Patent Publication Number: US-2017349406-A1

Title: Brake assembly of elevator system

Description:
BACKGROUND INFORMATION ON THE INVENTION 
     This invention relates generally to an elevator system, and more specifically to a brake assembly for an elevator system that does not have a machine room. 
     An elevator system without a conventional machine room is comprised of a car and a counterweight that are located in an elevator shaft. The car and counterweight are configured to move up and down in the elevator shaft, carrying passengers or cargo from one floor to another. The cable (e.g. comprised of numerous round tension cables or flat belts) connects the car and the counterweight to each other. A motorized, non-geared drive unit is located on the upper part of the elevator shaft, and is comprised of a drive pulley that engages the cable (typically by traction) to drive it, and the car and the counterweight are moved as the drive pulley rotates. A controller controls system operation. When a call is made for a desired destination (for example, a floor), the controller sends a signal to the drive unit to raise or lower the car to the floor and then to apply a brake (e.g. a disc brake or a clutch) to the drive unit as the car approaches the floor. The brake has a direct mechanical link to the drive pulley. When an emergency stop is registered, the brake is applied immediately to the drive unit. 
     More specifically, the brake may be comprised of a stationary element (such as a steel plate) attached to the drive unit, plus a pair of movable steel plates. Two elastic elements (e.g., springs,  0 -rings, or a combination thereof) are connected respectively to the movable plates, and an electromagnet (e.g., a coil) is configured to move the movable plates. A disc, which is comprised of a friction liner attached on both sides of the disc, is placed between the fixed plate and the movable plates. The disc is attached to a shaft that rotates with the drive unit when the car is moving, and thus the disc is rotating. The shaft extends in the brake. The coil and, for example, the springs are placed in a housing that is placed on one side of the movable plates, opposite to the fixed plate and the disc. 
     When braking becomes necessary, it is initiated by deactivating the coil. As a result, a magnetic force that holds the movable plates against the coil disappears, and the springs force the movable plates against the disc, which, in turn, moves against the fixed plate so that the disk is between the fixed plate and the movable plates. This establishes a contact between one lining and both of the movable plates, and the other lining is pressed against the fixed plate. In this way, torque (by means of friction) is generated and applied by the contact, which torque stops the rotation of the disc. Since the disc is attached to the shaft, stoppage is transmitted to the shaft and the drive unit, and stops the movement of the car. When it is necessary for the car to move again, the controller sends a signal and current is sent to the coil to pull the movable plates away from the disc and the fixed plate, allowing rotation of the disc and shaft, and, in turn, allowing movement of the car. 
     It may be required (e.g., by a regulation or standard) that the brake be redundant so that each movable plate (that is, each brake half) is able to provide an amount of torque to decelerate or halt 100% of a full system load. It may also be required that the complete brake be capable of decelerating 125% of the full load. In a conventional elevator system, the torque applied by each movable plate stops 100% of the full load. The torque of each movable plate is added to that of the other movable plate to establish a total brake torque (i.e., equal to twice the torque of a single movable plate) for 150% of the full load. Thus, the complete brake decelerates with an intensity of greater than 150% of the full load. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to a non-limitative example of the invention, a brake assembly of an elevator system is provided. The elevator system is comprised of a car and a shaft operatively connected to the car and configured to rotate in order to move the car through the elevator system. The brake assembly is comprised of a disc connected to and configured to rotate with the shaft. A first movable plate and a second movable plate are placed on respective opposite sides of the disc and configured to move axially toward and away from the disc. A first and a second electromagnet are configured to move respectively the movable plates away from the disc. A first and a second elastic element are configured to move respectively the movable plates toward the disc. The disc is free to move axially and is configured to stop the movement of the car by stopping the rotation of the shaft when the rotation of the disc is stopped by friction of the contact of the movable plates with the disc when the elastic elements move the movable plates toward the disc. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter that is considered to be the invention is indicated specifically and claimed distinctly in the claims at the end of the specification. The features, characteristics, and advantages of the invention described above are evident in the following detailed description, together with the attached drawings, in which: 
         FIG. 1  is a transversal view of a cross section of a non-limitative example of an elevator system without a machine room. 
         FIG. 2  is a perspective view of a non-limitative example of a drive unit of the elevator system illustrated in  FIG. 1 . 
         FIG. 3  is a schematic lateral view of a brake assembly of the drive unit illustrated in  FIG. 2 , according to a non-limitative example of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, a non-limitative example of an elevator system is indicated in a general manner by  10 . Although elevator system is  10  described in this invention as being an elevator system without a machine room (in which a drive unit of the elevator system  10  is located in an elevator shaft rather than in a conventional machine room), it should be easy to see that elevator system  10  may be any suitable type of elevator system. And, although elevator system  10  is described herein as being implemented during power failures and/or emergency stoppages, it should also be easy to see that elevator system  10  may be implemented under any other suitable conditions and with any suitable magnitude and type of deceleration. 
       FIG. 1  shows the system for elevator  10 . Elevator shaft  12  has at least one car guide rail  14  that is affixed to an inner wall  16  of the elevator shaft  12 , and it can be attached to the counterweight supports  18 , which, in turn, can be attached to the opposite interior wall  20 . In the design, elevator shaft  12  includes two rails  14 . Alternatively, the rails  14  may be attached directly to the opposite interior wall  20  or using separate supports (not shown). A car  22  is supported within and configured to move through the elevator shaft  12  along the rails  14 , which guide the vertical movement of the car  22  in the elevator shaft  12 . The car  22  has guide assemblies  24 ,  26  placed respectively in a lower part and an upper part of the car  22 , to maintain appropriate alignment of the car  22  as it moves along the rails  14 . The car  22  is connected to a counterweight  28 , which is moved up and down the elevator shaft  12  as the car  22  transports passengers or cargo from one floor to another. 
     The counterweight supports  18  effectively define a space that extends over the entire height of the elevator shaft  12 , for movement of the counterweight  28 . The term “counterweight  28 ” as used in this report, includes a counterweight assembly that may be comprised of various components as should be readily seen by technical expert. The counterweight  28  is moved opposite to the car  22 , as is known with a conventional elevator system. The counterweight  28  is guided by counterweight guide rails (not shown) mounted inside the elevator shaft  12 . 
       FIG. 2  illustrates a drive unit without gears, according to a non-limitative example of the invention, which drive unit is generally indicated by  30 , and is configured to drive the movement of the car  22  through the elevator shaft  12 . The drive unit  30  is located in the upper part of the elevator shaft  12 . More specifically, the drive unit  30  is placed and supported in an assembly location—such as on a shelf (not shown)—above at least one of the counterweight&#39;s guide rails. Supporting the drive unit  30  above the counterweight guide rail(s) eliminates the need for a separate machine room, as required in a conventional elevator system. The elevator system  10  requires much less overhead room in the elevator shaft  12  than do conventional elevator systems, and it eliminates the need for a separate machine room. The configuration of the cable and the placement of the elevator shaft  12  as illustrated in  FIG. 1  are only examples, and the information provided in this invention may be used in other configurations of the elevator system  10 . 
     The drive unit  30  is comprised of a longitudinal housing  32  that has a first base  34  and a second base  36 . A drive pulley  38  is placed inside the housing  32 , which defines many areas (e.g. grooves) for receiving the cable  40  ( FIG. 1 ). The cable  40  may include, for example, several round tension cables  40  or flat traction belts  40 . A motor  42  is placed on one end of the drive unit  30 , and a disc-type or clutch-type brake assembly, according to a non-limitative example, is generally indicated by  44  and is it is placed at the opposite end of the drive unit  30 , which brake assembly is operatively connected to the drive unit  30  and the car  22 . The motor  42  is connected to and rotates a shaft  46  around an axis A when the car  22  is moving through the elevator shaft  12 . The shaft  46  is also connected to the drive pulley  38  (alternatively, the drive pulley  38  may be an integral part of the shaft  46 ). The drive pulley  38  also has a direct mechanical connection to the brake assembly  44 . The drive pulley  38 , the motor  42 , the brake assembly  44 , and the shaft  46  are all placed around the axis A. The brake assembly  44  is configured to apply a braking force to the drive unit  30  and the car  22  such as through the shaft  46 —as described in more detail below. 
     The car  22  and the counterweight  28  have pulley assemblies  48  ( FIG. 1 ) that cooperate with the cable  40  and the drive unit  30  to raise and lower the car  22 . In one aspect of the embodiment, the drive unit  30  is suitable and is sized to be used with flat drive belts  40 , and the pulley assemblies  48  are attached to a base of the car  22 . However, the pulley assemblies  48  may be mounted at another location on the car  22 , or elsewhere in the elevator system  10 , as should be readily seen by a technical expert. 
     Referring to  FIG. 3 , the brake assembly  44  is comprised of a first housing  52  and a second housing  54 , a disc  56  that includes a friction liner  58  attached to each side of the disc  56 , a first and second movable steel plate  60 ,  62 , a first and second elastic element  64 ,  66 , and a first and a second electromagnet  68 ,  70  (in the form of, for example, coils  68 ,  70 ). The housings  52 ,  54 , the disc  56 , the movable plates  60 ,  62 , and the coils  68 ,  70 , rotate around the shaft  46 . The brake assembly  44  is connected to the shaft  46  through the disc  56 , for example, by means of splines (not shown) on the shaft  46  that engage in grooves (not shown) in a center (not shown) of the disc  56 . This connection causes the disc  56  to rotate with the shaft  46  and it allows the disc  56  to move axially along the shaft  46 . The brake assembly  44  is also secured to a non-rotating part of the drive unit  30 , whereby the first housing  52  of the brake assembly  44  is affixed to the drive unit  30  using, for example, bolts (not shown), and affixing the second housing  54  or even the first housing  52  or even the drive unit  30 . 
     More specifically, the movable plates  60 ,  62  are separated from and placed on respective opposite sides of the disc  56 . Each movable plate  60 ,  62  may be an annular disc or it may be formed of multiple segments. The housings  52 ,  54  are separated from and placed respectively over the exterior sides  72  of the movable plates  60 ,  62 , and an exterior side of the first housing  52  is affixed to an interior side of the drive unit  30 . According to one aspect of the embodiment, the elastic elements  64 ,  66  are springs  64 ,  66 . The springs  64 ,  66  are placed inside the corresponding housings  52 ,  54 , and each spring  64 ,  66  extends outside of the corresponding housing  52 ,  54  to be attached to the exterior side  72  of the corresponding movable plate  60 ,  62 . Although the springs  64 ,  66  may have any suitable relationship with the corresponding housings  52 ,  54 , in one aspect of the example the springs  64 ,  66  are placed, respectively, in the upper regions of the corresponding housings  52 ,  54 . The coils  68 ,  70  are placed in the corresponding housings  52 ,  54 , and concentric with the shaft  46 , and an inner side of each coil  68 ,  70  is placed flush with an inner side of the corresponding housing  52 ,  54 . 
     It should be readily seen that the liner  58  can be made of any suitable friction material. It should also be readily seen that each spring  64 ,  66  may be affixed inside the corresponding housing  52 ,  54  and/or the corresponding movable plate  60 ,  62 , and each coil  68 ,  70  may be attached inside the corresponding housing  52 ,  54 , in any suitable manner. It should further be readily seen that the first housing  52  may be affixed to the drive unit  30  in any suitable manner. Additionally, it should be readily seen that the housings  52 ,  54  may also contain noise-absorbing  0 -rings (not shown). In any event, it should be readily seen that the two halves of the brake assembly  44  are mirror images of each other. 
     Each movable plate  60 ,  62  is configured to be actioned by two forces—a force of the corresponding spring  64 ,  66 , which moves the movable plate  60 ,  62  toward the disc  56  (to provide a braking force) and a magnetic field from the corresponding coil  68 ,  70 , which moves the movable plate  60 ,  62  away from the disc  56 . In this regard, the movable plate(s)  60 ,  62  may have a finishing on them that reduces the likelihood that the corresponding linings  58  will stick to the movable plate(s)  60 ,  62 . It should be readily seen that, although not shown in the drawings, the movement of each movable plate  60 ,  62  can be guided in bushings (not shown) to ensure that the movement is parallel. The bushings may be constrained axially at one end by the first housing  52  or the drive unit  30 , and at the other end by the second housing  54 . A controller (not shown) for controlling operation of the elevator system  10  is connected to the drive unit  30  via the wiring (not shown) in the motor  42  and the coils  68 ,  70 . Thus, when a call to a floor is registered, the controller sends drive signals to the drive unit  30  to raise or lower the car  22  to that floor and then to actuate the brake assembly  44  to the drive unit  30  as the car approaches that floor, or when an emergency stop is registered. 
     In operation of the elevator system  10 , to move the car  22  up and down in the elevator shaft  12 , the controller sends drive signals through the wiring to the motor  42  to rotate the shaft  46  around the axis A. The rotation of the shaft  46  is transferred to the drive pulley  38 , which rotates, and, through traction drives the tension belts  40  to raise or lower the car  22  and the counterweight  28 , and, depending on how the drive signals are sent to the motor  42 , they cause the motor  42  to rotate the shaft  46 . Meanwhile, the controller also sends current through the wiring to the coils  68 ,  70  to produce a magnetic field that causes the movable plates  60 ,  62  to move axially toward the corresponding housings  52 ,  54 . Movement of the movable plates  60 ,  62  away from the disc  56  allows the disc  56  to rotate with the shaft  46 . 
     When a power loss is experienced, and/or emergency braking is desired, the controller stops sending the current to the coils  68 ,  70  and the movable plates  60 ,  62  are then released and secured to move axially toward the disc  56  due to the force exerted on the movable plates  60 ,  62  by the corresponding springs  64 ,  66 . When the springs  64 ,  66  move the movable plates  60 ,  62  axially away from the corresponding housings  52 ,  54 , a movable plate  60 ,  62  pushes the disc  56  into contact with the other movable plate  60 ,  62 . The friction resulting from the contact of the corresponding liners  58  with the movable plates  60 ,  62  stops the rotating disc  56 . This rotation stoppage is transferred to the shaft  46 , the drive pulley  38 , and the drive belts  40 , causing detection of the movement of the car  22  up or down in the elevator shaft  12  to be stopped. 
     The “mirror” design of the brake assembly  44  allows a torque amount of a movable plate  60 ,  62  (that is, half of the brake assembly  44 ) to be applied to a respective side of the disc  56  such that the disc  56  is free to move axially (i.e., toward the other movable plate  60 ,  62 ). Thus, the respective torques of the plates  60 ,  62  are not added to each other to establish a total amount of torque of the brake assembly  44 . Rather, the total amount of torque is equal to the amount of torque of one single movable plate  60 ,  62 . Therefore, each movable plate  60 ,  62  is configured to provide a sufficient amount of torque to decelerate in accordance with about 125% of the total load of the elevator system  10 . However, since the respective torques of the movable plates  60 ,  62  are not added together, the brake assembly  44  as a whole decelerates in accordance with the same percentage of the full load. Thus, the total torque amount remains at about 125% of the full load. 
     With the elevator system  10 , the torques of the two movable plates  60 ,  62  (that is, both halves of the brake assembly  44 ) are not added to each other, and thus the deceleration capability of the brake assembly  44  is only around 125% of the full load. This causes less torque resulting in smaller decelerations of the elevator system  10  during power failures and/or emergency stops, which may minimize or even eliminate passenger discomfort and resulting passenger complaints. More specifically, the total amount of torque of the brake assembly  44  may be reduced to about 25% above that of a conventional elevator system. This lower permissible torque value is particularly relevant in areas where power failures are frequent. 
     Compared to a conventional elevator system, the elevator system  10  allows a lower initial torque design for the complete brake assembly  44 . Also, the elevator system  10  allows the coils  68 ,  70  to be smaller. In addition, the elevator system  10  allows a distance between the movable plates  60 ,  62  (that is, a total air gap) that is substantially identical to the distance between the movable plate and the fixed plate in a conventional elevator system. Furthermore, at high speed the elevator system  10  allows the cable  40  to slide less in an emergency stoppage. 
     Although the invention has been described in detail in connection with just a few examples, it can be readily seen that the invention is not limited to the examples described. Rather, the invention may be modified to incorporate any number of variations, alterations, substitutions, or equivalent placements that have not been described up to this point, but which are in accordance with the spirit and scope of the invention. Additionally, although several non-limitative examples of the invention have been described, it should be understood that aspects of the invention may include only some of the examples described. Accordingly, the invention should not be regarded as limited by the foregoing description; rather it is limited only by the scope of the attached claims.