US2942581A - Hydraulic operator - Google Patents

Description

D. J. GAFFNEY HYDRAULIC OPERATOR June 28, 1960 5 Sheets-Sheet 1 I INVENTOR. DONALD J. GAFFNEY a 1 m a B Filed March 12, 1958 June 28, 1960 o. J. GAFFNEY HYDRAULIC OPERATOR 3 Sheets-Sheet 2 Filed March 12, 1958 M P ii- 5 H w 0 L 4 l 4 2/4 2 M M W a 6 M w m r H \l M 4 M 2 w 6 0 4r HEW 60 m DONALD 4 m a M a Z r a W Z 2 0- F P v z MVP 8 P P P \z 4 5 0 |1W 6 "/0 "W 52 7 w 1 z 9 8 7 M a M M 7 6 a 6 6 4 Q 5 WM 4/ V 4 4 w a J f mw I. w llll l I m 6 Z 3 #(bfll/ N 3 2 P 7 CI p 4. Zn a W, B e as w A We a W 7 i 6 3 H M "Mu, F a 1w 1 6 0 0 "M805 F AF 6 ma M P M June 28, 1960 D. J. GAFFNEY HYDRAULIC OPERATOR 3 Sheets-Sheet 3 Filed March 12, 1958 INVENTO. 3*-

YDONALD J. GAFFNEY w 0 Q. M0 5 #2 /f 0 n 7 n. 2 M w w a M E 4 z z z United States; Patent Qfiice HYDRAULIC OPERATOR Donald J. Gaifney, Marshalltown, Iowa, assignor to Fisher Governor Company, Marshalltown, Iowa, a corporation of Iowa Filed Mar. 12, 1958, Ser. No.'720,838 13 Claims. (Cl. 121-41) This invention relates to an electrically controlled hydraulic operator for valves and the like wherein hydraulic pressure is the actuating medium for the valve and is controlled by an electric command signal in such manner as to proportion the positioning of the valve in relation to the requirements of a condition such as the pressure in the downstreamside of the valve.

One object of the invention is to provide hydraulic means to position the final control element utilizing electric current such as used for lighting to produce the hydraulic energy. The hydraulic system lends itself readily to proportioning control, producing high forces where necessary. A hydraulic system using a relatively high fluid pressure together with a small actuating piston, when used with a suitable pilot system, makes it possible to obtain relatively high frequency response characteristics because of the low mass of the system, as compared with an electric motor-gear train system.

Another object is toprovide electric control for the hydraulic system to eliminate the necessity for a com pressed air supply system consisting of compressors, dehydrators, filters and standby equipment. Without appropriate dehydrators and filters pneumatic systems can be troublesome in cold climates where air line freezeups can occur, resulting in interruption-s of service. Further, it is possible to transmit electric control signals over long distances with better frequency response than with pneumatic control signals over comparable distances.

Still another object is to provide a high performance controller utilizing an electric control loop with or without the use of electronic amplification and utilizing only a simple force motor to control a hydraulic pilot whichin turn controls the hydraulic system that actuates the operator, and in which the pilot system incorporates'no close fitting parts such as sliding plates or spool valves but uses instead simple nozzle-flapper combinations to control the flow of hydraulic fluid.

A further object is to provide an hydraulic actuatorin which the hydraulic system including the motor-pump combination can be removed from the actuator itself with the exception of the hydraulic cylinder and piston so that for periodic maintenance or for replacing a malfunctioning actuator the pilot and motor-pump assembly can be removed as a unit and may be replaced with a standby unit in a matter of minutes, thereby resulting in very little down-time.

Still a further object is to provide nozzle valves for controlling the flow of hydraulic fluid in the system which nozzle valves are controlled by a simple force motor consisting of a coil suspended in the magnetic field of a permanent magnet to which direct current from a controller flowing through the coil produces a force which moves the coil through the magnetic field,,and the magnitude of the coil current determines the thrust of the force motor, thereby proportionally controlling the pilot valves if used and nozzle valves, and through them and the yd aul sy te ntro ling th c rr sponding P s of a main valve controlled.

An additional object is to provide a hydraulic pilot circuit that controls the pressure to the actuating cylinder for the main valve in response to movement of the force motor coil caused by input current change from an electric' controller and the pilot varies the pressure in pilot nozzles and bellows connected therewith and actuated by,

relatively low pressure so that the bellows then serve to actuate power nozzles that control the flow of hydraulic fluid at greater pressure to the actuating cylinder for the main valve, the pilot stage acting as a hydraulic amplifier and making possible the operation of the power nozzles with the small force available from the force motor, and the powerv nozzles controlling the pressure and/or flow applied to the hydraulic piston which actuates the main valve stem.

Another additional object is to provide feed back from the position of the valve to the force motor in which a feed-back cam of a shape to secure the desired operating characteristic relationship between input signal and main valve area may be used and is readily interchangeable with cams of other shapes, while at the same time the main valve itself may, always be of linear type thereby simplifying the changing of its operating characteristics by making it unnecessary to break into the main flow line with the attendant inconvenience and protracted downtime. In the prior art several types of main valves had to be on hand to give the required characteristics such as linear, parabolic or percentage types.

A further additional object is to provide a plugein arrangement whereby it is possible to remove the motor pump and allpilot parts from the main valve and its actuating means without disconnecting any fluid line, the pump and motor being bolted to a cover plate as is the pilot and second-stage assemblies and the force motor. In case of a failure of any pilot parts, the coil or magnet parts of the force motor, or the pump and motor, the plant personnel can remove the bolts holding the cover plate down, lift the entire unit comprising the plate with its attachments, disconnect the signal wires, remove the V ydraulic connections need be disconnected when chang- Yetanother objectis to provide a three-pump system 7 furnishing a separate supply of hydraulic fluid to produce an individual constant pressure source for each nozzle at all times. i

Still a further additional object is to provide a shut-01f valve feature in which shut-oftvalves are actuated by the pump to open position whenever the operator is m operation but which, in case of power, motor or pump failure,

automatically reclose under the action of springs, and a close the lines leading to the cylinder chambers above and below the actuating piston, thereby maintaining the piston in the last position it assumed prior to the'power, motor or pump failure. By means of a by-pass valve included in the operator it is possible to open fluid passages to both cylinder chambers, thereby making it possible to manually position the piston and main valve by manually operated mechanical means. Y

Other objects of theinvention are to provide good shut-ofi characteristics without vibration, objec ionable noise and wear in the flapperenozzle combinations-for the hydraulic power circuit of the actuator by the use of balls between the nozzles and flappers, the use of a counterweight for the beam of the pilot valve to prevent vibrations from the main pipe line being 'transmitted to the coil of the force motor and sympathetic v'ibra tioii at V Patented June 28, 1 960 1 or other final actuated element common frequencies or harmonics of motors, turbines, etc. that might be imparting vibrations to the main valve itself, and a means to take care of any oil leakage such that the leakage fluid can be directed away fromthe valve body structure which in many cases is in an extremely high ambient temperature and could cause a fire hazard should leakage fluid contact the hot surfaces.

'1 also contemplate the provisions of a modified form of the operator which is simplified by the elimination of pilot circuits where close and accurate control is notparamount, and my. operator can thereby be manufactured at lower cost but operates on the same general principle of electric force motor control of flapper-nozzle valves which in turn control the flow of hydraulicactuating fluid for the actuator of the operator. a 1

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my hydraulic operator, whereby the objects above contemplated are attained, as hereinaft er more fully set forth, pointed out in my claims and illustrated in detail on the accompanying drawings,

wherein:

Fig. l is a perspective view of an hydraulic operator embodying my present invention;

Fig. 2 is a diagrammatic view thereof to show the operation and includes a main valve controlled by the operator in a fluid flow controlling system, and an electric circuit responsive to the pressure in the system and controlling a force motor of the operator;

Fig. 3 is an enlarged vertical sectional view through my operator;

Fig. 3A is a further enlarged view of a flapper pivot thereof;

Fig. 4 is an enlarged sectional view on the line 44 of Fig. 3.

Fig. 4A is a further enlarged fragmentary view of a portion of Fig. 4 to show a flapper-nozzle construction;

Fig. 5 is a perspective view of my operator with the motor-pump and all pilot parts of the unit supported on the flat plate cover being removed from the reservoir and actuating cylinder for replacement, the cover for the force motor also being removed;

Fig. 6 is a vertical sectional viewsimilar to Fig. 3 showing a modified construction which does not use pilot .valves;

Fig. 7 is a diagrammatic view thereof similar to Fig. 2 .to show the operation; 1

Figs. 7A and 7B are similar .modifications of Fig. 7; and

Fig. 8 is a sectional view of a passageway and'restriction fitting used in the form of my invention shown in Figs. 6 and 7.

On the accompanying drawings I have used reference characters to indicate in general several of the important elements of my operator as follows:

B -bellows to control N B -be1lows to control N BAG-electronic amplifier controller F and F power flappers for N and N FM--force motor METmeasur-ing element transmitter N and N -valve controlling or power nozzles P and P Nozzle pumps for N and N PF and PF .-pilot flappers for PN and PN PM-pump motor PN -pilot nozzle for N PN?pilot nozzle for N PPpilot pump for PN and PN R-reservoir provided with cooling fins R restn'ction for PN 1 R --restriction for PN 2 V-main valve being operated The valve V, as shown in Fig. 1, has a head 10 to which an adapter yoke 12 is suitably secured so that the yoke is supported on the valve and in turn may support my operator contained in the reservoir R. Most of the mechanism of the operator and the pump motor PM are mounted on a mounting plate 26, the element 24 being a force motor cover. The valve V has a valve stem 16 extending therefrom and connected with a valve actuating piston rod 18 as also shown diagrammatically in Fig. 2.

The rod 18 extends from an actuating piston 20 in cylinder 22 located in the reservoir R as shown in Fig. 3. The cylinder has a lower head 25. The adapter yoke 12 incorporates an anti-spin arrangement since usually there is torsional force on the stem 16 caused by the fluid flowing through the valve V acting on the valve elements 28 diagrammatic views of (Fig. 2) therein, and it is necessary to prevent this rotation to avoid wear of seals, piston cylinder and cams, etc. for which purpose an arm 30 slides vertically in a slot 32 (Fig. 3). A suitable pointer 34 and scale 36 serve to show the position of the valve.

The mounting plate 26 is adapted to be removably secured to the upper end of the reservoir R by means of cap screws 38 and has a centrally located sleeve 40 that telescopes over a sleeve extension 42 from the upper end of the cylinder 22 with suitable O-ring seals to isolate annular passageways 44 and 46 from each other and seal them against leakage as between the sleeve 40 and the sleeve extension 42. The element 42 also serves as an upper head for the cylinder 22.

The annular passageway 44 communicates with the cylinder 22 below the piston 20 therein by means of a passageway 50 in the sleeve extension 42 anda conduit 52 leading to a T fitting 54 threaded into the lower head 25 of the cylinder 22 and communicating with a passageway 23 therein. The annular passageway 46 communicates with the cylinder 22 above the piston 20 therein through a passageway 48 in the sleeve extension 42.

Valve blocks 56 and 58 are mounted on a supporting block 78 and are thereby rigidly suspended from the mounting plate 26. The pilot nozzles PN and PN are mounted in the block 56 while the nozzles N and N are mounted in the block 58. The pilot flappers PF and PF coact with the nozzles PN and PN and consist of ,thin sheet metal strips as shown in Fig. 3a. The strip PF is in the horizontal plane and also serves as a support and pivot for a force motor arm 60 secured to a block 62 to which the strips PF and PF are secured, the strip PF being also secured to a stationary block 64. A strip .65 (which is similar to the strip PF except in the vertical plane) is also connected to the blocks 62 and 64 so that the flexure of the strips PF and 65 between their points of securement to the blocks 62 and 64 serve as a rotating pivot or flexure strip connection to eliminate hysteresis in the control system. The strip FF is bifurcated and the strip 65 is located between the two arms thereof to provide a mechanically balanced connection.

A pair of actuating bellows B and B communicate with the pilot nozzles PN and PN respectively and are mounted on a centrally pivoted bar constituting the flappers F and F for cooperation with the valve controlling nozzles N and N. The pivot of the bar F -F is preferably the same type (Fig. 3A) as provided for the flappers PF and PF. Two of the elements thereof are shown at 64 and 65 in Fig. 3.

The power nozzles N and N are advantageously provided with balls covering the nozzles as shown in Fig. 4A to accomplish two purposes. First, the balls make it possible to obtain very good shut-01f which is necessary to provide maximum cylinder pressure and/ or flow with the minimum loss of hydraulic energy. Second, regardless of the angle of the flapper beam F --F. which rotates about the flexure strip center, the orifice can be completely covered. It will also be found that a flat surface covering an orifice containing hydraulic fluid at 500 p.s.i. tends to vibrate and cause objectionable noise and wear, and the zles 'are'so adjusted in relation to the flappers that' the' balls, even at maximum opening of the combination as shown in Fig. 4A, cannot become dislodged from the nozzles by the oil flow.

A conduit 76 leads from the pilot pump PP to the valve block 56 for supplying hydraulic fluid under low pressure (such as 50 p.s.i.) to the valve block and through the restrictions R and R to the nozzles PN and PN and the bellows B and B as shown diagrammatically in Fig. 2. Shut-01f valves 80 as detailed in Fig. 4 are located in the supporting block 78 and are supplied with hydraulic fluid from the conduit 76 by means of a passageway 82 in the block 78 which passageway is also shown diagrammatically in Fig. 2. Each shut-01f valve 80 has a piston 84 and is normally closed under the action of a spring 86. When pressure is exerted on the pistons 84 from the passageway 82, the shut-oft valves 80 are opened as shown in Figs. 2 and 4 for operation of the system. This arrangement permits automatic reclosure of the shut-off valves 80 for a purpose which will hereinafter appear when the pressure in the passageway-82 fails for any reason.

All three pumps PP, P and P receive oil from the reservoir R through a filter 75 and a conduit 77. The nozzle pumps P and P are higher (such as 500 p.s.i.) than the pilot pump PP and deliver hydraulic pressure through conduits 86 and 88 to the valve block 58 and thereby to the power nozzles N and N respectively. As shown in Fig. 4 and diagrammatically in Fig. 2, passageways 90 provide branch paths leading to the shut-off valves 80 which are controlled by the pressure in 90 with the outlets from the valves 80 (one of which is shown at 92 in Fig. 4) communicating by means of conduits 94 and 96'with the annular passageways 44 and 46 respectively in the sleeve 40. Thus communication is established between the nozzle N and the lower end of the cylinder 22 and between the nozzle N and the upper end of this cylinder.

The lower and upper ends of the cylinder 22 are connected together by conduits 100 and 102 with a bypass valve 98 interposed between the two conduits (see Fig. 2), and this valve is normally closed but is adapted for manual opening for a purpose which will hereinafter appear. The upper end of the conduit 102 taps into the passageway 48 as shown in Fig. 3 whereas the lower end of the conduit 100 is connected into the T fitting 54 and thus communicates with the cylinder 22 below the piston 20 therein by means of the passageway 23 in the lower head 25 of the cylinder.

The force motor FM comprises a permanent magnet 104 having a pole disc 108 and a pole cup 106 which provide an annular flux gap for a control coil 110 wound on a sleeve 112 having a washer 114 at one end of the coil and a disc 1 16 at its other end. The parts 112, 114 and 116 are non-magnetic. The disc 116 is secured to the force motor arm and floats in the annular flux gap in such manner that increase and decrease of direct current in the coil will move the arm 60 in one direction or the other as will hereinafter be explained. The pole cup 106 is supported on a bracket 118 connected to the mounting plate 26.

A bias spring 120 has one end connected to an ear 122 of a bracket 124 that has an anchored end 126 secured to the force motor arm 60. The other end of the bias spring 120 is connected with a spring tension adjusting screw 130 supported by a stationary bracket 123 secured to the top of the mounting plate 26.

A feed-back spring 132 has one end connected to a lever 134 and its other end connected to a spring tension adjusting screw 136 that is carried by the anchored end 126 of the bracket 124. The'lever 134 is pivoted at 138 to the bracket 118 and has a slot 140 in which a roller carrying block 142 is adjustable. A roller 144 is rotatable on the block 142 and is held in contact with a cam 146 by the feed back spring 132. The force motor cover 24 encloses the force motor FM and the mechanism The force motor arm 60 is advantageously novided with an extension 148 downwardly from the block 62 as shown in Figs.-3 and 4 towhich acounterweight 150 is secured to help prevent vibrations from the'main pipe line of the valve 'V being transmitted to the force motor FM, and prevents the assembly from vibrating 'sym: pathetically at common frequencies or harmonics of motors, turbines and the like, connected with the pip ing for the valve V.

With respect to the form of invention shown in Figs. 6 and 8 and diagrammatically in Fig. 7, many of the parts correspond to those described in connectionwith the first five figures of the drawings and have been given the same reference numerals with the distinguishing characteristic a added. In this modified form of the invention a single pump- P is provided and the flappers F and F for the nozzles N and N are directly actuated by the force motor arm 60a rather than through a pilot arrangement as in the first described form of the invention. The modified form is therefore considerably simpler in construction and lower in cost although it does not have the fine coninstead of a plurality of pressures that reduces the over:

all cost of the operator. This form of invention includes a passageway and restriction fitting 149 shown in elevation in'Fig. 6 and in cross-section in Fig. '8.

Another feature of my present invention is associated with the prevention of oil leakage. The adapter yoke 12 has a chamber 152 formed therein-and located under the reservoir R, which chamber is supplied at the top with a high-pressure oil-tight seal 15 3', and at the bottom with a combined oil tight seal and felt wiper ring 151. Any oil leakage past the high pressureseal 15 3 is retained by the lower ring 151 so that it does not run downthe stem 18 where it would be exposed to atmosphere. The chamber has-a tapped hole. near the lower end so that the oil can be directed away from the valve body structure as through a drain-off conduit 1 54 to a remote point wherethere is no fire hazard as nmany cases the valve V is operating at extremely high ambient temperature and could cause a fire hazard should leakage oil contact the hot surface thereof. 7,

The valve actuating rodg18 constitutes a movable actuating element and may control the valve V or any other modulating type of device and the force motor FM may be-responsive to pressure or the like as disclosed or to any other condition. The reservoir R is filledwith oil through a suitable filler .plug '17 ,of the mounting plate 26 up to a level indicator 19. Thus, nozzles N N BN and PN are submerged in the oil for quiet operation and to avoid spraying. and the accompanying result of oil'fo amy Practical operation In the operation of my hydraulic operator reference is made to Fig. 2 as a typical installation wherein the valve V serves as a pressure-reducing valve between a supply line 156 at a given pressure and a downstream line therefrom '158'in which it is desired to maintain a predetermined lower pressure regardless of the pressure in the supply line 156. The system includes the measuring element transmitter MET connected as by conduit to the downstream line 158 to sense thepressure thereof and the transmitter is wired at '162 to the electronic amplifier controller EAC which is supplied with readily available house lighting current such as 110 v. A.C.

to the right, thereby increasing through wires 163. By way of example, the transmitter MET may have a bellows 166 responsive to the pressure in the line 158 and controlling a rh'ebstat 168 which varies the currentto the controller EAC wherein the variations of current may be amplified and supplied through'wires 164 to the control coil 110 of the force motor FM, or in some instances the rheostat 168 or an equivalent device may be directly connected with the control coil of the force motor since an input command signal change of small magnitude is sufficient in the type of force motor shown for varying the force motor thrust throughout its entire range. The force of the arm 60 is proportional to a change in the command signal and usually is very small in magnitude such as from 3 to 5 ounces change in force on the force motor arm 60 for a 1 to 5 milliamp. input change.

The pumps PP, P and P are of the constant pressure type having the necessary built-in relief valves set for the pressures desired. With the pump PP providing constant pressure of 50 p.s.i. supplied to the first or pilot stage of the system, I have in effect a hydraulic amplifier in that it makes it possible to operate the large power nozzles N and N with many pounds of flapper force from only a few ounces force available at the force motor. The restrictions R and R and the nozzles PN and PN are sized so that when the nozzle N is closed by the force motor, the bellows B has a pressure of 50 p.s.i. and the bellows B has a pressure approximating p.s.i. When the force motor flapper is horizontal as illustrated in Figs. 2 and 3, i.e. equally covering N and N pressure in each bellows is approximately 30 psi.

When the nozzle N is closed by the bellows B the full capacity of the pump P is applied to the under side of the piston forcing it upwardly and exhausting the upper end of the cylinder 22 through the orifice of the nozzle N This nozzle is sized so that it will exhaust the cylinder and also. pass the flow from the pump P with a minimum of back pressure. When the piston has traveled all the way up and contacts the upper end of the cylinder, the nozzle N is then passing only the volume pumped by the pump P at which condition pressure in the nozzle N and theline 90 leading thereto, and in the upper cylinder chamber is approximately 50 p.s.i.

The balls 74 contribute to silent operation of the device during the opening and closing of the nozzles N and N The counterweight 150 is used to reduce instability caused by main pipe line vibrations by virtue of its weight and moment arm counterbalancing that of the coil assembly 110, 114, 116.

Since the magnet assembly of the force motor FM is composed of magnet 104, the inner pole 108 and the outer annular pole 106 surrounding the pole 108, there is created thereby a concentration of magnetic field between the poles thus formed. The coil 110 is positioned within the gap between the poles and is caused to be urged right or left, depending on the direction of current flow in the coil 110.

The opposite action can be had when required, depending on the type of installation. by reversing the leads to the coil 110 (the current in 164 being DC.) or the action of the rheostat 168 can be reversed. When the coil 110 and the arm 60 move toward the left, the flappers PF and FF tend to close nozzle PN and open nozzle PN as obvious in the diagram Fig. 2 so that pressure will increase in the bellows B and decrease in'the bellows 13*, thus resulting in a counterclockwise rotation of the flapper F -F attached to the lower end of the bellows. This results in a closing of the nozzle N and a corresponding opening of the nozzle N resulting in an increase in pressure under the piston 20 and a decrease thereabove. The piston and feed-back cam 146 will move up which causes the feed-back lever 134 to move the feed-back spring load on the arm 60 until a balancewith the bias spring 1 2 0 is reached and the main piston stem will continue to move until the resulting increase in this feed-back spring load balances the force resulting from the current in the force motor coil modified by the bias spring at which time the flappers PF PF F and F will assume their neutral positions.

The normal range of input signal is usually from 1 to 5 milliamps. so that the main valve should start to move at l milliamp. and complete its stroke when the signal is at} milliamps. To start the system moving at l milliamp. the bias spring 120 is adjusted so that there is sufiicient unbalance between the force motor and the feed-back spring to allow the force motor beam to slightly close one nozzle and to slightly open the other. 7

Normally, the feed-back cam is machined with a straight surface as disclosed which results in a linear relationship between the input signal and the valve stem movement. In other words when the input signal is plotted on rectangular coordinates against stem position, the resulting curve is a straight line. If the main valve is a linear type valve (i.e. flow area plotted against travel is a straight line on rectangular coordinate paper), it can be seen that the flow area for the valve elements 28 will change linearly with the input signal change.

It is possible with my arrangement to always use a linear type valve element 28 and to provide the proper shape of cam 146 for the desired characteristic relationship between input signal and valve element 28 area, thereby making it unnecessary to break into the main flow line with the subsequent inconvenience and protracted down-time. 'Ihis cam may have any required shape as dictated by the plotting of flow area against valve travel, the surface of the cam being curved inwardly or outwardly or a compound curve as may be found necessary. Such an arrangement permits the changing of the operating characteristics of the valve V by merely removing the force motor cover 24 and replacing the cam 146 with another of the desired shape, the cam being mounted on the upper end of the actuating rod 18 by screw threading it thereto. The thread is shown at 170 in Fig. 3.

With reference to the plug-in" feature previously referred to, attention is drawn to Fig. 5 wherein the cover plate 26 is shown disconnected and elevated for removing the pumps, motor, force motor and flapper-nozzle valve mechanism as a unit so that it can be replaced by another unit in case of malfunctioning or for other reasons. The ease with which the pilot and motor-pump combination can be removed from the actuator is obvious. Every part except the hydraulic cylinder and piston may be removed as one unit. For periodic maintenance the entire unit may be replaced with a standby assembly in a matter of minutes resulting in very little down-time. It is unnecessary to break or make any hydraulic connections since, as illustrated, all the piping remains intact and the only two hydraulic connections that are necessary are those to the upper and lower ends of the cylinder 22 which are automatically taken care of by the telescoping plug-in connection 40--42.

In Fig. 5 the force motor cover 24 is also shown removed and elevated from the plate 26 to gain access to the force motor itself.

Summarizing the operation, the hydraulic pilot controls the pressure to the cylinder 20 in response to movement of the force motor coil caused by a change of input current from a controller. The beam and flappers of the pilot are attached to the coil of the force motor and are used to vary the pressure in the pilot nozzles and bellows. The pilot stage is a hydraulic amplifier making possible the operation of the power nozzles that control. greater pressures and/or flow with the small force available from the force motor.

The power stage of the controller controls the pressure and/or flow applied to the hydraulic piston which actuates the valve stem. Eachpower nozzle is connected to a high pressure pump section and also to one side of the hydraulic cylinder. When the nozzle N is closed the full pressure of the pump section P is applied to the underside of the piston. The nozzle N is sized so when open it will exhaust the upper side of the cylinder and also pass the flow from the lower pump section- With'minimum back pressure. When the nozzle N is closed the reverse of the above is true. The pilot utilizes simple durable flapper-nozzle combinations. Flappers F and F have hardened stainless steel buttons at points of'greatest wear. All orifices and restrictions are ample size for minimizing chance of failure from dirt in the oil.

With respect to the three-pump system disclosed for furnishing separate supplies of hydraulic fluid to produce an individual constant pressure source for each nozzle N and N it is possible to eliminate the use of restrictions such as R and R in connection with the pilot nozzles PN and PN as when a single source of pressure is provided as I do for the pilot system. If one pump supplied both nozzles N and N much of its output would be lost when one or the other of the nozzles is open.

The chief advantage of this system is the ability to pre vent excessive heating of the oil. When the main valve V is in some throttling position, the flapper systems are in a nearly neutral position with approximately 30 p.s.i. in each bellows, the flapper beam F -F being nearly horizontal and the nozzles N and N open nearly equal amounts. In that case the pressures from pumps P and P are approximately 100 p.s.i. each because nozzles N and N are sized to more than handle the capacity of their respective pumps. When the valve is in throttling position, the pumps P and P are operating at less than maximum pressure, the motor is not operating at, maxi- V mum load and consequently energy in the form of heat is reduced. Lower temperature operation increases greatly the life of the hydraulic fluid and the life of the P p Prior actuators of somewhat similar type use" spool valves or sliding plate valves which, when not called upon to deliver oil to either side of the piston, close on the pump supply so that the pump relieves its flow through the relief valve maintaining full set pressure on the pump, in most cases, 500 psi. The motor is therefore expending more power and develops more heat than with my system. i g

My disclosed operator uses maximum horsepower input and heats the hydraulic fluid the most when the command signal calls for the main valve to be fully closed or fully open, in which case one or the other of the nozzles N and N is closed creating a back pressure of 500 psi. on the one that is closed, approximately 75 psi. on the one that is fully open and 50 psi. on the pump PP which supplies the pilot system.

The spring-closed shut-oft valves 80 are automatically held in the open position by hydraulic pressure while the pump is operating. The close upon pump failure and thus provide a safety lock-up feature because the hydraulic fluid is locked in the cylinder 22 for holding the valve V in position until the cause of the failure is corrected. The by pass valve 98 provides means of equalizing the pressure across the piston so that the actuator stem 18 may be manually positioned if desired (not illustrated). Upon resumption of power, normal automatic functioning of the operator in response to the force motor is restored.

While I have disclosed a bias spring 120, it is quite possible to arrive at equal performance without it. It is used for two reasons: (1) It is possible to adjust the starting point for operation of the force motor without jarring the'coil beam 60 and (2) it is used to give an opposing load to the feed back spring 132 so that the feed back spring is loaded sufficiently to separate its coils. On the other hand, a light feed back spring with separated coils can be provided thereby eliminating the need of the bias spring 120. It is evident, therefore, that the bias spring is not an essential element of my operator.

While I have illustrated and described an electric force motor FM, a comparable pneumatic force motorcould motor in my claims could be for one that is operated electrically, pneumatically or otherwise. I prefer the electrical type as having advantages herein before referred to.

In the operation of the device shown in Figs. 6,7 and V 8 the power nozzles N and N are the only ones used and the restrictions R and R cooperate to control them from a single source of oil under pressure in the same manner as the pilot nozzles are controlled in Fig. 2 whereas the nozzles of Figs. 6, 7 and 8 control flow directly from this single source to and from the ends of the cylinder 22a without a pilot stage as in Fig. 2. Otherwise the operation is substantially the same. instead of a double acting piston Ztla as disclosed in Figures 6, 7 and 8 a single acting one may be used in which a spring 172 normally opens the valve V and only the upper nozzle N and the restriction R are used to control the flow of oil to and' from the upper end 'of the cylinder as disclosed in Fig. 7A. Conversely, the valve V may be normally closed under the bias of a spring 174 and only the lower nozzle N and the restriction R used as shown in Fig. 7B. The operation of these types are responsive to the command signal supplied to the force motor FM in a manner similar to the double acting piston type.

Some changes may be made in the construction and arrangement of the parts of my hydraulic operator Withpilot nozzles receive oil under one pressure through re-' strictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor from a condition responsive device, a feed-back spring connected with said force motor, and a cam operable by said movable actuating element to vary the load of said feed- 1 back spring proportional to the position of said actuating element, a reservoir in which said'cylinder, piston and nozzles are located and from which said pressure supplying means receive oil, a cover plate on said reservoir, said nozzles and force motor being mounted thereon for removal from the reservoir as a unit with said cover plate, a plug-in sleeve connection between said plate and cylinder, said sleeve connection including passageways leading from said power nozzles, and passageways com and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, separate means for individually supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows-actuated power flappers control the position of the piston in the cylinder in response to the pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice' versa in response to a control signal change supplied to said force motor, a feed-back spring connected with said force motor, a cam operable by said movable actuating element to vary the tension of said feed-back spring proportional to the position of said actuating element, a reservoir in which said cylinder, piston and nozzles are located and from which said pressure supplying means receive oil, and balls located between said power nozzles and said power flappers to coact with said nozzles under action of said flappers for proportioning the oil flow.

3. In a hydraulic operator for a movable actuating element, a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, said power nozzles and flappers having balls between them for seating on the nozzles by pressure from the flappers, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of the cylinder whereby said second nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor having a force arm operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other onetoward closed position and vice versa in response to a command signal change supplied to said force motor from a condition responsive device, a feed-back spring connected with said force motor, and a cam operable by said movable actuating element to vary the load of said feed-back spring proportional to the position of said actuating element.

4. In a hydraulic operator for a movable actuating element, 2. piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, said power nozzles and flappers having balls between them for seating on the nozzles by pressure from the flappers, separate means for supplying oil under higher pressure to each of said power nozzles individually and to opposite ends of the cylinder whereby said second nozzles and the bellows-actuated power flappers control the position of-said piston in said cylinder in response to said pilot flappers, a force motor having a force arm operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor from a condition responsive device, a counterweight on said force arm 'of said force motor to prevent the vibrations of said operator being transmitted to the force motor, a feed-back spring connected with said force motor, and a cam operable by said movable actuating element'to varythe' load of said feed-back spring proportional-to the position of said actuating element.

"5. A hydraulic operator for a movable actuating element comprising a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellowsactuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor from a condition responsive device, a feed-back spring connected with said force motor, and a cam operable by said movable actuating element to vary the load of said feedback spring proportional to the position of said actuating element, said feed-back cam being readily replaceable with cams of other shapes.

6. A hydraulic operator for a movable actuating element comprising a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, means for supplying oil under higher pressure to one of said power nozzles and to one end of said cylinder, means for supplying oil under similar pressure to the other of said power nozzles and to the other end of said cylinder independent of said first means whereby said power nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor, a feed-back spring connected with said force motor, a cam operable by said movable actuating element to vary the tension of said feedback spring proportional to the position of said actuating element, and a drain-01f chamber below said cylinder adapted to receive leakage oil from the cylinder and having a drain-01f connection to a remote point to prevent fire hazard.

7. A hydraulic operator for a movable actuating element comprising a piston, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with the pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and said bellows-actuated power flappers control the position of the piston in the cylinder in response to the pilot flapper, said power nozzles and flappers having balls between them for seating on the nozzles by pressure from the flappers, a force motor operatively connected with said pilot flapper for moving one pilot nozzle toward open position and moving the other one toward closed position and'vice versa in response to a command signal change supplied to said force motor, a feed-back spring conaerator nected with said force motor, and a cam operable by said movable actuating element'to vary the load of said feedback spring proportional to the position 'of said actuating element, said feedback cam being replaceable with cams of other shapes. 7 p

8. A hydraulic operator for a movable actuating ele-" ment comprising a reservoir, a cylinder therein, a piston in said, cylinder for moving said actuating element, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flappercombinations and bellows-actuated power'flapper-nozzle combinations in said reservoir, said pilot nozzles receiving oil under one pressure through restrictions and said bellows being connect'ed with said pilot nozzles for having their pressures controlled thereby and being actuated by said flappers for said power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and said bellows-actuated flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor, a feed-back spring connected with said force motor, a cam operable by said movable actuating element to vary the load of said feedback spring proportional to the position of said actuating element, a cover plate on said reservoir, said nozzles and force motor being mounted thereon for removal from the reservoir as a unit with said cover plate, a plugin sleeve connection between said cover plate and said cylin der, said sleeve connection including passageways leading from said power nozzles, and passageways communicating therewith and leading to the opposite ends of said cylinder.

9. A hydraulic operator for a movable actuating element comprising a reservoir, a cylinder therein, a piston in said cylinder for moving said actuating element, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations in said reservoir, said pilot nozzles receiving oil under one pressure through restrictions and said bellows being connected with said pilot nozzles for having their pressures controlled thereby and being actuated by said flappers for said power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and said bellows-actuated flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor, a feed-back spring connected with said force motor, a cam operable by said movable actuating element to vary the load of said feed-back spring proportional to the position of said actuating element, and a cover plate on said reservoir, said nozzles and force motor being mounted thereon for removal from the reservoir as a unit.

10. A hydraulic operator for a movable actuating element comprising a reservoir, a cylinder therein, a piston in said cylinder for moving said actuating element, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations in said reservoir, said pilot nozzles receiving oil under one pressure through restrictions and said bellows being connected with said pilot nozzles for having their pressures controlled thereby and being actuated by said flappers for said power nozzles, separate means for supplying oil under higher pressure and individually to each of said der'in response to said pilot flappers, saidpower nozzles andtheir flappers having balls between them for seating on the nozzles by pressure trorn the flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice' versa in response to a control signal change supplied to force motor from a condition responsive device, a feedback sp'ring connected with said force motor, a cam operable by said movable actuating element to vary the'load of said feed ba'ck spring proportional to the position of said actuating element, a cover plate on saidreservoir, s'aid nozzles and force motor being mounted thereon tor removal from the reservoir as a unit with said cover plate, a plug-in sleeve connection between said cover plate and said cylinder, said sleeve connection including passageways leading firom said power nozzles, and passageways communicating therewith and leading to the opposite ends of said cylinder.

11. A hydraulic operator for a movable actuating element comprising a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles,

means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal change supplied to said force motor from a condition responsive device, a feedback spring connected with said force motor, and a cam operable 'by said movable actuating element to vary the load of said feed-back spring proportional to the position of said actuating element. a

12. A hydraulic operator for a movable actuating element comprising a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movement of said piston comprising pilot nozzle-flapper combinations and bellows actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for having their pressures controlled thereby and actuate the flappers for the power nozzles, means for separately supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappets for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signal supplied to said force motor from a condition responsive device, a feedback spring connected with said force motor, a cam operable by said movable actuating element to vary the load of said feed-back spring proportional to the position of said actuating element, and a reservoir in which said nozzles are located and from which said pressure supplying means receive oil.

13. A hydraulic operator for a movable actuating element comprising a piston for moving said actuating element, a cylinder in which said piston is movable, a hydraulic system for controlling the movementof said piston comprising pilotnozzle-flapper combinations and bellows-actuated power flapper-nozzle combinations wherein the pilot nozzles receive oil under one pressure through restrictions and the bellows are connected with said pilot nozzles for 'having their pressures controlled thereby and actuate the flappers for the power nozzles, means for supplying oil under higher pressure to each of said power nozzles and to opposite ends of said cylinder whereby said power nozzles and the bellows-actuated power flappers control the position of said piston in said cylinder in response to said pilot flappers, a force motor operatively connected with said pilot flappers for moving one pilot nozzle toward open position and moving the other one toward closed position and vice versa in response to a control signalgchange supplied to said force motorfrom a condition responsive device, a feed-back springconnected with said force motor, a cam operable by said movable actuating element to vary the load of said feed-back spring proportional.to the position of said actuating element, a reservoir inwhich said cylinder, pistonand nozzles are located and from which said pressure supplying means receive oil, and a cover plate on said reservoir, said nozzles and said force motor being mounted thereon for removal from the reservoir as a 10 unit with said cover plate.

References Cited in the file of this patent UNITED STATES PATENTS

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