US3477695A

US3477695A - Lifting winches

Info

Publication number: US3477695A
Application number: US704602A
Authority: US
Inventors: Jean Noly
Original assignee: Potain SA Soc
Current assignee: Potain Sa soc
Priority date: 1967-02-20
Filing date: 1968-02-12
Publication date: 1969-11-11
Anticipated expiration: 1986-11-11
Also published as: DE1556371A1; GB1211437A; FR1520606A

Description

Nov. 11,1969

2 Sheets-Sheet 1 Filed Feb. 12, 1968 INVENTOR ATTORN Nov. 11, 1969 J. NOLY LIFTING WI NCHES 2 Sheets- Sheet 2 Filed Feb. 12, 1968 :the main motor. I

United States Patent 3,477,695" LIFTING WINCHES 7 Jean Noly, La Clayette, fiance, assignor to Societe Potain S.A., La Clayette, Saone et Loire, France, a joint-stock company of France j Filed Feb. 12, 1968, Scr. No. 704,602 Claims priority, applicjitigiilfrance, Feb. 20, 1967,

' Int. Cl. B66d 1750; F16d 67/06 US. Cl. 254-150 8 Claims ABSTRACT THE DISCLOSURE A lifting winch for a crane, swing bridge or like mechanism hasltwo driving motors 16 and 24 (FIGURE 1), which are "energised Simultaneously when the winch is operated. The main motor 16 rotates constantly in the direction of raising the load whilst the excess speed motor '24 acts on the drum 1 in the direction of lowering.

An eddy' current clutch 13-14 is connected between the main motor 16 and the drum, and its supply voltage is regulated to vary thespeed of the winch. This regulation operates by comparing the rotor voltage of the slip-ring induction motor 24 with an adjustable reference voltage.

The present invention relates to a lifting winch of the type fitted to cranes, swing bridges, or similar mechanisms. In a known arrangement such a Winch-includes a drum on which a cable is wound, and this drum must be able to turn atdiflerent speeds in one direction or the other.

In addition, the mechanism must have associated safety The invention is mainly intended to'avoid these -disadvantages by providing a winch which includes a reduction .gearof which the control may be carried out by two ordinary electric motors, whilst a progressive and continuous variation of drum rotation speed is permitted. In certain cases, a two-speed mechanical reduction-gear maybe used, to-allow the lifting of heavier loads at a lower rate.

A lifting winch according to the invention comprises a rotating drum having a shaft connected on the'one hand to a low-powered electric motor which is arranged for constant rotation in the direction'corresponding to the lowering of the load, the drumshaft being connected on the other-hand to one of the two armatures of an eddycurrent'clutch, of which the other armature is drivingly connected to the shaft-of a main motor which is arranged for constant rotation'in the direction corresponding to "the lifting: of the load, an electronic regulator being interposed between the rotor circuit of the low powered motor and a winding controlling the eddy-current clutch, in such a way as to let'this clutch slip to a greater or lower extent, in order to vary, or to maintain at any' chosen value, the

rotation-speed of the winch. According to a preferred feature of the invention, the device is equipped in addition with a mechanical brake controlled mechanically, pneumatically, electrically or hydraulically, in order to immobilise the load being handled in any-selected position. This brake may be-placed either directly on the shaft of the drum; or on the input shaft of the reduction gear. In this latter case, the shaft of the brake must then pass through ice It will be understood that such a device allows motors of low cost to be used and a continuous variation of the drum rotation speed to be obtained.

Two alternative arrangements in accordance with the invention will now be described, by way of examples only, with reference to the accompanying drawings, in which:

FIGURE 1 is a sectional view of one arrangement,

FIGURE 2 is a view similar to FIGURE 1 of the other arrangement, and

FIGURE 3 is an electrical diagram.

In the arrangement shown in FIGURE 1, there is a winch drum 1 which controls in the known way the winding of a lifting cable (not shown). This drum 1 is keyed onto a shaft 2 which turns in bearings 3 and 4. One of the ends of the shaft 2 is attached to a toothed bevel crown-wheel 5 with which there engages a bevel-pinion 6.

This pinion operates the input shaft 7 of a speed reduction gear 8 of which the output shaft 9 is linked by a flexible coupling 10 to a revolving shaft 11 which carries a brake disc 12. i

The

shafts

9 and 11 are coaxial and are aligned with the shaft 7 if the reduction gear 8 is epicyclic as in the example shown. In addition, the

shafts

7, 9 and 11 are disposed perpendicularly to the shaft 2, which is advantageous from a space point of view.

The shaft 11 is attached to the heavy rotor core 13 of an eddy-current clutch. This rotor turns inside a co-axial bell 14 which is attached to the hollow shaft 15 of the rotor of an electric motor 16 which is called the main motor. This is a squirrel-cage induction motor of which the power, sufficient to raise theload by turning the drum 1 in the direction of lifting, maybe for example, of the order of to kw. I

The core 13 of the clutch 13-14 is provided with a winding which has been designated by the reference number 17 in FIGURE 3. The electrical connection of this winding is ensured by slip-rings 18.

For convenience of assembly, it is advantageous to fit against the free end of the stator of the motor 16 the stationary control components 19 provided to apply the disc brake 12 as required. The control of this brake 12 is preferably carried out by electro-magnetic means able to cause the automatic braking of the drum 1, whether in case of accident, or to immobilise the load suspended from the cable in any position.

The flexible coupling 10 is fitted with a pulley 20 around which passes an endless belt 21 driven by a pulley 22 keyed onto the revolving shaft 23'of an auxiliary electric motor called the excess-speed motor. This latter may be placed alongside the main motor 16 as shown in FIG- URE 1. Of course the belt and pulley transmission 20- 21-22 could be replaced by gearing or by a chain and sprocket'device.

The excess-speed motor 24 is a wound-rotor induction motor of which the relatively low power may be, for example, equal to A of that of the main motor 16. The direction of rotation of the motor 24 is such that, when it is under voltage, it tends to turn the drum 1 in the direction which causes the load to be lowered. The electrical connection is as follows (FIGURE 3). The stator windings of the

motors

16 and 24 are supplied directly from a three-phase electrical supply 25. A switch 26 is preferably interposed in the feed of the excess-speed motor 24. 65 I The rotor windings of the motor 24 are star-connected and they feed into

variable resistors

27, 28 or29. The rotor current is in addition taken off to be fed into a three phase rectifier 30 which gives a direct current to the terminals of a resistance 31. A condenser 32 is connected in parallel with the latter. It is known that the voltage thus produced at the terminals of the resistance 31 increases in proportion as the rotor of the excess-speed motor 24 turns faster in the direction of lifting and decreases as this same rotor turns faster in the direction of descent. In addition, the cables of the supply 25, in which are interposed fuses 33, feed two three-phase transformers connected in parallel, namely a control transformer 34, and a main transformer 35 for the supply of the clutch 13-14.

The current supplied by the secondary of the trans- .former 34 is rectified by a rectifier 36, then fed to the terminals of a potentiometer which comprises a control resistance 37 and a calibration resistance 38. A slider 39 is provided on the calibration resistance to carry out the adjustment of the apparatus. Another slider 40 is able to be displaced along the resistance 37 and it constitutes the control component available to the operator to vary the speed of the winch at will.

The potentiometer 37-38-39-40 supplies a D.C. reference voltage which is applied to the terminals of the resistance 31 in opposition to the voltage supplied by the recifier 30, which indicates the speed of rotation of the rotor of the motor 24. Two Zener diodes 41 are interposed in series and in opposition in the circuit of the reference voltage in order to limit the voltage at the terminals of three

thyratrons

44, 45, 46 which will be mentioned later, in case the operator should push the slider 40 on starting to the limit (i.e. to the position for full speed), when the drum 1 would remain motionless. The Zener diodes 41 are chosen, for example, in such a way as to limit to volts the voltage at the control electrodes of the thyratrons.

The comparison of the D.C. voltages at the terminals of the resistance 31 and the condenser 32 will allow an impulse which is applied by a conductor 42 to a supply unit 43 of known type which receives directly the mains current through the transformer 35. This unit comprises three thyratrons 44-45-46 each one fitted in one of the phase circuits and the three having a common point connected to one of the terminals 47 of the winding 17. This winding is supplied with direct current in consequence of the presence of rectifying

diodes

48 and 49 in the circuit connected to its other terminal 50. Finally, there is fitted in parallel with the winding 17 and overload diode 51 provided to short-circuit the current supplied by the winding when its feed circuit is disconnected abruptly.

The operation of the arrangement is as follows:

It will be observed in FIGURE 3 that the main motor 16 is constantly under voltage, that is to say that it turns constantly in the direction of the raising of the load. This avoids its having to be directly started at each manoeuvre which would produce too severe conditions of operation for a cage-motor of this power.

When the operator wishes to raise a load, he operates a control switch of any known type, which causes simultaneously the release of the brake 12-19, the energising of the clutch 13-14, and the closing of the supply-switch 26 of the excess speed motor 24. The

rotor circuit resistors

27, 28 and 29 are given a high value, and by operating the slider 40 of the potentiometer, one regulates the base voltage, to which the D.C. voltage supplied by the rectifier 30 is compared. Thus the current supply to the Winding 17 of the clutch 13-14 is adjusted, which allows the degree of slip of the latter to be regulated very precisely. The power furnished by the main motor 16 therefore opposes to a greater or lesser extent the opposing action of the excess-speed motor 24, which allows the speed of rotation of the lifting winch 1 to be stabilised at the desired value. There is obtainable for example, a speed range equal to 1:100 metres per minute for raising the load.

During the lifting phase which has just been described, the raising is initiated by displacing the slider 40 to the right from the position of no speed provided in the centre of the resistance 37, that is to say, by pressing the slider 40 in the direction shown by the arrow 52.

To lower a load, the slide 40 is displaced to the left, that is to say, inthe direction of the arrow 53, so that there is sent into the electrical regulator a lower reference voltage, corresponding for example to the amount for a speed equal to m. per minute.

The release is carried out, moreover, likewise by operating a switch which simultaneously causes the release of the brake 12-19, the energising of the clutch 13-14 and the closing of the feed switch 26 of the excess-speed motor 24. The motor 24 drives the drum 1 in the direction of descent if no load is suspended on the cable. If there is a load, the effect of its weight is added to the action of the motor 24, and the movement is carried out with a greater acceleration. As soon as the selected speed is reached for example, a hundred metres per minute, the regulator partially energises the clutch 13-14, and the rotation of the drum is stabilised by the opposing effect of the motor 16.

If it is desired to drop the lifting hook suspended from the cable of the drum 1 rapidly and with no load, for example to lower it at or 300 metres per minute, the Weight of this hook alone would be insuflicientto overcome the internal friction of the device and to cause the rotation of the drum 1. The two

motors

16 and 24 are then energised whilst the clutch 13-14 is completely de-energised. The excess speed motor 24 therefore acts alone, and it provides the light torque necessary to overcome the friction and lower the hook. This operation is with advantage carried out by providing on the control unit an additional limit switch (not shown) causing simultaneously:

the complete opening of the circuit of the clutch 13-14; the cutting out of the rotor resistances 27-28-29.

It is advantageous to incorporate in this system a power limiter which does not allow this operation to take place except when the lifting hook is empty or carrying a negligible load.

During this phase of rapid descent, the braking of the drum 1 is carried out solely by friction, and if the rotor of the motor 24 tended to exceed its synchronous speed, it would send energy back into the supply 25 by means of its stator circuit. A

It will be seen that the apparatus according to the invention allows the speed of rotation of the drum 1 to be varied in a continuous and progressive manner in both directions.

Referring to FIGURE 2 in the alternative arrangement, the aforementioned main motor 16 is replaced by a motor 54 of the same power, but of a still lower cost. (In fact, the arrangement shown in FIGURE 1 necessitates the use of an induction motor 16 with a hollow rotor shaft.)

In the example illustrated in FIGURE 2, the shaft 55 of the motor 54 is connected directly to the flexible coupling 10, whilst the eddy-current clutch 13-14 is interposed between this coupling 10 and the reduction-gear 8. The pulley 20 which is connected to the excess speed motor may then be fixed to the rotating core 13, as shown in broken lines in FIGURE 2, where the excess-speed motor 56 is positioned alongside the coupling 10.

There could equally well be used an excess-speed motor 57 linked by an endless belt 58 to a reduction gear .59 keyed onto the shaft 2 of the drum 1.

The example shown in FIGURE 2 includes as a substitute for the aforementioned disc brake 12-19, a brake 60 which comprises some shoes 61 carried by a fixed support inside a rotating drum 62 fitted to the drum 1 of the winch. This arrangement allows the brake 60 to be located within the drum 1.

The operation of this variant is similar to that which has been described referring to FIGURES 1 and 3. It will be understood that the arrangement adopted in FIG- URE 1 allows the use of a brake 12-19 of low torque since it is fitted on the shaft 11 which turns rapidly, whilst 1 5 on the other hand the arrangement illustrated in FIGURE 2 permits the use of a main motor 54 of a completely standard type.

It must moreover be understood that the preceding description has been given only by way of example, and that it in-no way limits the scope of the invention which will not be avoided by replacing the constructional details described by any other equivalents. In particular, there could befprovided a mechanical reductign gear with two speed ratios, on order to use the winch for two different ranges ofload, for example, eight tons and sixteen tons.

Further, the reduction gears 8 and 59could be omitted or replaced by any speed reducing mechanism of known type.

I claim 1. A lifting winch comprising a rotatable drum; a drum shaft rotatable with said drum; a main driving motor arranged for constant rotation in the direction to raise a load applied to the winch; an eddy-current clutch for establishing driving connection Between said main motor and said drum shaft; a low powered excess speed electric motor drivingly connected to said drum shaft; said excess speed electric motor being arranged for constant rotation in the direction to lower said load applied to the winch; an electrical control circuit for said two motors including a circuit for the rotor of said excess speed motor and a winding controlling said eddycurrent clptch; and an electric regulator interposed between said rotor circuit and said winding, whereby said eddy-current clutch is permitted to slip at a rate required to control the speed of the winch in accordance with signals received from said excess speed motor.

2. A lifting winch according to claim 1, wherein a mechanical brake is provided for immobilising said drum in any selected position.

3. A lifting winch according to claim 2, wherein said brake comprises a fixed support, a brake drum drivingly connected to said drum, and a plurality of brake shoes mounted on said support and engageable with said brake drum.

4. A lifting winch according to claim 3, wherein said brake comprises a braking disc, a reduction gear connecting said brake disc to said drum shaft, and stationary control components for said braking disc mounted on said main motor.

5. A lifting winch according to claim 1, wherein said main motor is an induction motor with a rotor surrounding a hollow rotor shaft, said rotor being coupled to one armature of said eddy-current clutch, an inner/ shaft rotatable within said hollow shaft, said inner shaft being coupled to the second armature of said eddy-current clutch; means connecting said excess speed motor with said inner shaft, and a reduction gear connecting said drum shaft with said inner shaft.

6. A lifting winch according to claim 1, wherein said main motor is of a standard type and is drivingly connected to one armature of said eddy-current clutch, a reduction gear connected between said drum shaft and the other armature of said eddy-current clutch, and drive means connecting said excess speed motor with said other armature of said eddy-current clutch.

7. A lifting winch according to claim I, wherein said main motor is of a standard type and is drivingly connected to one armature of said eddy-current clutch, a first reduction gear connection between said drum shaft and the armature of said eddy-current clutch, and a second reduction gear connected between said excess speed motor and said drum shaft.

8. A lifting winch according to claim 1, including a potentiometer for setting a base voltage, a resistor and a condenser connected in parallel, a rectifier for converting the alternating current of said excess speed motor to a direct current, said resistor and said condenser being arranged in a circuit to compare said direct current with said base current, and a supply unit controlled by the signal from said resistor and said condenser said supply unit controlling said eddy-current clutch.

References Cited UNITED STATES PATENTS 9/1952 Jaeschke 254-173 3/1965 Bancroft 310- HARVEY C. HORNSBY, Primary Examiner