Abstract:
Disclosed is an elevator door with an improved clutch device suitable for increasing clutch speed and decreasing clutch distance of a car door and a hatch door. 
     The elevator door with an improved clutch device comprises a hatch door having a pair of clutch rollers; a car door having a pair of clutch plates; a door motor for giving force to move the car door; a reduction pulley for reducing rotating speed of the door motor; a plurality of links for converting rotation of the reduction pulley to angular movement; a cam link having one end rotatably connected to one of the links, the cam link including a curved portion having various curvatures formed at the other end thereof; and a rotating link positioned between a pair of the clutch plates, the rotating link being rotatably connected to one of the clutch plates and in contact with the other of the clutch plates, the rotating link contacting with the curved portion of the cam link at its mediate portion, wherein angular movement of the cam link pushes the rotating link along the curved portion, which brings a pair of the clutch plates into contact with a pair of the clutch rollers respectively.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical field 
     The present invention relates to an elevator door with an improved clutch device, and more particularly to a clutch system of an elevator door suitable for increasing clutch speed and decreasing clutch distance of a car door and a hatch door. 
     2. Description of the Prior Art 
     As the buildings are higher, there is need to provide an elevator, which may carry passengers to a destined floor faster. Faster movement of the elevator requires increasing vertical speed of the elevator as well as shortening time to open or close an elevator door. 
     Among those, the present invention deals with a technique of reducing time to open or close elevator doors with ensuring stable operation of the elevator doors. 
     The elevator door generally includes a car door installed to an elevator car and a hatch door installed to entrance of the elevator car in each floor. The car door may open with use of a driving unit mounted on the elevator car, while the hatch door moves along with the car door with use of a clutch system. In order to move the hatch door along with the car door, the clutch system performs a series of clutch operation, which will be explained in detail below. 
     Opening speed of the car door until completing the clutch operation of the car door and the hatch door (hereinafter, referred to “clutch speed”) is important to door opening time. As the clutch speed is slower, time to open or close the elevator door increases, which makes it inefficient to carry passengers fast. Therefore, increase of the clutch speed of the car door and the hatch door helps to reduce the time to open or close the doors. 
     FIG.  1  and FIG. 2 are horizontal section view and vertical section view respectively showing schematic configuration of a conventional elevator. As shown in the figures, the elevator car  2  carries passengers with moving vertically in hoist way  1  by a separate driving unit. The car door  10  is installed at entrance of the elevator car  2  to open and close laterally. The hatch door  20  is positioned at each floor of a building, which the elevator serves, in order to allow passengers to enter the elevator car  2 . The elevator door is a common name for designating both the car door  10  and the hatch door  20 . 
     Unexplained reference  3  is for a counter weight. 
     FIG. 3 is a front view showing the elevator door according to the prior art, viewed at a car door side. Referring to the figure, a door motor  4  is mounted on the elevator car  2  for providing power to open or close the car door  10 . At one side of the door motor  4 , first and second reduction pulleys  5   a ,  5   b  are sequentially installed to reduce rotating speed of the door motor  4 . The second reducing pulley  5   b  is combined with one end of a moving link  6  such that the moving link  6  may move in linkage with rotation of the second reduction pulley  5   b . The other end of the moving link  6  is rotatably combined with one end of a main link  7 , which is also rotatably combined with the elevator car  2 . The other end of the main link  7  is rotatably combined with a cam link  13 , which is positioned at a left door panel  10   a . Viewed from the figure, a pair of clutch plates  11 ,  12  are installed at the left door panel  10   a , a fixed clutch plate  11  of which the cam link  13  is rotatably combined with. A car frame  31  is mounted upon the elevator car  2  for supporting the elevator car  2 . The main link  7  is fixed to the car frame  31  with a rotating joint  7   a  at its mediate portion to possibly rotate on center of the rotating joint  7   a . A connecting link  8  is combined with an upper mediate portion of the main link  7 . The other end of the connecting link  8  is rotatably connected to a certain position of a sub-link  9  at a right door panel  10   b . One end of the sub-link  9  is rotatably fixed to the car frame  31  with a rotating joint  9   a , while the other end is also rotatably combined with one end of a cam link  16 . Viewed from the figure, a pair of clutch plates  14 ,  15  is installed to the right door panel  10   b , a fixed clutch plate  14  of which the cam link  16  is rotatably combined with. 
     A pair of clutch plates  11 ,  12  or  14 ,  15  at the left or right door panel  10   a  or  10   b  includes the fixed clutch plate  11  or  14  and a movable clutch plate  12  or  15 . The fixed clutch plate  11  or  14  is fixed to each door panel  10   a ,  10   b , and the cam link  13  or  16  is rotatably combined with the fixed clutch plate  11 ,  14  as described above. The movable clutch plate  12 ,  15  is combined with the fixed clutch plate  11 ,  14  with a hinge  17   a  or  17   b , which is well shown in FIG.  5  and FIG.  7 . 
     Referring to FIG.  4  and FIG. 5, a pair of clutch rollers  21 ,  22  or  23 ,  24  is installed to each door panel  20   a ,  20   b  of the hatch door  20 . The clutch rollers  21 ,  22  or  23 ,  24  include a fixed clutch roller  21  or  23  and a rotating clutch roller  22  or  24 . The pair of clutch plates  11 ,  12  or  14 ,  15  are installed to have certain clearance therebetween, such that the clutch rollers  21 ,  22  or  23 ,  24  may pass through the clearance when the elevator car is moving. However, when the elevator car  2  arrives at a destined floor, the clutch rollers  21 ,  22  or  23 ,  24  are interposed between and becomes contacted with the pair of clutch plates  11 ,  12  or  14 ,  15  for the purpose of opening or closing the hatch door  20  along with the car door  10 . 
     FIG.  6  and FIG. 7 are front and horizontal section views respectively showing the clutch system of the conventional elevator door. Referring to the figures, one end of the cam link  13  or  16  is rotatably combined with the main or sub-link  7  or  9  with a rotating joint J, while a roller  13   a  or  16   a  is mounted to the other end to freely rotate. A rugged cam  12   a  or  15   a  is formed on a side of the movable clutch plate  12  or  15  such that the roller  13   a ,  16   a  of the cam link  13 ,  16  may roll in contact with the rugged cam  12   a ,  15   a . On the rugged cam  12   a ,  15   a , a plurality of curved portions are formed in succession such that angular displacement of the movable clutch plate  12 ,  15  may be determined according to the height of the curved portions. 
     The fixed clutch plate  11 ,  14  and the movable clutch plate  12 ,  15  of the car door  10  and the fixed clutch roller  21 ,  23  and the rotating clutch roller  22 ,  24  of the hatch door  20  are installed to the left and right door panels  10   a ,  10   b  and  20   a ,  20   b  in mirror image. 
     The elevator door with the conventional clutch device as constructed above operates as follows. 
     At first when the elevator car  2  arrives at a destined floor, a door opening command is generated. The door motor  4  then starts to rotate clockwise according to the door opening command. Rotation of the door motor  4  is reduced through the first and second reduction pulley  5   a ,  5   b  and then moves the moving link  6 . If the moving link  6  moves in linkage with the second reduction pulley  5   b , one end of the main link  7  connected to the moving link  6  angularly moves clockwise. At this time, because the main link  7  is constructed to rotate on center of the rotating joint  7   a  at the mediate portion thereof, the other end of the main link  7  also rotates clockwise. When the other end of the main link  7  rotates clockwise, the cam link  13  of the left door panel  10   a  angularly moves counterclockwise, which makes the left door panel  10   a  opened left. On the other hand, clockwise rotation of the main link  7  is linked with the connecting link  8 , one end of which is combined at an upper mediate portion of the main link  7 , and then linked with the sub-link  9  combined with the other end of the connecting link  8 . However, while the main link  7  rotates clockwise, the sub-link  9 , one end of which is rotatably fixed to the car frame  31  with the rotating joint  9   a , rotates counterclockwise. If the sub-link  9  rotates counterclockwise, the cam link  16  of the right door panel  10   b  angularly moves counterclockwise, which makes the right door panel  10   b  opened aright. 
     At this point, when each cam link  13 ,  16  angularly moves clockwise or counterclockwise, the roller  13   a ,  16   a  of each cam link  13 ,  16  moves along the curved portion of the rugged cam  12   a ,  15   a . Due to variation of the depth of the curved portion, the movable clutch plates  12 ,  15  of the left and right door panels  10   a ,  10   b  angularly moves on center of the hinges  17   a ,  17   b  on the fixed clutch plates  11 ,  14 . Due to rotation of the movable clutch plate  12 ,  15 , the fixed and rotating clutch rollers  21 ,  23  and  22 ,  24  are closely contacted between the fixed and movable clutch plates  11 ,  14  and  12 ,  15 , which is completion of the clutch operation. 
     After that, the left and right hatch door panel  20   a ,  20   b  are opened to opposite directions according to movement of the left and right car door panel  10   a ,  10   b , which makes the elevator door open. 
     Such serial clutch operation is explained in detail with reference to FIG. 8 to FIG.  11 . FIG. 8 to FIG. 11 show the clutch operation of the clutch device according to the conventional elevator door in sequence, all of which have vertical section view and side view. 
     At first, FIG. 8 shows clutch operation of the car door  10  and the hatch door  20  at the time that the elevator car  2  is moving or arrives at a destined floor. Referring to the figure, the clutch plates  11 ,  12  and  14 ,  15  of the car door  10  and the clutch rollers  21 ,  22  and  23 ,  24  of the hatch door  20  maintain clearance therebetween as much as G 1  at this time. After that, when the car door  10  starts opening, the car door  10  moves while the hatch door  20  maintains its closed position until the fixed clutch plate  11 ,  14  of the car door  10  comes in contact with the rotating clutch roller  22 ,  24  of the hatch door  20 . 
     Next, FIG. 9 shows the time that the clutch operation begins between the car door  10  and the hatch door  20 . Referring to figure, moving distance of the car door  10  until the fixed clutch plate  11 ,  14  of the car door  10  comes in contact with the rotating clutch roller  22 ,  24  of the hatch door  20  corresponds to Sl. As the car door  10  opens as much as S 1 , angular displacement of the cam link  13 ,  16  is from A 1  to A 2 . In addition, the angular displacement of the cam link  13 ,  16  causes the movable clutch plate  12 ,  15  to angularly move on center of the hinge  17   a ,  17   b . At this time, the left and right hatch door panels  20   a ,  20   b  moves along with the left and right car door panels  10   a ,  10   b  and clearance between the movable clutch plate  12 ,  15  of the car door  10  and the fixed clutch roller  21 ,  23  of the hatch door  10  becomes G 2 . Furthermore, clutching state, at this time, is not perfect because of the clearance G 2  between the movable clutch plate  12 ,  15  of the car door  10  and the fixed clutch roller  21 ,  23  of the hatch door  20 , while the fixed clutch plate  11 ,  14  of the car door  10  is in contact with the rotating clutch roller  22 ,  24  of the hatch door  20 . 
     Next, FIG. 10 shows the time that the hatch door  20  starts to move along with the car door  10 . At this time, the car door  10  advances a little more than that of FIG.  9 . Referring to the figure, angle of the cam link  13 ,  16  displaces from A 2  to A 3 . In addition, the movable clutch plate  12 ,  15  begins to rotate on center of the hinge  17   a ,  17   b  due to the angular displacement of the cam link  13 ,  16 . Clearance between the movable clutch plate  12 ,  15  of the car door  10  and the fixed clutch roller  21 ,  23  of the hatch door  20  becomes G 3  due to angular movement of the movable clutch plate  12 ,  15 , which is slightly narrower than G 2  at the time that the car door  10  moves as much as S 1 . In FIG. 10, the car door  10  moves as much as S 2 , which is more advanced than S 1 . 
     Finally, FIG. 11 shows the time that the clutch operation between the car door  10  and the hatch door  20  is completed. As shown in the figure, if the car door  10  continues to move until as much as S 3 , the movable clutch plate  12 ,  15  of the car door  10  comes in contact with the fixed clutch roller  21 ,  23  of the hatch door  20  so to make clearance therebetween changed into 0 from S 3 . This is completion of the clutch operation between the car door  10  and the hatch door  20 . From closed state to the completion of the clutch operation, the car door  10  moves as much as S 3 , which is called as “clutch completion distance”. 
     When opening the door, the car door  10  and the hatch door  20  moves at a low speed until completion of the clutch operation, and at a high speed after the completion of the clutch operation. 
     Closing process of the elevator door is the reverse of the door opening process. 
     For the purpose of reducing time to open the conventional elevator door, there are methods of both or either increasing the clutch speed and/or reducing the clutch completion distance S 3 . However, in case of increasing the clutch speed, noises and vibration may be generated due to impact when the movable clutch plate  12 ,  15  of the car door  10  contacts with the fixed clutch roller  21 ,  23  of the hatch door  20 . On the other hand, in case of reducing the clutch completion distance, the curved portion of the rugged cam  12   a ,  15   a  should having a steep inflection point in the light of angular displacement of the cam link  13 ,  16  required to contact the movable clutch plate  12 ,  15  of the car door  10  to the fixed clutch roller  21 ,  23  of the hatch door  20 . However, such configuration requires stronger force for the roller  13   a ,  16   a  of the cam link  13 ,  16  to move along the steep slope of the rugged cam  12   a ,  15   a , which may cause a problem of the door motor  4  to be overloaded. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention is designed to overcome the above problems of the prior art. An object of the invention is to provide an elevator door with an improved clutch device which may reduce time to open or close the elevator door without requiring overload to a door motor by decreasing the clutch completion distance. 
     In order to accomplish the object, the present invention provides an elevator door with a clutch device comprising: a hatch door provided at each floor in a building for passengers to board on/off an elevator car, the hatch door having a pair of clutch rollers installed thereto; a car door installed to the elevator car for passengers to board on/off the elevator car, the car door having a pair of clutch plates installed thereto, a pair of the clutch rollers passing through or interposed between a pair of the clutch plate; a door motor for giving force to move the car door; a reduction pulley for reducing rotating speed of the door motor; a plurality of links connected to the reduction pulley for converting rotation of the reduction pulley to angular movement; a cam link having one end rotatably connected to one of the links, the cam link including a curved portion having various curvatures formed at the other end thereof; and a rotating link positioned between a pair of the clutch plates, the rotating link being rotatably connected to one of the clutch plates and in contact with the other of the clutch plates, the rotating link contacting with the curved portion of the cam link at its mediate portion, wherein angular movement of the cam link pushes the rotating link along the curved portion, which brings a pair of the clutch plates into contact with a pair of the clutch rollers respectively. 
     The rotating link can be rotatably combined with one of a pair of the clutch plate at one end thereof, and the rotating link may comprise a first rotating roller mounted at a mediate portion thereof for contact with the curved portion of the cam link, and a second roller mounted at the other end thereof for contact with the other of a pair of the clutch plates. 
     The first rotating roller may be detachable from the rotating link in order to modulate distance from a rotating center of the rotating link thereto. 
     One of a pair of the clutch plates is preferably fixed to the car door, and the other clutch plate is movable. 
     The fixed clutch plate may have a guide bracket which is slidably inserted into the movable clutch plate, the guide bracket guiding moving direction of the movable clutch plate. 
     It is more preferred that an elastic member be installed between a pair of the clutch plates in order to provide tension force to the clutch plate such that the clutch plates recover initial positions when broadened. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings, in which like components are referred to by like reference numerals. In the drawings: 
     FIG. 1 is a horizontal section view showing a conventional elevator schematically; 
     FIG. 2 is a vertical section view showing the elevator of FIG. 1 schematically; 
     FIG. 3 is a front view of a conventional elevator door viewed at a car door side; 
     FIG. 4 is a front view of the conventional elevator door viewed at a hatch door side; 
     FIG. 5 is a horizontal section view showing a clutch device of the conventional elevator door schematically; 
     FIG. 6 has a front view and a partially enlarged view for illustrating clutch operation of the clutch device of the conventional elevator door; 
     FIG. 7 is a horizontal section view of FIG. 6; 
     FIG. 8 to FIG. 11 show the clutch operation of the clutch device of the conventional elevator door in sequence, each of which contains a horizontal section view and a side view; 
     FIG. 12 is a front view for showing an elevator door according to the present invention, schematically; 
     FIG. 13 is a front view showing a clutch device of the elevator door according to the present invention; 
     FIG. 14 is a horizontal section view of the clutch device of FIG. 13; 
     FIG. 15 is a front view for showing a cam link of the clutch device of the elevator door according to the present invention; 
     FIG. 16 is a front view for showing a rotating link of the clutch device of the elevator door according to the present invention; 
     FIG. 17 is a diagram for illustrating clutch operation of the clutch device of the elevator door according to the present invention; 
     FIG. 18 shows essential parts for illustrating the clutch operation of the clutch device of the elevator door according to the present invention; and 
     FIG. 19 to FIG. 22 shows the clutch operation of the clutch device of the elevator door according to the present invention, each of which contains a horizontal section view and a side view. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     General configurations of the elevator door of the present invention except a clutch device are similar to the prior art, and same parts as the prior art are indicated with same references in conjunction with FIG.  1  and FIG. 2 together. 
     The elevator door with the clutch device according to the present invention includes a car door  100  and a hatch door  200  (see FIG. 19 to FIG.  22 ). Like the prior art, the car door  100  is installed to the elevator car  2 , which carries passengers with vertically moving by a separate driving unit in the hoist way  1  within a building. The hatch door  200  is installed at entrance of the elevator car  2  at each floor and opened and closed along with the car door  100 . 
     FIG. 12 is a front view showing the elevator door according to the present invention schematically. Referring to the figure, a door motor  4  is mounted on the elevator car  2  for providing power to open or close the car door  100 . At one side of the door motor  4 , first and second reduction pulley  5   a ,  5   b  are sequentially installed to reduce rotating speed of the door motor  4 . The second reducing pulley  5   b  is combined with one end of a moving link  6  such that the moving link  6  may move in linkage with rotation of the second reduction pulley  5   b . The other end of the moving link  6  is rotatably combined with one end of a main link  7 , which is also rotatably combined with the elevator car  2 . The other end of the main link  7  is rotatably combined with a cam link  113 , which is positioned at a left door panel  101 . Viewed from the figure, a pair of clutch plates  111 ,  112  is installed at the left door panel  101 , a fixed clutch plate  111  of which the cam link  113  is rotatably combined with. A car frame  31  is mounted upon the elevator car  2  for supporting the elevator car  2 . The main link  7  is rotatably fixed to the car frame  31  with a rotating joint  7   a  at its mediate portion to possibly rotate on center of the rotating joint  7   a . One end of a connecting link  8  is combined with an upper mediate portion of the main link  7 . The other end of the connecting link  8  is rotatably connected to a certain position of a sub-link  9  at a right door panel  102 . One end of the sub-link  9  is rotatably fixed to the car frame  31  with a rotating joint  9   a , while the other end is also rotatably combined with one end of a cam link  116 . Viewed from the figure, a pair of clutch plates  114 ,  115  is installed to the right door panel  102 , a fixed clutch plate  114  of which the cam link  116  is rotatably combined with. 
     A pair of the clutch plates  111 ,  112  or  114 ,  115  at the left or right door panel  101  or  102  includes the fixed clutch plate  111  or  114  and a movable clutch plate  112  or  115 . The fixed clutch plate  111  or  114  is fixed to each door panel  101 ,  102 , and the cam link  113  or  116  is rotatably combined with the fixed clutch plate  111 ,  114  as described above. The movable clutch plate  112 ,  115  is combined with the fixed clutch plate  111 ,  114  by a hinge  117   a  or  117   b , which is well shown in FIG.  14 . 
     In addition, referring to FIG. 13, a guide bracket  121  is mounted to the fixed clutch plate  111 ,  114 . One end of the guide bracket  121  is fixed to the fixed clutch plate  111 ,  114 , while the other end is slidably inserted into the movable clutch plate  112 ,  115  in order to guide a moving direction of the movable clutch plate  112 ,  115 . 
     Referring to FIG.  13  and FIG. 14, a pair of clutch rollers  211 ,  212  or  213 ,  214  is mounted to each door panel (not shown) of the hatch door  200 . The clutch rollers  211 ,  212  or  213 ,  214  include a fixed clutch roller  211 ,  213  and a rotating clutch roller  212 ,  214 . A pair of the clutch plates  111 ,  112  or  114 ,  115  is configured to have certain clearance therebetween such that the clutch rollers  211 ,  212  or  213 ,  214  may pass through the clearance when the elevator is moving. However, when the elevator car  2  arrives at a destined floor, the clutch rollers  211 ,  212  or  213 ,  214  are interposed between and becomes contacted with a pair of the clutch plates  111 ,  112  or  114 ,  115  for the purpose of opening or closing the hatch door  200  along with the car door  100 . 
     FIG. 15 shows the cam link  113 ,  116  of the clutch device according to the present invention. Referring to FIG. 15 in conjunction with the FIG. 13, the cam link  113 ,  116  is rotatably combined with the fixed clutch plate  111 ,  114  by a rotating joint J 2 . A curved portion  113   a ,  116   a  having various curvatures is formed at an end of the cam link  113 ,  116  to be in contact with a rotating link  118 ,  119  described below. When the cam link  113 ,  116  moves angularly, the cam link  113 ,  116  pushes the rotating link  118 ,  119  along the curved portion  113   a ,  116   a , and then consequently pushes the movable clutch plate  112 ,  115  in contact with the rotating link  118 ,  119 . The cam link  113 ,  116  has two joint inserting holes  113   b ,  113   c  or  116   b ,  116   c , respectively. Through the joint inserting hole  113   b ,  116   b , a rotating joint J 1  is installed to rotatably combine the cam link  113 ,  116  with the main and sub links  7 ,  9 , while the rotating joint J 2  is installed through the joint inserting hole  113   c ,  116   c  in order to rotatably combine the cam link  113 ,  116  with the fixed clutch plate  111 ,  114 . 
     FIG. 16 shows the rotating link  118 ,  119  of the clutch device according to the present invention. Referring to FIG. 16 in conjunction with FIG. 13, an end of the rotating link  118 ,  119  is rotatably combined with the fixed clutch plate  111 ,  114  by a rotating joint J 3  such that the rotating link  118 ,  119  may rotate on center of the rotating joint J 3 . A first rotating roller  118   a ,  119   a  is mounted to a mediate portion of the rotating link  118 ,  119 . The first rotating roller  118   a ,  119   a  is detachable so to possibly change its mounting position with the rotating link  118 ,  119 . The first rotating roller  118   a ,  119   a  rolls in contact with the curved portion  113   a ,  116   a  of the cam link  113 ,  116 . When the cam link  113 ,  116  moves angularly, the first rotating roller  118   a ,  119   a  is pushed by the curved portion  113   a , 116   a  such that the rotating link  118 ,  119  may rotate on center of the rotating joint J 3 . Changing the mounting position of the first rotating roller  118   a ,  119   a  makes a distance from the rotating joint J 3 , or center of rotating, to the first rotating roller  118   a ,  119   a  changed, which eventually changes angular displacement of the rotating link  118 ,  119 . A second rotating roller  118   b ,  119   b  is mounted at an end of the rotating link  118 ,  119 . The second rotating roller  118   b ,  119   b  is rotatable in contact with the movable clutch plate  112 ,  115 . 
     In addition, a tension coil spring  120  is positioned between each of the fixed clutch plate  111 ,  114  and the movable clutch plate  112 ,  115 , which is well shown in FIG.  13 . The tension coil spring exerts tension force for the movable clutch plate  112 ,  115  to recover its origin position when the clearance between the fixed clutch plate  111 ,  114  and the movable clutch plate  112 ,  115  is broadened. 
     The elevator door with the clutch device as constructed above operates as follows. 
     At first when the elevator car  2  arrives at a destined floor, a door opening command is generated. The door motor  4  then starts to rotate clockwise according to the door opening command. Rotation of the door motor  4  is reduced through the first and second reduction pulley  5   a ,  5   b  and then moves the moving link  6 . If the moving link  6  moves in linkage with the second reduction pulley  5   b , one end of the main link  7  connected to the moving link  6  moves angularly clockwise. At this time, because the main link  7  is constructed to rotate on center of the rotating joint  7   a  at the mediate portion thereof, the other end of the main link  7  also rotates clockwise. When the other end of the main link  7  rotates clockwise, the cam link  113  of the left door panel  101  angularly moves counterclockwise, which makes the left door panel  101  opened left. On the other hand, clockwise rotation of the main link  7  is linked with the connecting link  8 , one end of which is combined at an upper mediate portion of the main link  7 , and then linked with the sub-link  9  combined with the other end of the connecting link  8 . However, while the main link  7  rotates clockwise, the sub-link  9 , one end of which is rotatably fixed to the car frame  31  with the rotating joint  9   a , rotates counterclockwise. If the sub-link  9  rotates counterclockwise, the cam link  116  of the right door panel  102  angularly moves clockwise, which makes the right door panel  102  opened right. 
     While the prior art employs the rugged cam formed on the movable clutch plate, the present invention uses the curved portion  113   a ,  116   a  formed at an end of the cam link  113 ,  116  and the rotating link  118 ,  119  in contact with the curved portion  113   a ,  116   a . The process that the curved portion  113   a ,  116   a  of the cam link  113 ,  116  is linked with the rotating link  118 ,  119  is well shown in FIG.  17  and FIG.  18 . Referring to the figures, as the cam link  113 ,  116  moves angularly, the curved portion  113   a ,  116   a  formed at the end of the cam link  113 ,  116  rotates in contact with the first rotating roller  118   a ,  119   a  of the rotating link  118 ,  119 . Rotation of the curved portion  113   a ,  116   a  pushes the rotating link  118 ,  119  according to the curvature of the curved portion  113   a ,  116   a , which eventually pushes the movable clutch plate  112 ,  115  to move laterally. 
     FIG. 19 to FIG. 22 show the clutching operation of the clutch device according to the present invention in sequence. The clutching operation of the present invention is explained in more detail with reference to the figures. 
     At first, FIG. 19 shows clutching operation of the car door  100  and the hatch door  200  at the time that the elevator car is moving or arrives at a destined floor. Referring to the figure, the clutch plates  111 ,  112  or  114 ,  115  of the car door  100  and the clutch rollers  211 ,  212  or  213 ,  214  of the hatch door  200  maintain clearance therebetween as much as G 1  at this time in order that the clutch plates  111 ,  112  or  114 ,  115  of the car door  100  and the clutch rollers  211 ,  212  or  213 ,  214  of the hatch door  200  should not impact each other. 
     FIG. 20 shows the clutching operation at the time that the car door  100  starts to move after the elevator car  2  arrives at the destined floor. At this time, the hatch door  200  is not moving yet. At this time, the cam link  113 ,  116  begins to rotate clockwise by the door motor  4 , the reduction pulleys  5   a ,  5   b , the moving link  6  and the main link  7 . Referring to the figure, the curved portion  113   a ,  116   a  formed at the end of the cam link  113 ,  116  moves angularly in contact with the first rotating roller  118   a ,  119   a  mounted at a mediate portion of the rotating link  118 ,  119 . When the cam link  113 ,  116  moves angularly, a distance from a rotating center J 2  of the cam link  113 ,  116  to a contact point of the curved portion  113   a ,  116   a  with the first rotating roller  118   a ,  119   a  of the rotating link  118 ,  119  becomes slightly longer. Therefore, the rotating link  118 ,  119  becomes rotating with being pushed on center of the hinge  117   a ,  117   b  of the fixed clutch plate  111 ,  114 , which eventually pushes the movable clutch plate  112 ,  115  slightly. At this time, the fixed clutch plate  111 ,  114  comes in contact with the rotating clutch roller  212 ,  214  and moves the car door  100  as much as T 1 . Therefore, clearance between the movable clutch plate  112 ,  115  and the fixed clutch roller  211 ,  213  is broadened from G 1  to G 2 . 
     FIG. 21 shows the clutching operation at the time that the hatch door  200  begins to move along with the car door  100 . At this time, the car door  100  moves as much as T 2 , and the hatch door  200  moves as much as H 1  with being led by the car door  100 . Referring to the figure, as the cam link  113 ,  116  rotates a little more, the curved portion  113   a ,  116   a  of the cam link  113 ,  116  pushes the rotating link  118 ,  119  a little further. At this time, the fixed clutch plate  111 ,  114  is continuously in contact with the rotating clutch roller  212 ,  214  and the clearance between the movable clutch plate  112 ,  115  and the fixed clutch roller  211 ,  213  becomes narrow from G 2  to G 3 . 
     FIG. 22 shows the time that the clutching operation of the car door  100  and the hatch door  200  is completed. Referring to the figure, the car door  100  moves as much as T 3  and the hatch door  200  moves as much as H 2  with being led by the car door  100 . At this time, the cam link  113 ,  116  rotates more so that the curved portion  113   a ,  116   a  pushes the rotating link  118 ,  119  further. Therefore, the fixed clutch plate  111 ,  114  and the movable clutch plate  112 ,  115  come in contact with the rotating clutch roller  212 ,  214  and the fixed clutch roller  211 ,  213 , respectively. 
     In the described clutch device, the clutch speed can be adjusted by changing the curvature of the curved portion  113   a ,  116   a  of the cam link  113 ,  116 . In addition, the clutch speed can be also adjusted by modulating the contact point between the curved portion  113   a ,  116   a  and the first rotating roller  118   a ,  119   a . 
     Among the methods for adjusting the clutch speed, the method of modulating the contact point between the curved portion  113   a ,  116   a  and the first rotating roller  118   a ,  119   a  is described in detail. For the sake of the method, what is needed is to modulate distance from the rotating center J 3  of the rotating link  118 ,  119  to the detachable first rotating roller  118   a ,  119   a . If the first rotating roller  118   a ,  119   a  is positioned nearer to the rotating center J 3  of the rotating link  118 ,  119 , angular displacement of the rotating link  118 ,  119  for same angular movement of the cam link  113 ,  116  becomes increased. In other word, though the first rotating roller  118   a ,  119   a  moves same distance, the second rotating roller  118   b ,  119   b  moves further than the case before the modulation. Therefore, to increase the angular displacement of the rotating link  118 ,  119  in such manner has same effect as to increase the curvature of the curved portion  113   a ,  116   a  of the cam link  113 ,  116 . 
     Therefore, in order to increase the clutch speed, what is to do is to increase the curvature of the curved portion  113   a ,  116   a  of the cam link  113 ,  116  and/or relocate the first rotating roller  118   a ,  119   a  near the rotating center J 3  of the rotating link  118 ,  119 . In such manner, the clutch distance of the car door  100  and the hatch door  200  is reduced, which makes the low-speed travel region decreased and eventually makes it possible to reduce time to open or close the elevator door. 
     As described above, the elevator door with the improved clutch device has advantages in carrying passengers in light that the clutch completion distance of the car door and the hatch door may be reduced without requiring overload to the door motor. 
     The elevator door with the improved clutch device according to the present invention has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.