Patent Publication Number: US-6702541-B1

Title: Palletless rack-type parking system with stacker crane

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to a parking system for storing a plurality of vehicles in a limited area, and more particularly, to a palletless rack-type parking for quickly, precisely and safely taking a vehicle into and/or taking it out of the parking space system using a stacker crane operable in more than two axial directions to a rack unit having a plurality of parking spaces without a separate vehicle loading pallet. 
     2. Description of the Prior Art 
     In recent years, a rapid increase of vehicles causes the absolute lacking phenomena of parking places, so it becomes serious social problems of raising the difficulty of parking following by the traffic congestion and the environmental pollution. Particularly, the problem of parking places becomes more serious in very busy midtowns due to limited parking places, so it leads to frequent illegal parking, which blocks a traffic flow resulting in the terrible traffic jams. 
     In an effort to solve such problems of illegal parking and a shortage of parking places in busy cities, there have been attempted a variety of solutions, for example, strengthening of parking regulations and enacting of ordinances which oblige building owners to establish parking places in or around their buildings. However, the expansion of parking places couldn&#39;t help having a limitation due to the difficult of securing lands in busy cities. 
     Therefore, a variety of schemes have been studied in search of a better solution for effectively parking many vehicles on limited areas. As a result of such studies, several parking systems have been proposed and widely used to store vehicles in floors in parking spaces using a mechanical drive unit. 
     Such conventional parking systems are generally classified into several types such as a circulation-type system, a puzzle-type system, an elevator-type system, etc., in accordance with a drive system. Each of the circulation-type and puzzle-type systems must store a vehicle on its exclusive parking pallet defining a parking space thereon and follow the movement of a plurality of vehicles at the same time of loading or unloading one vehicle into or it out of a parking space, so the demand for such systems falls off nowadays. In place of the circulation-type and puzzle-type systems, elevator-type parking systems have been most widely used, which can simply enter a vehicle into a designated parking space or delivery it therefrom. 
     An example of a conventional elevator-type parking system is disclosed in Korean Patent No. 0271061 which comprises an elevator for carrying a vehicle loaded pallet to a position of an empty parking space of racks formed in floors and a traction unit for moving the vehicle from the elevator into the empty parking space in a horizontal direction to store it. Of course, the delivery of a vehicle out of the parking space is performed in the reverse order to the entering of the vehicle. 
     However, the parking system must have a complex configuration because of requiring additional pallets and transact units except the elevator. During the operating of the system, a loading of the system is increased by a weight of the pallets, so it is undesirable in respect that a lot of power and much time are required for the transportation of the vehicle. 
     In particular, after the loading of the vehicle into a designated parking space of a rack, if some vehicle-free or empty pallets are placed on the parking places, the elevator is moved to the empty parking space to pull out the empty pallet therefrom and then ready for another parking operation at a carrying-in position to be on standby. During being on standby, the elevator carries the empty pallet loaded thereon to be put on another pallet-free parking space according to a delivery control signal and then again moved from the standby position to a target parking space to store another vehicle. As a result, the parking system using such movable pallets undesirably needs a relative longer time for loading vehicles into or unloading them out of the parking spaces of racks. 
     In order to overcome these and those problems, there has been proposed a palletless rack-type parking system for loading or unloading vehicles into or out of parking spaces of multistory racks without requiring additional pallets. Examples of palletless rack-type parking system are referred to International Laid-open Publication No. WO87/02405 entitled “A Vertical Storage Apparatus and Control Method Thereof” and Japanese Patent Laid-open Publication No. Heisei 5-52058 entitled “A Stacker Crane-type Parking Garage. 
     The vertical storage apparatus disclosed in WO 87/02405 comprises a single rack unit including an elevation space and multi-storied storage racks provided on at least one side out of the left side, right side, front side and rear side of the lift space. The rack comprises a plurality of storage forks normally arranged on every story thereof to form two rows spaced apart in a regular interval from each another. The elevation space defined between the storage spaces comprises a pair of elevation forks mounted to be moved up and down therein to carry vehicles in a vertical direction. The storage fork reciprocates between a storage space and the elevation space by a drive unit (not shown) in a manner to be moved toward or away from a position above or under the fork bars of the elevation forks according to the guidance of a horizontal guide beam of the rack. The elevation fork comprises a pair of elevation forks faced to each other, fork bars of which are vertically passed through between fork bars of the storage fork to be placed at a loading/unloading position in the elevation space, without interfering with the fork bars of the storage fork. 
     In a storage operation, the elevation fork loaded with a vehicle on its fork bars is first moved upward in the elevation space to a desired position higher than that of a target empty storage fork. The target empty storage fork is horizontally moved inward into the elevation space by means of the drive unit to a loading position under the fork bars of the elevation fork. The elevation fork is moved downward to cross the fork bars of the storage fork in order to load the vehicle onto the storage fork. The storage fork is returned by means of the drive unit to its original position, so that vehicle is entered into a storage space of the rack. 
     However, the vertical storage apparatus free of a pallet has problems in that the drive unit must be provided to operate each storage fork, independently, and the moving distance of the elevation fork is relatively longer, because the elevation fork passes through or cross the storage fork, vertically, during a loading or unloading operation. 
     Furthermore, the target storage fork must be horizontally moved to a loading or unloading position under or above an elevation fork 2 without causing any interference between the vehicle and any one of the storage and elevation forks. For it, a substantial travel of the elevation fork is a sum of adding an operational allowance to two heights of the storage fork and the elevation fork, which takes a relative longer time for the storage and delivery of the vehicle, so the vertical storage apparatus has a limitation to the reduction of time taken during a loading or unloading operation. 
     The loading structure for stacker crane-type parking garages described in Japanese Patent Laid-open Publication No. Heisei. 5-52058 comprises two racks installed on a support surface to be spaced apart at an interval from each other and a stacker crane (not shown) mounted between the racks to enable a lift fork to be moved up and down with being loaded with a vehicle. Multiple cantilever support bars are provided on the right and left shelf members of each rack to form a storage space inside horizontal support beams. The lift fork includes a plurality of arm bars provided on both sides of a body of the stacker crane to cross the support bars without any interference during being lifted or lowered in a protruded state. 
     In a loading operation, the lift fork loaded with the vehicle is first moved upward in an elevation space to a desired position higher than that of the support bar and then horizontally to be entered into a target empty storage space of the racks. Thereafter, the lift fork is moved downward to cross the support bar of the rack. During the downward movement of the lift fork, the arm bars pass through the spaces between the support bars without any interference to load the vehicle onto the support bars. The lift fork is, thereafter, laterally moved from the position under the support bars to a position inside the elevation space, prior to being moved to a standby position where another vehicle is loaded on the lift fork. 
     However, the loading structure is constructed such that the lift fork passes through the support bars 6 from above its upper portion to below its lower portion thereby to return to its original position, so it has a limitation to the time reduction in loading the vehicle into or unloading it out of the storage space due to a relatively longer traveling distance. Therefore, a substantial travel of the lift fork is a sum of adding an allowance for entering into/retreating from the rack to two heights of the support fork and the lift fork. It has a limitation to the shortening of a vertical traveling distance of the lift fork. 
     SUMMARY OF THE INVENTION 
     According to the present invention, in order to resolve these and those problems, an object of the present invention is to provide a palletless rack-type parking system for quickly, precisely and safely taking a vehicle into and/or taking it out of the parking space system using a stacker crane operable in more than two axial directions to a rack unit having a plurality of parking spaces without a separate vehicle loading pallet. 
     In order to accomplish the object of the present invention, a palletless rack-type parking system comprises: 
     a plurality of multistory racks each having a plurality of parking spaces in a lattice form and arranged on a support surface to be spaced apart from each another at a regular interval to form vertical spaces between them; 
     a plurality of storage fork bars each including a first projection tab projected from a predetermined portion of a lower surface thereof to have a predetermined height and horizontally mounted on an upper surface of a first support beam in a regular interval through the first projection tap to cross the support beam in a right angle, at least one end of which is projected longer from the support beam of the rack in a beam form; 
     a transporting fork including a plurality of transporting fork bars each with a second projection tap projected from a predetermined portion of a lower surface thereof to have a predetermined height, in which the transporting fork bar is not higher than that of the storage fork bar, and arranged in a regular interval in parallel to each another to be alternately positioned between the storage fork bars, and a second support beam arranged to cross the storage fork bar in a right angle and for supporting the second projecting tap facing its lower surface; and 
     a stacker crane installed in each vertical space between two neighboring racks and operable in more than two-axial directions of leftward, rightward, upward and downward with the transporting fork being mounted thereon, in which the transporting fork laterally approaches the storage fork bars and the transporting fork bars enter into, moves up and down and retreats from the storage fork with being alternately overlapped between the storage fork bars. 
     According to the present invention, it is preferable that the upper surface of the transporting fork bar is positioned higher or lower than the upper surface of the storage fork bar by a predetermined level without any interference between them, when the transporting fork laterally approaches or withdraws from the storage fork bar. 
     It is more preferable that the heights of the storage fork bar and the transporting fork bar are equal to each other and the heights of their first and second projection tap are equal to each other, the height of the projection taps is determined to be at least larger than a level difference to be kept between the upper surfaces of the transporting fork bar and the storage fork bar, when the transporting fork laterally approaches or withdraws from the storage fork bar. 
     Accordingly, when the transporting fork approaches or withdraws out of the storage fork bar, the present invention enables any one of fork bars to be lifted up to at least minimum allowance gap relative to the other. It is possible for a vehicle to be quickly and safely taken into or taken out of a parking space without causing any interference between the fork and its relative fork bar and also excludes the use of a separate pallet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is schematically a front view illustrating a palletless rack-type parking system using a stacker crane according to the present invention; 
     FIG. 2 is a plan view illustrating the palletless rack-type parking system of FIG. 1; 
     FIG. 3 is a side view illustrating the palletless rack-type parking system taken along the line III—III of FIG. 2; 
     FIG. 4 is an enlarged perspective view illustrating racks of the palletless rack-type parking system in part according to the present invention; 
     FIG. 5 is a side view illustrating the rack of FIG. 4 on which a vehicle is parked; 
     FIG. 6 is a plan view illustrating a transporting fork of the palletless rack-type parking system according to the present invention; 
     FIG. 7 is a side view illustrating the transporting fork viewed in a direction as shown by the arrow VII of FIG. 6, with a vehicle loaded on the transporting fork as shown by the phantom line; 
     FIG. 8 is a cross-sectional view illustrating the transporting fork taken along the line VIII—VIII of FIG. 6; 
     FIG. 9 is a side view illustrating the storage fork bar and the transporting fork of the palletless rack-type parking system according to the present invention; 
     FIG. 10 is a schematic plan view illustrating a standby state of the palletless rack-type parking system for entering and delivering a vehicle according to the present invention; 
     FIGS. 11 a ,  11   b ,  11   c  and  11   d  are side views illustrating the parking procedures of the palletless rack-type parking system in orders according to the present invention; 
     FIGS. 12 a ,  12   b ,  12   c  and  12   d  are side views illustrating the delivering procedures of the palletless rack-type parking system in orders according to the present invention; 
     FIG. 13 is a cross-sectional view taken along the line XIII—XIII of FIG. 11 b ; and 
     FIGS. 14 and 15 are schematically side views illustrating important elements of a palletless rack-type parking system using a stacker crane according to other embodiments of the present invention, respectively. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. 
     Referring to FIGS. 1 to  5 , according to a primary embodiment of the present invention, a palletless rack-type parking system using a stacker crane comprises a plurality of racks  10  arranged in a lattice form to be spaced away in a regular interval from each another in order to have a plurality of parking spaces  14 , a plurality of storage fork bars  20  mounted in each of the parking spaces  14  of the rack  10  to support a vehicle C thereon and a transporting fork  30  arranged to take the vehicle C into or take it out of the storage fork bar  20  as it laterally approach or withdraw from the storage fork bar  20  and a stacker crane  40  moving the transporting fork  30  in at least two axial directions, for example three axial directions of forward and backward, leftward and rightward, upward and downward. 
     Each rack  10  fundamentally comprises a plurality of vertical posts  11  arranged in two rows to be spaced away in a regular interval from each another and a plurality of horizontal support beams  12  and  13  arranged to lie in a right angle between the neighboring ports  11 . The horizontal support beams  12  and  13  are mounted on every regular height along the lengthwise portion of the posts  11  to form a plurality of parking spaces  14  in a regular vertical interval in the rack  10 . 
     The storage fork bar  20  is in a long plate form with predetermined thickness and width, which is mounted straightly and widthwise on the upper surface of a longitudinal first horizontal support beam  13  to be in a right angle therewith. A plurality of storage fork bars  20  are arranged along the lengthwise of the horizontal support beam  13  to be spaced away in an interval larger than its thickness from each another. 
     At least one end of the storage fork bar  20  is in the form of a cantilever beam horizontally projected longer from the horizontal support beam  13  to allow the transporting fork  30  to laterally approach or withdraw from the storage fork bars  20 , with the fork bars  32  of the transporting fork  30  being alternatively overlapped between the storage fork bars  20 . Therefore, the storage fork bar  20  is formed on the whole as a fork-shaped configuration. 
     Each storage fork bar  20  includes two second projection taps  21  having a predetermined height, which is integrally provided on the lower surface thereof to be spaced away in an interval from each other. The storage fork bar  20  is horizontally mounted through the first projection taps  21  on an upper surface of a first horizontal support beam  13  of the rack  10 . 
     Herein, it is noted the storage fork bars  20  may be entirely mounted on the support beam  13  throughout the parking space  14  of the rack  10 , but it is preferable that the storage fork bars  20  include a front fork bar group  22  and a rear fork bar  23  spaced away from each other to be arranged to support only parts on which a vehicle C is laid, for example front wheels W f  and rear wheels W r . 
     On the other hand, a distance between the front and rear wheels of the vehicle C becomes different according to a vehicle model. Considering it, it is necessary to construct the rear fork bar group  23  to have a relative wider width “S 2 ” than a width “S 1 ” of the front fork bar group  22 , as shown in FIG.  5 . 
     An interval between the front and rear fork bar groups  22  and  23  is determined to be larger than a shortest wheelbase in vehicles on the market. The width “S 2 ” of the rear fork bar group  23  is determined to be larger than a distance difference between a longest wheelbase and a shortest wheelbase in vehicles on the market. Of course, the vehicles considered in design of the parking system of the present invention are limited to vehicles that may be parked in the system without causing any problem. 
     The width “S 1 ” of the front fork bar group  22  is preferably determined to be larger than a largest outer diameter in tires. The storage fork bars  20  constituted as the front fork bar group  22  has a different height from each another to correspond to a circular tread of the front wheels W f . 
     Therefore, the front fork bar group  22  forms a curved depression coinciding with an arc tread of the front wheels. The curved depression of the front fork bar group  22  functions to prevent an undesired movement of the vehicle C parked on the storage fork bars  20  as a reference base. 
     It is noted that the rack  10  and the storage fork bar  20  can have somewhat different configuration according to an installing position of the rack. 
     That is, in case of an edge rack  10   a  positioned at the outmost side of a plurality of racks  10 , the storage fork bars  20   a  are projected only from one side of the rack  10   a , because the transporting fork  30  approaches and withdraws only in one direction from the left and right sides of the storage fork bar  20   a , thereby allowing the storage of vehicles C in one row of the edge rack  10   a.    
     In order to allow the fork bars of the transporting fork  30  to laterally and smoothly approach or withdraw from the storage fork bars  20   a  with being horizontally alternated with each other, it is necessary to substantially project the ends of the storage fork bars  20   a  from the support beam  13  arranged on the transporting fork approaching side of the edge rack  10   a . However, if the storage fork bars  20   a  are arranged on the middle portion of the support beam  13  in a normal manner, the end rack  10   a  must have an idle space necessary for projecting the end of the storage bars  20   a  out of it, so it increase an installing area of a system. For it, a width of the rack  10   a  may be reduced to avoid the idle space. At that case, it is very unfavorable for the structural safety of the rack  10   a.    
     Therefore, it is preferable to allow the projection of the storage bar  20   a  out of the edge rack  10   a  by a predetermined length to enter the transporting fork  30  into or withdraw it from the storage bar  20   a , whereby the long horizontal support beam  13  is mounted at its both ends to each of two short horizontal support beam  12  to be leaned inward toward an outmost post  11  of the edge rack  10   a  opposite to the transporting fork approaching side. For it, the storage fork bar  20   a  includes first projection taps  21  formed at its one end opposite to the transporting fork approaching side and a position near to its middle portion. The storage fork bars  20   a  form a desired cantilever beam that allows the transporting fork  30  to laterally and smoothly approach them from the transporting fork approaching side. 
     The support beam  13 , arranged to the transporting fork approaching side of each edge rack  10   a , is thus eccentrically positioned inward from the middle portion of each storage fork bar  20   a  opposite to the transporting fork approaching side in order to allows the transporting fork  30  to completely approach the storage fork bars  20   a  in a horizontal direction. In that case, an eccentric amount of the support beam  13  of he end rack  10   a  is determined to be at least larger than a width of a support beam  31  of the transporting fork  30 . The support beam  31  of the transporting fork  30  may be occasionally referred to as a second support beam later herein so as to distinguish it from the first support beam  13 . Therefore, it allows vehicles C to almost completely fill the parking spaces  14  of the racks  10   a  without leaving a large idle space in the racks  10   a  and achieves a desired structural stability of the racks  10   a.    
     Intermediate racks  10   b  are installed between the outmost racks  10   a , from both side of which vehicles C are taken into or taken out of the storage fork bars  20   b  in two rows. The storage fork bar  20   b  of the intermediate rack  10   b  have a length twice as long as that of the storage fork bars  20   a  of the end racks  10   a . The storage fork bars  20   b  cross two longitudinal horizontal support beams  13  in a right angle to allows their both ends to be projected outside from each of the two support beams  13  opposite to each other, thereby creating an equal-arm beam structure. The storage fork bar  20   b  of the intermediate rack  10   b  includes two lower projecting taps  21  formed on two positions to be spaced apart in a constant interval from the middle portion of the storage fork bar  20   b  opposite to each other. 
     In order to allow a complete lateral approach of a transporting fork  30  relative to the storage fork bars  20   b  of the intermediate rack  10   b , the support beam  13  is positioned inward from both ends of each transporting fork bars  20   b  by more than at least ½ of a sum of a length of the transporting fork bar  32  and widths of the first and second support beams  13  and  31 . 
     As shown in FIGS. 6 and 7, the transporting fork  30  comprises a plurality of transporting fork bars  32  arranged in a regular line with the storage fork bar  20  and a support beam  31  integrally mounted on the lower middle surface of the transporting fork bars  32  to cross the transporting fork bar  32  in a right angle, thereby supporting the transporting fork bars  32 . 
     The transporting fork bar  32  is made in the form of a long strip with a predetermined thickness and width in the same manner as that of the storage fork bar  20 . The transporting fork bars  32  are mounted on the upper surface of the second support beam  31  with being raised widthwise, which are spaced apart in an interval larger than a thickness of the storage fork bar  20  to be laterally and smoothly superposed between the storage fork bars  20 . 
     As shown in FIGS. 8 and 9, the transporting fork bar  32  includes a projection tap  33  having a predetermined height integrally formed on the lower middle surface thereof. The transporting fork bar  32  is mounted to the support beam  31  through the lower projection taps  33 . The lower projection tap  33  of the transporting fork bars  32  may be occasionally referred to as a second lower projecting tap so as to distinguish them from the first lower projection taps  21 . And, the transporting fork bars  32  may be entirely installed on the second support beam  31 , but it is preferable that the transporting fork bars  32  are sectioned into a front fork bar group  34  and a rear fork bar group  35  so as to separately support the front wheels W f  and rear wheels W r  of a vehicle C in the same manner as that of the storage fork bars  20 . 
     The interval between the front and rear fork bar groups  34  and  35 , each width of the front and rear fork bar groups  34  and  35  and a shape of the front fork bar group  34  are designed in the same manner as those of the storage fork bars  20 , the detailed explanation of which is omitted for the purpose of avoiding the overlapping. 
     A height “a” of the storage fork bars  20  is equal to a height “b” of the transporting fork bars  32 , and a height “c” of the first lower projecting taps  21  is equal to a height “d” of the second lower projecting tap  33 . Each of the heights “c” and “d” of the first and second lower projecting taps  21  and  33  is determined to be at least larger than an operational allowance “g 1 ” or “g 2 ” defined between the upper surfaces of the transporting fork bar  32  and the storage fork bar  20  to avoid any interference with the vehicle C, when the transporting fork bar  32  laterally approach or withdraw from the storage fork bar  20  to load or unload the vehicle. 
     For example, when the transporting fork  30  loaded with a vehicle C laterally approaches the storage fork bar  20 , it is necessary to position the upper surface of the transporting fork bar  32  at a level higher than the upper surfaces of the storage fork bars  20  by an allowance “g 1 ” to avoid any inference between the vehicle C and the upper surface of the storage fork bar  32 . 
     On the contrary, when the transporting fork  30  withdraws from the storage fork bar  20  after loading the vehicle C onto the storage fork bar  20 , it is required to position the upper surface of the transporting fork bar  32  at a level lower than the upper surface of the storage fork bar  20  by a lower allowance “g 2 ” in order to avoid any interference between the vehicle C and the upper surface of the transporting fork bar  32 . Of course, the delivery of the vehicle C out of the storage fork bar  20  of a target parking space is performed contrary to the procedures of the vehicle storage. 
     Therefore, during the advancing and retreating of the transporting fork  30 , the storage fork bar  20  has to be free from the interference with the support beam  31  of the transporting fork  30 , and the transporting fork bar  32  has to be free from the interference with the support beam  13  of the storage fork bar  20 . Each of the heights “c” and “d” of the first and second projection taps  21  and  33  is thus determined to be at least larger than each of the operational allowances “g 1 ” and “g 2 ”. 
     The upper and lower operational allowances “g 1 ” and “g 2 ” are set at the minimum gaps which allows the storage and transporting fork bars  20  or  32  to be free from the interference with the vehicle C which is transported by the transporting fork  30  or loaded on the storage fork bars  20 . 
     A stacker crane  40  is mounted in a vertical space between racks  10  to move forward and backward along rails  50  mounted on a ceiling and bottom of a system, longitudinally. A carriage  42  is moved upward and downward along masts  41 . The transporting fork  30 , in place of a conventional laterally movable attachment fork, is installed in the carriage  42  to move the transporting fork  30  leftward and rightward by a drive unit  43  therein. 
     The drive unit  43  may be in the form of various types, but it has a two-stage sliding structure that is at the same time to quickly load the vehicle C onto or unload it from the storage fork bars  20 . 
     For example, as shown in FIG. 8, a slider  44  is installed on the carriage  42  to engage a rack gear  45  with two pinion gears  46 . A chain  48  driven by a motor  47  is installed on the slider  44  to rotate the pinion gears  46 . A bracket  49  is provided at an appropriate position of the chain  48  to mount the transporting fork  30  thereon. 
     In order to load the vehicle C on the transporting fork  30  or delivery the vehicle C taken out of the storage fork bar  20  of the rack  10 , there must be provided an entering/delivering apparatus at an exit/entrance of a system, which may be constructed as various types. 
     As shown in FIG. 10, an example of the entering/delivering apparatus is shown. A parking space  14  formed at the foremost position of one edge rack  10  is designated as a standby space  15  for entering/delivering vehicles C to be communicated with an exit/entrance of a housing (not shown) covering the racks  10 . In that case, a floor  16  is preferably laid on an area free of the storage fork bar  20  in the standby space  15 , which is flush with the storage fork bars  20 . The floor  16  forms a driver&#39;s passage that allows a driver to easily and safely pass through the standby space  15 . If necessary, an exit or entrance door may be provided in the housing for drivers. In case of intermediate racks  10   b  having two rows of parking spaces  14  per every story, one foremost parking space  14  may be designated as a standby space  15 , and other foremost parking space  14  may be used as a driver&#39;s passage. 
     The operation of a palletless rack-type parking system with stacker cranes according to the present invention will be described herein below with reference to FIGS. 11 a  to  11   d , FIGS. 12 a  to  12   d , and FIG.  13 . 
     When parking a vehicle C in a designated parking space  14  of a rack  10 , the vehicle C is moved into a standby space  15  of the rack  10  until the front and rear wheels W f  and W r  of the vehicle C are completely seated on the storage fork bars  20  of the front and rear fork bar groups  22  and  23 , as shown in FIG.  10 . 
     A parking system is, thereafter, operated under the control of a control unit (not shown) to laterally move the stacker crane  40  from the vertical space of the rack  10  into the standby space  15  with the transporting fork  30  mounted thereon. The vehicle C is thus loaded on the storage fork bars  20  of the standby space  15  through the transporting fork  30 . Next, the later operating of the transporting fork bar  20  is the same as that of the vehicle delivery as will be described later herein. 
     When the transporting fork  30  that the vehicle C is loaded on withdraws from the standby space  15 , the stacker crane  40  is moved along the rails  50  and, at the same time, the carriage  42  is moved upward or downward along the mast  41  to an empty parking space  14  of the rack  10  in the shortest distance from the standby space  15 . At that time, as the stacker crane  40  is operated under the control of a sensor (not shown, the transporting fork  30  is stopped at the position around the designated parking space  14  that the upper surface of the transporting fork bar  32  are raised upto a level higher than the upper surface of the storage fork bars  20  by the upper allowance “g 1 ”, as shown in FIG. 11 a.    
     As shown in FIG. 11 b , according to the operation of the drive unit  43  installed on the carriage  42 , the transporting fork  30  laterally approaches the storage fork bar  20  to force the transporting fork bars  32  to be alternately positioned between the storage fork bars  20 . At that time, the support beam  31  desirably approaches a position just around the support beam  13  placed at the transporting fork approaching side of the storage fork bar  20  without interfering with the upper surface of the storage fork bar  20 , because the transporting fork bar  32  includes a projecting tap  33  formed on the lower middle surface thereof and having a predetermined height “d” larger than the upper allowance “g 1 ”. 
     At the same time, the transporting fork bars  32  are completely advanced into the storage fork bars  20  without because the support beam  13  on the transporting fork approaching side is positioned inside to be leaned toward the opposite direction to the transporting fork approaching-side by a distance at least larger than ½ of a sum of a length of the storage fork bar  20  and widths of the first and second support beams  13  and  31 . 
     Thereafter, as shown in FIG. 11 c , the carriage  42  of the stacker crane  40  is moved downward by a height equal to a sum of the upper and lower operational allowances “g 1 ” and “g 2 ”. It gets the upper surface of the transporting fork bars  32  to be positioned at a level lower than the upper surfaces of the storage fork bars  20  by the lower allowance “g 2 ”, thereby enabling the vehicle C to be loaded from the transporting fork bars  32  onto the storage fork bars  20 . 
     This case also doesn&#39;t not causes any interference between the transporting fork bars  32  and the support beam  13  of the storage fork bars  20 , because a height “c” of the lower projection tap  21  of the storage fork bars  20  is determined to be at least larger than the lower allowance “g 2 ”. 
     As shown in FIG. 11 d , after loading the vehicle C onto the storage fork bars  20 , as the drive unit  43  of the stacker crane  40  is returned to its original position in the elevation space, the transporting fork  30  laterally withdraws from the storage fork bars  20  thereby to accomplish the loading operation for storing the vehicle C on the storage fork bars  20 . 
     On the contrary, In case of taking the vehicle C out of a designated parking space  14  of a rack  10 , as shown in FIG. 12 a , the empty transporting fork  30  is moved by the carriage  42  of the stacker crane  40  to a designated parking space  14  loaded with a vehicle C to be delivered. At that time, the upper surface of the transporting fork bar  32  is placed at a level lower than the upper surface of the storage fork bar  20  by the lower allowance “g 2 ” contrary to be placed at time of the loading operation. 
     As shown in FIG. 12 b , the transporting fork  30  laterally approaches the storage fork bars  20  to be alternately supposed with the storage fork bars  20 . And then, as shown in FIG. 12 c , the transporting fork  30  is moved upward by a height equal to the sum of the upper and lower allowances “g 1 ” and “g 2 ” thereby position the upper surfaces of the transporting fork bars  32  at a level higher than the upper surfaces of the storage fork bars  20  by the upper allowance “g 1 ”. It enables the vehicle C to be loaded from the storage fork bars  20  onto the transporting fork bars  32 . 
     As shown in FIG. 12 d , after completing the loading of the vehicle C onto the transporting fork  30  as described above, the transporting fork  30  is returned to its original position in the elevation space by the drive unit  43  and then moved to the standby space  15  of the rack  10  by the stacker crane  40 . When the transporting fork  30  loaded with the vehicle C reaches a position around the standby space  15 , the transporting fork  30  laterally approaches the storage fork bars  20  of the standby space  15  to load the vehicle C onto the storage fork bars  20  in the same manner as those of the loading operation. 
     As described above, according to the primary embodiment of the present invention, the palletless rack-type parking system enables the transporting fork  30  to laterally approach or withdraw from the storage fork bar  20  at an almost equal level with the storage fork bars  2  and to move the transporting fork  20  upward and downward by the sum of the upper and lower allowances “g 1 ” and “g 2 ” at a minimum, thereby loading or unloading the vehicle C. It simplifies the configuration of a parking system and minimizes the time taken in entering and delivering the vehicle C. 
     FIG. 14 shows a palletless rack-type parking system with stacker cranes according to a second embodiment of the present invention. 
     According to the second embodiment, a height “b” of a transporting fork bar  72  of a transporting fork  70  is subject to be less than a height “a” of a storage fork bar  60 . A projection tap  73  is provided on the lower surface of each transporting fork bars  72  to have a predetermined height “d 1 ”. 
     A height difference between the storage fork bar  60  and the transporting fork bar  72  is determined to be larger than upper or lower operational allowance “g 1 ” or “g 2 ”. A height “d 1 ” of the projection tap  73  is determined to be larger than a sum of the upper and lower operational allowances g 1  and g 2  which are required by the transporting fork  70  to smoothly load or unload the vehicle C onto or from the storage fork bars  60 , that is, d 1 &gt;g 1 +g 2 . 
     In that case, the entire height “d 1 +b” of the transporting fork bar  72  plus the lower projecting tap “d 1 ” is larger than the height “a” of each storage fork bar  60  by at least the upper allowance “g 1 ”. Therefore, even though the transporting fork  70  laterally approaches the storage fork bar  60  with the upper surfaces of the transporting fork bars  72  placed at a level higher than the upper surface of the storage fork bar  60  by the upper allowance “g 1 ”, the support beam  71  of the transporting fork  70  effectively can avoid any interference with the end of the storage fork bars  60  due to the taps  73 . 
     In addition, the height “a” of the storage fork bar  60  is larger than the height “b” of the transporting fork bar  72  by at least the lower allowance “g 2 ”. Therefore, after completely approaching the storage fork bars  60 , the transporting fork  70  is smoothly moved downward in a vertical direction relative to the storage fork bars  60  to position the upper surface of the transporting fork bar  72  at a level lower than the upper surface of the storage fork bar  60  by the lower allowance “g 2 ”. The transporting fork  70  thus effectively loads the vehicle C onto the storage fork bars  60  without causing any interference between the lower surface of the transporting fork bar  72  and the support beam  13  of the storage fork bar  60 . 
     Particularly, in the second embodiment, the front storage bars  22  may have different heights in their positions, but it is preferable that the storage fork bars  22  have the same height to each another and respectively includes a connecting tap (not shown) mounted in different heights from each another on its lower portion to be increased from the center toward both outsides, thereby forming its entire shape as a arc cross-section. In that case, the transporting fork bar  72  also is provided with the projection tap  73  of the height “d 1 ” that is increased from the center toward both outsides. 
     FIG. 15 shows a palletless rack-type parking system with stacker cranes according to a third embodiment of the present invention. 
     According to the third embodiment, the palletless rack-type parking system is constructed so that a transporting fork bars  92  of a transporting fork  90  and a storage fork bars  80  is contrary to those of the second embodiment. That is, a height “a” of the storage fork bar  80  is set to be less than a height “b” of a transporting fork bar  92  by at least operational allowance “g 1 ” or “g 2 ”. In addition, a lower projection tap  81  is provided at the lower surface of the storage fork bar  80  with a predetermined height “C 1 ”, and the storage fork bars  80  are mounted to the support beam  13  of the rack  10  through the lower projection taps  81 . 
     A height “C 1 ” of the lower projection tap  81  of the storage fork bar  80  is determined to be larger than a sum of the upper and lower allowances “g 1 ” and “g 2 ” which are required to enable the transporting fork  90  to smoothly load or unload a vehicle C onto or from the storage fork bars  80 . The operation of the parking system is performed in a manner similar to that of the second embodiment, and further explanation is thus not deemed necessary. 
     As described above, according to the present invention, a palletless rack-type parking system enables a transporting fork to be moved upward or downward within a minimum allowance that a vehicle is not interfered with transporting fork bars or storage fork bars of the transporting fork are horizontally alternated with the storage fork bars, when the transporting fork completely approaches the storage fork bar in a horizontal direction, thereby loading the vehicle onto or unloading it from the storage fork bars. Therefore, the parking system quickly loads or unloads vehicles into or from parking spaces of racks. 
     In addition, the transporting fork directly supports the vehicle on its transporting fork bars when loading or unloading the vehicle onto or from the storage fork bars of the rack. It needs not a separate pallet. 
     Therefore, the present invention has advantages in that quick and precise loading or unloading of vehicles into or from parking spaces can be accomplished and the operational reliability is improved, considerably. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.