Patent Publication Number: US-9834226-B2

Title: Travelling vehicle system and travelling method for travelling vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention claims the benefit of priority under 35 USC 119 of Japanese application no. 2015-071781, filed on Mar. 31, 2015, which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a travelling vehicle system and a travelling method for a travelling vehicle. 
     2. Description of the Related Art 
     It is known that in a suspension-type travelling vehicle system such as an overhead travelling vehicle system, a branching/merging part is provided on a track to make a track of travelling vehicle branch off or merge (e.g., JP 2012-162096 A). In the suspension-type travelling vehicle system, a shaft of the travelling vehicle is hung from the track, and it is thus difficult to make tracks intersect. 
     Accordingly, instead of making the tracks intersect, one track has been divided to form a plurality of branching/merging parts and connect the divided tracks. In this manner, however, it is necessary for the travelling vehicle to travel over a plurality of branching/merging parts so as to move between the divided tracks, and this makes the travelling time long and a track installation area large. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a suspension-type travelling vehicle system including an intersection where a vehicle smoothly travels, and provide a travelling method. 
     The present invention is a system for allowing a suspension-type travelling vehicle to travel along a rail provided on a track. The system includes an intersection in which tracks cross each other, and a gap in which a rail for supporting a weight of the travelling vehicle is interrupted in the intersection. The travelling vehicle includes a travelling wheel that makes the rail support the weight of the travelling vehicle, and intersection rollers that are attached both in front and rear of the travelling wheel along a travelling direction in positions different from a position of the travelling wheel along a direction orthogonal to the travelling direction within a horizontal plane, and inter-axial distances between the intersection rollers and the travelling wheel within the horizontal plane are both longer than a width of the gap along the travelling direction. The rail or the travelling vehicle is configured such that the intersection rollers are supported by the rail in the intersection, and are separated from the rail in places other than the intersection. 
     Further, the present invention is a method for allowing a suspension-type travelling vehicle to travel through a gap in an intersection where tracks cross. The travelling vehicle includes a travelling wheel that makes the rail support a weight of the travelling vehicle, and intersection rollers that are attached both in front and rear of the travelling wheel along a travelling direction in positions different from a position of the travelling wheel along a direction orthogonal to the travelling direction within a horizontal plane, and inter-axial distances between the intersection rollers and the travelling wheel within the horizontal plane are both longer than a width of the gap along the travelling direction. The rail or the travelling vehicle is configured such that the intersection rollers are supported by the rail in the intersection, and are separated from the rail in places other than the intersection. During passage of the travelling wheel through the gap, the weight of the travelling vehicle is supported by the front and rear intersection rollers by making both the front and rear intersection rollers in contact with the rail. 
     In the present invention, since the inter-axial distances between the front and rear intersection rollers and the travelling wheel within the horizontal plane are both longer than the width of the gap along the travelling direction, the front and rear intersection rollers are supported by the rail during passage of the travelling wheel through the gap. This can result in smooth travelling through the gap. Further, when the intersection roller is in contact with the rail in places other than the intersection, the straight stability of the travelling vehicle is enhanced, to prevent curve-travelling. However, the structure of the rail is set such that the intersection roller is in contact with the rail only in the intersection, or the structure of the travelling vehicle is set such that the intersection roller is separated from the rail in the places other than the intersection, and hence in principle, the intersection roller is not in contact with the rail in the places other than the intersection. In the present specification, a description of the travelling vehicle system is applied as it is to the travelling method, and a description of the travelling method is applied as it is to the travelling vehicle system. 
     It is preferable that an intersection guide for supporting the intersection rollers be provided on the rail from an upstream side through a downstream side of the intersection, and the intersection guide project from the rail so as to reduce the width of the gap. In this manner, the intersection roller is in contact with the rail only in the intersection, and further, the gap can be reduced due to the intersection guide. In order to make the intersection roller retreat, for example, a lifting mechanism for the intersection roller may be provided so that the intersection roller comes into contact with the rail at a lower position and retreats from the rail at an upper position. However, the above intersection guide does not require the lifting mechanism for the intersection roller, and the like. 
     It is preferable that the travelling vehicle include a pair of front and rear bogie vehicles, and a body supported from the front and rear bogie vehicles by vertical axles, and the travelling wheel is arranged so as to be rotated around one axle for each of the bogie vehicles, the rail include openings, which receive the vertical axles, at a center part in a width direction, the openings cross in the gap, and the travelling vehicle further include a turn preventive mechanism for preventing a turn of the bogie vehicle in the intersection. In the travelling vehicle with the body supported by the pair of front and rear bogie vehicles, the moment of force is transmitted from the body to the bogie vehicle, and in association with the travelling wheel being a single axis, the bogie vehicle may turn, namely a posture of the bogie vehicle may become unstable. In contrast, when the turn preventive mechanism is provided, it is possible to prevent the turn of the bogie vehicle in the intersection. 
     It is preferable that the turn preventive mechanism be a flange provided on the intersection roller and facing an opening-side end surface of the rail. The flange is made in contact with the end surface of the rail, to prevent the turn of the bogie vehicle. The contact between the flange and the end surface of the rail is made by sliding, not by rolling, thus generation of dust tends to occur. Hence it is preferable that a small gap be provided between the flange and the end surface of the rail, and the turn of the bogie vehicle be prevented by the flange when the bogie vehicle shifts to or beyond this gap. 
     Further, it is preferable that the turn preventive mechanism be a guide roller guided by the track from the upstream side through the downstream side of the intersection. While proving the guide rollers at the front and rear of the bogie vehicle is known, a guide roller is added to a center part of the bogie vehicle in the travelling direction, or to some other part, for example. When the tracks are made to intersect, there is generated a section in which the guide by the guide roller is interrupted. Then, in this section, the guide is performed by the additional guide roller. When the additional guide roller is continually guided by the track, curve-travelling and the like can be prevented. Therefore, the additional guide roller is guided from the upstream side through the downstream side of the intersection, and it is not guided in the other sections. In order to do this, for example, an extending/retreating mechanism for moving the guide roller is provided, or the shape of the track is set such that the normal guide roller and the additional guide roller are made different in height and the additional guide roller is guided only in and in the vicinity of the intersection. Further, it is preferable that a small gap be present between the additional guide roller and the guiding surface of the track, or the additional guide roller be elastically in contact with the guiding surface, so as to prevent an excess guide. As the turn preventive mechanism, other than the above, the inter-axial distance between the conventional guide rollers may be made longer than the gap in the guiding surface, and one guide roller may continually function in the intersection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view illustrating a layout of an overhead travelling vehicle system of an embodiment; 
         FIG. 2  is a sectional view of a main part of an overhead travelling vehicle and a track in the embodiment; 
         FIG. 3  is a bottom view of the overhead travelling vehicle in the embodiment; 
         FIG. 4  is a horizontal-plane sectional view of the tracks in an intersection in the embodiment; 
         FIG. 5  is a horizontal-plane sectional view illustrating the relation among the tracks, driven wheels, intersection rollers, and guide rollers in the intersection in the embodiment; 
         FIG. 6  is a horizontal sectional view of a main part, illustrating a gap between a rail and the intersection roller in the embodiment; 
         FIG. 7  is a waveform diagram illustrating the presence or absence of the rail and operation of each roller in and in the vicinity of the intersection in the embodiment; 
         FIG. 8  is a plan view of an overhead travelling vehicle in an alternative embodiment; 
         FIG. 9  is a waveform diagram illustrating the presence or absence of the rail and operation of each roller in and in the vicinity of the intersection in the alternative embodiment; and 
         FIG. 10  is a view illustrating traces of the guide rollers with respect to an overhead guide in a second alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment for carrying out the present invention will be shown. The scope of the present invention is to be set in accordance with the understanding of a skilled person in the art, taking into consideration the description in this specification, the known technique in this field, and the claims. 
     Embodiment 
       FIGS. 1 to 10  illustrate an overhead travelling vehicle system  2  of an embodiment, and modification thereof.  FIG. 1  illustrates a layout of the overhead travelling vehicle system  2 . A track  4  is a track on an inter-bay route, and tracks  6 ,  7  are tracks on an intra-bay route. A plurality of overhead travelling vehicles  12  travel along tracks  4 ,  6 ,  7 , and the tracks  4 ,  6 ,  7  have the same structure, for example. In  FIG. 1 , four parallel tracks  4  are arranged on the inter-bay route, but the number of tracks  4 ,  6 ,  7  is arbitrarily. The track  4  and the tracks  6 ,  7  may intersect at right angles at an intersection  8  in a horizontal plane, and may intersect not only at right angles but also diagonally. Providing the intersection  8  enables the tracks to intersect, and the intersection  8  means an area provided with special equipment for the tracks to intersect. 
     Numeral  10  denotes a branching/merging part, being a portion where the track of the overhead travelling vehicle  12  is branched or merged. Providing the intersection  8  enables reduction in time for movement between the tracks  6 ,  7  on the intra-bay route. When the tracks  6 ,  7  on the intra-bay route are connected by a large number of branching/merging parts as have hitherto been done, travelling across the inter-bay route takes a long period of time. Further, an installation place of the intersection  8  is arbitrary. The intersection  8  is provided not only in a place where the inter-bay route and the intra-bay route intersect, but also in a place where the tracks are to intersect. A rejection controlling (exclusive control) part  13  performs rejection control so as to prevent two overhead travelling vehicles  12 ,  12  from simultaneously getting into one intersection  8 , and a rejection controlling mechanism is arbitrarily. 
       FIGS. 2 and 3  illustrate a structure of the overhead travelling vehicle  12 , in which a pair of front and rear bogie vehicles  14 ,  14  are provided, and power feeding vehicles  16 ,  16  are provided below the bogie vehicles  14 ,  14 . A body  20  of the overhead travelling vehicle  12  is supported by the pair of front and rear bogie axles  18 ,  18 , and the overhead travelling vehicle  12  is a suspension-type travelling vehicle. Further, a driving wheel  28  and a travelling motor  30  are arranged so as to bridge between the pair of front and rear bogie vehicles  14 ,  14 . It is to be noted that the body  20  lifts and lowers a lift stage  24  by a hoist  22 , and the overhead travelling vehicle  12  holds an article such as a FOUP  26  by the lift stage  24 , and carries the article. 
     The bogie vehicle  14  includes outer driven wheels  32 ,  32  and inner driven wheels  34 ,  34 , and four driven wheels  32 ,  32 ,  34 ,  34  are arranged along one axle. As for the inside and outside, the center side of the track within the horizontal plane is shown as the inside and the opposite side thereto is shown as the outside. For example, basically, the outer driven wheels  32 ,  32  continually support the bogie vehicle  14 , and the inner driven wheels  34 ,  34  support the bogie vehicle  14  only in a curve section, the branching/merging part and the intersection  8 , and the like. At least each pair of the front and rear intersection rollers  36 ,  36  is provided on the inner side of the inner driven wheels  34 ,  34 , and the intersection rollers  36 ,  36  support the bogie vehicle  14  only in the intersection, for example. The inter-axial distance between the driven wheel  34  and the intersection roller  36  within the horizontal plane is longer than a gap d 1  in the opening  47  in the intersection  8 , which is illustrated in  FIG. 4 , and an inter-axial distance between the front and rear intersection rollers  36 ,  36  is longer than 2d 1 . The overhead travelling vehicle  12  is characterized by the intersection roller  36  and arrangement thereof. 
     A pair of front and rear guide rollers  38  is provided in an upper part of the bogie vehicle  14  and is guided by an overhead guide  37 , to stabilize a posture of the bogie vehicle  14 . In the upper portion of the bogie vehicle  14 , for example, a pair of right and left branching/merging rollers  40  is further provided, and is lifted and lowered by a lifting mechanism  44 . When the branching/merging roller  40  is lifted, the branching/merging roller  40  is guided by the overhead guide  37 , and when the branching/merging roller  40  is lowered, the branching/merging roller  40  comes out of contact with the overhead guide  37 . Lifting and lowering the branching/merging roller  40  controls the track of the overhead travelling vehicle  12  to branch off and merge. It is to be noted that in the present specification, right and left are directions orthogonal to a longitudinal direction of the track within the horizontal plane. 
     A main rail  44  is located below the track  4  and the like, and supports the driven wheel  32 . Further, the power feeding vehicle  16  includes a power receiving coil  50  and the like, and receives power from a litz wire or the like provided on the track  4  or the like in a contactless manner. It is to be noted that the power feeding vehicle  16  includes a capacitor or a secondary battery such as a lithium-ion battery, and can continue operation even when power supply is temporarily stopped. In the embodiment, the overhead travelling vehicle  12  has been shown as the travelling vehicle, but it only has to be a suspension-type travelling vehicle, and especially when a plurality of bogie vehicles are provided in the travelling vehicle, the embodiment applies to that case. Although the bogie vehicle  14  does not include a driving wheel in the overhead travelling vehicle  12 , a travelling motor may be provided in each bogie vehicle  14 , and the driven wheels  32 ,  34  may be replaced by driving wheels. 
       FIGS. 4 and 5  illustrate a structure of the track in the intersection  8 . In  FIGS. 4 and 5 , the track has been cut off horizontally at a height of the overhead guide  37  in the upper portion of the track and illustrated as seen from above.  FIG. 4  illustrates only the structure of the intersection  8 , and  FIG. 5  illustrates the relation with the wheels and the like of the bogie vehicle  14 . Further, in the intersection  8 , the branching/merging roller  40  has been lowered, and does not come into contact with the overhead guide  37 . 
     At the intersection  8 , a branching/merging rail  45  projects from a main rail  44  to reduce the gap, and an intersection guide  46  further projects from the branching/merging rail  45  to further reduce the gap. A gap between the intersection guides  46 ,  46  is referred to as d 1 , a gap between the branching/merging rails  45 ,  45  is referred to as d 2 , and a gap between the main rails  44 ,  44  is referred to as d 3 . The relation of those gaps is “d 1 &lt;d 2 &lt;d 3 ”, and a gap between the overhead guides  37 ,  37  is the same as d 3 , for example. It should be noted that the branching/merging rail  45  allows the bogie vehicle  14  to smoothly travel through the gap in the branching/merging part. The intersection guide  46  serves to reduce the gap in the intersection  8  and allow the bogie vehicle  14  to smoothly travel, and is one of characteristics of the embodiment. As described above, the inter-axial distance between the intersection roller  36  and the driven wheels  34  on the horizontal plane is made larger than d 1 , and the inter-axial distance between the guide rollers  38 ,  38  is made shorter than d 3  and longer than d 2 , for example, thereby reducing a body length of the bogie vehicle  14 . 
     When the driven wheel  34  and the intersection roller  36  are brought into contact with the track, the stability in a straight direction increases but curve-travelling becomes difficult, and hence the branching/merging rail  45  and the intersection guide  46  are provided only around the gap in the intersection  8 . Herein, the intersection guide  46  is provided over a section narrower than the branching/merging rail  45 , but these may be provided so as to have the same length. 
     As illustrated in  FIG. 6 , a flange  52  is preferably provided at the end of the intersection roller  36  on the inner side of the track, and made to face an end surface  53  of the intersection guide  46  on the inner side of the track. A gap between the flange  52  and the end surface  53  is referred to as d 4 , and when a lateral position of the bogie vehicle  14  shifts to or beyond gap d 4  in the intersection, the flange  52  is guided by the end surface  53 . Similarly to the conventional intersection roller, it is preferable that a body of the intersection roller  36  be made of an elastic body such as urethane rubber, and the flange  52  be made of a hard resin such as a POM (polyacetal) resin, to reduce generation of dust. Numeral  54  denotes an axle of the intersection roller  36 . 
       FIG. 7  illustrates the support and guide of the bogie vehicle in the intersection. During passage of the driven wheel  34  through the gap d 1 , the bogie vehicle  14  is supported by the intersection rollers  36 ,  36 , and the posture of the bogie vehicle is prevented from becoming unstable due to the gap d 3  in the overhead guide. In  FIG. 7 , 1) illustrates the gap in the overhead guide, 2) illustrates the gap in the branching/merging rail, and 3) illustrates the gap in the intersection guide. Symbol f denotes the front side and symbol r denotes the rear side. Since the inter-axial distances between the front and rear intersection rollers  36 ,  36  and the driven wheel  34  on the horizontal plane are longer than the gap d 1 , the front and rear intersection rollers  36 , are both supported by the intersection guide  46  during passage of the driven wheel  34  through the gap d 1 . Hence the gravity applied on the bogie vehicle  14  is continually stably supported. 
     Since the inter-axial distance between the guide rollers  38 ,  38  is shorter than the gap d 3 , there is a time period during which none of the front and rear guide rollers  38 ,  38  is guided by the overhead guide  37 . Then, the flange  52  is provided on the intersection roller  36 , to stabilize the posture of the bogie vehicle  14 . However, since the gap d 1  is short and the driven wheel  34  having high straight stability is supported by the track, the posture of the bogie vehicle  14  is hardly deformed even without the flange  52 . Accordingly, even without the flange  52 , the posture of the bogie vehicle is practically sufficiently stable. As described above, the overhead travelling vehicle  12  can smoothly travel through the intersection  8 . In addition, since the intersection roller  36  is located on the inside of the branching/merging rail  45 , it is not in contact with the track in the branching/merging part  10  and the curve section. 
       FIGS. 8 and 9  illustrate an overhead travelling vehicle  60  of an alternative embodiment. This is similar to that in the embodiment of  FIGS. 1 to 7  except for the respects that will be particularly pointed out, and especially the structure of the intersection  8  is the same. A bogie vehicle  61  is formed by providing in the bogie vehicle  14  the pairs of right and left guide rollers  62 ,  62  and lifting mechanisms  64 ,  64  which are lifatble. The guide roller  62  is, for example, provided in an upper part of the driven wheel  34 , namely on the right and left of the bogie vehicle  14  in the vicinity of the center of a bilateral direction of the bogie vehicle  14 . Further, the guide roller  62  may not extend or retreat vertically, but may extend or retreat laterally. The guide roller  62  is in contact with the overhead guide  37  only in the intersection  8 , and an inter-axial distance between the guide roller  62  and each of the front and rear guide rollers  38 ,  38  is made longer than the gap d 3 . At least two guide rollers  38 ,  62  are continually guided by the overhead guide  37  along a longitudinal direction in the intersection  8 . Further, the guide roller  62  is in contact with the overhead guide  37  only in the intersection  8 . It is to be noted that the flange  52  of the intersection roller  36  may not be present, and in order to prevent unnecessary force from functioning by the guide roller  62 , a slight gap is preferably provided between the overhead guide  37  and the guide roller  62  at a lifted position. 
       FIG. 9  illustrates the guide and support of the bogie vehicle  61 . As illustrated in 9), a guide by the guide roller  62  is added, and hence the bogie vehicle  61  is continually guided by the guide rollers both on its front and rear, leading to further improvement in stability of the posture. 
       FIG. 10  illustrates a second alternative embodiment. A height of the guide roller  62  is set to the middle between the guide roller  38  and the branching/merging roller  40 . In the intersection  8 , hanging parts  56 ,  56  are hung downward from the overhead guide  37  on both sides of the gap d 3 , to guide the guide roller  62 , but the overhead guide  37  is out of contact with the branching/merging roller  40 . Also in this manner, similarly to the alternative embodiment of  FIGS. 8 and 9 , it is possible to prevent the guide by the pair of front and rear guide rollers from being interrupted by the gap d 3 . In the alternative embodiment of  FIG. 10 , the guide roller  62  is in contact with the overhead guide  37  only in the intersection  8  and the branching/merging part  10 . 
     The embodiment has the following characteristics. 
     1) The intersection rollers  36 ,  36 , with an inter-axial distance to the driven wheel  34  being longer than the gap d 1 , are provided both in front and rear of the driven wheel  34 , thereby enabling support of the bogie vehicle  14  by the front and rear intersection rollers  36 ,  36  during passage of the driven wheel  34  through the gap d 1 .
 
2) By providing the intersection guide  46  in the intersection  8  in addition to the branching/merging rail  45 , the gap d 1  can be made narrower.
 
3) Since the inter-axial distance between the guide rollers  38 ,  38  is made shorter than the gap d 3 , the body length of the bogie vehicle  14  can be reduced.
 
4) Providing the flange  52  on the intersection roller  36  enables regulation of the posture of the bogie vehicle  14 .
 
5) The intersection roller  36  is in contact with the track only in the intersection  8 , and does not have an influence on travelling in the other sections.
 
     The alternative embodiments further have the following characteristics. 
     6) Since the inter-axial distance between the guide rollers  38 ,  38  is longer than the gap d 3 , the bogie vehicle  61  is continually guided by either of the guide rollers  38 ,  38  in the intersection  8 . 
     7) Further, when the guide roller  62  is provided and the inter-axial distance between the guide rollers  38 ,  62  is made longer than the gap d 3 , the pair of front and rear guide rollers  38 ,  62 ,  38  are continually guided by the overhead guide  37  in the intersection  8 . 
     It is to be noted that a mechanism for lifting and lowering the intersection roller  36  may be provided so that the intersection roller  36  retreats upward in places other than the intersection  8 .