Patent Publication Number: US-8109548-B2

Title: Vacuum lifting device for lifting and handling of objects

Description:
This application is a U.S. National Phase Application under 35 USC 371 of International Application PCT/SE2007/000737 filed Aug. 21, 2007. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vacuum lifting device for lifting and handling of objects, comprising a suction tube suspended at an upper end, a suction cup fitted at a lower end of the suction tube, a low pressure generating device communicating with the inner of the suction tube, which is extensible and contractible in dependence on the vacuum prevailing in the suction tube, a valve house protruding laterally from the suction cup, the inner of which valve house communicates with the inner of the suction tube, and a valve device with a hand grip rotatably mounted on the valve house for adjustable opening and closing of at least one aperture in the valve house wall by means of a regulating device actuated by the hand grip and comprising a closing member movable in relation to the aperture. 
     2. Description of Related Art 
     Devices of this type are priorly known, for example from U.S. Pat. No. 5,934,723 disclosing a valve means, known per se in other connections, comprising a rotary valve disc provided with apertures, which valve disc is pressed against a fixed wall also provided with apertures, which are placed such, that at a turning of the valve disc a flow aperture is formed that varies from zero to maximum. A drawback with such a valve arrangement in a wall, behind which a considerable vacuum prevails, consists in that the valve disc in closed position is sucked firmly against the wall, so that a comparatively big power is required to turn the valve disc till a certain opening is achieved. A further drawback when using this valve arrangement for regulating the vacuum in a hoisting device consists in that it is not possible to achieve a flow aperture that is large enough for the suction cup to release an object sucked to the suction cup. In that case the valve arrangement has to be completed with a further valve device coupled to the valve arrangement, which opens a complementary flow aperture that is large enough, which constitutes an undesired complication. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to achieve an uncomplicated and reliable device of the kind mentioned by way of introduction having the above mentioned drawbacks eliminated. 
     This has been accomplished according to the invention by the regulating device being provided with a cam disc rotatable together with the hand grip, which cam disc has a periphery designed to continuously displace the closing member an adjustable distance essentially perpendicular to the turning axis of the cam disc in dependence on the turning angle of the hand grip. With the closing member in closed position a certain power is required also in this case for starting the displacement of the closing member, which is simply remedied by giving the periphery of the cam disc a small increase of the radius at the beginning of the turning of the cam disc, but then after a maximum regulating opening has been achieved, it can continue with a strong increase of the radius, such that the closing member is opened rapidly to a flow aperture, that is large enough for the object to get released. 
     The closing member can have different shapes, for example the shape of shutter covering the aperture in the valve house wall and having a hinge at one edge of the shutter and at an opposed edge has a shoulder against which the cam disc is arranged to act in opening direction. As an alternative the closing member has the shape of a valve body, which is arranged to be displaced in opening direction perpendicular to a valve seat in the aperture, against which valve body the cam disc is arranged to act. Such a valve body may be spherical and in open position guided against the action of a spring in a cage surrounding the valve body. 
     The closing member may be actuated directly by the cam disc or via an intermediate member, as a rod in a sliding bearing bushing, and the closing member may be displaced against the direction of the air flow either in opening or in closing direction. 
     At the maneuvering of the suction cup the operator has, in a manner known per se, to grip a fixed handle attached to the valve house and the rotatable hand grip, which is located at a side of the valve house. According to a specially suitable embodiment the cam disc is located inside the valve house. The aperture and the closing member actuated by the cam disc may be located at the top side, the bottom side, or preferably the end wall of the valve house facing the operator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be explained in more detail in the following with reference to the accompanying drawings which schematically show different embodiments of devices according to the invention, chosen by way of example, and in which 
         FIG. 1  is a side view of an embodiment of the vacuum lifting device, 
         FIG. 2  is an end view of the valve house with an exterior cam disc, 
         FIG. 3   a  is an end view of the valve house with an interior cam disc, 
         FIG. 3   b  is a side view of a part of the valve house with the wall  9  cut away showing the interior cam disc, 
         FIG. 4   a  is a view from above of a part of the valve house with the upper half part cut away and showing a further embodiment of the valve device, 
       FIG.  4   b  is a side view of the cam disc shown in  FIG. 4   a , and 
         FIGS. 5 and 6  are the same views as shown in  FIG. 4   a  but with a spherical valve body. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a suction tube  1 , which is suspended movable along a roof rail  2 . The lower part of the suction tube is provided with a suction cup  3 , from which a valve house  4  protrudes laterally communicating with the interior of the suction tube through a flexible joint  5 . The upper part of the suction tube is closed by a cover plate  6 , to which the suction tube is rotatably and air tight attached, and to which a flexible hose  7  to a vacuum generating means (not shown) is connected. The suction tube  1  is designed in a manner known per se to contract when a vacuum is created, so that the suction cup  3  with an object  8  sucked to the suction cup is lifted. In order to regulate the lifting movement and a following lowering of the suction cup  3 , as well as releasing of the object  8 , the valve house  4  is provided with a valve device comprising a cam disc  10  rotatably journalled at the outside of one side wall  9  of the valve house, to which cam disc a hand grip  11  is attached for turning the cam disc. The valve house  4  has an end wall  12  in which an aperture  13  is located. The aperture is covered by a closing member in the shape of a shutter  14 , which at one edge is provided with a hinge  15  and at an opposed edge is provided with a shoulder  16  protruding out off the side wall  9  of the valve house. The periphery of the cam disc  10  has a radius designed such, that when the cam disc is turned in counter clockwise direction from an initial position the cam disc initially is brought in contact with the shoulder  16  after which the radius slowly increases such that shutter  14  against the action of the vacuum in the valve house and a spring, not shown, integrated with the hinge  15 , is opened letting in air in a regulated manner into the valve house and suction tube in dependence on the turning angle of the cam disc and the hand grip. The suction cup  3  with the object  8  is lifted and lowered in this manner, but in order to release the object  8  lowered to a support surface it is necessary to achieve a strong decrease of the vacuum inside the suction cup  3 . This is achieved by the fact that the cam disc  10  at a further turning past the real regulating range has a peripheral part  17  with a steep increase of the radius, such that the shutter  14  can be opened further very rapidly to about 45° opening. As an alternative the steep increase of the radius of the cam disc can be utilized in a known manner for opening of a further, laterally hinged shutter covering a further aperture in the side wall  9  of the valve house, or more suitable for opening of a hinged shutter covering a further aperture in the top side of the valve house, which can be carried out in a corresponding way as the opening of the shutter  14 . 
     As follows from  FIG. 3   a  and  FIG. 3   b  the cam disc  10  can have a more protected location at the inner side of side wall  9  of the valve house. In order to eliminate leakage it is suitable to have the shutter  14  actuated by the cam disc via a rod  18  journalled in a sliding bearing bushing at the inner side of the side wall  9 . 
     Air flowing through openings with more or less sharp edges has a tendency to cause noise that can be disturbing in many working environments.  FIG. 4   a  and  FIG. 4   b  show an embodiment that can eliminate such noise. An opening in the end wall of the valve house is here shaped to form a circular, slightly tapered edge that forms a valve seat  19  for a closing member in the shape of circular, bulging valve body  20  adapted to the valve seat. A rod  21  is attached to the centre of the valve body and is slidingly journalled in two bracings  22  fixedly mounted in the valve house. The rod  21  has a plate  23  attached to the inner end of the rod and between brick and the rear bracing  22  a compression spring  24  that holds the valve body  20  pressed against the valve seat  19 . A shaft  26  rotatably journalled in bushings  25  attached to the inner sides of the valve house is fixedly attached to a cam disc  10  located in the extension of the rod  21 . On the outside of the side wall  9  of the valve house is a rotatable hand grip  11  journalled in a fixed bushing  27 . A splined axle neck of the hand grip extends through an opening in the wall into a corresponding recess in the end of the shaft  26  such that it is possible to turn the cam disc  10  with rotatable hand grip  11 . 
     As indicated in  FIG. 4   a  and  FIG. 4   b  this embodiment has a valve house that is double-walled. This is for making it possible to assemble the complete valve device outside the real valve house and after that to slide the valve device into the valve house and in situ connect the rotatable hand grip  11 . 
       FIG. 5  is a less complicated variant of the embodiment described Above. The outwards directed end of the valve house  4  is open and designed to receive an end part  30  containing a spherical valve body  31  in a conical narrowing inlet tube  32  with a valve seat  33 . The outer end of the inlet tube  32  has an outwardly curving grid  34  and a compressed compression spring  35  is located between the grid and the valve body  31 . The cam disc  10  is fixedly attached to a shaft  36  rotatably mounted in the valve house, which shaft extends through the side wall  9  and is connected to the rotatable hand grip  11 . The cam disc  10  is pushing the&#39;valve body  31  in opening direction against the action of the spring  35  via a freely movable push rod  37  journalled in bracings  22 , which push rod is free from the valve body  31 . 
       FIG. 6  shows a device which differs from the device shown in  FIG. 5  in that the inlet tube  32  has a valve seat  38  which is directed inwards and the spherical valve body  31  is located between the valve seat  38  and the cam disc  10 , which, accordingly, is situated to influence on the valve body  31  in closing direction against the flow direction. With the valve body in open position it is guided laterally by thin ribs  39 . A corresponding design with the closing member displaceable in closing direction against the flow direction is applicable also to the embodiments described above, in which case the cam disc suitably is arranged to act directly on the closing member. 
     The three last described embodiments are easy to manufacture and have valve bodies which are easy to replace and are characterized by operating without disturbing noise. 
     The invention is 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, in which the rotatable cam disc operated by the rotary hand grip is the principal point.