US2533306A - Hydraulic follow-up system - Google Patents

Description

Dec. 12, 1950 i w. H. NEWELL 2,533,306

HYDRAULIC FOLLOW-UP SYSTEM Original Filed May 5, 1944 2 Sheets-Sheet 2 INVENTOR T Wq/nglfNewglb ATTORNEY Patented Dec. l2, 1950 HYDRAULIC FOLLOW-U1 SYSTEM William H. Nowell, New York, N. Y., assignor to The Sperry Corporation, a corporation of Dela- Ware Original application May 5, 1944, Serial No. 534,330. Divided and this application May 17, 1945, Serial N 0. 594,288

Claims.

This invention relates to automatic gun control systems of the type responsive to hydraulic pressures and in particular to a novel and improved hydraulic follow-up system responsive to a manual control device and including a pressure control valve mechanism adapted to control generated pressures and a pressure responsive servomotor for actuating the driving and computing mechanisms.

This application is a division of the copending application of Newell et al., Serial No. 534,330, filed May 5, 1944, for Automatic Gun Control System.

An object of the invention is to provide a valve mechanism of the above type having novel and improved details of construction and features of operation.

Other and more specific objects will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention a pair of pressure control valves are actuated in accordance with the position and rate of movement of the gunners control handle to vary hydraulic pressures in a manner to produce control pressures correspondin to the desired rates of train and elevation respectively. These control pressures are applied to the pressure responsive servomotors which are adapted to control rate input linkages of an automatic computing mechanism. The pressures may also be applied to precessing force motors which apply precessing forces to a gyroscope as more fully set forth in the patent application above identified.

Although the novel features which are believed to be characteristic of this invention are pointed out more particularly in the claims appended hereto, the nature of the invention will be better understood by referring to the following description, taken in conjunction with the accompanying drawings in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a section through a hydraulic pressure control valve block embodying the present invention showing the control handle and the hydraulic connections;

Fig. 2 is a side elevation of the manual control handle and support therefor;

Fig. 3 is a vertical section through the control handle and support taken along the line 33 of Fig. 1;

Fig. 4 is a partial horizontal section taken on line 4- of Fig. 1; and

Fig. 5 is a diagrammatic view of the follow-up system showing the pressure responsive servomotors in section.

Certain specific terms are used herein for convenience in referring to various details of the invention. These terms, however, are to be given an interpretation commensurate with the state of the art.

Pressure control valves Referring to the drawings more in detail, the pressure control valves are shown as mounted in a valve block I51 Control handles I55, adapted to be actuated by the gunner, are shown as mounted on a horizontal shaft I00 which is pivoted in a bracket I56 for rotation about a horizontal axis and carries an arm I, Fig. 3, which is attached by a pivoted link 2 to a slidable rod 3 which is located within the bracket I56 and carries a pair of collars t which actuate an arm 5 carried by a shaft 6. The shaft 6 in turn carries an arm 1 which is connected by a link 8 to a valve plunger 9 in a manner such that the valve plunger is shifted from a central position an amount corresponding to the rotational move-- ment of the handles I55 about their horizontal axis, The position and rate of movement of the valve plunger 9 controls the operation of an elevation pressure control valve Ill. The rotational position of the handles I55 corresponds to the elevation rates which control the position of the pressure responsive servomotor to be described later. These rates may also be applied to'an elevation precessing motor of a gyroscope to cause the gyroscope to precess at a corresponding rate. The position and rate of movement of the plunger 9 controls and is a measure of the pressure which is developed by the valve ID for actuating the pressure responsive servomotor and the elevation precessing motor. The pressures thus developed are controlled primarily in accordance with the position of the handles I55, but these pressures are modified somewhat due to the rate of movement of the handles.

Rotation of the handles l 55 and shaft l 09 about a vertical axis causes the bracket I56 to rotate and, in turn, to rotate a segment of a bevelled gear l2 which, through a bevelled rack l3, actuates a shaft is carrying an arm l5 which is attached by a link it to a valve plunger l8 which controls the operation of the train rate pressure control valve 20. The elevation rate pressure control valve I0 and the train rate pressure control valve 20 are similar in construction and are adapted to develop pressures corresponding to the .justable restriction formed axial displacement and rate of movement of the valve plungers 9 and i3 respectively.

Referring first to the valve H), the block I5! is formed with a valve chamber 25 in which slides a sleeve 26. The plunger 9 slides axially within a bore in the sleeve 25. The sleeve 2.5 is provided with end surfaces forming with the respective ends of the chamber 25, pressure chambers 27 and 28 respectively. The chamber 2'! is supplied with fluid from a constant pressure, P1 through a supply duct 29. The duct 29 contains an adby the adjusting screw 34, the end of which enters and partially closes the duct 29. The chamber 28 contains fluid under a pressure which is determined by the position and rate of movement of, the sleeve 26 and which constitutes the elevation rate pressure Pe which is suppl ed by passag 30 to a duct 3|. The end surfaces of the sleeve 25 are recessed to receive compression springs 32 and 33 which are seated within the chambers 21 and 28 respectively and serve normally to hold the sleeve .26 balanced in its mid-position, in which event the pressure in th chamber 23 will correspond to the pressure within the chamber 2?. Chamber 28 communicates through a passage 653 with an annular chamber 4! formed in the plunger 9. Passages 42 and 33 in the sleeve 26 terminate at the plunger 9 on opposite ends of the chamber 4! so that these passages are normally closed by the plunger 9 when the plunger is in the center position as shown, but are respectively brought into communication with the chamber 28 through. the chamber ll and the passage 49 when the plunger 9 is shifted in one direction or the other from its center position. The passage 42 communicates with an annular chamber 45 formed around the periphery of the sleeve 25 and the passage 63 communicates with an annular chamber 45 sim larly formed in the sleeve 26. The chamber 45 receives fluid under a constant pressure P2 which is double the pressure P1 and is supplied through a passage 41 in the block I51 which communicates with a supply duct 48 receiving fluid under the pressure P2 from a suitable source. The chamber 46 contains fluid under a low or zero pressure P which may constitute the intake pressure of the pump. The chamber 46 communicates through a passage 49 with a return duct 59 which leads. to th supply reservoir of the pump.

The pressure P1 is supplied by a P1 generator valve 55 formed in the block l! and comprising a chamber having a slide 56 provided with end surfaces 5'! and 58 forming end chambers 59. and 99 respectively. The end surface 5'! is .formed with one half of the area of the end surface 58 so that when the slid 55 is in balanced position the pressure within the chamber 69 will be. half that within the chamber 59.

The chamber 59 is connected to the passage 41 containing fluid under pressure P2 by means of a passa 62. The slide 56 is formed with an annular chamber 63 which communicates through a passage 64 with the duct 29 to supply fluid under the pressure Pl thereto, The annular chamber 53 communicates with the chamber 69 by means of a passage 55 in the slide.

The slide 58 is provided with a reduced diameter end portion '59 terminating at the surface 51 above mentioned and has an annular end surface ll surrounding the end portion 10. This annular surface 'H forms with an intermediate end wall of the valve chamber an annular chamber 12. The annular chamber 12 communicates through a passage 73 with the passage 49 containing fluid under return pressure P0. The passage l3 terminates at the slide 59 adjacent one end of the chamber 63 so that it is normally closed by the slide. A passage 75 communicates from the passage 62. to; the valve chamber on the opposite end, oi the annular chamber 63 so that when the slide 56 is in its mid position, the passages 75 and 73 are both closed. The fluid pressures in the two end chambers 59 and 60 are then balanced and, due to the differences in area of the end surfaces, the pressur P1 is generated at exactly one-half of the pressure P2. If the pressure Pi should, however, vary from this amount, the pressure within the chamber 60 would likewise vary, thereby unbalancing the slide 56. If the pressure in the chamber 60 is reduced, for example, the pressure P2 in the chamber 59 causes the slide 56 to move upwardly, thereby establishing communication from the passage 75 through the. chamber 63 to the passage 65, thereby introducing fluid from the passage 15 into the passage 65 and increasing the pressure in the latter passage. The, pressure will thus be built up until the pressures in the chambers 59 and 69 are again balanced.- at which time the. slide 5'5 returns to its mid position and cuts off further fluid from the'passage 15.

If, on the other hand, the pressure within the chamber 69 increases, the slide 58 will be forced downwardly establishing a communication from the passage 65 through the chamber 63 to the passage 13, thereby bleeding oif some of the fluid Within the passage 65 into the return duct 50. This will likewise continue until the pressure in the chamber 69 is reduced to P1, at which time a balance is again established. In this wa the pressure in the passage 54 is maintained at exactly one-half of the pressure (P2) in the duct 48.

In the operation of the elevation rate pressure control valve l9, beginning with the valve plunger 9 in the position shown, the pressure in the chamber 28' is exactly balanced against the pressure P1 in the chamber 2 The elevation rate pressure Pe accordingly is the same as P1. If now the gunner rotates the handles about the horizontal aXis for producing a rate in elevation, the valve plunger 8 will be moved axially in one direction or the other. Assuming, for example, that the plunger 9 is moved upwardly, the chamber 4| is brought into communication with the passage 42 and fluid under pressure P2 is supplied through the chamber 4| and passage 19 to the chamber 28, thereby increasin the pressure in the. chamber 28 and disturbing the balance between the chambers 2? and 28. This increased pressure in the chamber 28 causes the sleeve 25 to move upwardly, thereby compressing the spring 32 and reducing the compression on the spring 33. This increase in pressure in chamber 28 causes the sleeve 26,,tc follow the plunger 9 upwardly until the sleeve has again reached a position relative to the plunger 9 at which the passage 42 is closed 01?. If the sleeve should move past this closing position, then communication would be established between the chamber 28 and the passage 43 which would remove some of the fluid from the chamber 28 to the return passage 49 and would correspondingly reduce the pressure on the lower end of the sleeve 26. When a new position of rest has been reached, the pressure within the chamber 28 plus the pressure of the spring 33 will exactly equal the pressure in the chamber 21 plus the pressure of the spring 32. The upward displacement of the two springs, however, rep resents a net downward pressure on the sleeve 26 proportional to the displacement of the sleeve 26 from its mid-position. This downward pressure of the spring acting on the sleeve 26 is reflected as an increase in hydraulic pressure in the chamber 28 and in the pressure of the fluid Pa in the passage 39 and in the duct (H which communicates therewith. This increase in hydraulic pressure is thus primarily proportional to the amount of vertical movement of the plunger 9 and the corresponding movement of the sleeve 26.

The restriction formed by the screw 34 in duct 29 restricts the flow of fluid from the chamber 2'! and therefore the pressure in chamber 21 becomes higher than the normal P1 pressure during upward movement of the sleeve 26. This higher pressure in chamber 21 results in a further increased pressure in the chamber 28 during upward movement of the sleeve 25. The efiect of this transient change of pressure due to rate of movement of the handles I55 is to modify temporarily the generated pressure in a direction to apply a supplemental force to the pressure responsive servomotor to thereby overcome initial resistance to movement of the mechanism connected to the servomotor. When the generated pressure is used to apply processing forces to a gyroscope the temporarily modified pressure acts to correct the position of the gyroscope. The effect of this modification of the precessing pressure is to aid the gunner in tracking the target when the gyroscope is used to control a line of sight, since it is not necessary for him to set up excessive precession rates in order to brin the line of sight on the target when it has gotten off for any reason. The relative amount by which the generated pressure is thus modified by the rate of movement of the handles I55 may be varied to suit the operator by adjusting the screw 34.

Movement of the plunger 9 in a downward direction reverses the above mentioned operation, establishing communication between the chamber 23 and the return passage 49 and thereby reduc- 1;

ing the pressure in the chamber 28 to establish a pressure differential between the chambers 2! and 28 which causes the sleeve 26 to follow the plunger 9 downwardly. In this way the pressure within the chamber 28, and within the duct 3| wh ch is supplied thereby, is caused to increase or decrease from the normal pressure P1 by an amount determined by the direction, amount and rate of movement of the plunger 9 from its central position. The resultant pressure (Pe) established in the duct 3i accordingly represents the elevation rate (dE) which is to be set into the automatic computing mechanism and the direction and amount of the processing force which is to be applied to the gyroscope.

The construction of the valve 20 is identical with that of the valve ID. The description will accordingly not be repeated. The parts of the valve 20 have, however, been given corresponding reference characters with the addition of a t to indicate that they apply to the tra n rate pressure generating valve. The chamber 281E communicates through the passage 3% with a duct 38 which carries fluid under pressure Pt which represents the train rate (dBs) which is to be set into the automatic computing mechanism and the train precessing force to be applied to the gyroscope.

Rotational movement of the handles I55 and the shaft I about the vertical axis of the bracket Ill) I56 causes a corresponding axial movement of the plunger I8 which is followed by the sleeve 2623 to generate the pressure Pt in the chamber 2Bt which varies from the pressure P1 in a direction and by an amount determined by the direction, amount and rate of rotational movement of the bracket I56. This movement corresponds to the rate of train which the gunner desires to set into the control apparatus.

Pressure responsive SGT DOmOtOTS Referring now to Fig. 5, the rate amplifier servo block 2| 0 is shown as containing train rate amplifier servo 220, elevation rate amplifier servo 22! and a P1 generator valve 222 which is designed to generate a pressure P1 corresponding to the pressure P1 generated by the generator valve of Fig. 1.

Inasmuch as the P1 generator valve 222 is identical in construction with the P1 generator valve 55, the corresponding parts have been given identical reference characters with the addition of a prime and will not be re-described. Fluid under pressure P2 is supplied to the chamber 59' of the generator valve 222 from the P2 supply duct 43 through a duct 20! and a passage 223. Return fluid at a pressure P0 is fed to the return duct 53 from the valve chamber l2 through a passage 22 i and a duct 205. Fluid under pressure P1 is supplied from the valve chamber 60' to a passage 225.

The elevation servomotor 22I comprises a chamber formed in the block 2H), containing a hollow piston 23!} and a slide 23I which is mounted for axial movement within the piston 230. Chambers 232 and 233 are formed at the two ends of the piston 23!]. The chamber 232 is supplied with fluid at pressure P1 through a passage 234 which communicates with the passage 225. Chamber 233 is supplied with fluid at a pressure controlled by the operation of the slide 23I through a passage 235 communicating with an elongated chamber 236 in the piston 23h.

The slide 23I is acted upon at one end by the hydraulic pressure P1 from the chamber 232 and at its other end forms a closure for a chamber 231 formed within the bore of the piston 230. The slide 23! is acted upon by two opposed springs 238 and 233. The spring 238 extends between one end of the slide 23! and a ring 240 attached to the piston 23!! within the chamber 231. The spring 239 extends between the opposite end of the slide 23I and a pin 2M which is mounted in a fixed plate 2 52 forming an end closure for the chamber 232. The pin MI is adjustable for varying the tension of the spring 239. The slide 23! is formed with a central annular chamber 245 which communicates through a passage 246 in the piston 23!] with the chamber 236 and is thus in communication with the end chamber 233.

Fluid under pressure P2 is supplied through a passage 25!] from a passage 25I, which communicates with the duct 291, to an elongated chamber 252 formed in the piston 230 and thence to a passage 253 which terminates adjacent the lower end of the chamber 245 and is normally closed by the slide 23 I.

Fluid at the pressure P0 is returned from the valve 22! to the return duct 235 through a passage 255 in the block 210, which passage is connected to the slide 231 through a passage 25% in the block 2| 0 leading to an elongated chamber 25? in the piston 230, thence through a passage 258 in the piston 23!] which passage terminates adjacent the upper end of; the chamber 245, and is normally closed by the slide 23!. The passages 253 and 268 are so arranged that one or the other is brought into communication with the chamber 255 when the slide 23! moves axially from its balanced position.

Fluid under pressure P6 is supplied from duct 3! (Fig. 1) through passage 260 in the block ZIU to an elongated chamber 26! in the piston 236, thence through a passage 262 in the piston 23!) which communicates with the chamber 231.

The link 366 which connects to the automatic computing apparatus is connected to the piston 230 and extends outwardly from the block 2H1.

The speed of response of the piston, 230 to movements of the slide 23! is controlled by an adjusting screw 255 which extends into the passage 235 and controls the flow of fluid therethrough. Thus the controlling effect on the piston 236 of sudden changes in the controlling pressure due to the rate of movement of the handles I55 may be eliminated to a, large extent by the restricted flow through the passage 235. A stop screw 266 carried by the piston 230. extends into the chamber 245 to limit the axial movement of the slide 236 relative to th piston 238.

Assuming that the pressure Pe equals the. pres sure P1, then the pressure within the chamber 23'! will equal the pressure in the chamber 232 and the forces on the two ends of the slide 235 will be balanced. The slide will then take a posir tion at which the forces due to the springs 238 and 236 are also balanced and the piston 2.36 will be in a position relative to the slide 2,3i such that the passages 2,58 and 253 are both closed, as shown in Fig. 5.

If now the pressure Fe is assumed to increase, the pressure in chamber 23'! becomes greater than the pressure (P1) in chamber 232 and the slide 23! is caused to move downwardly thereby increasing the tension of spring 238. This down- Ward movement of the slide 23! opens the passage 253 to the chamber 245 and allows flu d under pressure P2 to pass from, the. passage 250 through the chamber 245 and the passag 235 to the chamber 233. This increases the pressure in the chamber 233 and causes the piston 233 to move downwardly. This action continues until the downward movement of the piston 238 with respect to the slide 23! again centers the piston with respect to the slide and closes the passage 253. As the piston 23!] thus follows the move" ment of the slide 23!, the tension of the spring 238 is restored to normal. The slide 23! and the piston 230 move down together, except for the efiect of the restriction in passage 235 caused by the screw 265, until the tension of the spring 239 is reduced by an amount corresponding to the in,- crease in the pressure Fe in chamber 23?. Since the pressure in the chamber 232 and tension of the spring 236 remain at their normal values, the slide 23i and the piston 236 assume a position where the increased effect of the pressure in chamber 23'! tending to move the slide 23! down is neutralized by the reduced effect of the spring 239.

The sleeve 230 accordingly not only follows the movement of the slide 23!, but, due to the large area of the end of the piston 23!] as compared to the area of the ends of the slide 23!, exerts an increased force which may be applied by the link 366 to the input of a computing mechanism such as that set forth in the patent application above identified. The ratio of the force exerted by the link 366 to that exerted upon the slide 23! may be varied as desired by changing the relative, dimensions of the parts. Hence, the piston 23!] may be caused to exert any necessary force upon the link 366 for actuating the computing mechanism.

As explained, the movement of the slide 23! and the piston 230 is proportional to the changes in pressure Pe. Hence the position of the link 366 represents the rate of elevation dE which is to be set into the computing mechanism.

It will be noted that the position taken by the link 366 is dependent only upon the pressure Pa and is not afiected by leakage in the hydraulic system provided the leakage does not change the pressures. For any static position of the plunger 9 there is an exact corresponding position for the link 366 which is determined by the spring and hydraulic pressures only, provided of course the hydraulic system has sufiicient capacity to keep the various passages and ducts full at the various pressures.

The elements of the train rate servomotor 220 are identical with those of the elevation rate servomotor above described and have accordingly been given the same referenc characters with the suifix t. Fluid under pressure Pt is supplied to the train rate servomotor from the duct through a passage 216 in the block 2!0. This causes a movement of the slide 23 It which is proportional to changes in pressure Pt and a corresponding movement of the piston 230? which actuates the link 355 to introduce the rate of train dBs into the computing mechanism.

Although specific embodiments of the invention have been shown for purposes of illustration, it is to be understood that the invention is capable of various adaptations as will be readily apparent to a person skilled in the art. The invention is only to be limited in accordance with the scope of the following claims.

What is claimed is:

l. A pressure control valve comprising a valve housing, a sleeve in said housing forming fluid chambers at its two ends, spring means balancing said sleeve, means supplying fluid at a fixed intermediate pressure to one of said end chambers, a high pressure chamber, a low pressure chamber, a plunger movable in said sleeve and passages adapted to selectively connect said high pressure chamber or said low pressure chamber to the other of said end chambers for causing said sleeve to follow said plunger and to establish a pressure diiference between said end chambers to counterbalance the unbalance of the spring pressures acting on the ends of said sleeve due to movement of said sleeve from its balanced position and means deriving a control pressure from said last chamber.

2. A pressure control valve comprising a valve housing, a sleeve in said housing forming fluid chambers at its two ends, springs biasing said sleeve to a mid-position, means supplying fluid at a fixed intermediat pressure to one of said end chambers, a high pressure chamber and a low pressure chamber in said sleeve, a plunger extending axially through said sleeve, a passage in said sleeve communicating with the other of said end chambers, a chamber in said plunger communicating with said passage, and passages in said sleeve normally closed by said plunger communicating with said high and low pressure chambers, said passages being adapted to be brought into communication with said plunger chamber and thence with said last end chamber by movement of said plunger relative to said sleeve to supply said high or low pressure to said last end chamber to cause said sleeve to follow said plunger, the pressure in said last end chamber being determined by the unbalance of said springs produced by and displacement of said sleeve from its mid-position and means deriving a control pressure from said last chamber.

3. A pressure control valve comprising a valve housing, a sleeve in said housing forming fluid chambers at its two ends, means centrally biasing said sleeve, a source of supply of fluid at a fixed intermediate pressure, a passage connecting said source of supply of fluid to one of said end chambers, means restricting the flow of fluid through said passage effective to vary the pressure in said end chamber during movement of said sleeve, a high pressure chamber, a low pressure chamber, an adjustable plunger movable relative to said sleeve to selectively connect said high pressure chamber or said low pressure chamber to the second of said end chambers and means deriving a control pressure from said last end chamber.

4. A pressure control valve comprising a valve housing, a sleeve in said housing forming fluid chambers at its two ends, means centrally biasing said sleeve, a source of supply of fluid at a fixed intermediate pressure, a passage connecting said source of supply of fluid to one of said end cham bers, means restricting the flow of .fluid through said passage elfective to vary the pressure in said end chamber during movement of said sleeve, a high pressure chamber, a low pressure chamber, an adjustable plunger movable relative to said sleeve, a passage in said sleeve communicating with the other of said end chambers, a chamber in said plunger communicating with said passage, and a pair of passages in said sleeve normally closed by said plunger and communicating with said high and low pressure chambers respectively, said passages being adapted to be brought into communication with said plunger chamber and thence with said last end chamber upon relative movement between said plunger and said sleeve and means deriving a control pressure from said last end chamber.

5. A fluid pressure control valve comprising a source of high pressure fluid, a source of intermediate pressure fluid, a chamber for exhaust fluid, a valve housing, a sleeve in said housing forming fluid chambers at its two ends, means centrally biasing said sleeve, a passage connecting the source of intermediate pressure to one of said end chambers, means restricting the flow of fluid through said passage effective to vary the pressure in said end chamber during movement of said sleeve, an adjustable plunger movable relative to said sleeve, a port in said sleeve connected to said source of high pressure, a second port in said sleeve connected to said chamber for exhaust fluid, and a third port connected to the second of said end chambers, said ports being positioned to selectively connect the first or second ports to the third port upon relative movement between the plunger and the sleeve whereby the sleeve follows the movement of the plunger and the pressure generated in said second end chamber is responsive jointly to the pressure in said one end chamber and the biasing force acting on the sleeve due to displacement of the sleeve from its centrally biased position and means deriving a control pressure from said last end chamber.

WILLIAM H. NEWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number

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