Patent Publication Number: US-7717236-B2

Title: Elevator and elevator brake

Description:
This application is a continuation of PCT/FI2007/000008 filed on Jan. 10, 2007, which is an international application claiming priority from FI 20060034 filed Jan. 16, 2006, the entire contents of which are hereby incorporated by reference. 

   CROSS-REFERENCE TO RELATED APPLICATIONS 
   BACKGROUND 
   1. Field 
   The present invention relates to an elevator and an elevator brake. 
   2. Description of Related Art 
   According to the regulations elevators must contain an emergency brake, which is switched on in exceptional situations, such as during an electricity power cut. The normal holding brake of the elevator, for example, is used as an emergency brake, which keeps the elevator car in its position in normal situations when the car is at a landing. Deceleration of the car in normal situations is usually effected as motor braking. Connection of the emergency brake when moving upwards in elevators without counterweight, combined with the earth&#39;s gravity, can cause such large deceleration of the elevator car that the safety of the passengers can be endangered. Thus when traveling upwards the emergency brake should not decelerate the elevator car of an elevator without counterweight too effectively or not necessarily at all. 
   SUMMARY 
   The elevator and/or elevator brake may eliminate the aforementioned drawback and may be simple and operationally reliable. The elevator and/or elevator brake may avoid unnecessary discomfort or dangerous situations for the passengers. The elevator according to the invention is discussed below. The elevator brake according to the invention is also discussed below. Some embodiments of the invention are characterized by what is disclosed in the claims. 
   Some inventive embodiments are also discussed in the descriptive section of the present application. The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of explicit or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Likewise, the different details presented in connection with each embodiment of the invention can also be applied in other embodiments. Problems solved separately can be for example adjustment of the air gap of the brake or the guiding of supporting forces to support in braking occurring in the upward or downward direction. 
   In the invention the braking exerted on the traction sheave of the brake is reduced in a situation where emergency braking occurs, in which the elevator car is moving upwards, by allowing the brake shoe to follow the movement of the traction sheave for at least some distance. Preferably the normal force exerted on the brake wheel of the brake shoe at the same time is simultaneously allowed to be lighter. 
   The advantage of the elevator according to the invention and its braking solution is that the upward movement of the elevator car in elevators without counterweight does not slow down too quickly in an emergency braking situation, in which case no danger is caused to the passengers in the car by sudden stopping of the elevator car. A further advantage is the dependable and operationally reliable construction. Another advantage is that the solution according to the invention is suitable for use also in elevators with counterweight, in which case slipping between the hoisting rope and the traction wheel and between the hoisting rope and the diverting pulleys caused by sudden deceleration can be prevented. This saves at least both the rope and the traction wheel and diverting pulleys. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention will be described in more detail by the aid of some example of its embodiment with reference to the attached drawings, wherein 
       FIG. 1  presents a diagrammatic and simplified side view of a traction sheave elevator without counterweight applicable to the solution according to the invention, 
       FIG. 2  presents a side view of a sectioned part of the brake appliance of an elevator, in which one embodiment of the solution according to the invention is used and 
       FIG. 3  presents a side view of a sectioned part of a brake appliance of an elevator according to  FIG. 2 , in which the brake lightening function is switched on. 
   

   DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     FIG. 1  presents a diagrammatic and simplified side view of one traction sheave elevator without counterweight applicable to the solution according to the invention, which comprises at least an elevator hoisting machine  5  with hoisting motor, a traction sheave  6 , an elevator control system  8 , as well as an elevator car  1  in a car sling  2  moving in an essentially vertical direction along guide rails  4 , which is suspended on hoisting ropes  3 . The first end of the hoisting ropes  3  is fastened to the top part of the car sling  2 , from where it is led to pass around and over the traction sheave  6 , and then under the diverting pulley  7  of the hoisting machine  5  and next over the traction sheave  6  again, from where it goes under the diverting pulley  9  fixed to the bottom of the elevator shaft, and then on to the bottom part of the car sling  2 , to which the second end of the hoisting ropes  3  is fastened. The elevator receives its lifting force from the hoisting machine  5  as a result of the friction between the traction sheave  6  and the hoisting ropes  3 . The roping suspension presented in  FIG. 1  is a simplified roping construction for an elevator without counterweight. Often the hoisting rope  3  is led to pass via numerous diverting pulleys, so that the suspension ratio is of the magnitude desired. In addition the hoisting machine contains e.g. two brakes  10 , which are positioned on opposite sides of the center axis. The brake  10  is primarily a holding brake, which keeps the elevator car  1  in its position when the car is at a landing. Normally braking of the movement of the elevator car occurs as motor braking by means of the hoisting motor. The brake  10  is also used for emergency braking, in which case very great deceleration is achieved with the brake, especially in an elevator without counterweight, owing to the good friction between the hoisting ropes and the traction sheave  6 . Deceleration that is too great is a problem, especially in elevators without counterweight when moving upwards, as mentioned above. For this reason the braking force of the brake  10  according to this invention is reduced by lightening the compression of the brake shoes on the brake wheel, if the brake  10  is switched on while the elevator car  1  is moving upwards. 
     FIG. 2  presents a side view of a sectioned part of the brake appliance of an elevator, in which one embodiment of the solution according to the invention is used. The brake is presented in a situation in which the brake is activated while the elevator is stationary, but the brake is in almost the same position also when emergency braking is effected when the elevator car is moving downwards. 
   The hoisting machine  5  comprises at least a fixed stator and a rotating rotor, along with which a brake wheel  11  provided with a braking surface  11   a  rotates. Additionally a traction sheave  6  is fixed to the rotor so that it rotates with the rotor. The brake  10  comprises at least a brake frame  13  fixed to the hoisting machine  5 , containing at least one electromagnet  20  equipped with windings. A brake plate  15  fitted to move in relation to the frame is located on the brake frame  13 , between the brake wheel  11  and the frame  13 , and a brake shoe  12  provided with a wedge piece  16  is further located between the brake plate  15  and the brake wheel  11  such that the wedge piece  16  is between the brake plate  15  and the brake shoe  12 . The wedge surface of the wedge piece  16  on the side of the brake plate  15  and correspondingly the surface of the brake plate  15  on the side of the wedge piece together form a substantially straight first sliding surface  16   a , which is inclined to an angle, which opens the brake wheel  11  in that direction of rotation in which the elevator car  1  moves upwards. The aforementioned direction of rotation is marked in the figure with the arrow A. In addition the second sliding surface  25  between the wedge piece  16  and the brake shoe  12  as viewed from the side is curved such that the wedge piece  16  slides on the sliding surface  25  in relation to the brake shoe  12 , but the wedge piece  16  does not come out from between the brake plate  15  and the brake shoe  12 . Preferably the wedge angle between the brake plate  15  and the wedge piece  16  is appreciably greater than the friction angle between them, and even better: in addition to or alongside a sufficient wedge angle the ease of a change in the inter-positioning of the brake plate  15 , the wedge piece  16  and the brake shoe  12  is achieved with a selection of materials suitable for these pieces in which case the friction between the brake plate  15 , the wedge piece  16  and the brake shoe  12  at their mutual sliding surfaces is slight. 
   The brake frame  13  contains a center hole in the center of the frame and extending through the frame, in which is a bore  24  extending through the frame on the side of the brake plate  15  and at least a second bore  22  with the same center, which is open to the opposite side of the brake plate  15  of the frame  13 . The bore  22  does not extend through the frame  13  and the diameter of the bore  22  is greater than the diameter of the bore  24  such that at the meeting point of the bores inside the frame is a ring-like collar  21 . In addition a presser pin  18  is fitted to pass through the bores  22 ,  24 , of which the diameter of the part mainly situated in the bore  24  is greater than the diameter of the part mainly in the bore  22 , such that there is a ring-like collar  19  on the presser pin  18  at the meeting point of the different diameters. The length of the part of the presser pin  18  of greater diameter is selected to be such that it is essentially greater than the length of the smaller diameter bore  24  of the center hole. A disc spring pack  14  locked at its first end with a locking element  23  is located around the presser pin  18  in the larger diameter bore  22 , which is fitted to press the presser pin  18  at its second end via the collars  19  towards the brake shoe  12 . The brake plate  15  contains a stop surface, against which the presser pin  18  presses and causes movement of the brake plate towards the brake shoe  12  in the braking phase. 
   In a braking situation current is disconnected from the electromagnets  20 , whereupon the disc spring pack  14  presses the presser pin on the collar  19  towards the brake wheel  11 . The presser pin  18  for its part presses the brake plate  15 , and the brake shoe  12  via both the brake plate and the wedge piece  16 , towards the brake wheel  11 . The collars  21  in the smaller diameter bore  24  of the frame prevent the disc spring pack  14  from pressing the presser pin  18  too long a distance towards the brake wheel  11 . When the brake is not activated, the electromagnets  20  keep the brake shoe  12  detached from the braking surface  11   a  of the brake wheel  11 .  FIG. 2  presents only one brake  10 , the other is situated for example on the opposite side of the hoisting machine  5 . In this case the brake  10  is on the upper and lower part of the hoisting machine, while in the solution according to  FIG. 1  it is on the sides of the hoisting machine. 
     FIG. 3  presents a part of a brake appliance of an elevator according to the invention in a situation in which the brake lightening function is switched on, when the emergency braking occurs while the elevator car is moving upwards. The idea of the invention is that when the elevator car  1  is moving upwards, the brake  10  does not substantially slow down the speed, even if the emergency braking is switched on e.g. in the event of an electricity power cut. Likewise, when the elevator car  1  is stationary or is moving downwards and the brake  10  is connected, the brake  10  operates in the conventional manner of a brake—i.e. it keeps the car  1  in its position or slows down downward movement. This is possible with the same brake due to the wedge solution of the invention. 
   When the elevator car  1  is moving upwards the brake wheel  11  rotates in the situation of the figure counterclockwise in the direction of the arrow A. When the brake  10  is switched on while driving upwards, the mutual shaping of the wedge piece  16  on the brake shoe  12 , the brake plate  15  and the brake shoe  12  enable the brake shoe  12  to move along with the brake wheel  11  in the direction of rotation of the braking surface  11   a  owing to the friction between the shoe and the braking surface  11   a , in other words in the direction of the arrow A. The wedge piece  16  then moves in relation to the sliding surfaces  16   a  and  25  and at the same time the brake shoe  12  moves away from the braking surface  11   a . The brake shoe  12  does not however manage to move too long a distance, because the spring-action stop and return element  17  supported against the frame prevents movement of the brake shoe  12  after a pre-determined distance. When the brake shoe  12  has moved far enough to the side below the brake plate  15 , the lowest springs of the disc spring pack  14  engage the collar  21  in the center hole of the frame  13 , whereupon the presser pin  18  no longer presses the brake plate  15  closer to the brake wheel  11 . In this case the aforementioned compression towards the brake wheel  11  is no longer exerted on the brake shoe  12  and the brake shoe  12  is able to move a little away from the braking surface  11   a , whereupon there is no longer any substantial braking force and the elevator car stops softly under the influence of the earth&#39;s gravity. 
   When the movement of the elevator car  1  upwards has stopped due to the earth&#39;s gravity, the elevator car simultaneously tries to move immediately downwards. In this case the brake shoe  12  wedges back into its normal position due to the spring force of the stop and return element  17  and also due to the friction between the brake shoe  12  and the braking surface  11   a , if the elevator car  1  has continued its downward movement after stopping. The brake  10  then stops the elevator car in its position and the brake thereafter operates as a normal holding brake. By adjusting the spring force of the stop and return element it is also possible to set the force of braking occurring in the upward direction to at least some extent. 
   The arrester element  26 , which is presented in the figure as an adjuster screw, determines together with the spring of the return element  17  the resting position of the brake shoe  12 . The arrester element  26  also prevents, at least for its part, the brake shoe from following the movement of the brake wheel when braking occurs in the downward direction. The arrester element  26  receives support for bearing braking in the downward direction from the brake plate  15  or possibly from another part of the brake. The adjuster screw functioning as the arrester element also determines within the scope of its adjustment tolerance the height of the entity jointly formed by the brake shoe  12 , the brake plate  15  and the wedge piece  16  in the direction of the brake stroke, in which case the air gap between the brake shoe  12  and the braking surface  11   a  is easily adjustable. 
   It is obvious to the person skilled in the art that the invention is not limited solely to the example described above, but that it may be varied within the scope of the claims presented below. Thus, for example, the lightening of the braking force in an emergency braking situation can also be implemented with separate device structures than that presented above. Instead of mechanical lightening of the braking force, the braking force can be lightened electrically with electromagnets or also hydraulically. 
   It is also obvious to the person skilled in the art that the suspension ratio of the elevator can be greater than a 1:1 ratio. For example 2:1, 4:1, 8:1 ratios, and also other ratios, including uneven ratios, are easy to implement from the standpoint of the invention. 
   It is further obvious to the person skilled in the art that the invention is suitable for use also, apart from in elevators without counterweight, in e.g. those types of elevators with counterweight, in which the counterweight is at most the weight of the empty elevator car. In this case slipping between the hoisting rope and the traction wheel and between the hoisting rope and the diverting pulleys caused by sudden deceleration can be prevented.