Abstract:
The invention relates to a four post parking platform for motor vehicles, comprising two longitudinally directed platform tracks ( 20, 21 ) for receiving the vehicle, a front and rear transverse member ( 5, 6 ) which both are guided on their ends at the posts ( 1 - 4 ) in a vertically displaceable manner, flexible traction cords ( 27, 28, 28 ′) which are provided for engaging at the transverse members ( 5, 6 ) for raising and lowering the platform tracks and can be wound and unwound on spool bodies ( 60 ), a torsionally rigid shaft ( 19 ) for connecting the two spool bodies ( 60 ) to each other, and with an electrical drive assembly ( 15 ) as rotary drive for the two spool bodies ( 60 ) and the shaft ( 19 ). According to the invention, the drive assembly ( 15 ) is mounted to a vertically liftable and lowerable transverse member ( 6 ). The shaft ( 20 ) is aligned parallel to the platform tracks ( 20, 21 ) and rotatably mounted to the two transverse members ( 5, 6 ). One end of the flexible traction cord ( 27, 28 ) is fixed at the upper end of each post ( 1 - 4 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a four post parking platform for motor vehicles, comprising two longitudinally directed platform tracks for receiving the vehicle, a front and rear transverse member which connect the platform tracks to each other and are both guided on their ends at the four posts in a vertical manner, flexible traction cords which are provided for engaging at the transverse members for raising and lowering the platform tracks and can be wound and unwound on spool bodies, a torsionally rigid shaft for connecting the two spool bodies to each other, and with an electrical drive assembly as rotary drive for the spool bodies and the shaft. 
     Generally, such parking platforms are prepared for use in parking lots, particularly in underground car parks and parking garages, to be able to park two vehicles one above the other on the same floor space. For this purpose, the supporting structure consisting of transverse members and longitudinally directed platform tracks is lowered to the floor level, and by using platform-related ramps a vehicle is driven up onto the platform tracks and secured, for example by applying the parking brake or by using other stopping means, e.g. blocks. The platform tracks are lifted via their transverse members together with the supported motor vehicle by starting the drive motor until they reach an upper parking position. The lift distance is dimensioned such that a sufficiently large space is now available for driving a second motor vehicle under the lifted platform. 
     2. Description of Related Art 
     FR-PS-1 050 578 discloses a four post parking platform for two lower and two upper cars wherein two transverse members vertically guided at the four posts are raised and lowered by four traction ropes. In total, four longitudinally directed platform tracks are mounted to the two transverse members, which are used to receive two cars. Two respective lateral posts are connected to a U-shaped frame by a horizontal longitudinal rail at their upper ends. A transverse shaft is mounted to the upper end parts of the two front posts, which carries a coiling drum at each end for simultaneously winding and unwinding a front and a rear traction rope, respectively. A drive assembly is mounted to one of the front posts, which makes the two coiling drums rotate synchronously via the common transverse shaft in order to lift or lower the longitudinally directed platform tracks by means of the traction ropes. In this known parking platform the stationary arrangement of the drive assembly at the upper end of one of the posts is considered a drawback. Furthermore, non-uniform lowering and lifting movements of the platform tracks and thus tilted positions of the vehicles supported thereon may result from the different lengths of the used front and rear traction ropes. 
     U.S. Pat. No. 2,857,060 discloses a parking garage for cars, having lifting units for the vehicles on several floors. These lifting units are mounted to carriages and supporting frames displaceable on horizontal tracks for transporting the vehicles supported thereon in their lowered positions on a floor into one of the stalls. The supporting frames are lifted and lowered via winches and cables driven by motors. 
     U.S. Pat. No. 2,233,055 describes a parking platform for two cars each, which is preferably used in garages and by means of which two cars may be parked one above the other. A continuous lifting plate guided on hollow profile posts in a liftable and lowerable manner is used to receive a vehicle. Vertical racks are mounted in the hollow profile posts which engage with rotatingly driven pinions. Two respective pinions are attached to a lateral longitudinal shaft driven on its end by an electric motor. 
     Finally, a parking garage comprising an integrated lifting platform is disclosed in U.S. Pat. No. 5,335,755. This lifting platform contains two platforms mechanically coupled to each other for receiving two cars. A central motor drives two winch assemblies via transverse shafts, on which a respective traction rope is wound and unwound for lifting and lowering the platform. 
     BRIEF SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a parking platform for vehicles which makes it possible to lift, hold and lower the vehicles supported thereon in an operationally safe and uniform manner with little technical effort. 
     According to the invention this object is obtained by the fact that the drive assembly is mounted to one of the vertically liftable and lowerable transverse members, the shaft arranged parallel to the platform tracks is rotatably mounted to the two transverse members and the traction cords are fixed to the upper end of a respective post. 
     Since the drive assembly in the inventive parking platform is mounted to one of the transverse members and the longitudinally directed shaft is rotatably mounted to two transverse members, these components accompany the vertical lifting and lowering movements of the platform tracks when the drive assembly is operated. 
     A particularly safe and stable guidance of the transverse members and thus of the platform tracks mounted thereon is achieved by the fact that posts have a square cross-section and that a guide engaging multilaterally on the related post and a deflection pulley for the elastic traction cord are provided at each end of the transverse members. Advantageously, the guides engaging multilaterally on the related post contain pairs of tapered pulleys running along the outer edges of the square posts. 
     In order to guarantee secure fixing of the platform tracks in the lifted upper position with or without a car supported thereon, a respective releasable locking mechanism is provided according to a preferred embodiment of the invention at the upper end of each post, which positively locks the transverse member in the raised end position. Advantageously, the locking mechanisms at the respective post may contain rotatably attached shapes on which the transverse members support themselves in the upper parking position by means of a respective support element on their end. In order to release the respective support elements actuators may be provided to rotate the shapes in an electromagnetic, fluidic or mechanic manner. 
     In the inventive parking platform relatively broad belts made of high-tensile materials, in particular of textile or plastics fabrics, are advantageously used. In general, such belts have an extremely high tensile strength and only a relatively small wall thickness such that the diameter of a winding spool changes at a relatively small degree when a belt is wound and unwound. 
     A particularly advantageous embodiment of the inventive parking platform is distinguished in that a respective spool body is supported in each of the two transverse members for winding and unwinding one, preferably two belts, the shaft connecting the two spool bodies being disposed inside a hollow platform track and coupled to the drive assembly mounted to the rear transverse member. Due to this arrangement the particularly sensitive components are removed from the influence of the environment, such as mechanical damage or dirt. The drive assembly constituted by an electric motor having a fitted transmission is self-locking and forcibly shut down when the power supply is cut off so that further lowering movements are prevented. 
     In the inventive parking platform it is essentially important with regard to the required operation safety that an automatically responding security system for monitoring the elastic traction cord for rupture and slack is provided which safely prevents lowering movements of the transverse members, for example when the respective traction cord is ruptured. This security system may have prestressed clamping elements which are mounted to the transverse members and in case of rupture or slack of the related traction cord get into firm clamping engagement with the side wall of the respective post. 
     In a particularly advantageous embodiment the security system has rockers pivotably supported on a trunnion between the lateral bridges of the transverse members and between which the respective deflection pulley for the traction cord is mounted. These rockers have cam surfaces optionally provided with a friction lining which in case of rupture or slack of the traction cord get into clamping engagement with the side wall by a pivoting movement of the rocker. 
     In another four post parking platform according to the invention the drive assembly consisting of an electric motor and a fitted transmission is mounted to the upper end of a post. An upper longitudinally extended shaft connects the upper ends of the two posts of a longitudinal side. In each post and on the inside of the transverse rails traction cords such as link chains, traction ropes or the like are disposed which are wound or unwound on winches by a rotary movement of the shaft. 
     Advantageously, in the parking platforms constituted according to the invention posts, platform tracks, and Transverse rails are used which are manufactured by reforming, in particular bending, and welding them into hollow profiles having respective suitable rounded or angular cross-sections. The posts, Transverse rails, platform tracks and other components of the lifting platform may advantageously also be made as aluminum molds which means a simplified and inexpensive manufacture as well as lesser self-weight. Particularly, the posts, Transverse rails and platform tracks may be open or closed hollow profiles of suitable cross-sectional dimensions manufactured in special facilities by extrusion molding. The hollow profiles are acquired as half-finished products by press plants and processed further by a few simple operations. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the following an embodiment of the inventive parking platform will be described in detail with reference to the drawings, wherein: 
         FIG. 1  shows schematic overall view of a four post parking platform; 
         FIG. 1   a  shows a schematic side view of an upper end of a post; 
         FIG. 2  shows a cross-section of a post with the guide of a transverse member and the deflection support of a traction cord; 
         FIG. 3  shows the longitudinal section of the lower part of a post with a transverse member guided alongside thereof; 
         FIG. 4  shows the schematic overall view of another embodiment of a four post parking platform according to the invention; 
         FIG. 5  shows the enlarged view of the installation of a ramp to a transverse member. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The parking platform shown in  FIG. 1  contains four vertical posts  1  to  4  consisting of dimensionally rigid square hollow profiles. At the two front posts  1 ,  3  and the two rear posts  2 ,  4  a respective transverse member  5 ,  6  is guided in a vertically displaceable manner. In the area between the related posts the transverse members  5 ,  6  have a rectangular square profile. At both ends of each transverse member  5 ,  6  two tabs  7 ,  8  are provided which extend parallel to the planar side walls of the related square post. The end parts of the tab pairs extending beyond the post profile are linked to each other via a rear bolt  9 ,  10 . As can be taken from  FIG. 2  in particular, two respective tapered pulleys  11 ,  12  are disposed on each of the bolts  9 ,  10 , which represent guiding elements for the lifting and lowering movements of the transverse members  5 ,  6  and which run with their conical circumferential surface on the rounded rear corner edges of the respective post  1  to  4 . 
     A drive assembly  15  having an electric motor  16  as well as a transmission  17  connected thereto is mounted to the rear side of the rear transverse member  6  of  FIG. 1 . A pipe  18  having upper and lower deflections is mounted to the post  4  in which among others the cables for the energy supply of the electric motor  16  are arranged and protected against dirt and mechanical stress. The transmission  17  drives a shaft  19  shown by dashes in  FIG. 1  which is rotatably mounted to the ends in suitable mounting arrangements in both transverse members  5 ,  6 . 
     Two platform tracks  20 ,  21  formed in a flat square cross-section are used as receivers for a motor vehicle to be lifted. At the front ends of the two platform tracks  20 ,  21  hinged ramps  22 ,  23  may optionally be provided. The front end parts of the two platform tracks  20 ,  21  are attached to the front transverse member  5  and the two rear end parts of the two platform tracks  20 ,  21  are attached to the rear transverse member  6 . Two dimensionally rigid clamps  24 ,  25  extend beyond the surface of the two platform tracks  20 ,  21  in the range of the rear transverse member  6  and are used as end stops for a received vehicle. 
     In the embodiment as shown the transverse members  5 ,  6 , together with the platform tracks  20 ,  21 , the drive assembly  15  and the shaft  19 , form an assembly which is approximately frame-shaped and performs lifting and lowering movements guided together in a vertical manner at the posts  1  to  5 . This assembly is suspended from elastic traction cords which in the present embodiment are formed as high-tensile flat belts  27 ,  28  from a special textile or plastics material. A flat belt  27 ,  28  respectively extends on the respective inner side of each post  1  to  4 . The upper end of each flat belt  27 ,  28  is formed as a noose  29  (cf.  FIG. 1   a ) and fixed to a U-shaped clamp  30  both vertical legs of which are attached to an end plate  32  of the respective post via a respective nut  31 . This attachment of the upper ends of the respective flat belts  27 ,  28  makes it possible to adjust and readjust the respective belt length. 
     In order to secure the upper end position of the two platform tracks  20 ,  21  with their transverse members  5 ,  6  separate locking mechanisms are provided for each post which make it possible to releasably fix the transverse members  5 ,  6  in their upper lifted parking position and to safely prevent an accidental lowering of the entire assembly with or without the vehicle supported thereon. Additionally to the self-locking function of the drive assembly  15  the function of the locking mechanisms guarantees sufficient operational safety against random lowering movements. The respective locking mechanisms  35  each contain a profile plate  36  which is rotatably mounted to the respective post  1  via a bolt  37  and has a tooth-shaped projection  38 . This projection  38  is used as a support for a plate  39  shown in  FIG. 3  and attached to the upper rail of the respective transverse member  5 ,  6 . As can be taken further from FIG.  1   a , the rotatable profile plate  36  shows a circular-arc shaped long slot  40  in its upper portion wherein a pin  41  fixed to the post is guided. The length and shape of the long slot  40  indicate the magnitude of the rotating movements of the profile plate  36 . 
       FIG. 2  shows the cross-section of the post  3  consisting of a one-piece square profile. The transverse member  5  is guided at the outer wall of the post  3  by means of the two extension tabs  7  and the rear tapered pulleys  11 ,  12 . At the front outer wall of the post  3  runs a deflection pulley  45  mounted to a bolt  46  in two antifriction bearings  47  in a freely rotatable manner. With its two ends the bolt  46  is placed in a respective one of the lateral extension tabs  7  of the transverse member  5 . Furthermore, two springs  48 ,  49  are disposed on the bolt  46 , respectively, via a corresponding sleeve. Moreover, a rocker  50  consisting of two plates  51 ,  52  is arranged at this bolt  46 . The tapering end parts (see  FIG. 3 ) of these two parallel plates  51 ,  52  are connected to each other by an encased transverse bolt  53 . The end part of the two plates  51 ,  52  of the rocker  50  on the right in  FIGS. 2 ,  3  has a cam shape  54  suggested in  FIG. 3 . 
     As can be taken from  FIG. 2  the deflection pulley  45  has a recess  55  in its center portion in which a flat belt  27  is received. This recess is defined by two lateral ring-profiled portions  56 . 
     The security system described above reliably prevents an accidental lowering of a transverse member when the related flat belt turns slack or ruptures. Under normal operating conditions shown in  FIG. 3  the encased connecting bolt  53  of the rocker  50  is pushed upwards against the force of the springs  48  by resting on the firmly tightened flat belt  27  such that the cam part  54  cannot get into action. As soon as slack or a tear occur in the flat belt  28  the rocker  50  pivots about the trunnion  46  by the force of the torsion springs  48  such that the cam  54  comes into clamping engagement with the outer wall of the post  3  and thus prevents a further lowering movement of the transverse member. 
     As can be taken from  FIG. 3  the shaft  19  is provided with spool bodies  60  on its ends which are formed such that two traction cords  28 ,  28 ′ may synchronously be wound on one spool body  60 . The shaft  19  as well as the spool body  60  are located and protected inside the transverse members and the one platform track  20 , respectively. By rotating the shaft  19  by means of the drive assembly  15  two front and two rear flat belts will be wound or unwound synchronously, resulting in a uniform lifting or lowering movement of the respective transverse member and thus of the platform tracks mounted thereon. A particular advantage is the fact that the flat belts are of a very short length so that material strains do not play a part in practice. 
     In the following the embodiment of the invention shown in  FIG. 4  will be described which corresponds to the four post platform described above with reference to  FIG. 1  as regards the essential features and measures. Accordingly, components having the same structure or function are denoted by the same reference numerals and their description will not be repeated. 
     The essential difference of the parking platform according to  FIG. 4  in contrast to the embodiment of  FIG. 1  lies in the arrangement of the drive assembly  70  which in this parking platform according to  FIG. 4  is fixedly mounted to the upper end of the post  4  and drives an upper shaft  71 . The shaft  71  extents on a lateral side between a front and a rear post  3 ,  4  and is rotatably mounted to mounting arrangements  72 ,  73  at the upper end part  74 ,  75  of these two posts  3 ,  4 . The right shaft end in  FIG. 4  is connected to the driven element of the drive assembly  70  advantageously formed as a drive motor. In this embodiment according to  FIG. 4  the supporting frame construction constituted by the two wide platform tracks  20 ,  21  and the two transverse members  5 ,  6  is lifted and lowered by tractions cords, in particular by traction belts or also by traction ropes which are wound and unwound on winches, drums or spools in a suitable manner. During the lifting und lowering movements the supporting frame construction  5 ,  6 ;  20 ,  21  is guided on the posts  1  to  4  by guide shoes  76  to  79  a respective one of which is attached to an end part of the transverse members  5  and  6 . Each guide shoe encompasses the related post on three sides on the outside. An exact guide low in friction and free from wear as far as possible of the transverse members  5 ,  6  is achieved by providing gliding and rolling elements, respectively, in each guide shoe. Slide blocks provided on several surfaces that are aligned at right angles towards each other may be used as gliding elements and cylindrical or conical runners may be used as rolling elements. 
       FIG. 5  shows a particular linkage of a ramp  22  to a transverse member  5 . In the parking platform of  FIG. 5  the transverse member  5  consists of an extrusion molded hollow profile made from a light metal, preferably an aluminum material of sufficient stability. On the one side wall  80  of the transverse member  5  shown in a partial cross-section a longitudinal rail  81  obliquely pointing upwards is formed to which an integral spheroidal end part  82  is joined. At the end of the ramp  22  a holder  83  is attached by screws  84 . The ramps  22  may also be manufactured of light metal profiles or as light metal cast parts such that the screws  84  represent the preferred means of connection. If the ramps  22  are formed from flat steel blanks or made from cast iron, welding connections may be chosen instead of screw connections. A cutout  85  is formed in the holder  83 , which in  FIG. 5  opens downwards to the right and has a circular part  86 . The longitudinal rail  81  formed to the transverse member  5  meshes with the cutout  85 . The shape and size of the spheroidal end part  82  is closely adapted to the circular part  86  of the cutout  85  such that pivoting movements of the ramp  22  about the center axis of the spheroidal end part  82  are possible and due to a constriction it is not possible that the spheroidal end part  82  slips out of the circular part  86  of the cutout  85 . The linkage of the ramp  22  to the respective transverse member  5  is fast and simple. For this purpose, the respective ramp  22  merely needs to be pushed laterally onto the rail  81  with the cutout  85  of its holder  83 . 
     The invention is not limited to the embodiments and details as shown and described. Thus, features shown and/or described in an embodiment may also be applied to other embodiments in the frame of the invention. For example, this applies to the materials of the supporting constructional elements, such as posts, platform tracks, supports, which may be individually or completely be formed of light metal, preferably as an extruded profile or as a shaped flat steel construction.