US3492921A - Hydraulic controller - Google Patents

Description

Feb. 3, 1970 w. A. RAY 3,492,921

HYDRAULIC CONTROLLER Filed Dec. 21. 1967 a Sheets-Sheet 1 INVENTOR W/d/AM ,4. 16/4 V A from 6V 4 Feb. 3, 1970 w. A. R Y 3,492,921

HYDRAULIC CONTROLLER Filed Dec. 21. 1967 6 Sheets-Sheet 2 INVENTOR W/a/A A 5W A TTOE/V'y Feb. 3, 1970 w. A. RAY

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HYDRAULIC CONTROLLER Filed Dec. 21, 1967 6 Sheets-Sheet 4 INVENTOR EZ'Q 6' W/A/AMA 64y ATTOZ/Vy 6 Sheets-Sheet 5 Filed Dec. 21, 1967 INVENTOR l V//AM A. my

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HYDRAULIC CONTROLLER 6 Sheets-Sheet 6 Filed Dec. 21, 1967 T M NA 6 EB 0 MA W M A m 1 4 W United States Patent O 3,492,921 HYDRAULIC CONTROLLER William A. Ray, North Hollywood, Calif., assignor to International Telephone and Telegraph Corporation, New York, N.Y., a corporation of Maryland Filed Dec. 21, 1967, Ser. No. 692,392 Int. Cl. F151) 13/06, 13/16 US. Cl. 9151 8 Claims ABSTRACT OF THE DISCLOSURE The invention includes an improvement on hydraulic apparatus which controls a large pressure by the use of a small change in pressure in a hydraulic amplifier, The small change in pressure is provided by varying the amount of hydraulic fluid which is permitted to escape from a bleed nozzle by the use of a vane movable toward and away from the nozzle orifice. The improvement comprises a diaphragm responsive to the pressure of hydraulic fluid in the nozzle to move the vane toward the nozzle orifice. This arrangement provides positive feedback which considerably increases the speed of response of the apparatus.

BACKGROUND OF THE INVENTION This invention relates to hydraulic controls and more particularly to a hydraulic feedback system to increase the speed of response of a hydraulic amplifier.

In the past, hydraulic amplifiers have been used very successfully in controlling extremely large loads with very small input pressure changes. However, such devices are often required to operate at speeds greater than are, at present, possible.

SUMMARY OF THE INVENTION In accordance with the device of the present invention, the above-described and other disadvantages of the part are overcome by providing positive feedback for a hydraulic amplifier.

In the past, conventional hydraulic amplifiers such as that disclosed in FIG. of W. A. Ray, US. Patent No. 3,087,471 employ a vane which provides a variable restriction at the orifice of a nozzle to control the hydraulic pressure inside the nozzle and to a cylinder having a piston therein. It is thus possible to control an extremely large force by controlling the fluid which is bled through the nozzle orifice. In accordance with the device of the present invention, means responsive to the increase in pressure inside the nozzle is employed to move the vane in a direction to close off the nozzle even more. Positive feedback is thereby provided. Thus, the device of the present invention can, as in the prior art, control a very large force with a small one, and yet provide for a rapid speed of response due to the said positive feedback.

The above-described and other advantages of the present invention will be better understood from the following descriptiOn when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a vertical sectional view through a control device of the present invention;

FIG. 2 is a vertical sectional view similar to FIG. 1 showing a portion of an orifice opening control device;

FIG. 3 is a top plan view of the control devices shown in FIGS. 1 and 2;

FIG. 4 is a side elevational view of the control device as shown in FIG. 3;

3,492,921 Patented Feb. 3, 1970 DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings in FIG. 1, one embodiment of the control device of the present invention is indicated at 20. Control device 20 has a housing 21 for an electric motor 22 which operates pumps 23 and 24 identical to those shown in the aforementioned patent. The outputs of pumps 23 and 24 provide inputs at 25 and 26 respectively to opposite ends of the cylinder 27. Thus, a difference in pressure at opposite ends of cylinder 27 will cause a piston 28 therein to move in one of two directions. Piston 28 has a rod 29 afiixed thereto which may adjust the opening at a valve or perform any other mechanical function. Alternatively, one of the cylinder inputs at 25 or 26 may be omitted and piston 28 may be spring biased, if desired. Such an arrangement is shown in FIG. 5 of U.S. Patent No. 3,087,471.

The pressure on opposite sides of piston 28 is controlled by hydraulic amplifiers 30 and 31 identical to that shown in the said patent, The outputs of hydraulic amplifiers 30 and 31 are bled through nozzles 32 and 33 respectively. A vane 34 pivoted at 35 controls the amount of hydraulic fluid which may be bled from nozzles 32 and 33.

Positive feedback is provided by connections 36 and 37 to chambers 38 and 39 respectively. Thus, an increase in pressure in nozzle 32 will tend to move vane 34 to close nozzle 32 through a diaphragm 40. Similarly, an increase in pressure inside nozzle 33 will tend to close nozzle 33 by a diaphragm 41.

A servo balance control 42 is connected from vane 34 to piston rod 29. Control 42 may be entirely conventional, if desired.

In the operation of the invention shown in FIG. 1, piston 28 will normally assume a position in cylinder 27 depending upon how van 34 is moved by control 42. When piston 28 is in the proper position, vane 34 will be located substantially midway between nozzles 32 and 33. Should control 42 tend to close nozzle 32 and open nozzle 33, hydraulic amplifier 30 will cause an increase in pressure in connection 25 and therefore move piston 28 upwardly. This condition will occur until vane 34 is again placed substantially midway between nozzles 32 and 33. During this transient response, the increase in pressure inside nozzle 32 created by vane 34 moving toward the same will be transmitted through connection 36 to tend to close nozzle 32. A degree of positive feedback will increase the speed of response of the device 20. Movement of piston 28 downwardly will take place in the same manner. The operation of hydraulic amplifiers 3G and 31 are identical to that disclosed in the said patent. The said patent should therefore be referred to for a detailed description of the ope ation thereof. A cavity on chamber 43 is provided at the bottom of housing 21. Opening from the chamber 44 in which nozzles 32 and 33 are located is then provided in the conventional way. The same is true of the chambers in which amplifier springs 45 and 46 are located.

A more detailed showing of the device 20 is illustrated in FIG. 2. Connections 36 and 37 have been omitted for clarity. Note will be taken that vane 34 is supported on flexure strips 94 shown in FIGS. 8 and 9 and sealed from upper chamber by a spring metal bellows 47. An arm 48 is fixed to vane 34 at the top of bellows 47. A cylindrical balance weight 49- is threaded through arm 48. Arm 48 is moved through an electromagnetic device 50 which may be conventional. A ferromagnetic core is provided at 51 which changes the position of a coil 52 fixed to arm 48 depending upon the amount of current which is supplied to coil 52.

As shown in FIGS. 3 and 4, piston rod 29 lifts an arm 53 pivoted on a shaft 54 when piston rod 29 rises. Arm 53 has a slot 55 through which a pin 56 is located. Pin 56 has flanges 57 on each side of arm 53 to hold pin 56 in slot 55. An arm 58 fixed to another arm 59 at 60 is pivoted from a shaft 61. As arm 59 moves upwardly the upper end 62 of a spring 63 is pulled upwardly by a wire 64 hooked to spring end 62 and fixed to arm 59 by a screw 65. The lower end of spring 63 is fixed to arm 48. Spring 63 and the other linkages between piston rod 29 and arm 49 thus provide a feedback from piston rod 29 to vane 34 through arm 48. This feedback may be conventional, if desired.

An alternative arrangement for controlling the position of vane 66 is shown at 67 in FIG. 5. This arrangement will be used when piston 28 is spring biased thus, only one nozzle 68 is employed. As before, arrangement 67 includes an arm 69 from which vane 66 is suspended. Flexure strips, not shown, support arm 69. Bellows 70 seals hydraulic fluid within chamber 47'. As before, a weight 71 is provided at one end of arm 69 and a coil 72 is provided at the other end thereof. Coil 72 is located around a ferromagnetic core 73. The same linkage may be employed for mechanical feedback from piston rod 29 to arm 69 as shown in FIGURES 3 and 4.

Still another arrangement similar to but somewhat different than arrangement 67 as indicated at 74 in FIG. 6. In this case, all of the structure shown is non-magnetic except for two vertical permanent magnets, now shown. One magnet may be located in a plane perpendicular to a supporting shaft 75 at one end thereof, and the other located at the other end thereof. Each permanent magnet may be simply a rectangular bar magnet polarized in the vertical direction so that the poles of both magnets will be the same at their upper ends and the same at their lower ends. An armature is rotatively suspended under shaft 75 which is fixed to non-magnetic side support plates, not shown. Energization of coils 76 and 77 will cause armature 78 to rotate about the center of shaft 75. Stops 80 and 81 are provided for armature 78, stops 80 and 81 being fixed to housing 79 by means of screws 82 and 83 respectively.

Similar to the embodiment of FIG. 5, a vane 84 for nozzle 85 is fixed to arm 78.

Still another embodiment of the invention is shown in FIG. 7 which includes coils 86 and 87 around fixed cores 88 and 89 respectively. Coils 86 and 87 are fixed to pposite ends of an arm 90 which, in turn, is fixed to a vane 91 for a nozzle 92.

A spring biased support for a vane inside a bellows 93 is shown in FIGS. 8 and 9 including flexure springs 94 and 95 fixed to opposite ends of an arm 96 that is, in turn, fixed to the vane. Spring metal flexure strips 94 and 95 are shown in FIG. -9.

A housing for a unit 20 is shown in FIG. including a piston 28 fixed to a piston rod 29. The structure shown in FIGURES 3 and 4 may be enclosed in a housing 97. The structure shown in FIG. 1 may be enclosed in a housing portion 98 threaded to housing 97. Electric motor and auxiliary connections may be made in housing 99 integral with housing 98.

From the foregoing, it will be appreciated that the positive feedback provided by connections 36 and 37 shown in FIG. 1 will increase the speed and improve response of piston 28 to changes in pressure in connections 25 and 26. In other words, diaphragms 40 and 41 tend to move vane 34 in a direction to increase pressure as required by control 42.

What is claimed is:

1. A hydraulic positioning device comprising: a pump; a pressure responsive device connected from the output of said pump; a bleed port. connected from the self same output of said pump; a hydraulic amplifier actuable in response to small changes in fluid pressure to restrict fluid flow through said portion varying degrees; a bleed nozzle connected from said hydraulic amplifier; a vane movable to restrict the fluid flow through said bleed nozzle in varying degrees in a manner to actuate said hydraulic amplifier by increasing the pressure of fluid inside said nozzle; a control device responsive to an input signal to move said vane, said control device being connected from said pressure responsive device to said vane; return means to move said pressure responsive device in a direction opposite that in which it is moved when the pressure of fluid inside said nozzle is increased; and means responsive to an increase in pressure inside said nozzle for applying a degree of force to move said vane toward said nozzle.

2. The invention as defined in claim 1, wherein said return means includes a second pump, said pressure responsive device is connected from the output of said second pump, a second bleed port connected from the same output of said second pump, a second hydraulic amplifier actuable in response to small changes in fluid pressure to restrict fluid flow through said second port in varying degrees, second'bleed nozzle connected from said second hydraulic amplifier, said vane being movable to restrict fluid flow through second bleed nozzle in varying degrees in a manner to actuate said second hydraulic amplifier by increasing the pressure of fluid inside said second nozzle, and third means responsive to an increase in pressure inside said second nozzle for applying a degree of force to move said vane toward said second nozzle.

3. The invention as defined in claim 2, wherein said pressure responsive device includes opposite sides of a piston inside a cylinder, said piston having a rod connected therewith, and a spring connecting said piston rod to said vane.

4. The invention as defined in claim 1, wherein said control device includes an arm, electromagnetic means at one end of said arm including a coil, said arm thereby being movable in response to current inside said coil, a weight at the other and of said arm, and a spring connected from said pressure responsive device to adjacent said other end of said arm.

5. A hydraulic positioning device comprising: a pump; a pressure responsive device connected from the output of said pump, said device including a piston rod; a bleed port connected from said same output of said pump; hydraulic amplifier actuable in response to small changes in fluid pressure to restrict fluid flow through said port in varying degrees; a bleed nozzle connected from said hydraulic amplifier; a vane movable to restrict the fluid flow through said bleed nozzle in varying degrees in a manner to actuate said hydraulic amplifier by increasing the pressure of fluid inside said nozzle; a control device responsive to an input signal to move said vane, said control device including a spring connecting said rod to said vane, the axes of said rod and spring being generally parallel; and return means to move said pressure responsive device in a direction opposite that in which it is moved to open said nozzle by said control device, said control device further including a first pivoted arm having said vane connected thereto, electromagnetic means associated with said first arm for shifting the arm in one direction, said spring biasing the arm in the opposite direction, second and third adjacent arms pivotally mounted at opposite ends for movement in generally parallel planes, said spring being connected to said second arm, said third arm being operatively engaged with said rod, and means interconnecting said second and third arms whereby the position of said rod is translated through said second and third arms, said spring and said first arm to said vane.

6. The invention of claim 5 wherein said first arm is pivotally mounted intermediate its ends, said electromagnetic means including a coil on said arm adjacent to one end thereof, said spring being connected to said first arm adjacent to the other end thereof, said vane being positioned intermediate said ends, said second and third arms being positioned generally laterally with respect to said first arm and in overlying relationship therewith, and said interconnecting means comprising a lateral projection on said third arm engaging a downwardly facing surface of said second arm.

7. The invention of claim 6 wherein said rod is generally vertically disposed and has an upwardly facing bearing surface, the free end of said third arm engaging said bearing surface whereby upward movement of said rod upwardly pivots said third arm, thereby lifting said second arm and tensioning said spring.

8. A hydraulic positioning device comprising: a pump; a pressure responsive device connected from the output of said pump, said device including a piston rod; a bleed port connected from said same output of said pump; hydraulic amplifier actuable in response to small changes in fluid pressure to restrict fluid flow through said port in varying degrees; a bleed nozzle connected from said hydraulic amplifier; a vane movable to restrict the fluid flow through said bleed nozzle in varying degrees in a manner to actuate said hydraulic amplifier by increasing the pressure of fluid inside said nozzle; a control device responsive to an input signal to move said vane, said control device including a spring connecting said rod to said vane, the axes of said rod and spring being generally parallel; and return means to move said pressure responsive device in a direction opposite that in which it is moved to open said nozzle by said control device, said rod and spring being generally vertically disposed, said control device including at least two pivoted arms extending laterally with respect to each other and in overlying relationship with respect to said rod with the end of said rod bearing against a downwardly facing surface of one of said arms, the other arm carrying said vane, said spring interconnecting said arms, and electromagnetic means for altering the position of said other arm and thereby the location of said vane with respect to said nozzle.

References Cited UNITED STATES PATENTS 3,023,763 3/1962 Lanctot 9l387 2,995,116 8/1961 Dobbins 91-359 3,316,815 5/1967 Chapin et al 91-3S9 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R. 9 l3 59, 387

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