Abstract:
A double brake protection device for elevator is provided. The device comprises at least one of emergency means and electromagnetic means coupled to brake in order to effect a stepwise stopping procedure for preventing elevator from free falling after brake is released.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to brakes and more particularly to a double brake protection device for elevator with improved characteristics.  
         BACKGROUND OF THE INVENTION  
         [0002]    Conventionally, a counterweight is provided in an elevator for balance during running. However, such balance may be compromized when persons enter the car of elevator. This unbalanced condition (i.e., the weight of car is significantly heavier than that of counterweight) may be worsen after brake is released. As a result, car may fall suddenly due to law of gravitation. This may endanger the lives of persons in the car. Thus improvement exists.  
         SUMMARY OF THE INVENTION  
         [0003]    It is therefore an object of the present invention to provide a brake protection device for an elevator comprising a main motor assembly including a first motor, a first shaft rotatably coupled to the first motor, a first sheave driven by the first shaft, a reduction gear coupled to the first shaft; a brake coupled to the main motor assembly, the brake including a rod-like spring-biased hand brake on the top; emergency means including a pair of idler wheels, a second sheave, a cable interconnecting the elevator and the second sheave through the idler wheels, a pair of pivotal link mechanisms coupled to the idler wheels, and a clutch having a recess coupled to one end of each link mechanism wherein the clutch is disengaged in a disabled state of the emergency means; and a secondary motor assembly coupled to the clutch, the secondary motor assembly including a second motor, a second shaft rotatably coupled to the second motor, and a third sheave coaxial with the second shaft, the third sheave having alternate peaks and valleys on a periphery in contact with the hand brake; wherein the cable is pulled to rotate the second sheave and the idler wheels; the link mechanisms are pivoted through a linking of the idler wheels for engaging the clutch; in response the third sheave rotates to cause the valleys and the peaks of the third sheave to engage with the hand brake alternately wherein when the hand brake is engaged with the peak of the third sheave, the hand break will be pulled down a predetermined distance for releasing the brake, or when the hand brake is engaged with the valley of the third sheave, the hand break will be pulled up the predetermined distance for applying the brake; and in response the elevator slows down stepwise until fully stops.  
           [0004]    In one aspect of the present invention, the second motor is operated by battery means.  
           [0005]    It is another object of the present invention to provide a brake protection device for an elevator comprising: a main motor assembly including a first motor, a first shaft rotatably coupled to the first motor, a first sheave driven by the first shaft, a reduction gear coupled to the first shaft; a brake coupled to the main motor assembly, the brake including a rod-like spring-biased hand brake on the top; and an electromagnetic mechanism including a spring-biased lever extended therefrom, the lever being biased to its highest position in an unexcited state of the electromagnetic mechanism and an extension coupled to a bottom of the lever; wherein when the electromagnetic mechanism is enabled, the hand brake will be pulled down a predetermined distance by the pressing of the lever for releasing the brake; in response a predetermined number of on-off operations are continuously performed on the electromagnetic mechanism, thus a release and an application of the brake are alternate; and in response the elevator slows down stepwise until fully stops. In another aspect of the present invention, the electromagnetic mechanism is operated by either a backup power of a building or battery means.  
           [0006]    The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a side view in part section of a portion of elevator incorporating a double brake protection device according to the invention;  
         [0008]    [0008]FIG. 2 is a fragmentary view of brake, electromagnetic device and sheave of FIG. 1;  
         [0009]    [0009]FIG. 3 is a plan view of another sheave of FIG. 1;  
         [0010]    [0010]FIG. 4 is a side view schematically showing link mechanism of FIG. 1 where clutch is disengaged;  
         [0011]    [0011]FIG. 5 is a view similar to FIG. 4 where clutch is engaged;  
         [0012]    [0012]FIG. 6 is a plan view of extension rod of FIG. 1; and  
         [0013]    [0013]FIG. 7 is a side view in part section of a portion of elevator which is activated by a hydraulic device according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    Referring to FIG. 1, there is shown a portion of an elevator incorporating a double brake protection device according to the invention. The elevator comprises a lower channel having a car  10  and a control including a first button  12  and a second button  68  within car  10 ; an upper control room  20  in which a variety of components are provided. These components comprise a motor  21 , a shaft  22  rotatably coupled to motor  21 , a drive sheave  23  driven by shaft  22 , a reduction gear  30  meshed with a gear associated with shaft  22 , a brake  40  coupled to reduction gear  30 , brake  40  having an automatic brake releasing device and a spring-biased hand brake  41  in the shape of a rod extended from top, an electromagnetic device  50  as a life saving and protection device in a first embodiment including a lever  51  into the electromagnetic device  50 , a spring  52  put on lever  51  biased against the top of electromagnetic device  50 , and a lower extension rod  53  coupled to the bottom of lever  51 . The operation of electromagnetic device  50  will now be described by referring to FIG. 2.  
         [0015]    In FIG. 2, lever  51  is biased to its highest position by spring  52  in an unexcited state of electromagnetic device  50 . Once electromagnetic device  50  is enabled, lever  51  will be pulled down to compress spring  52  until being stopped within electromagnetic device  50 . Hence, hand brake  41  is pressed down to release the brake  40 . As a result, car  10  will hoist or lower as the rotation of sheave  23  through a travelling cable  11  which interconnects car  10  and drive sheave  23 . It is designed that once electromagnetic device  50  is enabled by pressing the first button  12  a predetermined number of on-off operations are continuously performed on electromagnetic device  50 . Hence, a releasing and an application of the brake  40  are alternate. As a result, the running car  10  will slow down stepwise until fully stops in a desired level of a building. This can substantially eliminate the danger of sudden falling of brake experienced in prior art. Note that the power of electromagnetic device  50  is supplied by the backup power of the building or battery.  
         [0016]    Alternatively, the life saving and protection device may be implemented by other members in a second embodiment as detailed below. Referring to FIGS.  3  to  5  in conjunction with FIG. 1, emergency cable  60  interconnects car  10  and sheave  61  through a pair of adjacent idler wheels  62  which are in turn coupled to link mechanisms  63 . Link mechanism  63  is pivotably provided in control room  20 . Further, one end of each link mechanism  63  is coupled to a recess  71  of clutch  70 . In use, pull emergency cable  60  to rotate sheave  61  and thus idler wheels  62 . In response, link mechanisms  63  are pivoted through the linking of idler wheels  62 . As a result, clutch  70  is engaged.  
         [0017]    Referring to FIG. 6 in conjunction with FIGS.  1  to  5 , a secondary motor  66  powered by battery  67  is controlled by second button  68 . Secondary motor  66  is coupled to shaft  65  which is coaxial with sheave  64 . Hence, sheave  64  is rotated as shaft  65  is rotated by the pulling of emergency cable  60 . Hence, hand brake  41  is pressed down to release the brake  40  through the activation of sheave  64  and electromagnetic device  50 . In detail, the periphery of sheave  64  is formed of alternate smooth peaks  641  and valleys  642 . Hence, lever  51  is biased to its highest position by spring  52  when lever  51  is engaged with valley  642  of sheave  64  in an unexcited state of electromagnetic device  50 , while lever  51  is biased to its lowest position by spring  52  when lever  51  is engaged with peak  641  of sheave  64  for causing the electromagnetic device  50  to enter into an excited state. Similarly, once electromagnetic device  50  is enabled, hand brake  41  is pressed down to release the brake  40 . As a result, car  10  will hoist or lower as the rotation of sheave  23  through the travelling cable  11 . Likewise, a releasing and an application of the brake  40  are alternate. As a result, the running car  10  will slow down stepwise until fully stops in a desired level of a building. This has the same effect as the first embodiment described in FIGS. 1 and 2.  
         [0018]    Referring to FIG. 7, there is shown a hydraulic elevator. The lower extension rod  53  is coupled to the top of rod  82  which is vertically extended from hydraulic cylinder  81 . Also, sheave  64  is rotated as shaft  65  is rotated. When peak  641  of sheave  64  is engaged with lever  51 , the lower extension rod  53  is activated by lever  51  to press the rod  82 . As a result, fluid in fluid supply line  80  begins to flow as hydraulic cylinder  81  is activated by the pressing of rod  82 . In response, fluid supplied to hydraulic shaft  90  of elevator activates for lowering car  10 . Moreover, electromagnetic device  50  may be powered by battery  67  to cause the lower extension rod  53  to press the rod  82 . This achieves the same effect of activating car  10  by sheave  64 .  
         [0019]    Note that a desired effect envisioned by the invention may be realized by one of the first, second and third embodiments or a combination thereof (as detailed in above illustrated embodiments). As to only second embodiment is realized (i.e., without the provision of electromagnetic device  50 ), sheave  64  may be provided on top of hand brake  41 .  
         [0020]    While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.