US3273860A - Hydraulic system - Google Patents

Description

p 1966 c. o. WEISENBACH HYDRAULIC SYSTEM Filed March 4, 1965 INVENTOR CHAR|S O.WEISENBACH I -I m ll.

ATTORNEYS United States Patent 3,273,860 HYDRAULIC SYSTEM Charles 0. Weisenbach, Watertown, N.Y., assignor to The New York Air Brake Company, a corporation of New Jersey Filed Mar. 4, 1965, Ser. No. 437,167 6 Claims. (Cl. 254-184) This invention relates to hydraulically actuated hoisting and hauling system's, hereafter referred to simply as hoisting systems, employing a plurality of winches.

The object of the invention is to provide a versatile, drift-free hoisting system of the type just mentioned which permits independent operation of each winch as well as simultaneous operation of all or several of the winches. In all cases, the invention affords variable speed operation in both the reel in and the pay out directions.

The preferred embodiment of the invention is described herein in detail with reference to the accompanying drawing in which:

FIG. 1 is a schematic diagram of a manually controlled, two-winch system.

FIG. 2 is an axial sectional view of the control valve used in the system.

As shown in FIG. 1, the preferred hoisting system comprises two identical winch units 11 and 11 arranged to raise and lower a load indicated at 12. The winch unit 11 includes a winch 13 which is driven by a fixed displacement rotary hydra-ulic motor 14, and whose cable 15 is attached to one end of the load 12. Motor 14 is reversible, and has a pair of ports 16 and 17, either of which can serve as the inlet port when the other serves as the discharge port. For purposes of discussion, it is assumed herein that motor 14 drives which 13 in the reel in direction when port 16 is the inlet port, and in the pay out direction when port 17 is the inlet port. Although it is not illustrated in the drawing, it will be understood that the drive connection between motor 14 and winch 13 usually includes a speed reducing gear train.

The speed and direction of operation of motor 14 are controlled by a valve 18 which serves selectively to meter fluid under pressure to one of the ports 16 or 17 while simultaneously exhausting fluid from the other port. This control valve, which is the subject of my co-pending application Serial No. 433,856, filed Feb. v19, 1965, comprises a housing containing five ports 19, 21, 22, 23 and 24 which lead into the annular chambers 2529, respectively; the ports 19 and 24 being connected with a hydraulic reservoir or tank 31, the ports 21 and 23 being connected with the motor ports 16 and 17, respectively, by conduits 32 and 33, and the port 22 being connected with a discharge pressure compensated variable delivery pump 34 by conduit 35, shut-off valve 36 and branch conduit 37. The annular chambers 25-29 encircle a through bore into which is pressed a valve sleeve 38 formed with five longitudinally spaced sets of registering radial passages 39, and 41-44. The valve sleeve 38 contains a sliding valve spool 45 formed with two annular grooves 46 and 47 that define three spaced valve lands 48, 49 and 51. At its opposite ends, the valve spool 45 is provided with a pair of aligned rotary actuators 52 and 53 which are fixed against longitudinal movement relatively to the housing of the control valve. The inner end of actuator 52 is in the form of an enlarged head carrying right-hand threads, and this head is screwed into an axial bore formed in the spool. Actuator 53, on the other hand, is connected with the spool by a slip joint of the pin and slot type. It should be obvious from a study of FIG. 2, that relative rotation of the actuators 52 and 53 in opposite directions will cause valve spool 45 to shift longitudinally in opposite directions from the illustrated neutral position.

Actuator 53, which forms part of a feedback link for valve 18, is driven by one of a pair of rolls 54 between which passes the cable 15 of winch 13. Therefore, the speed and direction of rotation of this actuator correspond to the speed and direction of travel, i.e., the velocity, of cable 15. Actuator 52, on the other hand, is the input actuator for valve 18, and it is driven by a reversible DC. motor 55 through a speed reduction gear train 56. Motor 55 is energized from a common supply circuit 57, including a current source 58, a master speed control rheostat 53, and a pair of combined on-oif and reversing switches 61 and 62. The two wipers of the switches are ganged together, and each is provided with three contacts, labeled U, S and D to designate up, stop and down, respectively. The output leads 63 and 64 of the supply circuit 57 are connected with motor 55 by a branch circuit 65 which includes a second pair of reversing switches 66 and 67 and an individual speed control rheostat 68. As in the case of switches 61 and 62, the wipers of switches 66 and 67 are ganged together and each is provided with up, stop and down contacts U, S and D, respectively.

Since, as mentioned earlier, the two winch units 11 and 1 1 are identical, the elements of unit 11' are identified by the same reference numerals as their counterparts in unit 11, with primes added for clarity.

OPERATION When the hoisting system is in operation, supply pump 34 will be running and shutoff valve 36 will be open. If the reversing switches 66, 67, 66' and 67' are in their illustrated positions, the energization circuits for the motors 55 and 55' will be open, and the motors will be at rest. Under these conditions, the control valves 18 and 18' will assume the neutral position, illustrated in FIG. 2, wherein each valve blocks fiow to and from the conduits 32 and 33 or 32' and 33 and thus hydraulically locks the associated hydraulic motor 14 or 14. Since, at this time, the valves 18 and 18 also block flow from branch conduits 37 and 37', the flow demand imposed on pump 34 is a minimum and its delivery rate is automatically reduced to a small value sufficient only to replace the fluid lost from the system through leakage.

When the winches 13 and 13' are idle, but under load, leakage of oil from the motors 14 and 14' destroys the hydraulic locks and the load tends to drift downward. The present system inherently compensates for this condition. Thus, considering winch unit 11, as soon as the cable 15 commences to move downward, one of the rollers 54 will rotate actuator 53 in the direction of arrow A relatively to actuator 52, which is at rest, and cause valve spool 45 to shift to the right. This movement of the valve spool 45 causes peripheral groove 46 to interconnect ports 21 and 22, and thereby open a supply path to motor port 16, and causes groove 47 to interconnect ports 23 and 24 and establish an exhaust path leading from motor port 17 to tank 31. As a result, motor 14 drives winch 13 back to its original position. Since rollers 54 rotate actuator 53 and valve spool 45 in the direction of arrow B as the cable 15 is reeled in, it will be apparent that valve spool 45 returns to the neutral position as the winch 13 moves back to its original position. This same restorative action occurs automatically at winch unit 11', and, therefore, it is evident that the system prevents drifting of the load when the winches are idle.

In order to raise the left end of load '12-, the operator shifts the wipers of switches 61, 62, 66 and 67 onto their U contacts to thereby complete the energization circuit for electric motor 55. This motor, therefore, commences to rotate valve actuator 52 in the direction of arrow B at a speed determined by the settings of rheostats 59 and 68. Inasmuch as actuator 53 initially is at rest, this rotation of actuator 52 causes valve spool 45 to shift to the right and open a supply path from pump 34 to motor port 16, and an exhaust path from motor port 17 to tank 31. Opening of these flow paths causes hydraulic motor 14 to drive winch 13 and accelerate cable 15 in the reel in direction. As the cable 15 moves upward, one of the rollers 54 rotates actuator 53 and valve spool 45 in the direction of arrow B. This rotation of the valve spool 45 reduces its rate of movement in the longitudinal direction, and when the speed of cable 15 reaches a value at which the rotary speeds of the actuators are equal, longitudinal movement of the valve spool 45 ceases. It should be apparent that the distance valve spool 45 shifts from the neutral position determines the extent to which valve 18 throttles the flow of hydraulic oil to motor port 16. Furthermore, it should be kept in mind that as valve '18 opens and imposes a flow demand on pump 34, the compensator associated with the pump automatically increases its delivery rate so as to maintain the pressure in conduits and 37 substantially constant.

If the speeds of the actuators 52 and 53 become unequal, valve spool will shift longitudinally in that direction which causes hydraulic motor 14 to restore equality. For example, when the operator adjusts one of the rheostats 59 or 68 to increase the speed of electric motor 55, valve spool 45 will shift farther to the right and cause land 49 to uncover a larger portion of radial passages 42. This decreases the restriction to flow to motor port 16 and causes motor '14 to drive winch at a faster speed. When actuator 53 and valve spool 45 have been accelerated to the new rotary speed of actuator 52, the spool will again stop moving in the longitudinal direction. On the other hand, if readjustment of one of the rheostats 59 and 68 causes motor to run at a slower speed, valve spool 45 will shift to the left to increase the restriction to flow through radial passages 42 and thus bring about a decrease in the speeds of motor 14, cable 15 and actuator 53. When one of the sets of reversing switches 61, 62 or 66, 67 is shifted to its S contacts, motor 55 will stop and the valve spool 45 will be returned to the illustrated neutral position.

Lowering of the left end of load 12 is effected by reversing the direction of current flow through electric motor 55. This can be done by shifting either, but not both, of the sets of switches 61, 62 or 66, 67 onto their D contacts. When the motor 55 drives actuator 52 in the direction of arrow A, valve spool 45 shifts to the left from its neutral position and connects motor ports 17 and 16 with the pump 34 and tank 31, respectively. Under these conditions, motor 14 drives winch 13 in the pay out direction, and roller 54 rotates actuator 53 and valve spool 45 in the direction of arrow A. As in the preceding case, valve spool 45 will always assume a longitudinal position which causes actuator 53 to rotate at the same speed as actuator 52.

It should be apparent without detailed discussion that the right end of load 12 can be raised and lowered relatively to the left end by shifting switches 66 and 67 onto their S contacts, and by completing the energization circuit for electric motor 55 through switches 61, 62, 66 and 67 It should also be evident that when the wipers of the sets of switches 66, 67 and 66', 67' are on their U contacts, both of the winches will be driven in the reel in direction when the wipers of switches 61 and 62 are shifted onto their U contacts, and that both winches will be driven in the pay out direction when the wipers of switches 61 and 62 are shifted onto their D contacts. Under these conditions of simultaneous operation, the speed of each of the cables 15 and 15 can be varied independently by resetting the associated rheostat 68 or 68, and the speeds of the two cables can be varied equal amounts by resetting master rheostat 59. It also is possible, by shifting the wipers of one of the sets of switches 66, 67 and 66', 67' to their D contacts, to cause one cable to move in the reel in direction while the other is moved in the pay out direction.

While the reversing switches and rheostats in the illustrated embodiment are manually operated, it is obvious that these devices may be actuated by an automatic control system, such as a level control system, designed to maintain or change the orientation and position of load 12 in a prescribed manner. It also will be apparent that the load-handling capability of the hoisting system can be expanded by simply adding additional winch units, including a branch conduit, like conduit 37, and a branch electrical circuit, like circuit 65', for each added unit.

As stated previously, the drawing and description relate only to the preferred embodiment of the invention. Since changes can be made in the structure of this embodiment without departing from the inventive concept, the following claims should provide the sole measure of the scope of the invention.

What is claimed is:

1. A hoisting system comprising (a) a plurality of winches, each adapted to reel in and pay out a cable;

(b) reversible hydraulic motors, one connected to drive each winch and each having a pair of ports, the motor causing the winch to reel in cables when .one port is pressurized and to pay out cable when the other port is pressurized;

(c) a hydraulic reservoir;

((1) a discharge pressure compensated vaiable delivery hydraulic pump having an inlet port connected with the reservoir and to discharge port;

(e) a plurality of control valves, each connected with the two ports of one hydraulic motor and with both the discharge port of the pump and the reservoir;

(f) each control valve including a valve member movatale in opposite directions from a neutral position in which it prevents communication between the pump and reservoir and hydraulically locks the associated hydraulic motor, movement of the valve member in one direction serving to open progressively fiow paths between one motor port and the pump and between the other motor port and the reservoir, and movement of the valve member in the opposite direction serving to open progressively flow paths between said one motor port and the reservoir and between the said other motor port and the pump;

(g) a reversible electric motor associated with each control valve;

(h) feedback means associated with each winch and each including a rotary element which is driven at a velocity that varies with the velocity of the cable;

(i) actuating means associated with each control valve and operatively connected with the valve member and the associated rotary feedback elements and electric motor, each said actuating means being responsive to the speeds and directions of movement of the rotary feedback element and electric motor for positioning the valve member so as to maintain a predetermined proportionality between said speeds and a predetermined relationship between said directions of movement;

(j) electrical circuit means for energizing the electric motors;

(k) common control means associated with the circuit means for simultaneously and uniformly varying the speeds of all electric motors and for simultaneously reversing the directions of operation of all motors; and

(l) a plurality of independent control means associated with the circuit means, each independent control means serving to vary the speed of only one electric motor.

2. A hoisting system as defined in claim '1 in which each independent control means includes means for reversing the direction of operation of the electric motor it controls.

3. A hoisting system comprising (a) a plurality of winches, each adapted to reel in and pay out cable;

(-b) reversible hydraulic motors, one connected to drive each winch and each having a pair of ports, the motor causing the winch to reel in cable when one port is pressurized and to pay out cable when the other port is pressurized;

(c) a hydraulic reservoir;

(d) a discharge pressure compensated variable delivery hydraulic pump having an inlet port connected with the reservoir and a discharge port;

(e) a plurality of control valves, each connected with the two ports of one hydraulic motor and with both the discharge port of the pump and the reservoir,

(f) each control valve including a valve member movable in opposite directions from a neutral position in which it prevents communication between the pump and the reservoir and hydraulically locks the associated hydraulic motor, movement of the valve member in one direction serving to open progressively flow paths between one motor port and the pump and between the other motor port and the reservoir, and movement of the valve member in the opposite direction serving to open progressively flow paths between said one motor port and the rservoir and between the said other motor port and the pump;

(g) a reversible DC. motor associated with each control valve;

(h) feedback means associated with each winch and each including a rotary element which is driven at a velocity that varies with the velocity of the cable;

(i) actuating means associated with each control valve and operatively connected with the valve member and the associated rotary feedback element and electric motor, each said actuating means being responsive to the speeds and directions of movement of the rotary feedback element and the electric motor for positioning the valve member so as to maintain a predetermined proportionality between said speeds and a predetermined relationship between said directions of movement;

(j) common electrical circuit means including a source of direct current having positive and negative poles, first and second leads, means for varying the current flow through the circuit means, and switching means for selectively connecting the positive and negative poles with the first and second leads, respectively, or with the second and first leads, respectively; and

(k) a plurality of independent electrical circuit means connecting the electric motors in parallel across the first and second leads, each independent circuit means including means for varying the current fiow through the associated electric motor.

4. A hoisting system as defined in claim 3 in which the means for varying current flow through the common circuit means is capable of interrupting current flow through that circuit means.

'5. A hoisting system as defined in claim 4 in which each of the means for varying the current flow through an electric motor is capable of interrupting current flow through the associated motor.

6. A hoisting system as defined in claim 5 in which each independent circuit means includes means for reversing the direction of current flow through the associated electric motor.

References Cited by the Examiner UNITED STATES PATENTS 2,258,307 '10/1941 Vickers 254186 X 2,707,053 4/ 1955 Browning 254184 X 2,823,897 2/1958 Kellogg 254-484 X 2,831,554 4/1958 Reynolds 254186 X 2,881,882 4/1959 Gentile. 3,107,791 10/1963 Michael 254184 X SAMUEL F. COLEMAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,273,860 September 20, 1966 Charles 0. Weisenbach It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 33, for "to" read a line 56, for "elements" read element Signed and sealed this 1st day of August 1967.

(SEAL) Attest:

EDWARD M. FLETCHER, JR.

Attesting Officer EDWARD J. BRENNER Commissioner of Patents

Claims (1)

1. A HOISTING SYSTEM COMPRISING (A) A PLURALITY OF WINCHES, EACH ADAPTED TO REEL IN AND PAY OUT A CABLE; (B) REVERSIBLE HYDRAULIC MOTORS, ONE CONNECTED TO DRIVE EACH WINCH AND EACH HAVING A PAIR OF PORTS, THE MOTOR CAUSING THE WINCH TO REEL IN CABLES WHEN ONE PORT IS PRESSURIZED AND TO PAY OUT CABLE WHEN THE OTHER PORT IS PRESSURIZED; (C) A HYDRAULIC RESERVOIR; (D) A DISCHARGE PRESSURE COMPENSATED VARIABLE DELIVERY HYDRAULIC PUMP HAVING AN INLET PORT CONNECTED WITH THE RESERVOIR AND TO DISCHARGE PORT; (E) A PLURALITY OF CONTROL VALVES, EACH CONNECTED WITH THE TWO PORTS OF ONE HYDRAULIC MOTOR AND WITH BOTH THE DISCHARGE PORT OF THE PUMP AND THE RESERVOIR; (F) EACH CONTROL VALVE INCLUDING A VALVE MEMBER MOVABLE IN OPPOSITE DIRECTIONS FROM A NEUTRAL POSITION IN WHICH IT PREVENTS COMMUNICATION BETWEEN THE PUMP AND RESERVOIR AND HYDRAULICALLY LOCKS THE ASSOCIATED HYDRAULIC MOTOR, MOVEMENT OF THE VALVE MEMBER IN ONE DIRECTION SERVING TO OPEN PROGRESSIVELY FLOW PATHS BETWEEN ONE MOTOR PORT AND THE PUMP AND BETWEEN THE OTHER MOTOR PORT AND THE RESERVOIR, AND MOVEMENT OF THE VALVE MEMBER IN THE OPPOSITE DIRECTION SERVING TO OPEN PROGRESSIVELY FLOW PATHS BETWEEN THE SAID OTHER MOTOR PORT AND THE PUMP; AND BETWEEN THE SAID OTHER MOTOR PORT AND THE PUMP; (G) A REVERSIBLE ELECTRIC MOTOR ASSOCIATED WITH EACH CONTROL VALVE; (H) FEEDBACK MEANS ASSOCIATED WITH EACH WINCH AND EACH INCLUDING A ROTARY ELEMENT WHICH IS DRIVEN AT A VELOCITY THAT VARIES WITH THE VELOCITY OF THE CABLE;

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