Abstract:
The invention provides a stacker crane, configured to move on a single rail provided along one or more racks, includes: a first wheel that moves on the rail; a second wheel that moves on the rail, and that is disposed spaced apart from the first wheel in a fore-and-aft direction; a vehicle frame supported by the first wheel and the second wheel; first drive supported by the vehicle frame for driving the first wheel. The vehicle frame includes: a first support frame for supporting the first wheel and the first drive means; a second support frame for supporting the second wheel; and a connection frame that connects the first support frame and the second support frame. The stacker crane also includes a first support post that extends vertically and whose lower end portion is connected to the first support frame; a second support post that extends vertically and whose lower end portion is connected to the second support frame; and a vertically movable platform that is guided by the first support post and the second support post, and that can move vertically with respect to the vehicle frame.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to stacker cranes.  
         [0002]     Stacker cranes transport articles by moving a travel vehicle along a travel rail and raising and lowering a vertically movable platform on which an article is placed. In conventional configurations, the travel vehicle is constructed by connecting the lower end portions of a pair of front and rear support posts via a connection frame, and connecting a support frame that supports wheels and drive means to each of the front face of the front-side support post and the rear face of the rear-side support post, so that the lower end portions of the support posts are connected by and supported on the connecting frame and the support frames (see JP 2003-212308A, for example).  
         [0003]     When the stacker crane is long in the fore-and-aft direction, the range over which it moves becomes wide, and thus although it is preferable for the stacker crane to have a short fore-and-aft length, it was not possible to narrow the gap between the pair of front and rear support posts more than a set spacing that corresponds to the width of the spacing between storage racks to which articles are transferred. Accordingly, in order to shorten the fore-and-aft length of the stacker crane, it is possible for the lower ends of the support posts to be connected by and supported on the forward end portion or the rear end portion of the travel vehicle so as to shorten the fore-and-aft length of the travel vehicle. In the conventional configuration described above, however, the support frames are connected to the front face of the front support frame and to the rear face of the rear support frame, and the support frames and all of the drive means and travel wheels supported on the support frames are positioned either in front of or behind the support posts. This causes the front end portion and the rear end portion of the travel vehicle to project significantly outward from the positions where the support posts are supported and thus increases the fore-and-aft length of the travel vehicle and makes it difficult to shorten the fore-and-aft length of the stacker crane.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention was arrived at in view of the above circumstances, and it is an object thereof to provide a stacker crane whose length in the fore-and-aft direction can be shortened with ease.  
         [0005]     A stacker crane according to the present invention is configured to move on a single rail provided along one or more racks, and comprises: a first wheel that moves on the rail; a second wheel that moves on the rail, and that is disposed spaced apart from the first wheel in a fore-and-aft direction; a vehicle frame supported by the first wheel and the second wheel; first drive means supported by the vehicle frame for driving the first wheel. The vehicle frame comprises: a first support frame for supporting the first wheel and the first drive means; a second support frame for supporting the second wheel; and a connection frame that connects the first support frame and the second support frame. The stacker crane also includes a first support post that extends vertically and whose lower end portion is connected to the first support frame; a second support post that extends vertically and whose lower end portion is connected to the second support frame; and a vertically movable platform that is guided by the first support post and the second support post, and that can move vertically with respect to the vehicle frame.  
         [0006]     Since the support posts are arranged on support frames that support, at a minimum, the wheels, it is possible to provide a design that has the potential to allow the length of the stacker crane in the fore-and-aft direction to be shortened. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a lateral view of a stacker crane.  
         [0008]      FIG. 2  is a cross-sectional view of a support post.  
         [0009]      FIG. 3  is a lateral view of a travel vehicle.  
         [0010]      FIG. 4  is a lateral view of a travel drive unit.  
         [0011]      FIG. 5  is a front view of the travel drive unit.  
         [0012]      FIG. 6  is a front cross-sectional view of the travel drive unit.  
         [0013]      FIG. 7  is a plan cross-sectional view of the travel drive unit.  
         [0014]      FIG. 8  is a lateral view of the adjustment means.  
         [0015]      FIG. 9  is a front view of an adjustment mechanism. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Hereinafter, embodiments of a stacker crane according to the present invention are described with reference to the drawings. Throughout the specification the term “fore-and-aft direction” is used to indicate the orientation along which the stacker crane A moves.  
         [0017]     As shown in  FIG. 1 , a stacker crane A travels over a single travel rail  2  disposed on a floor surface along a work path formed between storage racks. A travel vehicle  3  that travels along the travel rail  2  is provided with a pair of support posts  5 , with a spacing between them in the longitudinal or the fore-and-aft direction, that serve as guides for raising and lowering a vertically movable platform  4 . The upper end portions of the support posts  5  are linked to each other by an upper frame  7  that is guided along a guide rail  6  disposed above the work path. The stacker crane A automatically moves over the work path and transfers articles to and from the storage racks. The stacker crane A and the storage racks together make up an automated warehouse.  
         [0018]     A raising and lowering wire  13  is connected to the front and rear end portions of the vertically movable platform  4 , supporting the vertically movable platform  4  in a suspended manner. Two article transferring devices  14  are arranged side by side in the front-to-back direction, that is, the direction in which the travel vehicle  3  moves, on the vertically movable platform  4 , and the article transferring devices  14  transfer articles between the storage racks and the stacker crane A.  
         [0019]     As for the raising and lowering wire  13 , one of its ends is connected to the vertically movable platform  4 , its middle portion is wound over driven pulleys  15  that are provided on the upper frame  7 , and its other end is connected to a winding drum  17  that is supported on one of the pair of front and rear support posts  5 . Accordingly, the vertically movable platform  4  is drivingly raised and lowered through the action of winding out or winding in the raising and lowering wire  13  by rotatively driving the winding drum  17  forward and in reverse with an electric motor for raising and lowering M 2 .  
         [0020]     As shown in  FIG. 2 , the support posts  5  serve as guides for guide rollers  8  (guided portions) provided on the vertically movable platform  4 . A recessed portion is provided in the longitudinal direction in one face of each of the support posts  5 , and a projecting portion  5   a  (guide portion) is provided within the recessed portion. The configuration is such that the guide rollers  8  are guided by the projecting portion  5   a , thereby guiding the vertically movable platform  4  along the raising and lowering path.  
         [0021]     As shown in  FIG. 2 , three guide rollers  8  that abut against the top surface and the two side faces of the projecting portion  5   a , respectively, are provided at the front end portion and at the rear end portion of the vertically movable platform  4 . When drivingly raising or lowering the vertically movable platform  4  by the electric motor for raising and lowering M 2  rotatively driving the winding drum  17  in the forward or reverse direction, the vertically movable platform  4  is guidingly raised or lowered while movement thereof in the fore-and-aft and lateral directions on the support post  5  is restricted by the guide rollers  8  abutting against the projecting portion  5   a , and thus the vertically movable platform  4  is raised and lowered along the raising and lowering path.  
         [0022]     The travel vehicle  3  is described next.  
         [0023]     As shown in  FIG. 3 , the travel vehicle  3  is provided with a pair of travel wheels  9 , disposed with a spacing therebetween in the fore-and-aft direction, that are rotatively driven by drive means  10  and travel along the travel rail  2 . The drive means  10  is fixedly supported on a vehicle frame  16  in the travel vehicle  3 , and the travel wheels  9  are rotatably supported at the front end portion and the rear end portion of the vehicle frame  16 . The drive means  10  is provided for each the travel wheel  9 .  
         [0024]     As shown in  FIG. 5 , the travel wheels  9  are rotatably supported to the left and right of the center of the vehicle frame  16 , and the drive means  10  is provided with a pair of left and right travel motors M 1  supported on the vehicle frame  16  and located to the right and the left of the travel wheels  9 . The right and left travel motors M 1  are configured so as to rotatively drive one travel wheel  9  each, and thus the two front and rear travel wheels  9  are rotatively driven by a total of four travel motors M 1 .  
         [0025]     As shown in  FIGS. 2 and 5 , the vehicle frame  16  is configured by connecting a pair of front and rear support frames  25  that support the travel wheels  9  and the drive means  10 , via a connection frame  12 . The connection frame  12  is constituted by right and left frame members  12   a  located on the respective side of the travel rail  2 .  
         [0026]     Each support frame  25  is configured such that the travel wheels  9  are rotatably supported to the left and right of center, the travel motors M 1  are fixedly supported on the right and left side portions, and the lower end portion of the support post  5  is connected to supported by the upper end portion. The travel wheel  9  and the drive means  10  are incorporated into a single unit with the support frame  25 , thereby forming a travel drive unit  11 .  
         [0027]     The travel drive units  11  are described next.  
         [0028]     As shown in FIGS.  4  to  7 , in addition to the travel wheel  9 , the drive means  10 , and the support frame  25 , each travel drive unit  11  is provided with a unit cover  19  that covers the drive means  10 , a pair of guide wheels  20  that are in contact with the travel rail  2  in order to restrict lateral movement of the stacker crane A with respect to the travel rail  2  and that guide the stacker crane A along the travel rail  2 , restriction wheels  21  that are in contact with the travel rail  2  so as to restrict upward movement and thereby restrict upward floating of the travel wheel  9  from the travel rail  2 , and a servo-type adjustment means  24  for adjusting the contact pressure of the restriction wheels  21  against the travel rail  2  by raising or lowering the restriction wheels  21 .  
         [0029]     An annular travel tire portion  9   a , which is an elastic member made of urethane rubber, is attached to the outer circumferential portion of the travel wheel  9 , and restriction tire portions  21   a , which are annular elastic members made of urethane rubber, are attached to the outer circumferential portion of the restriction wheels  21 .  
         [0030]     In other words, the configuration is such that lateral movement of the stacker crane A with respect to the travel rail  2  is restricted by the guide wheels  20  abutting against the side faces of the travel rail  2 , so that the stacker crane A is moved over and along the travel rail  2  by rotatively driving the travel wheels  9  with the drive means  10  so that the travel wheels  9  travel over the upper face of the travel rail  2 , which has a T-shaped cross-sectional shape when viewed in the fore-and-aft direction. Further, the travel wheels  9  are kept from floating upward from the travel rail  2  by the restriction wheels  21  abutting against the lower face of the travel rail  2 , keeping the travel wheels  9  from floating upward when the stacker crane A is accelerated or decelerated and thereby preventing the travel wheels  9  from slipping.  
         [0031]     As shown in  FIG. 5 , an extension guide rail  22  for guiding the guide rollers  8  of the vertically movable platform  4  upward and downward is provided on the support frames  25  in such a manner that it is continuous with the projecting portion  5   a  of the support post  5 . These allow the raising and the lowering platform  4  to be lowered close to the lower end of the stacker crane A.  
         [0032]     As shown in  FIG. 6 , the travel wheels  9  are supported in such a manner that they can rotate about an axis in the horizontal direction with respect to the support frame  25 . The drive means  10  are supported on the support frame  25  in such a manner that they are located on either side of the travel wheels  9 . The drive means  10  are configured such that the travel motors M 1  are fixedly supported on the right side and the left side portion of the support frame  25 , the right and left travel motors M 1  together rotatively driving one travel wheel  9 . It should be noted that the drive means  10  each are provided with a braking mechanism, which is not shown because it is conventional art, in addition to the travel motors M 1 . The drive means  10  can also include a deceleration gear mechanism.  
         [0033]     Describing the support frame  25  more specifically, as shown in  FIGS. 4 and 6 , the support frame  25  includes a support platform portion  25   a  for supporting the lower end portion of the support post  5 , and right and left support portions  25   b  that are positioned below the support platform portion  25   a  and that are for supporting the travel wheels  9  and the drive means  10 .  
         [0034]     The lower end of the support post  5  is connected to the support platform portion  25   a  through a flange provided at the lower end of the support post  5  and nuts and bolts, and the support post  5  is supported such that the lower end of the support post  5  is positioned above the upper end of the travel wheels  9  and the upper end of the drive means  10 .  
         [0035]     Furthermore, the travel wheel  9  is supported between the right support portion  25   b  and the left support portion  25   b  in such a manner that it can rotate about an axis in the horizontal direction. The travel motors M 1  are fixedly supported to the outer face side of the right support portion  25   b  and the left support portion  25   b , and each travel motor M 1  is provided on the support frame  25  so that the drive shaft of the travel motor M 1  rotates about the same axis as the travel wheel  9 .  
         [0036]     As shown in  FIGS. 4 and 7 , the frame members  12   a  are connected to the rear end portions of the left and right support portions  25   b  of the front-side support frame  25  and to the front end portions of the left and right support portions  25   b  of the rear-side support frame  25 , and thus the pair of front and rear support frames  25  are connected via the connection frame  12 .  
         [0037]     The guide wheels  20  are supported at the front end portions of the left and right support portions  25   b  of the front-side support frame  25  and at the rear end portions of the left and right support portions  25   b  of the rear-side support frame  25 , in such a manner that they can rotate about a vertical axis via guide support members  23 .  
         [0038]     Further, the restriction wheels  21  are supported at a central portion in the front-to-back direction of the left and right support portions  25   b  of the front-side support frame  25  and at a central portion in the front-to-back direction of the left and right support portions  25   b  of the rear-side support frame  25 , in such a manner that they can rotate about a horizontal axis via the adjustment means  24 .  
         [0039]     The restriction wheels  21  are supported by the support frames  25  in such a manner that they are in contact with the travel rail  2  with contact pressure that is due to the elasticity of the restriction tire portions  21   a . The restriction wheels  21 , being in contact with the lower face of the travel rail  2  with the contact pressure, keep the travel wheels  9  from floating upward from the travel rail  2 . Each restriction wheel  21  is supported in such a manner that it can be raised and lowered with respect to the corresponding travel drive unit  11 , and the contact pressure applied by the restriction wheels  21  to the travel rail  2  is adjusted by raising and lowering the restriction wheels  21  with the adjustment means  24  so as to elastically deform the restriction tire portions  21   a.    
         [0040]     Describing the adjustment means  24  more specifically, as shown in  FIGS. 6, 8 , and  9 , the adjustment means  24  is a servo-type eccentric cam mechanism that is provided with an operation member  27  that is supported by a base holder  26 , which is fixedly supported to the outer surface side of the right support portion  25   b  and the left support portion  25   b  of the support frame  25 , in such a manner that it can freely rotate about a horizontal axis, and a support member  28  that rotatively supports the pair of front and rear restriction wheels  21  via bearings and that is fitted into and supported by the operation member  27  in such a manner that it can pivot deviated with respect to the rotation axis of the operation member  27 . The adjustment means  24  is also provided with a lock mechanism  29  that can switch between a fastened state where rotation of the operation member  27  is locked and an unfastened state in which the lock on rotation is released.  
         [0041]     As shown in  FIG. 9 , the configuration of the eccentric cam mechanism of the support member  28  is such that the shaft portion  28   a  of the support member  28  is supported by the operation member  27  in such a manner that its pivot axis Y is parallel to the rotation axis X of the operation member  27  but deviated from the rotation axis X, so that by rotatively actuating the shaft portion  28   a  about the rotation axis X, the shaft portion  28   a  rotates in a relative manner about the pivot axis Y due to its own weight and being abutted against the travel rail  2 , causing the support member  28  to move along the rotation axis X while maintaining its orientation. As a result, the support member  28  is raised and lowered with respect to the travel drive unit  11 . Also, by raising and lowering the support member  28  in this manner, the two restriction wheels  21  supported by the support member  28  are also raised and lowered with respect to the travel drive unit  11 , causing the restriction tire portions  21   a  to be elastically deformed due to abutting against the lower surface of the travel rail  2  and therefore altering the contact pressure of the restriction wheels  21  with respect to the travel rail  2 .  
       Other Embodiments  
       [0042]     (1) In the foregoing embodiment, the support frames are provided with an extension guide rail over which the guided portion of the vertically movable platform is guidingly raised and lowered, but it is also possible for the extension guide rail to not be provided. For example, it is also possible to adopt a configuration in which the guide portions of the support posts extend below the lower end portion of the main support post, and that this extension guide portion is connected to the support frame.  
         [0043]     (2) In the foregoing embodiment, the drive means are supported on the support frames positioned to the side of the travel wheels, but the drive means may be supported on the support frames positioned on the front side portion and on the rear side portion of the travel wheels.  
         [0044]     (3) In the foregoing embodiment, the travel wheels and the support posts are supported by the support frames so that the travel wheels and the support posts overlap vertically when viewed in the lateral direction and the fore-and-aft direction, but the travel wheels and the support posts may be supported by the support frames so that the travel wheels are shifted in the lateral direction or the fore-and-aft direction in such a manner that they do not vertically overlap the support posts when viewed in the lateral direction, the fore-and-aft direction, or both directions.  
         [0045]     (4) In the foregoing embodiment, the restriction wheels  21  are supported by the support frames  25  in such a manner that they contact the travel rail  2  with contact pressure due to the elasticity of the elastic member  21   a . However, it is also possible for the regulation wheels  21  to be supported by the support frames  25  in such a manner that they contact the travel rail  2  with contact pressure without providing the elastic member  21   a.