LIFTING DEVICE

Abstract: A lifting device including a motor (2) with a motor shaft (3), a drum (7), which is connected to the motor shaft (3), a rope (11) connected to a drum (7) and a gripping device (15), which is attachable to and detachable from an object (14) to be lifted or lowered while one end (43) of the device is suspended in the ceiling (40) and the other end of the device carries the gripping device (15). A free wheel (8) is connected between the motor shaft (3) and the drum (7) to facilitate for the drum (7) to rotate in the direction of winding up the rope (80) relative to the motor shaft (3). A biased device (6) is provided to bias the drum (7) in the direction (80) of winding up the rope, whereby the biasing device (6) has a length corresponding to the required length of the extended rope from the drum (7).

Description: Lifting device The invention relates to a lifting device of the type described in the preamble of the main claim. A frequent working situation is when an operator is going to stack packages on top of each other and/or to place the packages next to each other in a storage area, e.g. on a lorry platform. Nowadays there are regulations preventing operators from frequently per¬ forming such work if the weight exceeds a relatively low limit. In the described situation it is commonly known that attempts have been made to install lifting means mounted in the ceiling. The lifting means can include a rope, the free end of which is in the form of a gripping device, which can temporarily grip onto the package or the like. The operator can then activate the motor, which will in turn activate the drum to wind or unwind the rope causing the package carried by the gripping device to be lowered/lifted. The gripping device, which can consist of a suction cup or a mechanical, squeezing device etc., constitutes a tool, which is then kept and controlled by the operator when moving the package sideways or vertically. The controlling means of the motor can be mounted on the gripping device proper. A problem with such a lifting device is, however, that those packages or the like, which are to be handled often, are rather light so that there is a risk that the operator himself manually lifts the gripping device and the package faster than the mechanically operated device is able to wind up the rope. Then this will lead to the rope being wound up unevenly onto the drum causing the rope to pinch itself, which in turn involves well-known problems when trying again to unwind the rope from the drum. Furthermore, it is desired to have the drum enclosed in a type of housing or cover having an opening, through which the rope can run. Due to wear and tear of the rope it is common that the rope will tangle at said opening. Such a tangle will cause the outermost turn of the rope on the drum to be enlarged and to become stuck into the rest of the rope causing it to potentially jam. The effect can be that obvious problems will arise when winding or unwinding the rope. It is furthermore difficult to adjust the unwinding speed to that desired by the operator while lifting or lowering the gripping device. The problems with the above-described lifting devices have been so troublesome that attempts have been made to develop other types of lifting means. One example is a gripping device in the shape of a simple vacuum suction cup, which in turn is hung up by means of a lifting tube closed at the top and the lower parts of which communicating with the suction cup itself. When there is a negative pressure the suction cup will stick fast to the goods or package and, upon continued nega¬ tive pressure, the package will be lifted together with the suction cup while the lifting tube still remains flexible. As previously described, the problem still exists when the operator tends to assist in lifting especially light packages. When the operator does so the pressure in the suction cup and the lifting tube will increase to the point where the suction cup will become separated from the package. This involves that the package will fall down and the suction cup will be moved upwards due to the spring back of the lifting tube. The object of the present invention is to develop the first-mentioned type of lifting means (comprising gripping devices, rope and electrically operated rope drum) in order to completely or partially eliminate said problems. This object is achieved with a device according to the enclosed main claim. Embodiments of the present invention are stated in the enclosed non-independent claims. In fact the invention relates to the rope drum being biased in a rotational direction corresponding to that of a wound-up rope by the aid of a coil spring or equivalent means having a length sufficient for the desired operation. Thanks to the coil spring also the weight of the gripping device will be balanced to some extent. Further, a free wheel/free hub will according to the invention be connected between the motor and the drum, which in turn will allow the drum to wind up with a higher degree of speed than the actual motor shaft proper while the drum will deliver the same rotational speed as the motor shaft in the direction of winding up the rope. The industrial applicability is that should the opera¬ tor decide to assist in lifting an object, e.g. a package, faster than the speed of the rope as deter- mined by the motor capacity of the drum in the winding direction, the drum will rotate freely in the winding- up direction relative to the motor shaft during the influence of the coil spring, the power of which is sufficient to quickly wind the excess rope. The problem mentioned above is hereby eliminated. A further technical effect of the invention is that while the motor is driven for unwinding the rope from the drum (lowering the gripping device) a braking of the drum in the winding-up direction, e.g. at the opening of the cover, will not result in that the winding turns on the drum expand, because, as soon as such a jam of the rope tends to start, the drum would be influenced by a corresponding braking power, where¬ upon the free wheel would allow the drum to rotate in the winding-up direction relative to the motor shaft, which is rotationally driven to unwind when the rope is to be fed out. Pulling the rope out would otherwise cause the drum starting to rotate bringing the free wheel to a locking position against the stationary motor shaft. According to preferred embodiments of the invention the motor control means are designed to give chosen speeds and speed variations/accelerations for the rope/ gripping device, while lifting and lowering the gripp¬ ing device in order for the device to operate with speeds and accelerations corresponding to those pre¬ ferred by the operator if working manually. According to a preferred embodiment of the invention an operating rod is at the one end pivotally connected to the gripping device, whereby the operating rod can support the motor control means in the places where it is natural for the operator to grip the operating rod. The operating rod helps in a simple manner to lengthen the reach of the operator. The operating rod can be as long as 1,5-2 m and be generally elongated. The invention will be described below by examples, reference being made to a schematically illustrated device. Fig. 1 shows the device according to the invention in a mounted state and partially sectioned and Fig. 2 shows a section along the line II-II in Fig. 1. In Fig. 1 is illustrated a highly positioned guide track 41 receiving a carriage 42, which through a connection 43 supports a winch mechanism 1. The device 1 consists of an electric motor 2 with a shaft 3. A rope drum 7 is mounted on a shaft 3 by a roller bearing 9. A free wheel 8 is provided between the shaft 3 and the hub 71 of the drum 7. A cover 4 surrounds the drum 7. The motor 2 is connect¬ ed to the cover 4. A coil spring 6 is at the one end 61 connected to the cover and at the other end 62 connect¬ ed to the drum 7, whereby the spring 6 is biasing the drum in the winding-up direction 80. A rope 11 extends from the housing or cover through an opening 10 and supports a gripping device 15 having suction cups 15', which are evacuated through a conduit 16 containing a control valve 17 and being in turn connected to a suction source 18. Further, the gripping device 15 is provided with con¬ trol means 24, 25 for controlling the speed, the acce¬ leration and the rotational direction of the motor 2. The control means 24, 25 are through cables 23 connect- ed to a control member 22, which controls current from a power source 26 via a cable 21 to the motor 2. An operating rod 50 is via a link 51 connected to the gripping device 15 to give the operator 30 an extended reach in relation to the gripping device 15 and that object, e.g. a package, 14 gripped by the gripping device 15. When the operator 30 has by the aid of the control valve 17 made the gripping device 15 grip the package 14, any of the control means 24, 25 can be actuated so that the motor via the shaft 3 and the free wheel 8 will rotate the drum 7 to wind up the rope 11 on the hub 71 with a chosen speed. Should the operator 30 manually lift the gripping device 15 faster than the rope 11 is wound onto the drum 7, then the spring 6 will immediately rotate the drum 7 faster than the motor shaft 3 in order for the rope 11 still to be wound up tight onto the drum. When the operator 30 actuates the motor control means 24, 25 in such a way that the rope 11 is fed out with no or low vertical pulling power in the rope 11 it would be expected that the rope 11 tangles or is jammed in the opening 10. It appears from Fig. 2 that the shaft 3 can be rotated clock-wise thanks to the free wheel 8 while the drum 7 stops due to the tangling of the rope 11 in the opening 10. The device has been illustrated by means of an embodi- ent, according to which the cover 4 is supported in the ceiling, while the free end of the rope 11 supports the gripping device 15 but it is, however, obvious that the free end of the rope 11 can be mounted in the ceiling and the gripping device 15 connected to the cover 4. Further, it is obvious that the suction cup 15 ' can be replaced by any other type of gripping mechanism suitable for the packages 14 to be handled. The device according to the invention is especially suitable for use in warehouses and in connection with loading/unloading trucks/lorries and containers. Also, the device can be used in the loading space of a truck/ lorry or inside a container. In Fig. 1 is for this purpose illustrated a guide track 41 supported on a cantilever structure 44, which is in turn supported by a stand 45 connected to a mobile trolley supported by wheels. A conveyor 47 can be supported by a wire for transporting packages 14 to and from the space in question. According to the embodiment the structure 44 is mounted at such a height that it will be close to the ceiling of a container 49, into which the structure can be guided by moving the trolley. Further, the units 18, 26 are shown supported by a wire and connected to the power source 26. The conduits 16, 21, 23 can preferably be supported from the ceiling or from the structure 44. The stand 45 can be arranged to be swivelling around its own axle for corresponding turning of the structure 44.

Claims: Claims 1. A lifting device comprising a motor (2) with a motor shaft (3), a drum (7) connected to the motor shaft (3) , a rope (11) connected to the drum (7) and a gripping device (15) connectable to and detachable from an object (14) to be lifted or lowered with the device, upon which one end (43) of the device is suspended in an overhead position (40) and the other end of the device carries the gripping device (15) , characterized in that a rotational biasing device (6) having a mobi¬ lity span corresponding to that of the actual length of extension of said rope (11) from the drum (7) is pro¬ vided to bias the drum (7) in the direction of winding up the rope (80) and that a free wheel (8) is connected between the motor shaft (3) and the drum (7) to allow the drum (7) to freely rotate in the direction of winding up the rope (80) in relation to the motor shaft (3) , when an object is lifted up faster than the normal winding-up speed of the rope onto the drum (7) by the aid of the motor (2) to prevent tangling of the rope (11) • 2. A device according to claim 1, characterized in that the drum (7) is enclosed by a cover (4) having an opening (10) for the rope (11) . 3. A device according to claim 1 or 2, characterized in that the outer end of the rope (11) is connected to the gripping device (15) . 4. A device according to any of claims 1-3 , charac¬ terized in that the one end (4, 43) of the device is supported by a carriage (42) , which is displaceable in a guide track (41) . 5. A device according to any of claims 1-4, charac¬ terized in that the gripping device (15) comprises a suction cup. 6. A device according to any of claims 1-5, charac¬ terized in that the device comprises control means (24, 25; 17) for controlling the rotational direction, speed and possible speed changes of the motor (2), including controlling the gripping device (15) . 7. A device according to any of claims 1-6, charac¬ terized in that the gripping device (15) is provided with an operating rod (50) , the one end of which being connected to the gripping device (15) to achieve greater reach of the gripping device (15). 8. A device according to claim 7, characterized in that the control means (24, 25, 17) are mounted onto the operating rod (50) . 9. A device according to claim 6 or 7, characterized in that the control means are mounted onto the gripping device (15) . 10. A device according to any of claims 4-9, charac¬ terized in that the guide track (41) is supported by a structure (44) , which is self-supported form a trolley.

Inventors: JANSSON CLAES-HAAKAN, JANSSON, CLAES-HAAKAN
Applicants: JANSSON CLAES HAAKAN, PROTEMA AB, JANSSON, CLAES-HAAKAN
Application year: 1996
Main classification: B66D3
IPC codes: B66C23, B66D3