NL2014838B1

NL2014838B1 - Rotator with crane hook for mounting to a crane.

Info

Publication number: NL2014838B1
Application number: NL2014838A
Authority: NL
Inventors: Kalkman Pieter
Original assignee: Kalkman Ip B V
Priority date: 2015-05-21
Filing date: 2015-05-21
Publication date: 2017-01-31
Also published as: NL2014838A

Abstract

A rotator (1) for mounting to a hoisting device, such as a crane (2), comprises a housing (4) having an upper mounting means (5) for mounting to the hoisting device, a a crane hook (10) rotatably supported with respect to the housing, a hydraulic piston/cylinder device (6) connected to the housing (4) and to the load engaging element (10) and a hydraulic motor (11). The hydraulic motor (11) is driveable by a flow of hydraulic medium from the piston/cylinder device (6), said flow of hydraulic medium being generated by discharging the piston/cylinder device (6). Furthermore an electric generator (13) is driveble by the hydraulic motor (11), and a battery (14) is connected to the electric generator (13). By means of an electric motor (15) which is electrically connected to the electric energy storage device (14) the load engaging element (10) can be rotated.

Description

Rotator with crane hook for mounting to a crane

The invention is related to a rotator for mounting to a crane. Such rotators enable the operator of the crane to rotate the crane hook, and thereby the load suspended from the crane hook, to be rotated according to a certain desired orientation. This is of advantage when handling for instance ISO-containers, pipe bundles etc, which generally have an oblong shape. The rotator can be integrally mounted in the lower block of cable hoist mechanism; other types of rotators can be retrofitted to the lower block.

The power to rotate the crane hook by the rotator can originate from different sources. According to a first example, the rotator is driven in an electric fashion. An electric cable may be used to supply electric current to the rotator, although such layout may severely hamper the proper operation of the crane. According to EP-A-409748, electric power may be obtained from an electric generator which is driven by the rotating sheaves which are accommodated in the lower block. Further examples include full hydraulic drives which derive the required power form a small relative displacement between the load and the lower block. In other words, potential energy from the load is converted into kinetic energy so as to displace the hydraulic medium.

An object of the invention is to provide an improved rotator. A further object is to provide a rotator which can be controlled in precise fashion. These and other objects are obtained through a rotator comprising a housing having an upper mounting means for mounting to the hoisting device, a load engaging element, such as a crane hook, rotatably supported with respect to the housing, a hydraulic piston/cylinder device the upper end of which is connected to the housing and the lower end of which is connected to the load engaging element, a hydraulic motor which is hydraulically connected to the piston/cylinder device, said hydraulic motor being driveable by a flow of hydraulic medium from the piston/cylinder device, said flow of hydraulic medium being generated by discharging the piston/cylinder device under the influence of a load exerted on the load engaging element, an electric generator which is driveably connected to the hydraulic motor, an electric energy storage device which is electrically connected to the electric generator for storing the electric energy generated by the electric generator, and an electric motor which is electrically connected to the electric energy storage device, said electric motor being drivingly connected to the load engaging element for rotating said load engaging element.

In use, the rotator is able to generate energy by converting potential energy of the load into kinetic energy. Thereby, a flow of hydraulic medium is obtained which through the hydraulic motor and the electric generator coupled thereto, is converted into electric energy, the electric energy is stored in the battery. This has the advantage that the electric energy can be used at a later stage, for bringing the crane hook in the correct position. Usually, the conversion of potential energy into kinetic energy takes place at the first stages of lifting the load, whereas the rotation of the load may have to be postponed to a later stage due to for instance spatial restrictions.

Preferably, an accumulator is provided which is hydraulically connected to the hydraulic motor for receiving hydraulic medium from the hydraulic motor and thereby charging the accumulator. Thus, the hydraulic medium may be retained in a closed circuit. To that end, the accumulator and the piston/cylinder device may be directly connected to each other through a bypass line for returning hydraulic medium from the accumulator to the hydraulic piston/cylinder device and thereby discharging the accumulator and charging the piston/cylinder device. The bypass line may comprise a check valve allowing flow of hydraulic medium from the accumulator to the piston/cylinder device. Thereby, it can be ensured that the hydraulic medium is compelled to flow through the hydraulic motor, instead of by passing the hydraulic motor. The availability of a battery furthermore has the advantage that other components such remote control components, sensors and the like can be supplied with electric energy.

The accumulator may be carried out in several ways. According to a first possibility, the accumulator is preloaded for providing an overpressure in the hydraulic medium charged therein, e g. by a mechanical spring or a gas spring. Alternatively however, the accumulator may be a constitute by a hold at atmospheric pressure, in which the hydraulic medium is collected. In such case, e.g. a return pump may be present to pump the hydraulic medium back into the piston/cylinder device at the end of a load transfer cycle.

The invention is furthermore related to a method for operating the rotator according to any of the preceding claims, comprising the steps of: - mounting the rotator to a hoisting device, - making the piston/cylinder device being charged, - connecting a load to the crane hook of the rotator, - activating the hoisting device and thereby gradually increasing the load exerted on the crane hook, - under the influence of the load exerted on the crane hook discharging the piston/cylinder device and thereby causing a flow of hydraulic medium from the piston/cylinder device through the hydraulic motor, - making the hydraulic motor rotate under the influence of the flow of hydraulic medium and thereby generating electric power by the electric generator, - storing the electric energy generated by the electric generator in the electric storage device, - supplying electric energy from the electric storage device to the electric motor and thereby rotating the crane hook.

With the aim of influencing the hoisting process as little as possible, it is preferred that in the initial stages thereof the hook remains in position with respect to the lower block. This can be achieved by the steps of: - closing the hydraulic connection between the piston/cylinder device and the hydraulic motor, - thereafter hoisting the load, - opening the hydraulic connection between the piston/cylinder device and the hydraulic motor after hoisting the load and thereby making hydraulic medium flow from the piston/cylinder device to the accumulator.

As mentioned the hydraulic medium may be fed from the hydraulic motor to an accumulator and thereby charging the accumulator. The method may further comprise the steps of: - after rotating the crane hook, depositing the load, - during and/or after depositing the load, discharging the accumulator and charging the piston/cylinder device.

The rotator is then directly ready for the next hoisting operation. In case the accumulator is preloaded, the method may comprise the step of discharging the accumulator and charging the piston/cylinder device under the influence of said preload. Alternatively, in case the accumulator is at atmospheric pressure, the method may comprise the step of discharging the accumulator by pumping the hydraulic medium from the accumulator to the piston/cylinder device.

Furthermore, while discharging the piston/cylinder device, it is desirable to make the upward speed of the housing of the rotator exceed the speed of extending the piston rod mechanism with respect to the housing. Thereby, it is ensured that the load is always properly lifted from the ground or from a deck and the like, and that sagging of the load is avoided. To that end, a control device may be incorporated in the rotator, which influences the flow of hydraulic medium from the piston/cylinder device to the accumulator in such a way that this effect is achieved.

The invention will now be further described with reference to the figures.

Figure 1 shows a crane with rotator and load.

Figure 2 shows the rotator in cross section.

Figures 3a-8a show the various stages of hoisting.

Figures 3b-8b show the various stages of the rotator corresponding to figures la-6a.

Figure 1 shows a crane 2 onto the hoisting gear 3 of which a rotator 1 is connected. This rotator 1 is shown in cross section through the vertical axis in figure 2. The rotator has a housing 4 with an upper mounting means 5 to be connected to the hoisting gear 3 of the crane. Furthermore, a piston/cylinder device 6 is accommodated in the housing 4. The cylinder 7 thereof is fixedly connected to the housing, and the piston 8 with a piston rod mechanism 9 is moveable up and down with respect to the housing 4. At the lower end of the piston rod mechanism 9, a crane hook 10 is connected. By means of a control unit 21, the several functions of the rotator are coordinated and controlled.

As shown in figures 3a-8a, the rotator has a hydraulic motor 11 which is hydraulically connected to the space in the cylinder 7 beneath the piston 8 which is filled with oil. The hydraulic motor 11 in turn is hydraulically connected to the accumulator 12. An electric generator 13 is connected to the hydraulic motor for generating electric power which is stored in battery 14. The electric power can be supplied by the battery 14 to the electric motor 15.

The electric motor is connected to a drive mechanism which comprises i.a. the rotatable shaft 16. This rotatable shaft is coupled in rotational direction to the piston rod mechanism 9. The piston rod mechanism 9 is free to move up and down with respect to the rotatable shaft 16 of the drive mechanism, e g. by means of splined tracks in both the piston rod mechanism 9 and the rotatable shaft 16. Thus, the electric motor through the cooperating rotatable shaft 16 and the piston rod mechanism is able to rotate the crane hook 10 into the desired position.

The hydraulic connection between the piston/cylinder device 6 and the hydraulic motor 13 has a valve 17. Initially, this valve is closed until the load 20 has been hoisted over a limited height as shown in figures 3a, b. Subsequently, the valve 18 is opened while the hoisting operation is continued, as shown in figure 4a, b. Thereby, oil flows from the piston/cylinder device 6 through the hydraulic motor 11 and thereafter to the accumulator 12. This means that the piston 8 and the piston rod mechanism 9 are extended out of the housing 4 in downward direction; due to the continued hoisting operation however the load 20 will not move downward.

During the functioning of the hydraulic motor, electric energy is generated by the electric generator 13. The electric energy is stored in the battery 14 as shown in figures 5a, b. The piston 8 and the piston rod mechanism 9 then reach the lowermost position with respect to the cylinder 7, as shown in figures 6a, b. Driven by the electric energy stored in the battery 14, the electric motor 15 is now able to rotate the crane hook 10 and load 20 through the cooperation of the rotatable rod 16 and the piston rod mechanism 9, as shown in figures 6a, b as well.

Once the load 20 has been rotated thus in the proper position, it is lowered onto a surface as shown in figures 7a, b. By further relaxing the tension in the hoisting mechanism 3, oil is driven from the accumulator 12 through the bypass line 19, check valve 18 and into the piston/cylinder device 6, as shown in figures 7a. b and 8a, b. The rotator is thereby returned to the position ready for the next loading cycle.

List of reference numerals 1. Rotator 2. Crane 3. Hoisting gear of crane 4. Housing of rotator 5. Upper mounting means of rotator 6. Piston/cylinder device 7. Cylinder 8. Piston 9. Piston rod mechanism 10. Crane hook 11. Hydraulic motor 12. Accumulator 13. El ectri c generator 14. Battery 15. Electric motor 16. Rotatable rod 17. Valve 18. Check valve 19. Bypass line 20. Load 21. Control unit

Claims

A rotator for attachment to a hoisting device, such as to a crane (2), comprising a housing (4) with an upper mounting means (5) for mounting to the hoisting device, a load engaging element (10), such as a crane hook, rotatably supported with respect to to the housing, a hydraulic piston / cylinder device (6) whose upper end is connected to the housing (4) and whose lower end is connected to the load engaging element (10), a hydraulic motor (11) that can be driven by a flow hydraulic medium from the piston / cylinder device (6), which flow of hydraulic medium is generated by discharging the piston / cylinder device (6) under the influence of a load (20) exerted on the load engaging element (10), an electric generator ( 13) drivably connected to the hydraulic motor (11), an electrical energy storage device (14) generated by the electric generator, and an electric motor (15) electrically connected to the electric energy storage device (14), which electric motor is drivingly connected to the load engaging element (10) for rotating that charge engaging element.

The rotator (1) according to claim 1, wherein an accumulator (12) is provided which is hydraulically connected to the hydraulic motor (11) for receiving hydraulic medium from the hydraulic motor and thereby loading the accumulator.

The rotator (1) according to claim 2, wherein the accumulator (12) and the piston / cylinder device (67) are directly connected to each other through a bypass (19) for returning hydraulic medium from the accumulator to the hydraulic piston / cylinder device and thereby discharging the accumulator and charging the piston / cylinder device.

The rotator (1) according to claim 3, wherein the bypass (19) comprises a non-return valve (18) that allows flow of hydraulic fluid from the accumulator (12) to the piston / cylinder device.

A rotator (1) according to any one of the preceding claims, comprising remote control means for operating the electric motor.

Rotator (1) according to one of the preceding claims, wherein the accumulator (12) is pre-loaded to provide an overpressure in the hydraulic medium loaded therein, for example by a mechanical spring or a gas spring.

Method for operating the rotator according to one of the preceding claims, comprising the steps of: - attaching the rotator (1) to a hoisting device, - ensuring that the piston / cylinder device (6) is loaded, - connecting a load (20) on the load engaging element (10) of the rotator (1), - activating the hoisting device (3) and thereby gradually increasing the load exerted on the load engaging element (1), - under the influence of the load exerted on the load load engaging element (10) discharging the piston / cylinder device (6) and thereby causing a flow of hydraulic medium from the piston / cylinder device through the hydraulic motor (11), - rotating the hydraulic motor (11) under the influence of the flow of hydraulic medium and thereby generating electrical power by the electrical generator (13), - storing the electrical energy generated by the electrical generator (13) in the electrical impact device (14), - supplying electrical energy from the electric storage device (14) to the electric motor (15) and thereby rotating the load engaging element (10).

Method according to claim 7, comprising the steps of: - closing the hydraulic connection between the piston / cylinder device (6) and the hydraulic motor (11) after hoisting the load (10) and thereby causing hydraulic fluid to flow from the piston / cylinder device to the accumulator.

A method according to claim 7 or 8, comprising the step of: - supplying the hydraulic medium from the hydraulic motor (11) to an accumulator (12) and thereby charging the accumulator.

Method according to claim 9, comprising the steps of: - after rotation of the load engaging element (10), depositing the load (20), - during and / or after depositing the load (20), discharging the accumulator ( 12) and loading the piston / cylinder device (6).

The method of claim 9, wherein the accumulator is preloaded, comprising the step of discharging the accumulator (12) and charging the piston / cylinder device (6) under the influence of said preload.

The method of claim 10, wherein the accumulator is at atmospheric pressure, comprising the step of discharging the accumulator by pumping the hydraulic medium from the accumulator to the piston / cylinder device.

A method according to any one of claims 7-12, during discharging of the piston / cylinder device (16), ensuring that the upward speed of the housing (4) of the rotator (1) is the speed of projecting out of the rod mechanism (9) with respect to the housing (9).