Abstract:
An emergency stop apparatus for an elevator having a simple structure as well as effectiveness, which may facilitate to reduce manufacturing and maintaining cost. The emergency stop apparatus for an elevator includes a pair of wedges for stopping the elevator by constricting the guide rail when the elevator moves in excess speed; a flexible cable for drawing the wedges upward when the elevator moves in excess speed; a cam having a rotary shaft engaged with the flexible cable for drawing the cable upward when the elevator moves in excess speed; a disk roller which rides and rolls on the guide rail on the center of a rotary shaft thereof when the elevator moves and receiving pressure from the cam means toward the guide rail when the elevator moves in excess speed; a centrifugal weight having same rotary shaft as the disk roller for rotating the cam means when the elevator moves in excess speed; and a spring for biasing the centrifugal weight to come in contact with the cam means when the elevator moves in excess speed.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an emergency stop apparatus for an elevator, and more particularly to an emergency stop apparatus for an elevator having a simple structure as well as effectiveness, which may facilitate to reduce manufacturing and maintaining cost. 
     2. Description of the Prior Art 
     The elevator is generally designed to ascend and descend at a regular speed in an at least two-story building. However, the elevator car often descends much faster than a normal speed for reasons of malfunction of controller or other units, especially in downward motion. In order to prevent accidents by such factors, the elevator ordinarily includes an emergency stop apparatus. 
     U.S. Pat. No. 5,299,661 issued on Apr. 5, 1994 discloses an elevator system having a bidirectional overspeed control device and a governor rope circularly connected to sheaves mounted to upper and lower portions of a hoist way. According to the patent, the bidirectional overspeed control device includes a bidirectional governor, safety brakes and a bidirectional linkage apparatus, in which the bidirectional governor clutches the governor rope in the event of an overspeed condition, thereby operating the bidirectional linkage apparatus which connects the governor rope to the safety. 
     FIG. 1 shows the emergency stop apparatus employed in such elevator system schematically. Referring to the figure, the emergency stop apparatus of the conventional elevator system is installed to an elevator car  2  moving vertically along a guide rail  1  in a hoist way inside a building. The emergency stop apparatus includes a speed governing unit  10  installed to one side of the guide rail  1  for detecting speed of the elevator car  2  in order to brake the elevator car  2  when the car  2  moves faster than a certain speed, a transmission unit  20  connected to the governor  2  for transmitting power from the speed governing unit  10 , and a brake  30  installed under the elevator car  2  for restraining the elevator car  2  by receiving power from the speed governing unit  10  through the transmission unit  20 . 
     The speed governor  10  includes a governor  11 , a driven pulley  12 , and a governing loop  13 . The governor  11  includes a rotating body  11 A for rotating at the same speed as speed of the elevator car  2  and stopping when the elevator car  2  moves faster than a regular speed, and a centrifugal weight  11 B having same rotary axis as the rotating body  11 B. The driven pulley  12  is mounted at a lower end of the guide rail  1  and the governing loop  13  is wound through the rotating body  11 A and the driven pulley  12 . 
     The transmission unit  20  includes a connecting member  21  and a multi-joint link member  22 . The connecting member  21  is combined to the governing loop  13  in order to lift at the same speed as the governing loop  13 . The multi-joint link member  22  is combined to the connecting member  21  and activates a pair of wedges  31  of the brake  30  described below when the governing loop  13  comes to a halt. 
     The brake  30  is well shown in FIGS. 2 and 3. Referring to the figures, the brake  30  includes the wedges  31 , an elastic ring  32 , a wedge seat  33  and sliding rollers  34 . When stopping the elevator car  2  in emergency, the wedges  31  are drawn by the link member  22  of the transmission unit  20  and then come in contact with the guide rail  1 . As described above, the wedges  31  in contact with the guide rail  1  make frictional force to the guide rail  1 , and at this time, the elastic ring  32  exerts vertical force to the wedges  31  in order to increase the frictional force between the wedges  31  and the guide rail  1 . The wedge seat  33  is mounted between outer sides of the wedges  31  and an inner side of the elastic ring  32 . The wedge seat  33  has is formed to become gradually narrower in its upward direction such that the wedges  31  may be pressed by more vertical force from the elastic ring  32  as the wedges  31  ascend. The sliding rollers  34  are located between the outer surface of the wedge seat  33  and the inner surface of the wedges  31  and play a role of eliminating friction between the wedges  31  and the wedge seat  33  such that the wedges  31  may ascend inside the wedge seat  33  more smoothly. 
     The emergency stop apparatus of the conventional elevator system as constructed above is operated as follows. 
     If the elevator car  2  moves in excess speed due to a breakdown or a falling in the hoist way, the governor  11  is activated by the rotating body  11 A and the centrifugal weight  11 B rotating at the same speed as speed of the elevator. The governor  11  acts for stopping the governing loop  13  moving along with the elevator car  2 . If the governing loop  13  stops, the link member  22  of the transmission unit  20  is linked to draw the wedges  31  of the brake  30 . 
     If the wedges  31  are drawn by the link member  22  as described above, the wedges  31  move upward inside the wedge seat  33  formed to become gradually narrower in its upward direction, and then receives strong press inward through the wedge seat  33  from the elastic ring  32 . Therefore, an inner surface of each wedge  31  comes in contact with an outer surface of the guide rail  1 , resulting that the elevator car  2  stops by frictional force generated in the contact surface. 
     However, such emergency stop apparatus of the conventional elevator system has a problem of low spatial utility rate because it needs separate space for installing the speed governing unit  10  having the governor  11 , the driven pulley  12  and the governing loop  13  outside the guide rail  1 . Furthermore, because a separate link member  22  should be linked for transferring action of the governor  11  to the wedges  31 , it has high manufacturing cost, and it is difficult to fabricate, install and repair the link member  22 . 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention is designed to overcome such problems of the prior emergency stop apparatus. An object of the present invention is to provide an improved emergency stop apparatus of an elevator, which may increase spatial utility rate, lowers manufacturing cost, and allows fabricating, installing and repairing the apparatus easily. 
     In order to obtain such object, the present invention provides an emergency stop apparatus for an elevator which is vertically movable along a guide rail installed vertically to a wall of hoist way in a building, comprising: a pair of wedge means for stopping the elevator by constricting the guide rail when the elevator moves in excess speed; a flexible cable, one end of which is combined with one of the wedge means, the other end of which is combined with the other one of the wedge means, the flexible cable drawing the wedge means upward when the elevator moves in excess speed; cam means having a rotary shaft engaged with the flexible cable, the cam means drawing the cable upward when the elevator moves in excess speed; a disk roller which rides and rolls on the guide rail on the center of a rotary shaft thereof when the elevator moves, the disk roller receiving pressure from the cam means toward the guide rail when the elevator moves in excess speed; a centrifugal weight having same rotary shaft as the disk roller, the centrifugal weight rotating the cam means when the elevator moves in excess speed; and a spring, one end of which is fixed to the rotary shaft of the disk roller, the other end of which is fixed to the centrifugal weight, the spring biasing the centrifugal weight to come in contact with the cam means when the elevator moves in excess speed. 
     The emergency stop apparatus for an elevator may further include first spring for biasing the disk roller toward the guide rail; second spring for maintaining height of the disk roller, the second spring allowing the rotary shaft of the disk roller to move upward by contact between the cam means and the disk roller; and third spring for maintaining position of the cam means, the third spring allowing the rotary shaft of the cam means to move upward by contact between the cam means and the disk roller. 
     The emergency stop apparatus for an elevator may also further include a limit block having an inclined portion for limiting rise of the rotary shaft of the cam means. 
    
    
     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 schematic diagram for showing an emergency stop apparatus for an elevator according to the prior art; 
     FIG. 2 is a section view for showing a brake of the emergency stop apparatus for an elevator according to the prior art; 
     FIG. 3 is a side view for showing the brake of FIG. 2; 
     FIG. 4 schematically shows an emergency stop apparatus for an elevator according to the present invention; 
     FIG. 5 is a section view for showing essential parts of the emergency stop apparatus for an elevator according to the present invention; and 
     FIG. 6 is a side view showing the essential parts of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 4 shows an emergency stop apparatus of an elevator according to the present invention schematically and FIG.  5  and FIG. 6 are section and side views showing essential parts of the emergency stop apparatus, respectively. The emergency stop apparatus for an elevator according to the present invention is installed to a lower end side of an elevator car  2  which moves vertically along a guide rail  1  mounted to a hoist way in a building. Referring to the figures, it can be shown that the emergency stop apparatus including a speed governing unit  100  for braking the elevator car  2  when the elevator car  2  is detected to move faster than a predetermined speed, a transmission unit  200  for transmitting power from the speed governing unit  100 , and a brake  300  linked with the transmission unit  200  for restraining the elevator car  2  is installed in the hoist way between both guide rails  1 . 
     The speed governing unit  100  includes a disk roller  110 , a centrifugal weight  111  and a cam  120 . The disk roller  110  is installed to the elevator car  2  and rotates in contact with an inner surface of the guide rail  1  toward the hoist way. One end of the centrifugal weight  111  is fixed to a rotary shaft of the centrifugal weight  111  while the other end is coaxially connected to the disk roller  110  through a spring  114  coupled to the centrifugal weight  111 . Radius of gyration of the centrifugal weight  111  changes in accordance with rotating speed of the disk roller  110 . The cam  120  rotates with pressure of the centrifugal weight  111  protruded by centrifugal force when the elevator car  2  moves in exceed speed. At this time, the cam  120  contacts and fixes the disk roller  110  to the guide rail  1 . Particularly, when the cam  120  is rotated by the protruding and rotating centrifugal weight  111  so to contact and fix the disk roller  110  to the guide rail  1 , the cam  120  is configured to move upward together with the disk roller  110 . 
     At this time, it is preferred that the centrifugal weight  111  is connected to a rotary shaft  110 A of the disk roller  110  through a resilient spring  114  such that the centrifugal weight  111  may extrude outside the disk roller  110  when the disk roller  110  rotates faster due to excess downward movement of the elevator car  2 , while, on the other hand, the centrifugal weight  111  may restore its original position when rotating speed of the disk roller  111  is decreased. 
     A separation preventing spring  112  may be installed to the disk roller  110 . One end of the separation preventing spring  112  is coupled to the rotary shaft  110 A of the disk roller  110  while the other end is fixed to a spring seat (not shown in drawing) on a side wall of the speed governing unit  100 . The separation preventing spring  112  presses the disk roller  110  toward the guide rail  1  such that the disk roller  110  would not become apart from the guide rail  1  when the elevator car  2  moves in a normal speed. Therefore, in normal operation of the elevator car  2 , the disk roller  110  rotates in continuous contact with the guide rail  1 . 
     In addition, a rotary shaft holding spring  113  is preferably mounted to the disk roller  110 . One end of the rotary shaft holding spring  113  is coupled to the rotary shaft  110 A of the disk roller  110 , while the other end is fixed to a spring seat (not shown) on a connecting plate  410 . The rotary shaft holding spring  113  is configured to play a role for maintaining height of the rotary shaft  110 A of the disk roller  110 , while, on the other hand, the shaft holding spring  113  may allow the rotary shaft  100 A of the disk roller  110  to move upward in the event of urgent stopping of the elevator car  2 . 
     Another rotary shaft holding spring  121  similar to, or same as, the rotary shaft holding spring  113  is also mounted to the cam  120 . One end of the rotary shaft holding spring  121  for the cam  120  is coupled to a rotary shaft  120 A of the cam  120 , while the other end is fixed to a spring seat (not shown) on the connecting plate  410 . The rotary shaft holding spring  121  for the cam  120  maintains vertical position of the rotary shaft  120 A of the cam.  120 , but may also allow the rotary shaft  120 A of the cam  120  to move upward in the event of urgently stopping the elevator car  2 . 
     In addition, a limit block  130  may be included at a position in contact with the rotary shaft  120 A in order to limit upward movement of the rotary shaft  120 A in the event of the emergent stopping. The limit block  130  has a plane portion and an upper inclined portion in a surface contacting with the rotary shaft  120 A. Preferably, the limit block  130  makes it possible that the rotary shaft  120 A moves toward middle of the hoist way when ascending to the inclined portion such that the space between the rotary shafts  110 A,  120 A may become wide. 
     The transmission unit  200  includes a flexible cable  210  and a plurality of pulleys  220 . The flexible cable  210  is tightly supported and guided by a plurality of the pulleys  220 . The flexible cable  210  is connected to the brake  300  at its both ends and conjunct with the rotary shaft  120 A of the cam  120  at a certain intermediate position thereof. The flexible cable  210  as constructed above is drawn upward when the rotary shaft  120 A of the cam  120  ascends during emergent stopping of the elevator car  2 , which exerts upward tension to the brake  300 . 
     The brake includes a pair of wedges  310 , an elastic ring  320 , a wedge seat  330  and slide rollers  340 . The wedges  310  are drawn by the flexible cable  210 , which is drawn upward together with the rotary shaft  120 A of the cam  120  when the elevator car  2  stops in an emergent case. The wedge seat  330  formed to become gradually narrower in its upward direction between an outer side of the wedges  310  and an inner side of the elastic ring  320 . Therefore, while moving upward between a pair of the wedge seat  330 , the wedges  310  generate frictional force in contact with the guide rail  1 , which is positioned inside the wedges  310 . The elastic ring  320  is formed to press an outer surface of the wedge seat  330  inward. The elastic ring  320  increase the frictional force between the guide rail  1  and the wedges  310  by exerting elastic force centripetally such that the wedge seat  330  does not widen while the wedges  310  move upward inside the wedge seat  330 . The slide rollers  340  are positioned between an inner side of the wedge seat  330  and outer sides of the wedges  310 . The slide rollers  340  prevent friction generation between the wedges  310  and the wedge seat  330  when the wedges  310  move upward inside the wedge seat  330  such that the wedges  310  may easily move upward inside the wedge seat  330 . 
     Referring to FIG. 5, it will be understood that in the emergency stop apparatus of the present invention, the speed governing unit  100  may be formed upon or integrated with the brake  300 . The emergency stop apparatus may be also combined to a lower frame of the elevator car  2  with use of, such as, the connecting plate  410 , and such combination can be reinforced with use of supporting members  420 . 
     The emergency stop apparatus according to the present invention as constructed above operates as follows. 
     If the elevator car  2  reaches at excess speed due to, for example, a breakdown or a falling in the hoist way, the disk roller  110 , rotating in contact with the guide rail  1 , becomes rotated at the same excess speed as speed of the elevator car  2 . If the disk roller  110  rotates in the excess speed, the centrifugal weight  111 , connected to same rotary shaft as the disk roller  110 , also rotates in the excess speed. The centrifugal weight  111  rotating in the excess speed then protrudes outside the disk roller  110  due to its centrifugal force, which makes radius of gyration thereof increased. This makes the centrifugal weight  111  contacted with the cam  120 , and the cam  120  rotate to an opposite direction to the disk roller  110 . 
     With rotating, the cam  120  pushes the disk roller  110  toward the guide rail  1 . The disk roller  110  pushed by the cam  120  is then pressed to the guide rail  1  and then stops its rotation. While the disk roller  110  is pressed to the guide rail  1  and then stops its rotation by the cam  120 , the elevator still moves downward, by which the disk roller  110  and the cam  120  thus move upward. At this time, the disk roller  110  and the cam  120  move upward with pressing the rotary shaft holding springs  113 ,  121 . If the cam  120  moves upward, the flexible cable connected to the rotary shaft  120 A of the cam  120  is drawn. If the flexible cable  210  is drawn, the wedges  310  connected to both end of the flexible cable  210  are also drawn. Therefore, a pair of the wedges  310  moves upward with use of the slide rollers  340  inside the wedge seat  330  formed to become gradually narrower in its upward direction, which makes the wedges  310  pressed inward. The wedges  310  pressed inward then come in contact with the guide rail  1  therebetween and generate friction. 
     At this time, the rotary shafts  110 A,  120 A of the disk roller  110  and the cam  120  move upward with maintaining a certain space therebetween. If the rotary shaft  120 A reaches the inclined upper portion of the limit block  130 , the space between the rotary shafts  110 A,  120 A becomes wide so that the disk roller  110  and the cam  120  become apart from each other. After that, the disk roller  110  separated from the cam  120  begins rotation again along the guide rail  1 . 
     The flexible cable  210  is drawn until the cam  120  reaches the inclined portion of the limit block  130 . After the cam  120  reaches the inclined portion, external force to draw the wedges  310  upward is vanished. However, though upward force is disappeared, the wedges  310  move upward more because of friction with the guide rail  1 . Therefore, the wedges  310  become pressed by the wedge seat  330  more and more, which results in more powerful friction with the wedges  310  while tightening the guide rail  1  stronger. Therefore, the elevator car  2  is then eventually stopped. 
     As described above, the emergency stop apparatus for an elevator according to the present invention may increase spatial utility rate in the fact that all of the speed governing unit, the transmission unit and the brake required for stopping the elevator car in emergency are installed in the hoist way between the guide rails. 
     In particular, employing the flexible cable to the transmission unit instead of the link members helps to lower manufacturing cost, and makes it easy to install and maintain the apparatus. 
     The emergency stop apparatus for an elevator 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.