Patent Publication Number: US-2009229184-A1

Title: Door derailing prevention member installation structure for elevator

Description:
BACKGROUND SECTION 
     The present invention pertains to a structure for installing a door derailing prevention member used to prevent a sliding door of an elevator from derailing from a door rail. 
     As described in Japanese Patent Application No. 2000-26053, for example, an elevator sliding door is hung from a door rail via a door hanger equipped with hanger rollers and up-thrust rollers, and the sliding door opens/closes the doorway of the elevator along the door rail as the aforementioned hanger rollers travel on the door rail. On the other hand, the up-thrust rollers are provided such that they approach the door rail from below, and they function as door derailing prevention members, that is, the up-thrust rollers come into contact with the door rail when the hanger rollers are lifted from 
     Conventionally, an up-thrust roller has been used for this purpose, wherein a roller is provided on a pedestal equipped with a slotted and threaded stud while its center of rotation is off-center with respect to the axial center of the threaded stud. The aforementioned up-thrust roller is fixed to the door hanger at a prescribed distance from the door rail using the aforementioned threaded stud and a nut. 
     Here, when the gap between the aforementioned up-thrust roller and the door rail is to be adjusted, the aforementioned nut is tightened with a wrench to tentatively attach the up-thrust roller to the door hanger, and the aforementioned installation stud is rotated by means of a screwdriver using the aforementioned slot in order to adjust the gap between the aforementioned roller and the door rail appropriately. The nut is then tightened further using the wrench while using the screwdriver to prevent the aforementioned installation stud from rotating in order to secure the up-thrust roller to the door hanger. 
     In the case of the aforementioned conventional up-thrust roller, because the aforementioned installation stud is fixed at its center in order to prevent it from rotating when attaching the up-thrust roller to the door hanger after the aforementioned gap is adjusted, it is difficult to completely prevent the aforementioned installation stud from rotating, and there is the risk that the aforementioned gap may change if the aforementioned installation stud also rotates when the nut is tightened. Therefore, this method is not desirable in that it becomes necessary to adjust the roller installation position by taking the amount the installation stud may rotate when the nut is tightened into consideration, and the operation becomes cumbersome. 
     In addition, it is not desirable in terms of strength because the aforementioned roller is essentially cantilevered and the aforementioned pedestal is positioned between the aforementioned roller and the door hanger so that, a heavy load is applied to the aforementioned installation stud when the aforementioned roller is pressed against the door rail. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the invention include a door derailing prevention member having a body with a middle section and a circumferential surface. An installation stud is positioned at the middle section and a boss part is mounted to the body and is configured to mate with a hole and secure the body in a fixed position. The body has a radius that varies along the circumferential surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a diagram showing a first embodiment of the present invention, wherein an oblique view of a sliding door which opens/closes the doorway of an elevator is shown. 
         FIG. 2  is an oblique view of the derailing prevention member in  FIG. 1  when it is disassembled. 
         FIG. 3  is a front view of the derailing prevention member in  FIG. 2 . 
         FIG. 4  is a diagram showing the relative positions between the derailing prevention member and the door rail when the position in which the boss part and the installation hole are engaged is changed in stages in the rotational direction. 
         FIG. 5  is a diagram showing a second embodiment of the present invention, wherein an oblique view of a derailing prevention member is shown. 
         FIG. 6  is a diagram showing a modified example of the positioning protrusion and positioning hole shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is an oblique view of a sliding door which opens/closes the elevator doorway in a specific embodiment of the present invention. 
     As shown in  FIG. 1 , elevator doorway  1  is formed between facing vertical frames  2 , and said vertical frames  2  are connected together at the top using header  3 . Header  3  is equipped with door rail  4  which is provided running along the longitudinal direction, and sliding door  5  is hung from and supported by said door rail  4 , with sliding door  5  being guided by door rail  4  to open/close doorway  1 . Furthermore, although doorway  1  is opened/closed using multiple sliding doors  5 , they are omitted in the illustration since each sliding door  5  has the same structure and is hung from door rail  4 . 
     More specifically, nearly flat plate-like door hanger  6  is installed between sliding door  5  and door rail  4 , and door hanger  6  is integrally connected with sliding door  5 . Hanger rollers  7 , which can rotate freely, are provided on the right-hand side and the left-hand side of said door hanger  6 , and said hanger rollers  7  move by rotating on door rail  4  while they are engaged with door rail  4 . 
     In addition, a door derailing prevention member  8  is located on door hanger  6  so as to face hanger rollers  7 . In this way, door rail  4  is sandwiched from above and below by hanger rollers  7  and derailing prevention member  8 , and a minute gap is formed between derailing prevention member  8  and door rail  4 . Therefore, when hanger rollers  7  are lifted from door rail  4 , that is, when door hanger  6  is lifted from door rail  4 , the circumferential surfaces of derailing prevention member  8  functioning as contact surfaces come into contact with door rail  4  to prevent lifted sliding door  5  from derailing. 
       FIG. 2  is an oblique view of derailing prevention member  8  in  FIG. 1  when it is disassembled. 
     As shown in  FIG. 2 , derailing prevention member  8  has a body  11  in which an installation stud  9  projects from a pedestal surface  8   a.  The installation stud  9  is located at a middle section  12  of the body  11 . The material of the body  11  includes a hard resin, metal, and rubber. The installation stud  9  is fitted by insertion and integrally fixed with derailing prevention member  8 , while equilateral hexagonal boss part  8   b,  which protrudes from pedestal surface  8   a,  is formed concentrically with installation stud  9 . Furthermore, male threads, are formed on the circumferential surface of installation stud  9 . 
     In addition, an installation hole  6   a,  which is used also as a positioning hole, is created in door hanger  6 . The installation hole  6   a  is hexagonal, just like boss part  8   b , and one of the flat inner wall surfaces  6   b  which constitute said installation hole  6   a  is formed parallel with the bottom surface of door rail  4 . It is noted that installation hole  6   a  can be any polygon shape, so long as it matches boss part  8   b.    
     Installation hole  6   a  and boss part  8   b  can be engaged with and disengaged from each other, and the rotational position around installation shaft  9  in which boss part  8   b  and installation hole  6   a  are engaged can be adjusted in stages. In this way, after boss part  8   b  is fitted into installation hole  6   a  by inserting installation stud  9  into installation hole  6   a  so as to seat pedestal surface  8   a  against door hanger  6 , derailing prevention member  8  is fixed to door hanger  6  using installation stud  9  and nut  10  serving as the threaded member to be screwed to it. In other words, although the position in which derailing prevention member  8  is installed on door hanger  6 , that is, the rotational position around installation stud  9  in which derailing prevention member  8  is installed, is determined as boss part  8   b  is fitted into installation hole  6   a,  the rotational position in which derailing prevention member  8  is installed can be adjusted in stages, 60° at a time, by selectively changing the relative position between said boss part  8   b  and installation hole  6   a  in the rotational direction. 
       FIG. 3  is a front view of derailing prevention member  8 , and  FIG. 4  is a diagram showing the relative positions between derailing prevention member  8  and door rail  4  when the position where boss part  8   b  and installation hole  6   a  are engaged is changed in stages in the rotational direction. 
     As is clear from  FIG. 3 , decentered cam-like derailing prevention member  8  is formed to have an essentially cam-like cross section, such that the distance between its circumferential surface  8   c  itself and installation stud  9  changes gradually in the rotational direction around installation stud  9  along nearly the entire perimeter of said circumferential surface  8   c;  and the cross section of circumferential surface  8   c  is formed as a spiral line as represented by an involute curve, for example, and part of it includes flat surface  8   d.    
     The positions on circumferential surface  8   c  obtained by dividing body  11  into six equal parts, at 60° in the circumferential direction, are then set as contact spots P 1  through P 6 , and contact spot P 6  is positioned on flat surface  8   d.  That is, the respective contact spots P 1  through P 6  are arranged such that their distances from the axial center of installation stud  9  vary, whereby the distances from the axial center of installation stud  9  to respective contact spots P 1  through P 6  increase or decrease in stages in either the forward rotational direction or reverse rotational direction of body  11 . Also, in terms of the relative positions between respective contact spots P 1  through P 6  on circumferential surface  8   c  and hexagonal boss part  8   b , flat surface  8   d  on said circumferential surface  8   c  is set such that it becomes parallel to one of the flat surfaces  8   e  on boss part  8   b.  As a result, respective contact spots P 1  through P 6  are positioned over respective center lines A which bisect respective flat surfaces  8   e  on boss part  8   b,  as shown in  FIG. 3 . 
     That is, one of flat surfaces  8   e  of boss part  8   b  is placed facing and parallel to the bottom surface of door rail  4  when boss part  8   b  is fitted into installation hole  6   a,  and one of contact spots P 1  through P 6  which correspond to said flat surfaces  8   e  comes into contact with door rail  4  so as to perform the door derailing prevention function in order to prevent hanger roller  7  from being lifted from door rail  4 . Here, when the position where boss part  8   b  is fitted into installation hole  6   a  is changed in the rotational direction around installation stud  9 , the contact spot which executes the door derailing prevention function is also changed, so that the gap between derailing prevention member  8  and door rail  4  is also changed. 
     For example, in the present embodiment, the cross section of circumferential surface  8   c  of body  11  is arranged such that the radius is at the maximum at contact spot P 1 , and the radius is at the minimum at contact spot P 6 . Furthermore, the radiuses of respective contact spots P 2  through P 5  other than contact spots P 1  and P 6  are set such that the radius is reduced in stages from the maximum radius at contact spot P 1  toward the minimum radius at contact spot P 6  in the clockwise direction in  FIG. 3 . Then, as shown in  FIG. 4  and as described above, because the positions on body  11  where the radiuses at respective contact spots P 1  through P 6  change in stages are determined at 60° intervals with reference to line B corresponding to the bottom surface of door rail  4  in order for respective contact spots P 1  through P 6  to be positioned facing line B, the gaps between the respective contact spots P 1  through P 6  and line B are changed also. In this case, the gaps between them becomes the minimum, that is, zero, when contact spot P 1  is placed at the position facing line B, and gaps g 1  through g 4  between line B and said contact spots P 2  through PS are also increased in stages as the contact spot facing line B changes from P 2  to P 5  in stages. Furthermore, gap g 5  becomes the maximum when contact spot P 6  is placed at the position facing line B. Thus the cross section of circumferential surface  8   c  of body  11  is arranged to obtain g 1 &lt;g 2 &lt;g 3 &lt;g 4 &lt;g 5 . 
     During installation of derailing prevention member  8  configured in the aforementioned manner on door hanger  6 , even when installation stud  9  is first inserted into installation hole  6   a  on the door hanger  6  side, installation hole  6   a  and boss part  8   b  never engage with each other, body  11  is kept in a condition in which it can rotate with respect to door hanger  6 , and flat surface  8   d  (contact spot P 6 ) of circumferential surface  8   c  of body  11  is placed face to face with the bottom surface of door rail  4 . While the condition in which installation hole  6   a  and boss part  8   b  are not engaged continues to be maintained, body  11  is turned in the clockwise direction so as to press a portion of circumferential surface  8   c  of body  11  against the bottom surface of door rail  4 , and the position at which the gap between circumferential surface  8   c  of body  11  and the bottom surface of door rail  4  becomes essentially zero is determined. (This determined position is referred to as the reference position.) 
     Once derailing prevention member  8  is placed at the reference position, body  11  is turned slowly in the counterclockwise direction while it is pressed against door hanger  6  in order to find the position where pedestal surface  8   a  seats on door hanger  6  as installation hole  6   a  engages with boss part  8   b  for the first time. The gap created between circumferential surface  8   c  of body  11  and the bottom surface of door rail  4  is then checked to find if it is appropriate or not. If it is appropriate, nut  10  is tightened onto installation stud  9  from the back side of the door hanger using wrench S in the manner shown in  FIG. 2 , in order to fix derailing prevention member  8  in said position. The installation of derailing prevention member  8  is now complete. 
     On the other hand, if the position of engagement between installation hole  6   a  and boss part  8   b  creates a gap between circumferential surface  8   c  of body  11  and the bottom surface of door rail  4  that is not appropriate (too small), the engagement of installation hole  6   a  with boss part  8   b  is undone, and body  11  is then turned in the counterclockwise direction while it is pressed against door hanger  6  in the same manner as that described above in order to determine the position where installation hole  6   a  and boss part  8   b  engage with each other. As a result, the gap between circumferential surface  8   c  of body  11  and the bottom surface of door rail  4  becomes greater than before. Whether the gap is appropriate or not is checked, and nut  10  is tightened onto installation stud  9  from the back side of the door hanger in the same manner as was described above in order to fix derailing prevention member  8  in the position. The installation of derailing prevention member  8  is now completed. In addition, if a decision is made that the original gap is more appropriate as a result of checking the gap, body  11  is turned in the clockwise direction by  1  stage in order to restore the previous condition. 
     Furthermore, in the event that the gap between derailing prevention member  8  and door rail  4  has increased due to wear of the door rail  4  or hanger rollers  7  and needs to be adjusted, nut  10  is loosened using wrench S to undo the engagement of boss part  8   b  with installation hole  6   a  and release derailing prevention member  8 , the position where boss part  8   b  should be engaged with installation hole  6   a  is determined, they are engaged with each other at said engagement position, and derailing prevention member  8  is fixed to door hanger  6  using nut  10 . 
     Therefore, when the installation structure employing derailing prevention member  8  and having the aforementioned configuration is adopted, derailing prevention member  8  cannot rotate relative to door hanger  6  since boss part  8   b  is engaged with installation hole  6   a,  so that there is no need to secure derailing prevention member  8  to make it immovable when screwing nut  10  onto installation stud  9 , and the installation of derailing prevention member  8  not only becomes easy, but also the maintainability can be improved. Moreover, the fixing work to prevent derailing prevention member  8  from turning is no longer needed when screwing nut  10  onto installation stud  9 , so design of the derailing prevention member  8  arrangement becomes flexible. 
     In addition, because derailing prevention member  8  is seated directly on door hanger  6 , the contact areas between derailing prevention member  8  and door hanger  6  are increased, which is advantageous in that the amount of so-called cantilever wherein derailing prevention member  8  project from door hanger  4  is further reduced, the load applied to installation stud  9  when the circumferential surfaces of derailing prevention member  8  are pressed against door rail  4  is reduced to offer an advantage in terms of strength, and spatial efficiency can be improved due to the small amount that derailing prevention member  8  project from door hanger  4 . 
     Furthermore, changes in the gap between derailing prevention member  8  and door rail  4  due to the relative rotation between derailing prevention member  8  and door hanger  6  can be prevented since boss parts  8   b  are engaged with installation holes  6   a , resulting in the advantage that the frequency with which the gap between derailing prevention member  8  and door rail  4  is adjusted can be reduced. 
     Furthermore, although door rail  4  was designed to be sandwiched between hanger rollers  7  and derailing prevention member  8  in the present embodiment, when a channel-shaped door rail is used, for example, hanger rollers  7  and derailing prevention member  8  can of course be provided inside the “ko”-shape [the shape of a sideways U″]. 
     In addition, although boss part  8   b  was formed as an equilateral hexagon in the example of the present embodiment, polygonal shapes other than the equilateral hexagons, such as equilateral octagons, the equilateral dodecagons, etc., can of course be adopted for boss part  8   b.  When boss part  8   b  is formed as a polygon, flexibility in determining the position of derailing prevention member  8  can be improved. 
     In addition, as can be understood from the figures, derailing prevention member  8  can include multiple derailing prevention member  8  on one door hangar  6 . 
       FIG. 5  is an oblique disassembled view of the derailing prevention member of a second embodiment of the present invention. 
     In the second embodiment shown in  FIG. 5 , installation hole  20   a  created in door hanger  20  is circular, multiple positioning holes  20   b  are created along a concentric circle around the axial center of said installation hole  20   a,  that is, the axial center of installation stud  9 . A boss part  21   b,  which in this embodiment is formed as a hemispherical positioning protrusion, is created at the position on pedestal surface  21   a  of derailing prevention member  21  where it corresponds to positioning holes  20   b.  Here, positioning hole  20   b  is a round hole and boss part  21   b  is shaped to match the shape of positioning holes  20   b,  and boss part  21   b  can be engaged with and disengaged from positioning holes  20   b.    
     During the installation of derailing prevention member  21  on door hanger  20 , the position at which a positioning hole  20   b  is engaged with boss part  21   b  is determined in the same manner as in the first embodiment, they are engaged with each other at said engagement position, and derailing prevention member  21  is fixed to door hanger  20  using nut  10 . 
     Therefore, according to derailing prevention member  21  of the second embodiment, an effect similar to that of the first embodiment can be achieved. 
       FIG. 6  is a diagram showing a modified example of positioning hole  20   b  and boss part  21   b  in  FIG. 5 . 
     In the modified example shown in  FIG. 6 , positioning holes  20   c  are formed as oblong holes, and a boss part  22   b  is in the shape of a parallel key and formed to protrude from pedestal surface  22   a  of derailing prevention member  22  and fit into a positioning hole  20   c,  thereby achieving an effect similar to that of the second embodiment. 
     Because it is no longer necessary to fix the door derailing prevention member to prevent it from turning when the nut is screwed onto the installation stud because the relative position of the door derailing prevention member with respect to the door hanger is determined when the boss part and the positioning hole are fitted together, not only does the installation of the door derailing prevention member become easy, but also the maintainability of adjustment of the gap between the door derailing prevention member and the door rail can be improved. 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.