Patent Publication Number: US-8113556-B2

Title: Lifting device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. National Stage of International Application No. PCT/DE2008/000308, filed on 15 Feb. 2008. Priority is claimed on German Application No. 10 2007 008 603.4, filed on 22 Feb. 2007. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is directed to a lifting device and, more particularly, to a lifting device for lifting a workpeice. 
     2. Description of the Related Art 
     DE 20 2005 007 464 U1 discloses a conventional lifting device. This lifting device has two arms forming pincers, each arm comprising a lifting arm and a gripping arm with a gripping element at its free end. Each arm of the pincers is pivotably mounted between the lifting arm and the gripping arm for opening and closing the pincers. Further, the lifting device has a cross member to which the two arms of the pincers are pivotably connected at a distance from one another, and each of the lifting arms has one or more points of application for connecting nonrigid pulling means. 
     Other lifting devices are known, for example, from DE 39 07 200 C1, JP 09124267 A, and DD 251 721 A1. 
     In such known lifting devices, it is often problematic to correctly position the lifting devices in relation to the workpiece to be lifted so as to ensure a secure lifting motion. However, particularly in industrial manufacturing, it is a requirement that the lifting devices can grip the workpiece to be lifted and be connected to it quickly and reliably, all at the same time. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved lifting device which makes it possible to lift a workpiece quickly and securely at the same time. 
     This and other objects and advantages are achieved in accordance with the invention by a lifting device, such as a device for lifting cylinder heads, which includes a scissor-type linkage having two gripping arms supported at the linkage in an articulated manner and with a cross member such that the two gripping arms of the lifting device can be inserted in a simple manner into associated cylinder head bores, and a tilting of the two gripping arms occurs in the cylinder head bores during the lifting process of the lifting device due to the scissor mechanism such that the cylinder head can be lifted reliably and securely. To this end, the lifting device comprises the above-described scissor-type linkage having two arms, and the two rod-like gripping arms, and a cross member which has at least two axially adjacent elongated holes extending in the axial direction of the cross member. The two gripping arms are each guided through one of the two elongated holes and have a fixing element for preventing the gripping arms from being unintentionally pulled out of the associated elongated hole during the lifting process of the lifting device. During the lifting process of the lifting device, the scissor-type linkage causes a rotation of the two gripping arms around an axis extending transverse to the longitudinal direction of the associated elongated hole and transverse to the through-direction of the associated elongated hole so that the free ends of the gripping arms tilt in the associated lifting openings of the workpiece, i.e, in the cylinder head bores, and accordingly make it possible for the workpiece to be lifted. 
     Each free end of the gripping arm advisably has an anti-slip coating. In this respect, it is conceivable that an anti-slip coating of this kind, particularly a plastic or rubber coating, protects the cylinder head bores during the insertion of the rod-like gripping arms on the one hand and, on the other hand, prevents the tilted gripping arms from being pulled out of the lifting openings when the workpiece is lifted or at least makes it more difficult for this to happen. 
     In an embodiment of the invention, a stop element is provided at each gripping arm in the area of the elongated hole, which stop element defines a depth to which the free end of the gripping arm can be inserted into the associated lifting opening on the one hand and, on the other hand, protects an entry area of the lifting openings from damage during the lifting process. The stop element can be constructed, for example, as a typical plastic element, such as a rubber element, and can be dimensioned such that its diameter is greater than the diameter of the associated lifting opening. 
     Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment example of the invention is shown in the drawing and is described in more detail in the following description. 
         FIG. 1  shows a lifting device in accordance with the invention; and 
         FIG. 2  shows an anti-slip coating at the free end of a gripping arm of the lifting device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     As shown in  FIG. 1 , a lifting device  1  for lifting a workpiece  2 , such as for lifting a cylinder head, includes a scissor-type linkage  4  having two arms  3  and  3 ′ and two rod-like gripping arms  5  and  5 ′ which are connected thereto in an articulated manner. Further, the lifting device  1  comprises a cross member  6  which has at least two axially adjacent elongated holes  7  and  7 ′ extending in the axial direction of the cross member  6 . The elongated holes  7  and  7 ′ are respectfully arranged in the area of a longitudinal end of the cross member  6 . The two gripping arms  5  and  5 ′ are guided through a respective elongated hole  7 ,  7 ′ and have a respective fixing element  8  and  8 ′ to prevent the gripping arms  5  and  5 ′ from being pulled out of the associated elongated hole  7 ,  7 ′ unintentionally. The fixing elements  8 ,  8 ′ prevent the cross member  6  from falling down during the lifting process of the lifting device  1 . 
     With further reference to  FIG. 1 , each of the two gripping arms  5 ,  5 ′ is rotatable around an axis which extends transversely to the longitudinal direction and transversely to the through-direction of the associated elongated hole  7 ,  7 ′ and which extends substantially perpendicularly to the drawing plane as referring to the sole drawing. As a result, it is possible for the free gripping arm ends  9 ,  9 ′ to tilt in an associated lifting opening  10 ,  10 ′ of the workpiece  2  when the latter workpiece is lifted. 
     At the remote end of the respective gripping arm  5 ,  5 ′, the two arms  3  and  3 ′ are respectively connected in an articulated manner to a strut  11 ,  11 ′, respectively, preferably a push/pull strut, with these struts  11 ,  11 ′ being supported in an articulated manner at their other respective end at a common holding element  12 . The lifting device  1  can be fastened to a crane hook, for example, by the holding element  12 . The struts  11 ,  11 ′ are connected to the holding element  12  such that the weight of the scissor-type linkage  4  and the workpiece  2  held at the scissor-type linkage  4  acts symmetrically on the holding element  12 . As seen from the Figure, strut  11 ′ is fastened to the holding element  12  in the front in the viewing direction, while strut  11  is fastened to the holding element  12  in the back in the viewing direction. 
     In order to improve tilting of the free gripping arm ends  9 ,  9 ′ in the respective associated lifting opening  10 ,  10 ′, an anti-slip coating for example, a rubber or an elastic plastic, can be additionally arranged at each free gripping arm end  9 ,  9 ′, as shown in  FIG. 2 . 
     The arm  3  is provided with two locking elements  15  which form a stop for the adjoining strut  11 ′ when the scissor-type linkage  4  folds together. The arms  3 ,  3 ′ are dimensioned such that the distance between the gripping arm ends  9 ,  9 ′ corresponds to the distance between the lifting openings  10 ,  10 ′ when the scissor-type linkage  4  folds together (i.e., when the strut  11 ′ stops against the locking element  15  of arm  3 ) so that the gripping arm ends  9 ,  9 ′ can be inserted easily into the lifting openings  10 ,  10 ′. 
     A stop element  13 ,  13 ′ is provided at each gripping arm  5 ,  5 ′ at its end remote of the free gripping arm end  9 ,  9 ′ in an area of the associated elongated hole  7 ,  7 ′. This stop element  13 ,  13 ′ defines an insertion depth of the free gripping arm end  9 ,  9 ′ in the associated lifting opening  10 ,  10 ′, on the one hand, and prevents damage to an opening rim of the respective lifting opening  10 ,  10 ′ when the workpiece  2  is lifted by means of the lifting device  1 , on the other hand. For this purpose, the stop element  13 ,  13 ′ can be made of elastic plastic, for example, particularly rubber. The gripping arm end  9 ,  9 ′ is provided with a notch serving in an area adjacent to the stop element  13 ,  13 ′ to prevent damage to the edges of the bore openings  10 ,  10 ′ on the workpiece  2  during lifting and/or transporting. 
     The articulated connections between the individual arms  3 ,  9  and  11  are produced by commercially available screw connections. 
     Thus, while there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. Moreover, it should be recognized that structures shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.