GB2467149A

GB2467149A - Load Orientation Device

Info

Publication number: GB2467149A
Application number: GB0901113A
Authority: GB
Inventors: Robert Ian Davidson; Anthony Agnew; Mathew Belay; James Dodds; James Dunlop
Original assignee: ENGINEERING AGENCY Ltd
Current assignee: ENGINEERING AGENCY Ltd
Priority date: 2009-01-23
Filing date: 2009-01-23
Publication date: 2010-07-28
Also published as: GB0901113D0

Abstract

A device for orientating a suspended load 107 comprises a flywheel (25 fig 1) mounted in a housing 2 and rotatable in use about a single axis by a drive means such as an electric motor (11 fig 4b) and attachment means 103, 103' connecting the housing 2 to the load 107, which load 107 is orientated about the single axis by rotating the flywheel 25 and imparting a torque to the housing 2 to cause the suspended load 107 to rotate about the single axis. The flywheel may rotate about a vertical axis. The device may include a pulley (106 fig 1) and winch motors 3, each winch motor winding a tether 103' in order to orient the load about a further two axes of rotation 109, 110. Each tether 103' may be connected to the load at two points 12. A crane mounting point may be provided which is rotatable through 360° and mounted on bearings. Decelerating the flywheel may regeneratively charge power storage means for the electric motor such as accumulators (4 fig 4a).

Description

Load Orientation Device The present invention relates, in general, to a load orientating device capable of orientating a suspended load. In particular, the device enables a rotation of the load about all three axes of rotation. The present invention is particularly relevant to lifting attachments for cranes, which permit and control rotation of a slung load.

In addition to the dangers of dropping large masses at great height, contemporary crane systems used, for example, in construction sites suffer from complications arising during the orientation of slung loads. Where an upper pulley block and lower pulley block of the crane are connected by few flexible ropes, the load being carried by the crane has little effective resistance to rotation. Where the load twists due to uncontrolled forces such as local winds, internal magnetic effects (for example in steel-reinforced concrete), momentum, the unexpected motion of large masses can damage an ongoing construction site or surrounding buildings. The costs of repairing such damage and the delays to a construction project as well as potential worker harm are considerable.

An existing solution to this problem of rotational positioning is to have workers orient the slung load and resist unwanted rotation by ropes attached to the physical extremities of the slung load and hanging down from it. This requires strong hands and good judgement to ensure that the load is positioned correctly at the end of its journey. However, there remain downsides to this approach, namely that high winds can pull the hanging ropes away from the workers or that the workers can be dragged by the movement of the load and communication from the crane operator to the rope operators can be hard when using two hands on a rope. If workers are placed at height, the risk of a worker being dragged from the structure and falling are great, coupled with the risk of being hit by the slung load being manipulated.

An alternative solution would be to include, attached to the lower pulley block, a flywheel with axis of rotation vertical. The flywheel allows rotational acceleration of the slung load by proving a torque reaction. However, whilst the flywheel provides a degree of stability due to its gyroscopic properties, these are insufficient to provide useful moments to orient the load.

Various approaches are known in the art to solve the above problem.

is US 3608384 discloses a device for rotationally positioning a supported load in which a motor is used to drive against the gyroscopic effects created by an inner flywheel, which rotates about a horizontal axis.

According to US 3608384 the load is securely attached to the device.

There is therefore a need for a device and method enabling the orientating of a suspended load, which overcomes, or at least reduces some of the above-mentioned problems of the prior art.

According to a first aspect of the present invention, there is provided a load orientating device as claimed in claim 1. Thus the invention provides, in a preferred embodiment, a device capable of orientating a suspended load with respect to a vertical axis of rotation.

According to a second aspect of the present invention, there is provided a method of orientating a suspended load as claimed in claim 11. Thus the invention provides, in an alternative preferred embodiment, a method of orientating a suspended load about two orthogonal horizontal axes of the suspended load.

Preferred features are disclosed in the dependent claims.

Embodiments of the present invention will now be more fully described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagram of a Crane Load Orientation Device, according to one embodiment of the present invention; Figure 2 is a diagram of the Crane Load Orientation Device comprising a suspended load and crane fixing; Figure 3 is a diagram of the auxiliary rotation coupling; Figure 4a is an exploded view of a portion of a Crane Load Orientation Device; and Figure 4b is an exploded view of the Crane Load Orientation Device.

In a brief overview of a first embodiment of the present invention, there is shown in Figure 1 a diagram of a Crane Load Orientation Device 102. The Crane Load Orientation Device 102 has a frame 2, flywheel 25, flywheel motor (not shown in Figure 1), winch motors 3, chains 103, fixing means 105, pulley 106 and energy store 113. The flywheel motor is obscured by flywheel 25 but can be seen in Figure 4a and Figure 4b.

The frame 2 hangs from a standard crane hook (not shown) and is connected to the crane hook at the fixing means 105. The crane load (not shown) is suspended below the frame 2 from the chains 103.

The winch motors 3 are mounted in the frame 2 and the chains 103 run through the winch motors 3. Attached to the frame 2 is the flywheel motor. The flywheel motor drives the flywheel 25. The flywheel 25 rotates about a substantially vertical axis and may be mounted and driven directly by the flywheel motor, or may be geared and driven by a flywheel motor placed a distance from the flywheel 25. An optimal position for the flywheel 25 will locate it co-axially with the centre of mass of the Crane Load Orientation Device 102, which avoids using energy unnecessarily to overcome the second moment of inertia.

The flywheel motor controls rotation of the flywheel 25 and the torque supplied imparts angular acceleration to the flywheel 25. As a result of Newton's Third Law of Motion, the torque applied to the flywheel 25 is equally opposed in the motion of the crane load and the other parts of the Crane Load Orientation Device 102. As a result, the flywheel 25 may be used to orient the Crane Load Orientation Device 102 and a crane load about the vertical axis. The flywheel 25 may be driven through a direct connection to the flywheel motor or may be connected via a clutch mechanism and therefore free to rotate, only being propelled by the flywheel motor when adjustments to its rotational speed are desired. The flywheel motor can be geared to provide a range of gear ratios, such gear ratios providing course and fine control over the speed of the flywheel 25. The flywheel motor may be an electric, pneumatic, hydraulic or fuel-powered motor and may have the energy store 113, whether electric, pneumatic, hydraulic or fuel powered, located on the Crane Load Orientation Device 102. The energy store 113 may afternatively be located not on the Crane Load Orientation Device 102 and may supply energy to the flywheel motor by cables, pipes or other means.

The energy store 113 may comprise batteries or capacitors which store electric energy and which drive the flywheel motor. The batteries or capacitors may additionally be charged by transferring and converting kinetic energy from the rotation of the flywheel to electric energy which is stored in the capacitors. A person skilled in the art will appreciate that energy transfer and conversion is subject to losses and imperfect efficiency. The person skilled in the art will further appreciate that the means by which kinetic energy is transferred and converted to electric energy may include a secondary generator in addition to the flywheel motor, or the flywheel motor may be adapted to operate as a generator while providing deceleration to the flywheel 25 and in so doing may recharge the batteries or capacitors.

In particular, the flywheel motor may be a hydraulic motor incorporated in a hydraulic system which uses high-pressure tanks or accumulators to provide fast and powerful impulses to adjust the speed of the flywheel 25. The initial energy in the accumulator tanks may be provided from an additional pump on to the Crane Load Orientation Device, or supplied via hoses running from accumulator tanks or pump located not on the Crane Load Orientation device.

The Crane Load Orientation Device 102 may be controlled by a freely ambulant human operator in addition to the crane operator, or may be operated by the crane operator, such control system providing clockwise and anti-clockwise rotational control. The control system for the flywheel 25 may further incorporate automated systems for adjusting accidental rotations in the crane load arising from wind, imbalances, load momentum or compass effects. Such a system may use GPS, compasses, or other rotation sensors in a feedback loop to ensure that the crane load is rotated only to the angle desired by the operator.

Also attached to the frame 2 are winch motors 3. The winch motors 3 drive the chains 103 to orient the suspended load about two orthogonal horizontal axes. The motors may be electric, fuel powered, hydraulic or pneumatic as above. The motors drive winches (not shown) through which the chains 103 run. The chains 103 may be replaced by any other strong tether, such as steel cable, high tensile strength rope, webbing, tape or other type of chain. The winches may be incorporate capstan drives or chain sprockets. The chains 103 are connected to the crane load (not shown) in two looped tethers. One looped tether passes through the winches and via the upper wheel of pulley 106, the other passing only via the lower wheel of pulley 106. The pulley is arranged to equalise tension in the chains and to allow the first looped tether to move in concert with the second looped tether. The method and arrangement by which the chains orient the crane load is more fully described below.

The frame 2 may be shaped as a box frame, a bell frame optimised for the round space required for the flywheel 25, or an A-frame. A person skilled in the art will recognise the available varieties of frame design, member cross-section, component layout, construction materials and protective coatings suitable for a Crane Load Orientation Device used in the field of construction.

There is shown in Figure 2 the Crane Load Orientation Device 102 comprising a crane load 107. Using the same reference numerals as previous figures, there is additionally shown in Figure 2 a crane load 107 and a suspension line 108. As in Figure 1, the flywheel motor is obscured by the flywheel 25. The flywheel motor can be seen in Figure 4a and Figure 4b.

In the device of Figure 2, the Crane Load Orientation Device 102 is suspended from the crane (not shown) by the suspension line 108 and the crane load 107 is suspended from the Crane Load Orientation Device 102. When in motion, crane load 107 and Crane Load Orientation Device 102 are rotatable under the control of an operator and is not free to rotate in a hazardous and unwanted direction such that the crane load 107 is not free to collide with and cause damage to other equipment, personnel or facilities in its surroundings. In use, the flywheel 25 is driven by the flywheel motor to orient the crane load 107 and Crane Load Orientation Device 102 and also to counteract any unwanted rotation in the crane load 107. The torque applied to the frame 2 by the flywheel motor both causes and counteracts the rotation of the crane load 107 and can be used to minimise unwanted rotation of the crane load 107. The flywheel motor may supply a continuous drive to the flywheel 25, or may use a clutch device (not shown) to allow the flywheel 25 to rotate freely when the flywheel motor is not driving the flywheel 25.

In Figure 3 there is a diagram of the auxiliary rotation assembly 108.

The same reference numerals are used as in previous figures. The auxiliary rotation assembly 108 is incorporated in the frame 2 and has chains 103,103', a control box 104 (not shown) and a pulley 106 and a pair of winch motors 3, 3' which drive frame-mounted sprockets (not shown in Figure 3). The crane load 107 is suspended from the frame 2. A first chain 103 runs from the crane load 107, via the lower wheel of pulley 106 and back to the crane load 107. A second chain 103' runs from the crane load 107, over a first frame-mounted sprocket (not shown) driven by the first winch motor 3, via the upper wheel of pulley 106, over a second frame-mounted sprocket (not shown) driven by the second winch motor 3' and finally runs back to the crane load 107. The pulley 106 ensures that a first chain 103 moves in sympathy with a second chain 103'. The crane load 107 has a major axis of rotation 109 and a minor axis of rotation 110 about which the auxiliary rotation assembly 108 causes and controls rotation. The first chain 103 is tethered to the crane load 107 at a first pair of points 111 themselves spaced apart by a distance in the minor axis 110 of rotation. The second chain 103' is also tethered to the crane load at a second pair of points 112 themselves spaced apart by a distance in the minor axis of rotation 110. The first pair of points 111 is spaced apart from the second pair of points 112 by a distance in the major axis 110 of rotation.

Preferably, the pairs of points 111,112 are aligned parallel to the axes of rotation 109,110, such an arrangement providing increased stability and minimising unbalanced torsion caused by the crane load 107.

It will be clear to a person skilled in the art that the major axis 109 and minor axis 110 may be interchanged in the above description without compromise to the chain 103,103' tethering.

In use, the auxiliary rotation assembly 108 causes and controls rotation of the crane load 107 about the major axis 109 by running the winch motors 3, 3' so that the second chain 103' moves through the frame mounted sprockets in an opposite direction at each frame-mounted sprocket (i.e. that one frame-mounted sprocket will rotate clockwise and the other anti-clockwise). The auxiliary rotation assembly 108 causes rotation of the crane load 107 about the minor axis 110 by running the winch motors 3, 3' so that the second chain 103' moves through the frame mounted sprockets in a like direction at each frame-mounted sprocket (i.e. that both frame-mounted sprockets will rotate clockwise or both frame-mounted sprockets will rotate anti-clockwise). The flywheel 25 (not identified in Figure 3) may be used as a useful source of inertia or, if spinning, a gyroscope to counteract any imbalance which may arise in the use of the auxiliary rotation assembly 108.

The pulley 106 may allow both the first chain 103 and the second chain 103' to run freely, or may provide restriction to any unwanted movement of chain 103. The frame-mounted sprockets may be arranged anywhere within the frame 2 and may preferably arranged to be co-axial but spaced apart.

In use, the auxiliary rotation assembly 108 allows the driver of the crane (not shown) or a separate operator (not shown) to control the rotation of the crane load 107 about two perpendicular axes in a substantially horizontal plane. The pulley 106 and the pair of winch motors 3, 3' provide a minimal control system to enable rotation about two perpendicular axes. When both motors 3, 3' run in a like direction, the crane load rotates about a first axis, and when both motors 3, 3' run in an opposing direction, the crane load rotates about a second axis, such axes being distinct from the substantially vertical axis about which the counter rotation member (not identified in Figure 3) rotates.

In an overview of a preferred embodiment of the present invention, there is shown in Figure 4a and exploded view of a portion 101 of a Crane Load Orientation Device 102. Using the same reference numerals as previous figures, such device has a flywheel motor 11 driving a flywheel 25, held in housing 28. In use, the Crane Load Orientation Device 102 is suspended from a crane (not shown) and has a crane load (not shown) suspended from the Crane Load Orientation Device 102. The flywheel 25 rotates about a substantially vertical axis. The flywheel motor 11 is preferably a hydraulic motor connected by hydraulic piping (not shown) to accumulators 4 which are fed hydraulic fluid (not shown) from hydraulic fluid tank 33. The accumulators 4 provide pressurized hydraulic fluid (not shown) to the flywheel motor 11, such an arrangement having the advantage of being able to supply a large impulse to the flywheel motor 11, which allows the flywheel 25 to create, sustain and stop large energies of rotation quickly and significantly reduce its energy consumption for a particular duty.

Such large impulses allow the orientation of larger loads, up to the structural limits of the Crane Load Orientation Device 102.

There is shown in Figure 4b an exploded view of the Crane Load Orientation Device 102, sharing reference numerals with Figure 4a.

In Figure 4b, in addition to the portion 101 of the Crane Load Orientation Device 102, there is also shown a frame 2 and winch motors 3, which move chains (not shown in Figure 4b). The frame 2 has fixing means 105, such as a hook, to which the crane (not shown) is attached.

The housing 28 additionally comprises a diesel engine 35 which is connected to a generator (not shown) to provide electrical power or to the hydraulic pump (not shown) to provide hydraulic power and charge the accumulators 4 which, in turn, power the flywheel motor 11 and winch motors 3, 3'. The flywheel motor 11 and/or winch motors 3, 3' may be electric, hydraulic, pneumatic or fuel-powered.

The flywheel motor 11 causes rotation in the flywheel 25 and such rotation is used to create, control and reduce rotation in the Crane Load (not shown) suspended from the Crane Load Orientation Device 102. The flywheel 11 may be controlled (via control box, not shown) directly by the crane operator or by a separate operator at a distance from the Crane Load Orientation Device 102, or may be controlled partially or fully by an automatic system driving the flywheel motor 11 in proportion to values of torsion in the fixing means 105, in proportion to values of rotation detected in a rotation plate (not shown) within the fixing means 105, or in proportion to compass-detected or GPS-detected deviation from the desired axis orientations.

Example Flywheel and Motor: For a concrete staircase block with dimensions (WxDxH) of 1.5m x lOm x 0.3m, concrete density p=z 2400kg/rn3 and the block has mass m = p*(W*D*H) = 2400*(1.5*1O*O.3)= 1O.8*lO3kg.

The block also has moment of inertia about Height axis b =m112*L =90000kgm2.

The flywheel is made from steel, weighs 101 kg and has outer radius of 0.75 m and inner radius of 0.56 m. The rim of the flywheel has depth 16.5 mm=0.0165 m to achieve the required mass for the flywheel. The flywheel has moment of inertia If =44.3kgm2.

The example motor is capable of a maximum of 3800 rpm and so the centrifugal force due to half the flywheel trying to break from other half is F=m*G*c02 =5O.5*O.42*(3800*2*,z/6O)2=3.36MN.

where G is radius of centre of gravity of half of flywheel (0.42m) m is mass of half the flywheel (50.5kg) w is speed of rotation (3800rpm) The area loaded by these stresses is A =thickness*(Rr)*2=zO.O165*(O.75O.56)*2 =O.00627m2 Thus the average hoop stress over the rim cross-sectional area is F/A = 3.36 *106/0.00627 = 536 MPa.

Alternative calculation methods put the value of maximum stress higher or lower dependent on the method but of the same order of magnitude and well within the acceptable load stresses for stronger steels.

The motor is capable of supplying continually 276 Nm of torque and so can accelerate the flywheel at 276Nm/44.3kgm2 = 6.23rad/s2 (approximately 60rpm per second) and can accelerate the concrete block at 276/90000 = 0.OO3O7rads/s2 (approximately 0.029rpm per second). This results in a time to rotate the concrete block through 900 (from zero rotation speed and back to zero speed) of 45 seconds. The slow rate of rotation provides a safety advantage in ensuring controlled movement of the 10.8 tonne concrete block.

It will be appreciated by one skilled in the art that the performance of the device in rotating loads about a vertical axis is significantly enhanced by the incorporation of energy storage devices, meaning that primary power sources need only to be of limited output, so ensuring the device is economical to operate and of reduced mass.

It will be appreciated that although only one particular embodiment of the invention has been described in detail, various modifications and improvements can be made by a person skilled in the art without departing from the scope of the present invention.

Claims

Claims 1. A load orienaing device comprising a flywheel mounted in a housing and roaable in use about a single axis by a drive means; the housing comprising attachment means connected o a load suspended from the housing; wherein in use the suspended load is orientated about the single axis by roaing the flywheel and imparting a torque o the housing o cause the suspended load o roae about the single axis.
2. A load orienaing device as claimed in claim 1, wherein the single axis is in use a subsanially vertical axis.
3. A load orienaing device as claimed in claim 1 or claim 2, wherein the attachment means comprises a pair of winches and one or more winch motors, each such winch driven by the one or more winch motors.
4. A load orientating device as claimed in claim 3, wherein each winch is provided with a tether connected to the load at two points of contact.
5. A load orientating device as claimed in claim 4, wherein each tether passes through a linked attachment point provided between one pon of conac and each winch.
6. A load orientating device as claimed in claim 5, wherein the linked attachment point is a pulley system.
7. A load orientating device as claimed in any preceding claim, wherein the device is connected to a crane by a crane -14-mounting point, wherein the crane mounting point is rotatable about 360 degrees.
8. A load orientating device as claimed in claim 7, wherein the crane mounting point is mounted on bearings.
9. A load orientating device as claimed in any preceding claim, wherein the drive means comprises an electric motor and a power storage device.
10. A load orientating device as claimed in any preceding claim, wherein the power storage device is arranged so that decelerating the rotation of the flywheel provides regeneration of charge in the power storage device.
11. A method of orientating a load suspended from a housing; comprising rotating a flywheel mounted in the housing about a single axis and thereby imparting a torque to the housing and causing the suspended load to rotate about the single axis.
12. A method of orientating a suspended load as claimed in claim 11, wherein the single axis is a vertical axis.
13. A method of orientating a suspended load as claimed in claim 12, wherein the suspended load is connected to the housing by a pair of tethers, each tether connected to the load at two points of contact and connected to the housing by a winch; the method comprising winching a tether and tilting the load about a single axis.
14. A method of orientating a suspended load as claimed in claim 13, wherein the single axis is a horizontal axis.
15. A load orienaing device subsanially as hereinbefore described and/or with reference o Figures 1 o 4 of the accompanying drawings.