US2884904A

US2884904A - Hydraulic motor control

Info

Publication number: US2884904A
Application number: US466925A
Authority: US
Inventors: Carroll G Gordon
Original assignee: FLETCHER AVIAT CORP
Current assignee: FLETCHER AVIAT CORP; FLETCHER AVIATION Corp
Priority date: 1954-11-04
Filing date: 1954-11-04
Publication date: 1959-05-05
Anticipated expiration: 1976-05-05

Description

May 5, 1959 I C. G. GORDON @Pfau a@ 0,1/

@M www 2,884,904 HYDRAULIC MDTOR CONTROL Application November 4, 1954, Serial No. 466,925 4 Claims. (Cl. 121-39) The present invention relates toy hydraulic motor control apparatus which is designed to be used in inllight refueling apparatus.

A broad general object of the invention resides in pro viding a novel hydraulic motor control by which the fluid ow to and from a hydraulic motor is controlled in response to the load on the hydraulic motor.

A further object resides in providing a hydraulic motor' control in which iluid ow to and from the motor is directed in response to variations in motor load reected by pressure changes in the motor operating fluid balanced against a reference pressure source.

Further novel features and other objects of this invention will become apparent from the following detailed description, discussion and the appended claims taken in conjunction with the accompanying drawing showing a preferred structure and embodiment, in which:

The single figure is an enlarged diagrammatic view illustrating a hydraulic motor control in accord with this invention, shown in the fluid line connections to a reversible hydraulic motor which is drive connected to I an inight refueling hose and drogue reel, the load on the motor.

As the present hydraulic motor control invention was conceived in connection with inight refueling apparatus, the schematic construction shown in the 'drawing shows a refueling reel carrying a trailing hose 22 with a drogue 18 attached to the extremity of the trailing hose to depict a load on a rotary hydraulic motor 38. The motor 38 is reversible fluid motor, preferably a positive displacement type, and can be chosen from many such wellknown motors.

The precise sequential operation of the entire apparatus, and speciiically the hydraulic motor 38, is best apparent from a consideration of the drawing. Within a control box (not shown) which can be mounted on reel support structure closely adjacent the motor 38y is main control valve 87 having a rotary valve body 88 to which there is attached an external lever arm 90. The precise rotary control valve structure 87 preferably employed with the invention is a hydraulically balanced fluid valve such as is shown in the co-pending Gordon application Serial No. 384,196 entitled Balanced Fluid Valve, now Patent No. 2,822,821, although other valve means having similar characteristics can in all probability he employed with the invention with varying results depending upon the characteristics of such` other valve means.

When the rotary valve body 88 and the lever arm 90 are in the positions shown, hydraulic fluid from an appropriate source of hydraulic fluid under pressure (not shown) is conveyed to this valve 87 by means of apipe 91 so as to place a central passage 92 within the' valve body 88 under pressure. As the lever arm 90 is turned in a clockwise direction as viewed in the drawing, by means of al solenoid 95 being actuated so asf to cause part of this solenoid to bear against the lever armI 90, `the-central passage 92 is placed in communication with United States Patent t) passages 96 within the valve 87. These passages are joined together within this body in vsuch a manner that as the rotary valve body is turned in this direction liuid flows from the pipe 91 through the central passage 92, and thence into these passages 96 and out into a common pipe 97. Simultaneously, return passages 98 within the control valve 87 are placed in lluid communication with side passages 100 formed within the valve body 8S, permitting hydraulic uid to llow through passages 101 within the valve 87 into these side passages 100 and into the return passages 98, and thence out of the valve ,87 through a pipe 102 serving to conduct hydraulic fluid back to an appropriate reservoir. The passages 101 are connected to a common pipe 103 leading from the valve 87.

If the lever arm 90 is rotated in a counterclockwise direction as by a solenoid 105 being `actuated so as to cause part of this solenoid to bear against the lever arm 90, the valve body 88 within the valve 87 will be moved in such a manner that hydraulic fluid flowing through the pipe 91 will be conveyed throughpthe central passage 92 to the passages 101 and the pipe 103, and, simultane ously, the return pipe 102 will be connected by means of the side passa-ges 100 to the passages 96 and the pipe 97. It is seen from this description that by rotating the lever arm 90 in either a clockwise or a; counterclockwise direction, essentially the same type of fluid ow is created within the valve 87 except for one major difference. lf this lever arm 90 is' rotated in one direction, the pipe 97 will convey hydraulic liuird under pressure from the pipe 91, and the pipe 103 will be in communication with the hydraulic fluid return pipe 102; whereas if the lever arm 90 is rotated in the opposite direction, the pipe 91 serving to connect the valve 87 to a source of hydraulic fluid under pressure will be connected to the pipe 103 while the pipe' 97 will be in communication with the hydraulic iiuid return pipe 102.

The pipes 102 and 91 are preferably respectively connected to an appropriate hydraulic reservoir (not shown) and a hydraulic pump (not shown) of conventional cate'- gory to which the hydraulic motor 38 is attached.

The direction of rotation of the hydraulic motor 38 is dependent upon whether the pipe 97 or the pipe 103 is used to convey fluid underv pressure from the control valve 87 to: the motor 38 and direction of rotation of the hydraulic motor 38 may be reversed by moving the lever arm 90 of the control valve 87. One important feature of the instant invention lies in the' fact that it is possible to Very closely regulate the hydraulic motor 3S so as to obtain any desired rotational speed, depending upon the position of the lever arm 90.

The pipe 103 is connected to a branch pipe 120 which leads directly to a small hydraulic cylinder 121 so that the interior of this cylinder is placed in fluid communication with the pipe 103:,` and so that the position of a small piston 122 within this cylinder 121 may -be regulated by the fluid pressure within the pipe 103 so as to cause a projecting arm 125 attached to the piston 122 to bear against the lever arm 90. The pipe 120 is provided with a ibranch` pipe 126 through which hydraulic iiuid from the pipe 103 is conveyed past a 'solenoid controlled valve 127 to a second hydraulic cylinder 128. This cylinder is equipped with a piston 130 which is adaptedto be moved by hydraulic lluid under pressure conveyed to it from the pipe 103. This piston is provided with aprojee'tingl al'rn 1311 which is adapted to bear against the lever` arm 90 on the side of this arm' remote fi-'oni the projecting arm` 125i` Thus, with this construction, the lever armi 90 may be moved' in either a clockwise or' a counterclockwiseV direction as' either of the pistens 122 or 1'350is* moved within the hydraulic cylinders 121 or 128; In effect, these' pistons aref balanced against one another by the projecting

arms

125 and 131 bearing against the lever arm 90. Between the solenoid control valve 127 and the hydraulic cylinder 128 there is connected to the branch pipe 126 a hydraulic accumulator 132 which is employed for a purpose as will be more fully described.

One major advantage in the use of a positive displacement hydraulic motor 38 with the instant invention lies in the fact that the pressure of the hydraulic lluid employed to drive this member is directly related to the load placed upon the motor. Thus, with the construction shown and illustrated in the drawings, the amount of drag placed upon the drogue 18 and the extended hose by the airstream during the operation of the inight refueling apparatus results in a tension force through the hose 22 to the reel 25, which varies with varying airspeeds and can be detected by means of the hydraulic pressure employed to turn the hydraulic motor 38. With the construction illustrated in the drawings, the pressure of the hydraulic uid used in the hydraulic motor 38 may be employed so as to automatically regulate the operation of the hydraulic motor by turning the control valve 87 so as to keep any desired amount of tension within the hose 22.

With the construction shown the branch pipe 120 is employed to convey hydraulic uid under pressure to the hydraulic cylinder 121, the hydraulic cylinder 128, and the various attached pipes and members as indicated in the preceding discussion. These hydraulic cylinders and attached members and parts are all located within a control box along with the control valve 37. When, by virtue of operation of the appropriate solenoid 95 or 10S, ythe motor 38 has been operated so that the hose 22 is extended by rotation of the reel so as to place the drogue 18 in a position in which it may be employed in inflight refueling, the lever arm 90 is returned under solenoid control to the position shown in the drawing. At this point the valve 127 is in open position so that the hydraulic `cylinders 121 and 128 are balanced against one another; that is to say, the projecting

arms

125 and 131 attached to the pistons 122 and 130 within these hydraulic cylinders are both extended against the lever arm 90 in such a manner that this lever arm is centered. At this point, when, as above noted, the drogue and hose are in extended operative position, the solenoid control valve 127 is closed, keeping the hydraulic fluid within the hydraulic cylinder 128, the branch pipe 126, and the hydraulic accumulator 132 at a substantially fixed pressure. As the pressure within the pipes 120 and 103 varies thereafter, this variation will be transmitted to the hydraulic cylinder 121 causing the piston 122 to either be retracted within this cylinder or extended therefrom an amount proportional to the difference in pressure between the pressure in the cylinder 121 and the pressure in the cyliuder 128, simultaneously causing appropriate clockwise or rcounterclockwise rotation of the lever arm 90. Such rotation of the lever arm 90, as previously described, governs the rotation of the hydraulic motor 38, and thus, will cause the hose 22 to be either reeled in or reeled out at a speed proportional to the amount the lever arm 90 is rotated.

This mechanism is exceedingly important for inflight refueling in accordance with the instant invention inasmuch as with it the load upon the hose 22 may be regulated so as to obtain very satisfactory inflight refueling characteristics. Thus, with the construction shown, as the drogue 18 is engaged by a following aircraft to receive fuel, the pressure within the pipe 103 will automatically drop as the drogue 18 is pushed towards the apparatus 10 by virtue of the motion of the receiving aircraft engaging the drogue coupling which reduces drag on hose 22, decreasing hose tension and reducing the load on the hydraulic reel motor, which is working against the hose drag. This change in pressure in the pipe 103 will be reected by the means indicated above 4l l so as to rotate the lever arm 90, causing the hose 22 to be reeled in upon the reel 25. As an aircraft being ret fueled in flight drops behind the complete inight refuel- I ing apparatus, the increased pull upon the hose 22 will 'be reected by an increase in the pressure of fluid within the pipe 103, and will cause, by means described above, the lever arm to be rotated in such a manner as to operate the reel 25 to extend the hose. Thus, with the instant invention, an exceedingly simple, very elective apparatus is employed to keep the precise amount of tension desired upon the hose in inight refueling, regardless of minor variations of speed within the receiving aircraft and the aircraft employed to convey fuel to this receiving aircraft.

A pipe 135 is shown connected to the pipe 91 so as lo convey hydraulic fluid from this pipe 91 under pressure past a dheck valve 136 and a hydraulic accumulator 137 to a solenoid controlled valve 138 which is used to gorern the admission of hydraulic fluid into the brake cylinders 37. For convenience of explanation, only one of these lcylinders is indicated in Fig. 5 of the drawings. Spent hydraulic fluid is conveyed by means of a pipe 139 back to the pipe 102 which carries it to an appropriate reservoir for hydraulic iluid. The valve 136, the accumulator 137, and the valve 13S are all, for convenience, located within the control box.

It will be realized by those skilled in the art that a number of minor modifications may be made within the basic teachings of this specification without departing from the essential features of the instant invention. For this reason, the present invention is considered to be limited by the appended claims forming a part of this specification.

I claim as my invention:

l. Control means for use in governing the operation of a hydraulic motor, comprising: a valve, including a movable element, adapted to be connected to a hydraulic motor so as to control iiow of hydraulic fluid to and from the motor and control rotational operation of the motor; an arm attached to said movable element shiftable in a path between two positions to thereby operate said valve to control flow of hydraulic fluid; servo-motor means for moving said arm toward either position from a neutral position; a reference pressure source connected to bias said servo motor means in one direction; conduit means adapted to be connected in fluid communication with the operating uid between said valve and the hydraulic motor and in fluid communication with said servo motor means so said operating iiuid will oppose the bias of said reference pressure source whereby variations in motor operating pressure will result in servo motor actuation of said valve to maintain operating pressures to a predetermined value as represented by said reference pressure source.

2. A control means as defined in claim 2 including means connected between said reference pressure source and said conduit means for disabling said servo motor means and means operably connected to said arm for moving said arm independently of said servo motor means.

3. Control means for use in governing the operation of a hydraulic motor, comprising: a valve including uid pressure inlet and outlet ports adapted to be connected to a source of and return to pressure fluid, two ports adapted to be connected to the operating lines of -a hydraulic motor, a movable valve element adapted to be positioned to alternatively connect either one of said two ports to a pressure source and the other of said two ports to return or to block all flow between pressure and return ports and said two ports; an actuating arm connected to control said movable valve element; a double acting servo motor means operatively connected to said operating arm for valve controlling movement; a first uid conduit in communication between one of said two ports and one side of said servo motor means; an

accumulator in fluid communication with the other side of said servo motor means; a second fluid conduit in communication between said hydraulic accumulator and said one side of said servo motor means including a shut-off valve.

4. A device, to be utilized in governing the operation of a hydraulic motor, which comprises: a valve connected to said hydraulic motor so as to control the ow of motor operating hydraulic uid to and from said motor; a movable element included in said valve; a control arm attached to said movable element so that as said control arm and movable element are shifted, the flow of hydraulic fluid to and from said hydraulic motor is controlled; a reference pressure source; and means responsive to dilerences in pressures between said reference pressure and the pressure of hydraulic fluid within said hydraulic motor for shifting said control arm an amount proportional to said differences in pressure whereby the pressure of hydraulic uid within said motor is maintained at a value represented by said reference pressure source.

References Cited in the le of this patent UNITED STATES PATENTS 1,718,673 Wettstein June 25, 1929 1,815,100 Francis July 21, 1931 2,071,594 Trumbach Feb. 23, 1937 2,490,353 Hannay Dec. 6, 1949 2,536,965 Taylor Ian. 2, 1951 2,573,868 Newell Nov. 6, 1951 2,573,938 Tyler et al. Nov. 6, 1951 2,596,455 Williams May 13, 1952 2,615,756 Granberg Oct. 28, 1952 2,669,226 Adams Feb. 16, 1954 2,674,853 Born Apr. 13, 1954 2,692,102 Cobham et al. Oct. 19, 1954 2,723,833 Burfeind Nov. 15, 1955 2,764,365 Davis et al Sept. 25, 1956 2,789,542 Vander Kaay Apr. 23, 1957 FOREIGN PATENTS 136,889 Sweden Aug. 12, 1952 314,523 Germany Sept. 25, 1919 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 2,884,904 May 5, 1959 Carroll G. Gordon It is hereby certified lthat error appears in the printed specification of theA above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

KAEL H.. AXLTNE Column 4,. line' 55,- for the claim reference numeral "2" read l Signed and sealed this 25th day Lof August 1959.

(SEAL) Attest:

ROBERT C. WATsoN Attesting Ocer Commissioner of Patents