853, and each comprises (as vshown in connection with valve |430) a diskshaped closure member |3|, normally biased into seating engagement with a jet Vor seat member |32 through which, when the disk is lifted upon energization oi the eiectromagnet, iluid can pass from the valve inlet chamber |33 to the outlet |23. The inlet chambers |33 and |34 of the valves |30 and |20 are interconnected by a horizontal passage |35, from the middle of which branches a passage |36 which communicates, at the upper end of its extension |31 in base with the' main pressure-fluid supply passage I0. If the electromagnetic valve |29 is energized, the resultant subjection of piston Lto the pressure uid 'rocks lever 50 counterclockwise (throughthe medium of pin H1) thereby opening the lefthand pair of valve closures 24 and 35; the strain-release spring |03 permitting the elevation of the left-hand end of lever'll necessary for this movement. In' a like manner, if valve |30 is energized, lever 00 is rocked clockwise and the other pair of valve closures 23 and 35 are opened; the resultant movement of lever 1| beingin a direction away lfrom the pins 14 and 15.

'For sealingly interconnecting the-ends of the [passages |23, 125,124, las, and isi, ist, m base e a pair of pistons gi and |`|2 which work in ependently in bores upper end of bore H4. Resting in cavities formed in the top surfaces of the pistons and ||2 are pins I1 and H8, respectively, the upper portions ofvwhich' extend outwardly of the piston bores and are adapted toengage the underside of the opposite ends offthe channelled portion 53 of ,lever 50 when the pistons are raised; cavities ||5 and |20 being provided in these portions for receiving and loosely guiding the pins, which pins are of such length that they donot impede movement of lever 50 in the normal automatic operation of the valve. The pistons are provided with restricted openings |2| and |22 through which the uid trapped beneath them can bleed when, after operation, they are returned to their normal depressed positions by the force of springs ||0 and||5.` *l

For operating the pistons and ||2, means are provided whereby pressure uid can be selectively suppliedto the areas beneath them. For

this purpose, the bottom ends of the piston bores ||3 and ||4 are connected by passages |23 and |24, in base and registering cored passages Il and sub-base'12'respectively, thesef'palrs of passages are enlarged at their junctions at the interconnecting surfaces of the bases toreceive bushings |45, |48 and |41, respectively. The

material of the'base surfaces around each of the passages is recessed to provide, with the bushings, coniining spaces for annular packing membersl |40, |40, and |50, of rubber or other deformable material, which, when thebases are bolted together (with a gasket |5| therebetween), are compressed and thereby seal the connections. Also formed in the ,interconnecting surfaces of the. bases, surrounding but spaced`from the passage connections, is' an elongated cavity |52 which is connected by avent passage |53 in base with the outlet chamber 49 thereabove. In the event of leakage around the passage connections, only thesmall areas of the lbase surfaces surrounding the connections are subjected to the pressure of the uid, which then passes harmlessly to the outlet. If such yent lmeans were not provided, it would be necessary that the means for holding the bases together should be of such strength that lthey could' withstand the pressure of the escaping fluid acting across the whole surfacev areas of the bases.

' operation In Fig'. '1, the vafive 'illustrated in Figs. 1 6- is shown connected to control the operation of 'a uid pressure motor |54 which comprises a |5'. The valve openings I4 and |5 are respectively conectedby pipes u' and is' to the cham- |25 and |26, in the sub-base l2, with the outlets 15 bers |59 and |50 ofthe motor |54 at opposite 7 sides of its piston |56. Extending from piston |56 is a stem |6| which is adapted to be connected to the means to be positioned in accordance with the temperature at the thermostatic unit 9|, 95. When the valve is employed to control the temperature of the cooling liquid of an airplane engine (such being an important application of the valve of this invention), the ste |6| may be connected to operate the aps or anes which must be positioned to control air iiow to the liquid tank or radiator. The stem |6| is also connected, by a. link |62, to an arm |63 secured to the outer end of the stop screw 11.

In the diagram of Fig. 8, the parts have been assigned numerals corresponding to those of the equivalent parts of the structure shown in the other gures. For the sake of clarity, some of the parts have been considerably modied; for instance, in the diagram the connection between the stop pin 14 and the valve stem |6| comprises a bell-crank, whereas in the structure the pin is positioned by the rotation of screw 11 by the valve stem through link |62 and arm |63. However, it is believed that the general correspondence of the parts of the diagram and of the structure will be quite clear to those skilled in the art. n

rn the diagram, the lever so (which includes the valve-actuating end portions 63 and 64, and the portion 69 therebetween) is shown in its neutral position wherein all the valve closures 2,3, 36, 35 and 24 -are ,unactuated, and hence held closed by their biasing springs; the thermostatic unit 95 being at the desired temperature which (assuming that the valve is connected in an airplane engine temperature control sysvtem of the character described above) is maintained in the cooling liquid. under existing conditions, by the air aps being in partly open position, as is indicated by the medial position of the piston |56 in its cylinder.

If the temperature of the1thermal unit now rises, the resultant downward movement of the bellows stem tends to rock` lever 1| counterclockwise; however, since free movement of this lever is restrained by the stop pin 14, it rocks rather about the stop pin as a iulcrum, thereby effecting clockwise rotation of lever 60, through its pivotal connection therewith. (It should be remembered that the strain-release spring |03 does not yield during the normal or automatic operation of the valve.) The resultant opening of the right-hand pair of closures 23, 36 permits ilow of pressure uid past closure 23, through passage 29 and pipe l5', to the motor chamber |60; the fluid in the other chamber |59 simultaneously discharging through pipe I4', passage 30, and around the open closure 36-the exhaust fluid then passing through the main chamber 49 of the valve and returning to the reservoir |58 through the pipe I6', these elements not being shown in the diagram. The resultant right-hand movement of the piston effects wider opening of the flaps, and also acts through the members |63 and 11 to raise the stop pin 14, thereby permitting lever 60 to return .to its neutral position under the inuence of spring ||0 lever 1| now being effectively fulcrumed on pin 15) so that movement of the motor piston is arrested; lever 1| assuming a diierent angular position with respect to lever 60 due to the elevation of the stop pin 14.

Should the temperature of the thermal unit now decrease, the resultant rise of pin 15 permits lever 60 to rock counter-clockwise under theiniiuence of spring ||0, thereby opening the other pair of valve closures 35, 24. This results in the application of pressure fluid to motor chamber |59 and the exhausting of chamber |60, so that the piston now moves in an opposite direction; its movement again being arrested due to the follow-up connection between the piston and the lever system which acts to restore lever 60 to its neutral positin; the new angular position of lever 1| being determined by the .positions of pins 14 and 15. It is tobe understood, of course, that the piston can move continuously to the limit of its travel in either direction if the prevailing temperature conditions are such that it should; the stop or follow-up pin `14 then moving' substantially in accordance with the movement of pin 15.

The embodiment of my invention herein shown and described is obviously susceptible of modilcation'without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a system for adjusting the position of a member; a motor for operating said member and capable of moving it in opposite directions; a first lever pivoted for movement through a small angle; means operated by the movement of said rst lever in opposite directions for so controlling the operation of said motor that said member is correspondingly moved in opposite directions, said rst lever having a neutral position wherein said motor is unoperated; a second lever pvotally mounted intermediate of its ends directly on said irst lever at a point thereon spaced from its pivot; means movable in a rectilinear path in response to change in a controlling condition and directly engageable with one end of Vsaid Asecond lever; stop means engageable bythe other end of said second lever; means biasing said rst lever in a direction such that the ends of said second lever are urged into engagement, respectively, with said condition responsive moving means and with said stop means, movement of said condition-responsive moving means thus being effective to rock said second lever about said stop means as a fulcrum and thereby rock said rst lever from its neutral position; and means operated by the resultant movement of said member for so adjusting the position of said stop means that said rst lever Vis restored to its neutral position by said bias.

2. In a. system for adjusting the position of a. member: a motor for operating said member and capable of moving it in opposite directions; a rst lever pivoted intermediate of its ends for movement through a'small angle; means alter- ,nately engageable by the opposite 'ends of said first lever when the same is rocked for so controlling the operation of said motor that said member isv correspondingly moved in said opposite directions; a second lever pivoted intersecond lever; stop means engageable by the other end of said second lever; means biasing said first lever in a direction such that the ends of said second lever are urged respectively into engagement with said condition-responsive moving means and with said stop means, said conditonresponsive moving means thus being eective in its movement to rocksaid second lever about said Ystop means as a fulcrum and thereby rock said rst lever; and means operated by the resultant movementl of said member for Vso adjusting the position of said stop means that said first lever is restored to its unrocked position by said bias, in which position said motor is unoperated.

3. In a system for adjusting the position of a member: a uid pressure motor for operatingV said member and capable of moving it in opposite directions; a rst lever pivoted intermediate of its' ends for movement through a small angle; iirst valve means adapted to be engaged by one end of said rst lever when the same is rocked in one drection for operating said motor to move the member in one direction, and second valve means adapted to be engaged by the other end of the rst'lever when the same is rocked in an opposite direction for operating said motor to move the member in an opposite direction, said iirst lever o having a neutral position wherein it is out of engagement Vwith both of said valve means s o that 'the motor `is unoperated; a second lever pivoted intermediate of its ends directly on said iirst lever at a point thereon between its' pivot and one of its ends; means movable in a rectilinear path in response to change in a controlling condition and directly engageable with one end of said second lever; stop means engageable by the other end of said second lever; means biasing said iirst lever in a dirctionsuch that the ends of said second lever are urged respectively into engagement with said condition-responsive moving means and with said stop means, said conditioneresponsive moving means thus being efabout said stop means asafulcrum and thereby rock said first lever;l and means operated by the .resultant movement of said member for so ad- `justing the position of said stop means that said rst lever is restored to its neutral position by the force of said bias.

4. In a system for adjusting the position of a member: a motor for operating said member and capable of moving it in opposite directions; a iirst lever pivoted intermediate of its ends for moveinent through a small angle; means alternately trolling `conditionv and directly engageable with one end of said second lever; stop means engageable by the other end of said second lever; said condition-responsive means and said stop means being movable in -parallel rectilinear paths and engageable with the sameside of said second lever; a spring biasing said ilrst lever in a direction such that the ends of said second lever are urged respectively into engagement with said condition-responsive means andY with said stop by the resultant movement. of said member," for so adjusting the position of said stop means that said rst lever is restored to its neutral position 6. In a system for adjusting the position of a I member: a fluid pressure Vmotor for' operating said member and capable of moving it in opposite directions; a first lever pivoted intermediate of its ends for movement through a' small angle; rst` valve means adapted to be engaged by'one end ofsaid first lever when the same is rocked in one direction for operating said motor to move the member in one direction, and second valve means adapted to be engaged by the other end of the first lever when the same is rocked in an opposite direction for operating said motor to move the gagem'ent with both of said valve means so that- .25.

` fective in its movement to rock said second lever condition-responsive means and with said stop I means, said condition-responsive means thus being effective in its movements to rock said second lever Vaboutsad stop means as a fulcrum and thereby rock said rst lever; and means, operated member in an opposite direction, said first lever having a neutral position wherein it is out of enthe motor is unoperated; a second lever pivoted intermediate of its ends directly on said first lever at a point thereon between its pivot'and one of its ends, said levers being substantially coextensive: means movable in response to change in a controlling condition and directly engageable with one end of said second lever; stop means engageable by the other end o`f said second lever; said condition-responsive means and said stop means being movable in parallel rectilinear paths and engageable with-the same side of said second lever; a spring biasing said first lever' in a direction such that the ends of said second lever are urged respectively into engagement with said means, said condition-responsive means thus being effective in its movements to rock said second lever about saidV stop means as a fulcrum. and

thereby'rock said rst lever; and means, operated by the resultant movement of said member, for so adjusting the position of said stop means that said ilrst lever is restored to its neutral position by said spring. I I

'7. The combination dened in claim 6, and including: a base for supporting said levers; and means, removably secureddao said base, for supporting said condition-responsive means and said stop means.

4 WILLIAM A. RAY.

REFERENCES CITED i 'The Iollowing'references are of record in the le of thispatent: o

UNITED STATES PATENTS

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