Patent Publication Number: US-8978832-B2

Title: Holding brake with locking mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to European Patent Application No. 10166041.3, filed Jun. 15, 2010, which is incorporated herein by reference. 
     FIELD 
     The disclosure relates to a holding brake for an elevator installation. 
     BACKGROUND 
     Elevator systems of a conventional kind generally comprise a drive, a drive control associated with the drive and a braking system. 
     Holding brakes, which usually must fulfill prescriptions with regard to safety regulations, are employed at the elevator cages. 
     A hydraulically actuable disc brake is known from patent specification EP 0 648 703 B1, in which, in the case of braking, brake plates engage a guide rail and the elevator cage is secured at a story stop against impermissible upward movements and downward movements. 
     A locking device which is engageable from outside and which in company with the movement in upward direction or downward direction of the elevator cage builds up the necessary braking force in order to stop the elevator cage is known from patent application EP 0 999 168 A2/A3. 
     An elevator installation with a cage brake has become known from EP 1 840 068 A1, in which brake wedges slide on tracks extending obliquely with respect to a guide rail. In the case of braking a respective hydraulic actuator pushes a respective brake wedge along the track against the travel direction of the elevator cage. As soon as the brake wedge comes into contact with the guide rail the brake wedge moves further on the track and wedges between the guide rail and the track in brake-amplifying manner. 
     SUMMARY 
     At least some embodiments of the disclosed technologies comprise a holding brake which combines a simple construction with a safe function. In particular embodiments, the holding brake can exert a direct braking action. 
     At least some embodiments are equipped with a locking mechanism, possibly a double-acting locking mechanism, for holding a elevator cage in a fixed shaft position. 
     The holding brake can exert a form of symmetrical clasping action. The clasping action can arise due to unilaterally acting traction elements of the locking mechanism. 
     In one embodiment the holding brake comprises a double-acting brake which acts symmetrically. In that case, two opposite brake shoes act as active brake shoes and produce a braking force at a guide rail. 
     Use can be made of a holding brake which is designed specifically for use in an elevator installation comprising an elevator cage. The holding brake is designed for application of a mechanical braking action relative to a guide rail of the elevator installation so that the elevator cage or the counterweight, after actuation of the holding brake, keeps its vertical position. For this purpose the holding brake can comprise a locking mechanism, possibly a double-acting locking mechanism, which is so designed that it acts on the guide rail from two mutually opposite sides and amplifies the braking force. 
     In some embodiments, a minimum vertical movement of the elevator cage or of the counterweight is sufficient in order to trigger an amplified or self-amplifying locking function of the holding brake. This locking function can be triggered by use of the locking mechanism not only if the elevator cage or the counterweight should move a small amount upwardly (here termed impermissible movement), but also if the elevator cage or the counterweight should move a small amount downwardly (here termed impermissible movement). 
     In further embodiments, the holding brake has a self-locking function, since sometimes even in the case of a small undesired movement of the elevator cage the braking action increases quasi-automatically. 
     In additional embodiments, the locking mechanism is equipped with at least one actuator in order to be able to so adjust, in an initial movement or adjusting movement, brake bodies that in the activation case they only have to execute a small closing movement (engagement movement) in order to more firmly fix the elevator cage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed technologies are described in detail in the following on the basis of exemplifying embodiments and with reference to the figures. 
         FIG. 1  shows a elevator installation with a first holding brake, in substantially simplified schematic illustration; 
         FIG. 2  shows details of a first holding brake; and 
         FIG. 3  shows details of a second holding brake. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a first exemplary embodiment in a schematic overall illustration. An elevator installation  10  is shown in strongly schematic form. The elevator installation  10  comprises an elevator cage  12  and a corresponding counterweight  19 , which are guided to be vertically movable in opposite sense in a elevator shaft. The elevator cage  12  can serve several stories (here two stories A and B are shown). The elevator cage  12  can be moved by a drive  11  which, by way of example as indicated in  FIG. 1 , is disposed at the upper shaft end. Apart from the drive  11 , the elevator installation  10  comprises a drive control  15 , which is associated with the drive  11 , and a braking system  13 . The elevator cage  12  is here connected with the counterweight  19  by way of a support means  18  which runs around a drive pulley of the drive  11 . The linking, in terms of control, of the drive control  15  with the elements of the elevator installation  10  is schematically indicated by a double arrow  16 , which symbolizes a connection between the drive  11  and the drive control  15 . The drive control  15  typically receives signals by way of, for example, the control link  16 . These signals are converted into control magnitudes. If the drive  11  sets the elevator cage  12  in motion, at least one holding brake  20 , which is arranged at the elevator cage  12  and mechanically interacts with at least one guide rail  17  in the elevator shaft  14 , is released. 
     On reaching a destination story (for example story B in  FIG. 1 ) the speed of the drive  11  is slowed down and the braking system  13  is activated. When the correct vertical position in the elevator shaft  14  has been reached, the holding brake  20  comes into action in order to hold the elevator cage  12  exactly at the correct vertical position. 
     The holding brake  20 , which is described in more detail in two different forms of embodiment with reference to  FIGS. 2 and 3 , is designed for use in an elevator installation  10 . The holding brake  20  serves for application of a mechanical braking action relative to a stationary guide rail  17  of the elevator installation  10 . The elevator cage  12  is held in its vertical position in the elevator shaft  14  by the holding brake  20  after actuation thereof. 
     The holding brake  20  comprises a locking mechanism  21 , possibly a double-acting locking mechanism  21 . The locking mechanism  21  is so designed and constructed that it acts on the guide rail  17  from two mutually opposite sides S 1 , S 2 . 
     A view of the holding brake  20  is shown in each of  FIGS. 2 and 3 , in which the double-acting locking mechanism  21  acts from the left (side S 1 ) and from the right (side S 2 ) on the guide rail  17 . In the case of action on the guide rail  17  the locking mechanism  21  exerts, for example, an advancing force BK 1  and an oppositely directed advancing force BK 2  on the guide rail  17 . 
     The locking mechanism  21  can comprise a first brake body  22 . 1  and a second brake body  22 . 2 . These brake bodies  22 . 1 ,  22 . 2  are opposite one another. The first brake body  22 . 1  has a first brake shoe  23 . 1  on a side facing the second brake body  22 . 2 . The second brake body  22 . 2  has a second brake shoe  23 . 2  on a side facing the first brake body  22 . 1 . The first brake body  22 . 1  presses together with the first brake shoe  23 . 1  by the advancing force BK 1  or by a force proportional to the advancing force BK 1  from the side S 1  against the guide rail  17 . The second brake body  22 . 2  presses together with the second brake shoe  23 . 2  by the advancing force BK 2  or by a force proportional to the advancing force BK 2  from the side S 2  against the guide rail  17 . 
     The first brake body  22 . 1  and the second brake body  22 . 2  can be so movably mounted at a guide body  26  that they are movable towards and away from one another. 
     The locking mechanism  21  can be designed that the two advancing forces BK 1  and BK 2  are of equal magnitude. It is thereby achieved that the double-acting locking mechanism  21  is constructed/arranged to be symmetrical mechanically and/or in terms of force with respect to the longitudinal axis L of the guide rail  17 . 
     The locking mechanism  21  can be coupled to a traction device  24  acting from the sides S 1 , S 2 , as is shown in  FIGS. 2 and 3 . 
     This traction device  24  is so constructed/arranged symmetrically with respect to the first brake body  22 . 1  and the second brake body  22 . 2  that two traction elements  24 . 1 ,  24 . 2  of the traction device  24  are connected with the first brake body  22 . 1  and two further traction elements  24 . 3 ,  24 . 4  of the traction device  24  are connected with the second brake body  22 . 2   
     The traction device  24  can comprise a traction cable (for example a steel cable) which is arranged so that four cable sections  24 . 1 ,  24 . 2 ,  24 . 3 ,  24 . 4  of the traction cable result, as shown in  FIG. 2 . The four cable sections  24 . 1 ,  24 . 2 ,  24 . 3 ,  24 . 4  can form a form of lozenge or parallelogram with lateral corner points or lateral points UL, UR at the two distal ends of the brake bodies  22 . 1 ,  22 . 2  and with an upper distal point or upper deflection point UO at a fastening element  25  of the holding brake  20  and with a lower distal point or lower deflecting point UU at the fastening element  25  of the holding brake  20 . 
     The traction cable of the traction device  24  can be fixedly connected at the lateral deflecting points UL, UR with the respective brake body  22 . 1  or  22 . 2 . Possibly provided at the upper deflecting point UO and at the lower deflecting point UU are (deflecting) rollers  27  (as shown in  FIG. 2 ) or slide posts, so that the traction cable can run around or slide around these deflecting points UO and UU. The axes R 1 , R 2  of these rollers  27  or slide posts are perpendicular to the plane E (which here coincides with the plane of the drawing). 
     The holding brake  20  can comprise a fastening element  25  and a guide body  26 , as shown in  FIGS. 2 and 3 . The fastening element  25  is designed for fastening the holding brake  20  to the elevator cage  12  and the guide body  26  is mounted to be displaceable along the fastening element  25 . The corresponding displacement movement is indicated in  FIG. 2  and  FIG. 3  by the double arrow P 1 . 
     The guide body  26  can have two mutually parallel extending rails or slide surfaces  28 , which in the mounted state run parallel to the longitudinal axis L. In addition, the guide body  26  comprises a cross member  29  which is fixedly connected with the rails or slide surfaces  28 . 
     The fastening element  25  and the cross member  29  can be arranged perpendicularly to one another and form a kind of cross. 
     The cross member  29  can carry (horizontal) guides  30  for horizontal guidance of the brake bodies  22 . 1 ,  22 . 2 . The two brake bodies  22 . 1 ,  22 . 2  can be mounted to be so movable in, at or between the guides  30  that they can execute an advancing movement in the direction of the guide rail  17 . 
     In some embodiments at least one active actuator is employed in order to be able to actively execute initial movements or advancing movements. These movements serve the purpose of bringing the locking mechanism  21  into a position in which this can build up the holding force with a minimum advance travel. In the case of the form of embodiment shown in  FIG. 2 , use can be made of a total of three actuators  31 . 1 ,  31 . 2 ,  31 . 3 . The actuator  31 . 1  advances the brake body  20 . 1  in the direction of the guide rail  17  so that the first brake shoe  23 . 1  presses, when required, against the guide rail  17 . The actuator  31 . 2  advances the brake body  22 . 2  in the direction of the guide rail  17  so that the second brake shoe  23 . 2  presses, also when required, against the guide rail  17 . Use can be made of a middle (restoring) actuator  31 . 3  in order to be able to urge the brake shoes  23 . 1 ,  23 . 2  apart for release of the holding brake  20 . The position of the brake shoes  23 . 1 ,  23 . 2  can be optimally preset and in the case of need also re-adjusted by co-operation of the actuators  31 . 1 ,  31 . 2 ,  31 . 3 . The actuators  31 . 1 ,  31 . 2  trigger a first braking action. The actuator  31 . 3  releases the holding brake  20  again. 
     The presetting of a minimum braking force by one or more actuators can also be employed so that the holding brake  20  does not automatically open in the case of a corresponding transition through the zero position when a load change from an empty elevator cage  12  to a full elevator cage takes place. 
     In  FIG. 3  only a central actuator  32  is employed, which extends parallel to the longitudinal axis L and is seated between the upper deflecting point UO and the lower deflecting point UU. This central actuator  32  combines the braking action and the release of the holding brake  20  in one. The actuator  32  thus replaces the actuators  31 . 1 ,  31 . 2 ,  31 . 3 . 
     In at least some embodiments, the locking mechanism  21  is equipped with at least one actuator in order to be able to so advance the brake bodies  22 . 1 ,  22 . 2  in an initial movement that they exert a braking action in order to fix the elevator cage  12 . 
     In at least some cases, the actuators comprise a spring and an active actuator element which expands or contracts by, for example, application of a voltage. An actuator in the sense of the present disclosure is a component or an element which converts a signal of a regulating means into mechanical work or movement. The signal can be an electrical, a hydraulic or a pneumatic signal. 
     The locking mechanism  21  can comprise a traction cable with several sections  24 . 1  to  24 . 4 , as shown in  FIG. 2 . The rollers  27  serve as deflecting rollers around which the traction cable is guided. The traction cable is fastened at the points UL and UR so as to be able to build up a traction force which by virtue of the symmetrical disposition/path of the traction cable acts at the points UL and UR perpendicularly in the direction of the guide rail  17 . 
     However, the locking mechanism  21  can also comprise, instead of the traction cable, a linkage  33  with several rods  34 . 1  to  34 . 4  loadable in tension and compression, as shown in  FIG. 3 . In order that this locking mechanism  21  according to  FIG. 3  is equivalent in effect to the locking mechanism according to  FIG. 2 , a short length of a traction cable  35  is attached at each of the deflecting points UO and UU. These traction cables  35  are tensioned between the points UO 1  and UO or between UU 1  and UU. 
     The traction cable of  FIG. 2  and the linkage  33  inclusive of the short traction cables  35  constitute a so-termed traction element acting from one side. The action of this unilaterally acting traction element is as follows: 
     When the elevator cage  12  is located at a story (for example story B in  FIG. 1 ), the holding brake  20  comes into play as follows: 
     The brake bodies  22 . 1 ,  22 . 2  are advanced by the actuators  31 . 1 ,  31 . 2  and the brake shoes  23 . 1 ,  23 . 2  come into interaction with the guide rail  17 . A first braking action thereby results. If the elevator cage  12  should now drop a small amount, for example because a large load is contained in the elevator cage  12 , the fastening element  25 , which is fixed to the elevator cage  12 , displaces downwardly in company with the elevator cage  12  a few millimeters. At the same time the traction elements  24 . 2  and  24 . 3  pull obliquely downwardly at the points UL and UR. By virtue of this symmetrically acting traction force the brake bodies  22 . 1 ,  22 . 2  are further advanced and the brake shoes  23 . 1 ,  23 . 2  press even more firmly from both sides symmetrically against the guide rail  17 . 
     In at least some embodiments, by virtue of their unilateral character, the traction elements  24 . 1  and  24 . 4  do not exert any pressing force on the brake shoes  23 . 1 ,  23 . 2 , which would impair the braking action. 
     The converse takes place if the elevator cage  12  should move upwardly a small amount, for example if a large load is removed from the elevator cage  12 . Here the traction elements  24 . 1 ,  24 . 4  come into play. 
     In a form of embodiment according to  FIG. 3  in which the unilaterally acting traction element comprises a linkage  33  with traction cables  35  the manner of effect is in principle the same. In the case of a downward movement of the elevator cage  12  the lower cable length  35  pulls at the point UU and the rods  34 . 2 ,  34 . 3  symmetrically pull at the points UL, UR. Through this symmetrically acting traction force the brake bodies  22 . 1 ,  22 . 2  are further advanced and the brake shoes  23 . 1 ,  23 . 2  press even more firmly from both sides symmetrically against the guide rail  17 . 
     The converse takes place if the elevator cage  12  should move a small amount upwardly. Here the upper cable length  35  pulls at the point UO and the rods  34 . 1 ,  34 . 4  pull symmetrically at the points UL, UR. 
     As a result, in at least some embodiments, every smallest positional deviation of the elevator cage  12  is immediately converted into an amplified braking action of the holding brake  20 . In the embodiment according to  FIG. 2 , the (deflecting) rollers  27  guarantee that the respective traction elements  24 . 1  to  24 . 4  pull with the same forces symmetrically at the points UL, UR. In the case of a form of embodiment according to  FIG. 3 , the short traction cables  35  ensure a uniform traction effect as long as the lengths of the rods  34 . 1  to  34 . 4  are identical and the positions of the points UO and UU are central. 
     In order to release the braking action of the holding brake  20 , use can be made of the actuator  31 . 3  or  32  which urges the brake shoes  23 . 1 ,  23 . 2  apart. The release of the holding brake  20  typically takes place only when the drive  11  has applied sufficient torque (termed pre-torque) for driving the elevator cage  12 . 
     Some embodiments eliminate a load measurement in the elevator cage  12 , since the actuator can open the holding brake  20  only when there is sufficient pre-torque. For this purpose the pre-torque can be increased until the actuator is in a position of releasing the holding brake  20 . In the case of incorrect pre-torque, release of the holding brake  20  is generally hardly possible, which can lead to improved safety. In the embodiment of  FIG. 3 , the actuator  32  is shortened and thereby urges, due to the stiffness of the rods of the linkage  33 , the brake bodies  22 . 1 ,  22 . 2  outwardly. Release of the holding brake  20  takes place here in this manner. 
     The holding brake  20  is thus a braking device which symmetrically engages a stationary guide rail  17  on both sides. 
     Such a holding brake  20  can be mounted on the elevator cage  12  and/or the counterweight  19 . 
     The holding brake  20  can prevent drifting of the elevator cage  12  away from the story level. Re-regulations by the elevator drive  11  can be eliminated. 
     Having illustrated and described the principles of the disclosed technologies, it will be apparent to those skilled in the art that the disclosed embodiments can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of the disclosed technologies can be applied, it should be recognized that the illustrated embodiments are only examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims and their equivalents. I therefore claim as my invention all that comes within the scope and spirit of these claims.