VACUUM HOISTING DEVICE

The present invention relates to a vacuum hoisting device with a vertical hoisting tube suspended at an upper end and connected to a vacuum source adapted to be switched on and off, which tube at a lower end is provided with a suction foot and a positioning handle sucured to the suction foot for manoeuvring the suction foot, and a manually operated valve device for permitting admission of air to the hoisting tube such that the hoisting tube is axially extensible and contractible in dependence on the air pressure prevailing in the hoisting tube.

Devices of this kind are commonly known when the manoeuvring of the suction foot in vertical direction usually is carried out by a valve device for admission of air into the hoisting tube. It is also known to control a device for adjusting the suction capacity of the vacuum source by a control means at the suction foot. Moreover, it is also known to use a combination of these two manoeuvring devices. Quite a lot of exercise is necessary in order to learn manoeuvring of the suction foot with safety and precision for lifting objects of different weights, often easily damaged, by the known vacuum hoisting devices, which are provided with manoeuvring devices working in different ways.

The object of the invention is to achieve a manoeuvring device, which from a general point of view is operated in a logical and easily comprehensible way together with all existing vacuum hoisting devises of the above mentioned kind. This is achieved according to the invention by using a positioning handle that is tubular and constitutes an obliquely downwards directed connection between the interior of the hoisting tube and the interior of the suction foot, and is provided with an outside, axially between an upper and a lower end position slidingly mounted grip sleeve which is connected to the valve device by a connecting means , which against the action of a spring force causes opening of the valve device when the grip sleeve is slided towards its lower end position. Without actuation of the grip sleeve the valve device is closed and with working suction source the suction foot is kept hanging immovable or is slowly lifted to an upper lift position depending on the trimming of the vacuum hoisting device. When the grip sleeve, which an operator grips for guiding the suction foot laterally, is slided downwards the valve device is opened and air flows into the hoisting tube such that the vacuum in it is reduced and the suction foot is lowered. After the suction foot has been positioned on an object the grip sleeve can be slided upwards so that the valve device assisted by the spring force acting on the valve device is closed and the object is sucked firmly to the suction foot and by this is lifted upwards when the hoisting tube starts contracting due

to the increasing vacuum inside the hoisting tube. The lifting movement is slowed down and interrupted by interrupting the upwards directed movement of the grip sleeve and holding it vertically immovable. By this operation the valve device is opened a bit causing the lifting movement to be interrupted and changed to a lowering movement when the grip sleeve is slided downwards such that the valve device is fully opened.

It is priorly known to have, at the lower part of the hoisting tube, a regulating device with a connection to the vacuum source for switching on and off of the vacuum source and also for regulation of its suction capacity. Since the suction capacity has to be adapted among others to the weight of the object and/or its air permeability, which becomes apparent only at the beginning of the hoisting operation when one usually does not have a hand free for operating a control means, a control connected to the vacuum source is, according to an embodiment of the invention, arranged to switch on an increased suction capacity of the suction source by the regulating means of the valve device at the sliding of the grip sleeve from an intermediate position to the upper end position, during which sliding the valve device is closed.

Tests carried out with the device according to the invention have shown that some jerkiness of the suction foot may arise at sliding operations of the grip sleeve in relation to the positioning handle owing to an absence of feedback to the grip sleeve from the motion imparted to the handle. Hence, according to a preferred embodiment of the invention, a portion of the surface of the grip sleeve is covered by a rib flange fixedly attached to the positioning handle and extending along a major part of the lengtnof the grip sleeve. In that way the hand feels the sliding motions of the grip sleeve in relation to the positioning handle, owing to the fact that the hand slides along the rib flange when the grip sleeve is displaced. This means that the hand feels the motions of the positioning handle and accordingly the motions of the suction foot, which has proved to make it possible to eliminate the tendency of jerkiness of the suction foot.

Further measures for improving the the device according to the invention are set forth in claims 4-6.

The invention will now be explained in more detail in the following with reference to the accompanying drawings which schematically show embodiments of the invention chosen by way of example and in which Figure 1 is a side view of a hoisting device according to the invention, Figure 2 is sectional side view of the lower part of the hoisting tube with positional handle and valve device, and Figure 3 is the same sectional view as in Fig.2, but with the

device provided with an automatic adjustment of the suction capacity of the vacuum source.

The vacuum hoisting device shown in Fig.1 has a hoisting tube 2 suspended from a telpher 3 movable along a horizontal rail 1, in which telpher a vacuum source in the shape of an ejector 4 is positioned, which is fed by a compressed-air line 5 from an air compressor, not shown. The compressed air is supplied to the ejector 4 via a regulating means 6 for switching in and off and for continuous regulating of the supplied compressed air. The regulating means 6 is controlled by a line 7, which in helical form (not shown) extends in the hoisting tube 2 to a control knob 8 positioned on the lower part of the hoisting tube. The ejector 4 has a suction opening 9 communicating with the interior of the hoisting tube 2.

A closure 10 is attached to the lower end of the hoisting tube 2, which closure is provided with a central port 11 covered by a springclosing valve plate 12. The closure 10 is also provided with a downwardly directed tube 13, which extends down to a conventional suction foot 14. An intermediate part of the tube constitutes an obliquely downwardsdirected positioning handle 15 on which a grip sleeve 16 is axially slidable between an upper and a lower end stop 17 and 18, respectively. A narrow rib flange 20 is fixedly attached to the postioning handle 15, which rib flange extends along a major part of the length of the sleeve 16.

The closure 10 has a transvers partition wall 21 with a central opening 22 into which the tube 13 ends, and two further openings 23 and 24. The opening 23 has an upwardly directed pipe 25 communicating with the interior of the hoisting tube 2 and having a valve device 26, which is adapted to open downwards against the action of a draw spring 27, the upper end of which is secured to a pin at the inner end of the pipe 25. The valve device 26 is linked to a connecting means 28 comprising a jointed arm 30 linked to a stud 29 attached to the tube 13 and to the grip sleeve 16 via a swivel arm 31 in order to permit proper operation of the valve device. The valve device 26 is shown in closed position, but becomes opened at sliding of the grip sleeve 16 towards the lower end position 18. Moreover, there is an arm 32 linked to the stud 29. This arm is connected with an air admission valve 33 in the opening 24, which valve opens against the action of a tension spring 34 when the arm 32 is pushed against the grip sleeve 16 such that a connection is opened via the central opening 22 between the interior of the positioning handle and the suction foot and the exterior of the hoisting tube 2.

The hoisting device shown in Fig.1 and 2 is switched on by the control knob 8 for starting and adjusting the ejector 4 for creating a suitable vacuum inside the hoisting tube 2, such that a weak stream of air is sucked through the suction foot 14 and the tube 13 and

passes by the spring-actuated valve plate 12. If the suction foot 14 rests upon an object to be lifted it will be sucked firm to the suction foot, and if the object is impervious to air the hoisting tube starts contracting with its wall folding in a manner known per se to an upper hoisting position or till the grip sleeve 16 is kept immovable in vertical direction, such that it is slided in relation to the positioning handle 15 and opens the valve device 26 a bit and admits air into the hoisting tube such that the upward motion of the suction foot is interrupted. Then the suction foot 14 can be moved laterally by operating the positioning handle 15 and the grip sleeve 16, and after that the suction foot may be lowered by sliding the grip sleeve downwards on the positioning handle. When the object comes to rest on a support the grip sleeve may be slided to its lower end position, and the adherence between the suction foot 14 and the object will cease after a while. In order to speed up the loosening of the object it is possible to push the arm 32 towards the grip sleeve 16 so that the valve 33 is opened and admits air from the outside directly into the interior of the suction foot via the tube 13 resulting in an immediate loosening of the object.

At the embodiment shown in Fig.3 the arm 30 of the connecting means 28 is connected with the valve device 26 such, that the arm 30 can be swung upwards a distance from the position shown in Fig.3 with a closed valve device 26. This can be carried out by the grip sleeve 16, which is slidable from an intermediate position on the positioning handle 15 to the upper end position 17. The arm 30 is provided with an extension consisting of an arm 35, which at the swinging upwards of the arm 30 pushes a gudgeon 36 of a Bowden wire 37 upwards a distance, such that a gudgeon at the other end of the Bowden wire can actuate the regulating means 6 of the ejector 4 to which the Bowden wire is connected (not shown). In this way it is possible by sliding the grip sleeve towards an upper end position to gradually increase the suction capacity of the ejector without the necessity of using a separate control for this purpose.

The invention is of course not limited to the embodiments shown and described by way of example but can be modified in different ways within the scope of the invention defined by the patent claims. This concerns especially the Bowden wire 37 for the automatic adjustment of the suction capacity of the ejector, which may be designed in other known ways. Further, the positioning handle 15 may of course be attached to the side of the lower part of the hoisting tube 2. Also other types of vacuum pumps can be utilized, e.g. electrically driven vacuum pumps.