GB2187160A - Multiple linear winch system - Google Patents

Abstract

A dual linear winch system for hoisting and/or lowering a load includes a pair of linear winches (12, 14), each of which is connected by a cable to the load (32) and each of which has a hydraulically powered reciprocating cable gripper. A power unit supplies pressurized hydraulic fluid to the winches and a programmable controller monitors the reciprocating movement of the winches and controls the output of the power unit so that the reciprocating movement of the winches is synchronized. <IMAGE>

Description

SPECIFICATION Multiple linear winch system The present invention relates to the use of multiple linearwinches as lifting winches and more particularly to the co-ordinated operation of multiple intermittent linear winches.

Intermittent linearwinches such as that shown in U.S. Patent No. 4,427,180 have been used singularly to provide a pulling or hoisting function. The present invention relates to the co-ordinated use of a plurality of such winches.

According to the present invention in one of its aspects there is provided a dual linear winch system for hoisting/lowering a load comprising a first linear winch connectable by a cable to the load and having a powered reciprocatory cable gripper; a second linear winch connectable by a cable to the load and having a powered reciprocatory cable gripper; power means to supply powerforthe reciprocating movement and the gripping action of the linear winches; and a programmable controller connected to the two winches and to the power means and arranged to be responsive to the reciprocating movement of the winches for controlling the output of the power means to thewinches.

In accordance with another aspect of the invention,there is provided a dual linear winch system for hoisting/lowering a load comprising a first linearwinch for connection bya cable to the load and having hydrauliccylinder meansforproviding reciprocating movement of a cable gripper; a second linearwinchforconnection by a cable to the load and having hydraulic cylinder means for providing reciprocating movement of a cable gripper; power means for providing pressurized hydraulic fluid to said winches; and a programmable controller connected to said winches and to said power means and responsive to the reciprocating movement of said winches for controlling the flow of pressurized hydraulic fluid to and from said power means.

According to yet another aspect of the invention, there is provided a multiple linear winch system comprising a first and at least one second power winches each connectableto a load by means of a cableand comprising cyclically operable meansfor selectively pulling-in and letting-out such cable in a plurality of successive steps each corresponding to a stroke of the winch, monitoring means associated with each winch for providing an indication ofthe condition ofthewinch, and control means responsive to said monitoring meansfor co-ordinating the cyclical operation of the two winches such that a load coupled to thewincheswill be substantially evenly moved by the winches.

In a preferred embodiment the monitoring means comprise limit switches at the ends ofthe strokes of the winches for communicating corresponding winch status indications to the control means, and the control means is adapted to be responsive to such status indication to delay a return movement of anyone of said winches when it is atthe end of its stroke until such time as the or each other winch is at the corresponding end of its stroke. Furthermore, additional limit switches are provided in advance of the ends of the strokes of the winches, and the control means is adapted to slow down the operation of the winches in response to outputs from said additional limit switches indicative that the winches are approaching the ends oftheirstrokes.

As will be explained hereinafter, the present invention provides a dual linearwinch system in which the intermittent pulling movement of the winches is co-ordinated so as to provide even lifting ofthe load.

The invention together with furtherfeatures and advantages thereof will best be understood from consideration ofthe following description of an exemplary embodiment which is given with reference to the accompanying drawings wherein: Figure lisa schematic showing of the electrical connections between a pair of intermittent linear winches and a power unit utilized to co-ordinate their operation; Figure2 is a schematic showing of the positioning of the linear winches relative to the load; and Figure 3 is a front view of one type of linear hydraulic winch which may be used in a dual winch system according to the present invention.

As shown in Figure 2, a dual linearwinch system 10 includes a pair of linearwinches 12 and 14 mounted on a bridge or support 16.

Also mounted on bridge 16 is power unit 18which supplies the electrical and hydraulic powerfor linear winches 12 and 14.

Adual linearwinch system also includes a pair of storage reels 20 and 22 which store the cable 24 and 26 for linear winches 12 and 14 respectively. Cables 24 and 26 run through linearwinches 12 and 14 and through pulley systems 28 and30which are inturn attached to substantially opposite ends of load 32.

Each of intermittent linear winches 12 and 14 is of the type which is shown in Figure 3. A linearwinch of this type provides an intermittent pulling action and the operation and construction of such a linear winch is described in detail in U.S. Patent No.4,247,1 80to which reference may be made for a fuller understanding.

The linear hydraulicwinch 12 shown in Figure3 utilizes two sets of wedges 34 and 36 for clamping cable aligned one above the other; and it comprises a fixed frame 38 to which are fixed the outerfixed elements 40 of the upper clamping wedge, comprising truncated cylinders 42 between the oblique parallel faces of its fixed elements 40 and its inner movable elements 44. These truncated cylinders 42, when they pivot during relative movement of the elements of the clamping wedge, are interlocked with each other by means of pairs of studs 46, engaged in corresponding holes of bars 48, parallel to the oblique bearing faces of the outer 40 and inner44 elements of the clamping wedge.

With the two double-acting hydraulic cylinder 50, disposed parallel to the cable on each side thereof and on each side ofthetwo aligned clamping wedges 34 and 36, these two clamping wedges may be moved towards or away from each other, one being interlocked in transiation with the cylinders thereofandtheotherwiththe pistonsthereof.

Means are further provided so that, for lifting the load, corresponding to the retraction of the cylinders, the lower clamping wedge 36 is locked on to the cable and the upper clamping wedge 34 released, when the two clamping wedges are moved towards each other, and conversely whereas, for lowering the load, corresponding to the extension of the cylinders, the lower clamping wedge 36 is locked on to the cable and the upper clamping wedge 34 released, and conversely.

Two friction plates 52 are inserted symmetrically, on each side ofthe cable, between the lateral faces of the inner movable elements 44 and 54 of the upper 34 and lower 36 clamping wedges and the flanges 56 and 58 ofthese clamping wedges; these friction plates 52 are resiliently pressed against said lateral faces by means of springs.

Assuming thatthewinch is in the position shown in Figure 3 and that the lower clamping wedge 36 is locked on to the cable and the upper clamping wedge 34 released, if the doubleacting cylinders 50 are operated to cause extension thereof and consequently to move the lower clamping wedge 36 away from the upper clamping wedge 34, the outer elements 60 of the lower clamping wedge 36 are pushed downwardly, which causes unclamping thereof; simultaneously, the friction plates 52 are driven downwards by the inner elements 54 of the lower clamping wedge 36 and so urge the inner elements 44 ofthe upper clamping wedge 34 downwardlywhich lockon to the cable.

The lower clamping wedge 36 may thus move freely away from the upper clamping wedge 34; this latter, clamped on to the cable, holds thins latterfixed and the load which is suspended therefrom at the level previously reached, until the lower clamping wedge 36 arrives in its endmost position corresponding to the maximum extension of the double-acting cylinders 50.

If, atthis moment, with the upper clamping wedge 34 locked on to cable 1 and the lower clamping wedge 36 released, the double-acting cylinders 50 are operated in the reverse direction, so as to retract them and consequently to bring the lower clamping wedge36 closertothe upperclamping wedge 34,the outer elements 60 of the lower clamping wedge 36 are drawn upwardly and exert a pressure on the inner elements 54 of said lower clamping wedge 36 which lock on to the cable; simultaneously, the raising of the inner elements 54 ofthe lower clamping wedge 36 causes, via the friction plates 52, an upward thrust on the inner elements 44 ofthe upper clamping wedge 34which isthusunlocked.

The cable may then freely slide in the upper clamping wedge 34 and the lower clamping wedge 36, drawn upwardly by the two double-acting cylinders 50 drags along the cable to which it is locked as well as the load suspended from this cable, and this until it reaches the initial position shown in Figure 3; this cycle may then be repeated as often as necessary so asto gradually raise the load, each time by a height corresponding tothe maximum extension ofthe double-acting cylinders, until it has reached the desired level.

The linear hydraulicwinch shown further comprises hydraulic locking jacks 62 and 64 which lock the movable inner elements 44 and 54 of the upper34 and lower36 clamping wedges in their inactive position. They are used during lowering of the load and their action, synchronized with the reciprocal movements of the pistons of the double-acting cylinders, may be controlled by means of electric circuits which the pistons ofthe double-acting cylinders may switch on or off automatically during their reciprodating movements.

The pressurized hydraulic fluid neededforthe operation of cylinders 50 and locking jacks 62 and 64 is provided by a power unit 18 which supplies pressurized hydraulic fluid to the cylinders via outlets 68 and to the locking jacks via outlets 70.

As can be seen from the above description, the linear winch provides an intermittent pulling force i.e., the cables 24 and 26 are intermittently pulled and then held in position, while the cylinders 50 move the wedges backto their initial position. In orderto provide as smooth a lifting operation as possible, it is necessarytoco-ordinatethe movement of cylinders 50 on each of the linearwinches 12 and 14. Without this co-ordination, one end of load 32 would be lifted whilethe other end was stationary and vice versa.

In order to accomplish this co-ordinated lifting, each of linearwinches 12 and 14is provided with a set of limit switches contained within one ofthe cylinders 50. Limit switches 72 and 74 are placed at the extreme ends of the cylinder so that these switches are tripped only when the hydraulic cylinder is in its fully extended orfully retracted position.

The hydraulic cylinders are also provided with limit switches 76 and 78 which are placed slightly ahead of limit switches 72 and 74. In the present embodiment hydraulic cylinders 50 typically have a stroke of approximately 27 inches and thus limit switches 74 and 72 are approximately 27 inches apart. In this situation, limit switches 76 and 78 would be placed approximately 3-1/2 inches before limit switches 72 and 74. Thus, limit switches 76 and 78 are tripped slightly before the tripping of limit switches 72 and 74.

The electrical signal generated bythese limit switches is relayed to programmable controller 80 which controls the power unit 18 and thus controls the flow of hydraulicfluid to linearwinches 12and 14. Powerunit 18 is a hydraulic power unit purchased from GT Hydraulique of Sannois, France.

Power unit 18 contains the valves and hydraulic pump utilized for powering the dual winch system including storage reels 20 and 22. Programmable controller 80 is a PC 49 availablefrom Giddings and Lewis and is programmed to control the power unit by means of appropriate softwarn According tothis program, programmable controller 80 operates the solenoids that control the valves which in turn control the flow of pressurized hydraulicfluid to and from linear winches 12 and 14. Upon receiving a signal from either limit switch 76 or78, programmable controller 80 will decrease the flow of fluid to hydraulic cylinder 50 so that the cylinder begins to decelerate.Then, upon receiving a signal from either limitswitch 72 or74, programmable controller 80 will stop the flow offluid to hydraulic cylinder 50. Prior to supplying hydraulic fluid to the opposite side of cylinder 50 so that it may begin its return trip, programmable controller 80willwaitfor an identical stop signal from the other linearwinch so that neither winch is allowed to commence another cycle withoutthe other winch having completed its cycle. Thus, the pulling motion of winches 12 and 14 is maintained substantially in unison and neither end of load 32 is moved without corresponding movement of the other end.

while the invention has been particularly shown and described with respect to a preferred embodiment thereof, it will be understood by those skilled in the artthattheforegoing and other changes in form and details may be madetherein without departing from the scope of the invention as defined by the appended claims.

Claims (13)

1. Adual linearwinch system for hoisting/lowering a load comprising: afirstlinearwinch connectablebyacabletothe load and having a powered reciprocatorycable gripper; a second linearwinch connectablebyacabletothe load and having a powered reciprocatorycable gripper; power means to supply powerforthe reciprocating movement and the gripping action of the linearwinches; and a programmablecontrollerconnectedtothetwo winches and to the power means and arranged to be responsive to the reciprocating movement of the winchesforcontrolling the outputofthe power means to the winches.

2. A dual linearwinch system as claimed in claim 1 wherein the linearwinches are hydraulically powered and said power means is adapted to provide pressurized hydraulicfluid to the winches, and the programmable controller is adapted to control the flow of pressurized hydraulic fluid to and from the power means.

3. A dual linearwinch system as claimed in claim 1 or 2 wherein the reciprocatory movement of said linear winches is provided by hydraulic cylinder means.

4. Adual linearwinch system as claimed in claim 3 wherein position indicator means are associated with said hydraulic cylinder means for sensing the position of the hydraulic cylinder means during it stroke, and the programmable controller is connected to said position indicator means and is adapted to control the power means in responseto the sensed positions of the hydraulic cylinder means.

5. Adual linearwinch system as claimed in any of the preceding claims wherein the programmable controller is adapted to prqvide reciprocatory movement of said winches in substantial unison with each other.

6. Adual linearwinch system for hoisting/lowering a load comprising: afirstlinearwinchforconnection byacabletothe load and having hydraulic cylinder meansfor providing reciprocating movement of a cable gripper; a second linearwinchforconnection buy a cableto the load and having hydraulic cylinder means for providing reciprocating movement of a cable gripper; power means for providing pressurized hydraulic fluid to said winches; and a programmable controller mounted to said winches and to said power means and responsive to the reciprocating movement of said winchesfor controlling the flow of pressurized hydraulic fluid to and from said power means.

7. Adual linearwinch system as claimed in claim 6 wherein position indicator means are associated with said hydraulic cylinder means for sensing the position of the hydraulic cylinder means during its stroke and said programmable controller is connected to said position indicator means and is arranged to control said power means in responseto the sensed positions of said hydraulic cylinder means.

8. Adual linearwinch system as claimed in claim 4 or claim 7 wherein the position indicator means associated with said hydraulic cylinder means comprise means for providing an indication when the associated hydraulic cylinder means is at the respective ends of its travel, and the programmable controller is arrangedto be responsiveto such indications to delay the return movement of the hydraulic cylinder means of one of said winches when it is at one end of its travel pending completion of the corresponding movement of the other winch.

9. Adual linear winch system as claimed in claim 8 wherein the position indicator means associated with said hydraulic cylinder means further comprises additional means for providing an additional indication when the associated hydraulic cylinder means is at a predetermined distance from the respective ends of its travel, and the programmable controller is arranged to slow the movement of the hydraulic cylinder means in response to such additional indication.

10. Amultiple linearwinch system comprising a first and at least one second power winches each connectable to a load by means of a cable and comprising cyclically operable means for selectively pulling-in and letting-out such cable in a plurality of successive steps each corresponding to a stroke of the winch, monitoring means associated with each winch for providing an indication ofthe condition of the winch, and control means responsive to said monitoring means for co-ordinating the cyclical operation ofthetwo winches such that a load coupled to the winches will be substantially evenly moved by the winches.

11. A dual linear winch system as claimed in claim 10 wherein the monitoring means comprise limit switches at the ends of the strokes ofthe winches for communicating corresponding winch status indications to the control means, and the control means is adapted to be responsive to such status indications to delay a return movement of any one of said winches when it is at the end of its stroke until such time as the or each other winch is atthe corresponding end of its stroke.

12. Adual linearwinch system as claimed in claim 11 wherein additional limit switches are provided in advance of the ends of the strokes of the winches, and the control means is adapted to slow down the operation of the winches in response to outputs from said additional limit switches indicative thatthe winches are approaching the ends oftheir strokes.

13. Adual linea r winch system substantial Iy as herein described with reference to the accompanying drawings.