Patent Publication Number: US-2019177126-A1

Title: Elevator rope sway restriction device

Description:
BACKGROUND 
     This invention generally relates to elevator systems. More particularly, this invention relates to an elevator rope sway restriction device for restricting the swaying of main ropes. 
     Many elevator systems include an elevator car and counterweight that are suspended within a hoistway by roping comprising one or more main ropes. Typically, a plurality of ropes, cables or belts are used as the main ropes for supporting the weight of the elevator car and counterweight and for moving the elevator car to desired positions within the hoistway. The main ropes are typically routed about several sheaves according to a desired roping arrangement. 
     There are conditions where one or more of the main ropes may begin to sway within the hoistway. Rope sway may occur, for example, during earthquakes or very high wind conditions because the building will move responsive to the earthquake or high winds. As the building moves, long ropes associated with the elevator car and counterweight will tend to sway from side to side. This is most prominent in high rise buildings where an amount of building sway is typically larger compared to shorter buildings and when the frequency of the building sway is an integer multiple of the natural frequency of a rope within the hoistway. 
     Excessive rope sway conditions of the main ropes are undesirable for two main reasons; they can cause damage to the ropes or other equipment in the hoistway and their motion can produce objectionable vibration levels in the elevator car. 
     Various proposals have been made for mitigating or minimizing sway of main ropes within a hoistway. One example approach includes an elevator rope guide system comprising a plurality of rope guides for restricting the sway of at least one main rope and a plurality of stop mechanisms installed on car guide rails to stop a corresponding rope guide. 
     While previous approaches have proven useful, those skilled in the art are always striving to make improvements. 
     BRIEF SUMMARY 
     According to one embodiment, an elevator system is provided which comprises an elevator car vertically movable within a hoistway, a counterweight connected to the elevator car via at least one rope and vertically movable within the hoistway and a rope sway restriction device for restricting the swaying of the at least one rope. The rope sway restriction device includes a rope sway restrictor vertically movable within the hoistway and at least one restrictor rope connecting the rope sway restrictor to the counterweight so that the rope sway restrictor moves vertically within the hoistway in response to movement of the counterweight. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor is connected to the counterweight such that the ratio of the travel distance of the rope sway restrictor to the travel distance of the counterweight is about 1:2. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor is positioned at about halfway of the at least one rope in the hoistway on the car side. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a pair of movable pulleys. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restriction device further includes a pair of fixed pulleys positioned in a machine room or an upper portion of the hoistway and the restrictor rope is connected at one end to a dead end hitch in the machine room or the upper portion of the hoistway, extends through the pair of movable pulleys and the pair of fixed pulleys, and is connected to the counterweight at the other end. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the axes of the fixed pulleys are positioned at an angle of 90 degrees with respect to the axes of the moving pulleys. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the axes of the fixed pulleys are positioned at an oblique angle with respect to the axes of the moving pulleys. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a rope guide which allows the at least one rope to pass there through and which contacts the at least one rope when an undesired amount of sway of the at least one rope occurs. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope guide includes a box-shaped guide frame and a rubber or plastic material covering the inner surfaces of the guide frame. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope guide includes a box-like support frame rotatably supporting a pair of longitudinal rollers and a pair of lateral rollers. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor is guided along car guide rails. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a guiding mechanism on both ends for guiding the rope sway restrictor along the car guide rails. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the guiding mechanism is a sliding mechanism. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the guiding mechanism is a roller mechanism. 
     According to another embodiment, a rope sway restriction device for restricting the swaying of at least one rope connecting an elevator car and a counterweight of an elevator system is provided. The rope sway restriction device comprises a rope sway restrictor vertically movable within the hoistway and at least one restrictor rope connecting the rope sway restrictor to the counterweight so that the rope sway restrictor moves vertically within the hoistway in response to movement of the counterweight. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor is connected to the counterweight such that the ratio of the travel distance of the rope sway restrictor to the travel distance of the counterweight is about 1:2. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor is positioned at about halfway of the at least one rope in the hoistway on the car side. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a pair of movable pulleys. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a rope guide which allows the at least one rope to pass there through and which contacts the at least one rope when an undesired amount of sway of the at least one rope occurs. 
     In addition to one or more of the features described above, or as an alternative, further embodiments may be included wherein the rope sway restrictor includes a guiding mechanism on both ends for guiding the rope sway restrictor along car guide rails. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which like elements are numbered alike in the several Figs. 
         FIG. 1  illustrates a schematic view of an elevator system including the elevator rope sway restriction device of the present invention. 
         FIG. 2  illustrates a top view of a rope sway restrictor of the elevator rope sway restriction device shown in  FIG. 1 . 
         FIG. 3  illustrates a perspective view of a further embodiment of a rope guide of the rope sway restrictor shown in  FIG. 2 . 
         FIGS. 4A and 4B  illustrate exemplary perspective views of a guiding mechanism of the rope sway restrictor shown in  FIG. 2 . 
         FIG. 5  is a top plan view showing the arrangement of the sheaves, pulleys and guide rails of the elevator system shown in  FIG. 1 . 
         FIG. 6  is a top plan view similar to  FIG. 5  of another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically shows selected portions of an elevator system  1  of the present invention. An elevator car  2  and counterweight  3  are both vertically movable within a hoistway  4 . A plurality of main ropes  5  couple the elevator car  2  to the counterweight  3 . In this embodiment, the main ropes  5  comprise round steel ropes but the main ropes  5  may comprise belts including a plurality of longitudinally extending wire cords and a coating covering the wire cords. A variety of roping configurations may be useful in an elevator system that includes features designed according to an embodiment of this invention. 
     The main ropes  5  support the weight of the elevator car  2  and counterweight  3  and propel them in a desired direction within the hoistway  4 . An elevator machine  6  is positioned in a machine room  7  or in an upper portion of the hoistway  4  and includes a traction sheave  8  that rotates and causes movement of the main ropes  5  to cause the desired movement of the elevator car  2 , for example. The example arrangement includes a deflector sheave  9  to guide movement of the main ropes  5 . The illustrated example comprises a single wrap configuration. However, other roping arrangements such as a double wrap configuration are also possible. 
     The elevator car  2  is guided along car guide rails  10  respectively installed on a hoistway wall  4   a  ( FIG. 5 ) on opposite sides of the elevator car  2 . The counterweight  3  is guided along counterweight guide rails  11  respectively installed on a hoistway wall  4   a  on opposite sides of the counterweight  3 . The car guide rails  10  and counterweight guide rails  11  have a generally T-shaped cross section such as shown in  FIG. 2  with a base portion  10   a  that is secured to the hoistway wall  5   a  and a blade portion  10   b  extending away from the base portion  10   a . The blade portion  10   b  provides guiding surfaces along which guide rollers or slides travel during movement of the elevator car  2  or counterweight  3 . 
     The example elevator system  1  includes a rope sway restriction device for restricting the swaying of the main ropes  5 . The rope sway restriction device comprises a rope sway restrictor  12  positioned above the elevator car  2  and vertically movable along the car guide rails  10 , at least one restrictor rope  14  connecting the rope sway restrictor  12  to the counterweight  3 , and a first fixed pulley  15  and a second fixed pulley  16  which may be positioned in the machine room  7  or an upper portion of the hoistway  4 . The rope sway restrictor  12  comprises a rectangular base plate  17  rotatably supporting a first movable pulley  18  and a second movable pulley  19 . 
     The restrictor rope  14  is connected at one end to a dead end hitch  20  which may be positioned in the machine room  7  or an upper portion of the hoistway  4  and extends downward to and around the first movable pulley  18 . From here the restrictor rope  14  extends horizontally to and around the second movable pulley  19  and then extends upward to and around the first fixed pulley  15 . The restrictor rope  14  further extends horizontally to and around the second fixed pulley  16  and then downward to the counterweight  3  to be connected to the counterweight  3  at the other end. In this embodiment, the restrictor rope  14  is a steel wire rope. However, the restrictor rope  14  may a resin rope. Further, a belt may also be used as the restrictor rope  14 . 
       FIG. 2  shows a top view of the rope sway restrictor  12 . The base plate  17  extends laterally between the elevator guide rails  10  and has a first surface  17   a  facing the car guide rails  10  and a second surface  17   b  facing away from the car guide rails  10 . The first and second movable pulleys  18 ,  19  are positioned on the second surface  17   b  of the base plate  17 . The first and second movable pulleys  18 ,  19  may be made of cast iron or cast steel. The movable pulleys  18 ,  19  may also be made of resins such as nylon for reduction in weight. The rope sway restrictor  12  further comprises a guiding mechanism  22  provided on both lateral ends of the base plate  17  for guiding the rope sway restrictor  12  up and down along the car guide rails  10  and a rope guide  24  fixed to the first side  17   a  of the base plate  17  for restricting the sway of the main ropes  5 . 
     The rope guide  24  includes a rectangular box-shaped guide frame  25  which has open upper and lower end faces for allowing the main ropes  5  to pass there through and a rubber or plastic material  26  covering the inner surfaces of the guide frame  25  to protect the main ropes  5  from being damaged upon contact with the guide frame  25 . The rope guide  24  will not substantially contact the main ropes  5  under normal conditions. However, under conditions where an undesired amount of sway of the main ropes  5  occur, the rope guide  24  will contact the main ropes  5  and restrict the swaying thereof. 
     In a further embodiment shown in  FIG. 3 , the rope guide  24  may include a pair of longitudinal rollers  27  and a pair of lateral rollers  28  each rotatably supported on a rectangular box-like support frame  29  which has open upper and lower end faces for allowing the main ropes  5  to pass there through. Under sway conditions, the rollers  27 ,  28  will roll about their axes responsive to contact with the main ropes  5  and restrict swaying of the main ropes  5 . 
     The guiding mechanism  22  may be similar to a conventional guide shoe and may be spring loaded. For example, the guiding mechanism  22  may comprise a sliding mechanism  22   a  such as shown in  FIG. 4A  or a roller mechanism  22   b  such as shown in  FIG. 4B . The sliding mechanism  22   a  includes a housing  30  which receives an insert  31  for slidingly engaging the blade portion  10   b  of the car guide rail  10 , for example. The insert  31  may be retained within the housing  30  by a retaining element  32  bolted to the housing. The roller mechanism  22   b  includes a pair of rollers  34  each having an axis parallel to the blade portion  10   b  of the car guide rail  10  and a roller  35  having an axis perpendicular to the blade portion  10   b  of the car guide rail  10 , for example. The rollers  34 ,  35  are fixed to a bracket  36  and rotatably contact the guiding surfaces of the blade portion  10   b.    
       FIG. 5  is a top plan view of the hoistway  4  showing the arrangement of the traction sheave  8 , deflector sheave  9 , fixed pulleys  15 ,  16 , rope sway restrictor  12 , car guide rails  10 , counterweight guide rails  11  and restrictor rope  14 . The elevator car  2  and counterweight  3  are shown in phantom. The movable pulleys  18 ,  19  of the rope sway restrictor  17  are offset from a centerline CL extending through the car guide rails  10  to avoid interference with the main ropes  5 . The fixed pulleys  15 ,  16  are positioned on a lateral side of the sheaves  8 ,  9  so as not to interfere with the main ropes  5 . The axes of the fixed pulleys  15 ,  16  are at an angle of 90 degrees with respect to the axes of the moving pulleys  18 ,  19 . 
       FIG. 6  shows a top plan view similar to  FIG. 5  of another embodiment of the present invention. In this embodiment, the counterweight  3  is positioned on a side of the elevator car  2 . The axes of the traction sheave  8  and deflector sheave  9  are positioned at an angle with respect to the elevator car  2  and counterweight  3 . The base plate  17  of the rope sway restrictor  12  has a U-shaped cross section so as not to interfere with the main ropes  5 . The axes of the fixed pulleys  15 ,  16  are at an oblique angle with respect to the axes of the moving pulleys  18 ,  19 . 
     Referring again to  FIG. 1 , as the elevator car  2  travels up and down along the hoistway  4 , the counterweight  3  travels along the hoistway  4  in an opposite direction as is conventional. Since the rope sway restrictor  12  is connected to the counterweight  3  via the restrictor rope  14 , the rope sway restrictor  12  travels together with the counterweight  3 . The direction of travel of the rope sway restrictor  12  is the same as the elevator car  2 . In this embodiment, the pulley and restrictor rope roping configuration causes the rope sway restrictor  12  to travel about half the distance of car and counterweight travel. In other words, the ratio of the travel distance of the rope sway restrictor  12  to the travel distance of the car  2  and counterweight  3  is about 1:2. However, other ratios such as 1:3 or 1:4 are also possible. A variety of pulley and restrictor rope roping configurations may be used to achieve such ratios. 
     Accordingly, the rope sway restrictor  12  will always be positioned at about halfway of the main ropes  5  in the hoistway  4  on the car side and limit rope sway of the main ropes  5  at this position which is effective to restrict rope sway. When the elevator car  2  reaches its uppermost position in the hoistway  4 , the rope sway restrictor  12  will be positioned between the elevator car  2  and the ceiling of the hoistway  4 . The rope sway restrictor  12  will not in any case contact the elevator car  2  or the hoistway ceiling. 
     The present invention provides an elevator rope sway restriction device which does not require the installation of stop mechanisms on car guide rails to stop a rope guide. Additionally, since the rope sway restrictor  12  of the present invention is moved up and down along the hoistway  4  by the counterweight  3 , no sensors, actuators or electronic devices are required and a simple and effective device for restricting rope sway may be provided. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. While the description has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to embodiments in the form disclosed. Many modifications, variations, alterations, substitutions or equivalent arrangement not hereto described will be apparent to those of ordinary skill in the art without departing from the scope of the disclosure. Additionally, while the various embodiments have been described, it is to be understood that aspects may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.