Patent Publication Number: US-10781075-B2

Title: Emergency safety actuator for an elevator

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to elevator braking systems and, more specifically, to magnetic triggering mechanisms and friction force providers for elevators. 
     BACKGROUND OF THE DISCLOSURE 
     Elevator systems are widely used in a variety of applications for transporting passengers from point to another. Typical contemporary elevator systems often include an emergency braking system that reduce speed or altogether halt the progression of the elevator car if the elevator system loses power. Conventional emergency braking systems are large and generally include a large number of mechanical parts, which not only decreases the load carrying capacity of the elevator car, it increases the size of the elevator shaft to accommodate the braking system, and increases construction and maintenance costs of the elevator system. 
     In conventional emergency braking systems, a governor is used to activate and maintain a ready state of the emergency braking system. The governor, which is usually situated at the top of an elevator hoistway, monitors the speed of the elevator as it travels through the hoistway and, activates the emergency braking system if the elevator car begins moving too quickly. This in turn requires a connection between the governor and the elevator car of the elevator system. The connection adds complexity to the elevator car and the hoistway, thereby further increasing cost and maintenance time. 
     Therefore, an improved emergency braking system with a reduced size, complexity, and cost compared to prior art emergency braking systems is desired. It will also be beneficial if the improved emergency braking system could maintain an indefinite ready state and an engaged state. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with one aspect of the disclosure, a device for a friction force provider for an emergency safety actuator for an elevator system is disclosed. The friction force provider may include a housing having a first end and an opposing second end, where the first end may define an opening. The friction force provider may further include a primary magnet positioned within the housing and configured to move between an armed position and a working position. The primary magnet may be configured to create a force on a rail of the elevator system in the working position and be held within the housing in the armed position. 
     In a refinement, the friction force provider may further include a triggering mechanism having a holding plate formed of a magnetically sensitive material mounted within the housing. The friction force provider may yet further include an electro-magnetic coil positioned within the housing and associated with the primary magnet. 
     In a further refinement, the electro-magnetic coil may be mounted in a stationary position within the housing. 
     In another further refinement, the electro-magnetic coil may be mounted with the primary magnet such that the electro-magnetic coil may move with the primary magnet. 
     In yet a further refinement, the friction force provider may further include a secondary magnet positioned within the housing and may be mounted with the primary magnet and the electro-magnetic coil such that the secondary magnet may move therewith. The primary magnet and the secondary magnet may be positioned on opposing ends of the electro-magnetic coil. 
     In another refinement, the friction force provider may further include a spring positioned within the housing to bias the primary magnet towards the first end. The friction force provider may also include a latch positioned to retain the primary magnet within the housing. 
     In a further refinement, the friction force provider may be configured to operate with a ropeless elevator. 
     In yet another refinement, the friction force provider may include a guard mounted with the primary magnet, the guard may be configured to move with the primary magnet. The guard may have a trapezoidal shaped portion that may extend through the opening of the housing while the primary magnet is in the working position. 
     In yet another embodiment, the friction force provider may further include a braking pad mounted with the primary magnet such that at least in the working position the braking pad may extend through the opening of the housing. 
     In accordance with another aspect of the present disclosure, an elevator system is disclosed. The elevator system may include a hoistway, a car disposed within the hoistway, a counter weight disposed within the hoistway, a support structure operatively associated with the car and counter weight, a rail associated with the car and an emergency safety actuator operatively associated with the car and rail and having a friction force provider configured to apply a force to the rail. The emergency safety actuator may have a triggering mechanism associated with the friction force provider to activate the actuator. 
     In a refinement, the triggering mechanism may be integral with the friction force provider and the friction force provider may include a housing having a first end and an opposing second end, the first end defining an opening. The friction force provider may also include a primary magnet positioned within the housing, the primary magnet configured to move between an armed position and a working position, an electromagnetic coil associated with the primary magnet and a holding plate mounted within the housing. 
     In a further refinement, the electro-magnetic coil may be mounted with the primary magnet such that the electro-magnetic coil may move with the primary magnet. 
     In yet another refinement, the friction force provider may further include a secondary magnet mounted with the primary magnet and electromagnetic coil such that the secondary magnet moves with both, and is positioned such that the primary magnet and secondary magnets are positioned on opposing ends of the electromagnetic coil. 
     In another further refinement, the electro-magnetic coil may be mounted in a stationary position within the housing. 
     In another refinement, the triggering mechanism may be external to the friction force provider, and the friction force provider may include a housing having a first end and an opposing second end, the first end defining an opening, a spring positioned within the housing at the second end and configured to expand towards the first end and a latch configured to retain the spring within the housing at the second end. The triggering mechanism may include a trigger housing having a first end and an opposing second end, the first end of the trigger housing defining an opening, a holding plate mounted within the trigger housing, an electro-magnetic coil mounted within the trigger housing, a trigger magnet moveably positioned within the trigger housing, the trigger magnet having an armed position and a working position and a pin mounted with the trigger magnet such that in the working position the pin may move and release the latch of the friction force provider. 
     In a further refinement, the friction force provider may further include a primary magnet positioned within the housing and associated with the spring such that in the working position the primary magnet may be directed towards the first end of the housing to contact the rail. 
     In accordance with yet another aspect of the present disclosure, a method of activating a magnetic friction force provider of an elevator emergency safety actuator is disclosed. The method may include retaining a primary magnet within a housing of the friction force provider in an armed position, releasing the primary magnet from the armed position by transmitting an electrical signal through an electro-magnetic coil of a triggering mechanism, extending the primary magnet from the armed position to a working position, and retaining the primary magnet in the working position. 
     In a refinement the method may further include retaining the primary magnet within the housing of the friction force provider in the armed position through a magnetic attraction from the primary magnet to a holding plate, activating the triggering mechanism to neutralize the magnetic attraction between the primary magnet and the holding pate to release the primary magnet from the armed position, extending the primary magnet through an opening in the housing of the friction force provider to the working position through magnetic attraction of the primary magnet to the rail and retaining the primary magnet in the working position through a magnetic attraction from the primary magnet to the rail. 
     In another refinement, the method may further include retaining the primary magnet within the housing of the friction force provider in the armed position with a latch and biasing the primary magnet towards a working position with a spring, retaining a trigger magnet in an armed position within a trigger housing of the triggering mechanism by a magnetic attraction from the trigger magnet to the holding plate, activating the triggering mechanism by transmitting a signal through the electro-magnetic coil to neutralize the magnetic attraction from the trigger magnet to the holding plate, moving the trigger magnet within a trigger housing of the triggering mechanism through magnetic attraction, and moving the pin with the movement of the trigger magnet, releasing the latch with the pin, extending the primary magnet through an opening in the housing of the friction force provider with the spring and retaining the primary magnet in the working position and in contact with the rail through a magnetic attraction from the primary magnet to the rail. 
     In yet another refinement, the method may further include retracting the primary magnet from the working position to the armed position by transmitting a second electrical signal through the electro-magnetic coil. 
     These and other aspects and features of the present disclosure will be better understood in light of the following detailed description when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary elevator system, constructed in accordance with an aspect of the present disclosure; 
         FIG. 2  is a cross-sectional view of an electrical safety system for use in the elevator system of  FIG. 1 , the electrical safety system constructed in accordance with an aspect of the present disclosure; 
         FIG. 3  is a perspective view of a friction force provider for use with the electrical safety system of  FIG. 2 , the friction force provider constructed in accordance with an aspect of the present disclosure and detailing a transitional position and a stationary coil. 
         FIG. 4  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a transitional position and a moveable coil. 
         FIG. 5  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a working position. 
         FIG. 6  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing an armed position. 
         FIG. 7  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a working position. 
         FIG. 8  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a secondary magnet. 
         FIG. 9  is a perspective view of the friction force provider built in accordance with an aspect of the present disclosure and detailing an armed position and a guard piece. 
         FIG. 10  is a cross-sectional view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a spring force provider with a magnet. 
         FIG. 11  is a perspective view of an external triggering mechanism built in accordance with an aspect of the present disclosure and detailing an armed position 
         FIG. 12  is a cross-sectional view of the friction force provider built in accordance with an aspect of the present disclosure and detailing a spring force provider without a magnet. 
     
    
    
     It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein. 
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an exemplary elevator system  10  is illustrated. It is to be understood that the elevator system shown in  FIG. 1  is for illustrative purposes only and to present various elements of a general elevator system. As illustrated, the elevator system  10  may include a car  12  coupled to a counter weight  14  via a supporting structure  16 . The support structure  16  may extend over a traction sheave  18  and may be driven by a machine  19  to move the car  12  and the counter weight  14  through a hoistway  21 . A set of rails  40  positioned within the hoistway  21  may guide the car  12  and counter weight  14  as both move through the hoistway. The elevator system  10  may further include an electrical safety system (ESS)  23  positioned on the car  12  proximate the rails  40 . 
     Turning now to  FIG. 2 , a cross-section of an exemplary one of the ESS  23  is shown, in accordance with at least some embodiments of the present disclosure. As shown, the ESS  23  may include a body  22  defining a sloped slide path  24 , a bolt  26 , a wedge  28  positioned within the sloped slide path  24 , an emergency safety actuator (ESA)  20  having a friction force provider (FFP)  30  mounted on the wedge  28 , and a secondary block  32  spaced apart from the body  22  and defining a passage  34  therebetween. In some embodiments, the body  22  and secondary block  32  may be provided as a unitary piece, while in other embodiments, the body and the block may be provided as separate pieces held in a stationary relationship to each other, such as by a bolt or the like. 
     The wedge  28  may include a spring  36  and a braking pad  38  mounted to the spring and facing the passage  34 . Multiple springs  36  or sets of springs  36  may also be utilized with the wedge  28 . The ESS  23  may also include an optical speed/acceleration sensor that monitors the speed of the car  12  in the hoistway  21  and transmits signals to activate the ESA  20  during an emergency, such as loss of power or excessive speed. This sensor eliminates the need for a governor, and equipment linking the governor and the car  12 , thereby greatly simplifying the elevator system  10 . A ropeless elevator is one exemplary elevator that may utilize such an ESS  23 . Another exemplary elevator may be a low speed elevator, where the sensors may be mounted on the counter-weight  14 . 
     As the car  12  ascends and descends, the ESS  23  may travel along the rail  40 , where the rail  40  may be positioned in the passage  34 . Upon power loss, run away, free fall, or a similar emergency, a signal may be transmitted from a source, such as the optical speed sensor, to the ESA  20 . The friction force provider  30  may react to this signal by extending to contact the rail  40  and creating a force that may be used to create a friction force required to move the wedge  28  with the rail  40  along the sloped slide path  24  until the wedge  28  encounters the bolt  26 . If the car  12  is moving when the friction force provider  30  is active, the wedge  28  may move along the sloped slide path  24 . As the wedge  28  moves, the braking pad  38  may contact the rail  40  and compress the spring  36 , which may facilitate a smooth transition from free motion to braking. 
     This friction between the braking pad  38  and the rail  40  may reduce the speed of the elevator and eventually bring the car  12  to a stationary position relative to the rail  40 . If the power were to fail while the car  12  is stationary, the friction force provider  30  may extend, but the wedge  28  may not move. This ensures that the brakes would be engaged in an emergency, but would not cause unnecessary wear on the braking pad  38  and the rail  40 . 
     As can be seen in  FIG. 3 , the friction force provider  30  may include a housing  42  having a first end  44  defining an opening  46  and a second end  48 , opposite the first end  44 . The friction force provider  30  may further include a primary magnet  50 , provided as a permanent magnet. For the purposes of the present disclosure, a permanent magnet is any magnet formed from a material that has a natural quality of creating a constant magnetic field. This is opposed to an electro-magnet that can create either a constant or a varying magnetic field, but only when supplied with an electrical current or signal. The primary magnet  50  may be moveably mounted within the housing  42  to have at least an armed position and a working position. In the armed position, the primary magnet  50  may be retained in a recessed position within the friction force provider  30 , and in the working position, the primary magnet may be positioned such that a magnetic flux of the primary magnet  50  is closed through the rail  40 . 
     Friction Force Provider with Integrated Triggering Mechanism 
     In the following embodiments, the ESA  20  may further include a triggering mechanism  51  (see  FIG. 11 ) that may be provided integral with the friction force provider  30  and may include an electro-magnetic coil  52  mounted within the housing  42  of the friction force provider. The coil  52  may be provided as a stationary component or may be moveably mounted. As illustrated in  FIG. 3 , the coil  52  may be mounted in a stationary position within the housing  42  at the second end  48 . Alternatively, the coil  52  may be moveably mounted with the primary magnet  50 , as illustrated in  FIGS. 4 and 5 . In each of these cases, a holding plate  54  may also be included in the triggering mechanism and mounted in a stationary position. The holding plate  54  may be formed of any magnetically sensitive material, such as steel. In the armed position, the magnetic flux of the primary magnet  50  may be closed through the holding plate  54 . 
     The positioning of the primary magnet  50  relative to the holding plate  54  and coil  52  may help to manage the holding force in both the armed and working positions. For example, in the embodiments illustrated in  FIGS. 3 and 4 , the coil  52  is positioned between the holding plate  54  and primary magnet  50 . This positioning may create a stronger bond with the rail  40  when in the working position, while having a weaker bond with the holding plate  54  when in the armed position. As an alternate embodiment to those presented in  FIGS. 3 and 4 , the primary magnet  50  may be moveably mounted in the housing  42  between the coil  52  and the holding plate  54 , as in  FIG. 5 . This positioning may create a stronger bond between the primary magnet  50  and the holding plate  54  in the armed position, as opposed to the bond between the primary magnet  50  and rail  40  in the working position of this same embodiment. 
     In the armed position of  FIG. 6  for one embodiment, the primary magnet  50  may be held within the housing  42  of the FFP  30  in a recessed position. In this position the magnetic flux from the primary magnet  50  may be closed through the holding plate  54 , and thereby the primary magnet  50 , and coil  52  in some embodiments, may be held in this position. As can be seen, the armed position may be held indefinitely without the use of electricity. 
     An electric signal may be transmitted through the coil  52  to initiate a transition of the primary magnet  50  from the armed position to the working position. This electric signal may originate from a great many apparatuses, such as the optical speed/acceleration sensor discussed above. The signal may cause the coil  52  to create a magnetic field of its own. A signal may be transmitted through the coil  52  in two directions: one direction may create a magnetic field that opposes the field of the primary magnet  50  in the armed position, and the other direction may create a magnetic field that compliments the field of the primary magnet  50  in the armed position. To initiate a transition from the armed position to the working position, an opposing magnetic field may be created. By doing so, the magnetic bond between the primary magnet  50  and holding plate  54  may be interrupted, allowing the primary magnet  50  to move away from the holding plate  54  through a magnetic attraction to the rail  40 . This attraction may pull the primary magnet  50  towards the rail  40 , where the magnetic flux of the primary magnet  50  may then be closed through the rail  40 , thus holding the primary magnet in the working position, as illustrated in  FIGS. 5 and 7 . 
     Once in the working position, the primary magnet  50  may not release until the friction force provider  30  is reset. This may be accomplished through mechanical or electrical means. To reset the friction force provider  30  through electrical means, a second, reverse, electrical signal may be transmitted through the coil  52 . In the embodiment of  FIG. 3  where the coil  52  is stationary within the housing  42 , the second signal may create a magnetic field that attracts the primary magnet  50  away from the rail and back into the armed position, where the primary magnet  50  is retained through its own magnetic field. In the embodiments of  FIGS. 4 and 5  where the coil  52  is moveably mounted with the primary magnet  50 , the second signal may create a magnetic field that interrupts the magnetic attraction between the primary magnet  50  and the rail  40  and redirects the magnetic field towards the holding plate  54 . This may pull the combined primary magnet  50  and coil  52  away from the rail  40  towards the holding plate  54  and into the armed position, where the combined primary magnet  50  and coil  52  may be retained through the magnetic field produced by the primary magnet  50  alone, and the field from the coil  52  is no longer needed. In both of these embodiments, the magnetic attraction between the coil  52  and the holding plate  54  created by transmitting the second signal through the coil  52  may be strong enough to redirect the field from the primary magnet  50  directed towards the rail  40  to overcome the latter attraction. 
     As illustrated in  FIGS. 3-7 , a braking pad  56  may be provided moveably mounted with the primary magnet  50  at the first end  44  of the friction force provider  30 . Specifically, the braking pad  56  may be positioned such that in the working position, the braking pad  56  is positioned in contact with the rail  40 . The braking pad  56  may cushion the impact between the friction force provider  30  and rail  40  when the primary magnet  50  transitions to the working position and prevents any direct contact between the rail  40  and primary magnet  50  or the rail  40  and the coil  52  while the primary magnet  50  is in the working position. This increases the life of the primary magnet  50 , the friction force provider  30 , and the rail  40  and increases friction coefficient which allows for a reduction in the required force, further reducing the size requirements for the friction force provider  30 . The braking pad  56  may be formed of a magnetically sensitive material to convey the magnetic field from the primary magnet  50  to the rail  40 , but other materials are also possible. As illustrated in  FIG. 8 , the friction force provider  30  may also be provided without a braking pad  56  to reduce weight and part count of the friction force provider. 
     A secondary magnet  58  may also be provided moveably mounted with the primary magnet  50  and coil  52  as illustrated in  FIG. 8 . More specifically, the secondary magnet  58  may be provided within the housing  42  such that a permanent magnet is positioned at both ends of the coil  52 . This configuration assists in the resetting procedure by reducing the magnetic field strength, specifically of the field created by the coil  52 , needed to separate the primary magnet  50  from the rail  40 . 
     A guard piece  60  may also be provided around the primary magnet  50  as illustrated in  FIG. 9 . This guard  60  may also be moveably mounted with the primary magnet  50  to be retracted and extended with the primary magnet  50  or a stationary and integral element of the housing  42  of the friction force provider  30 . When the primary magnet  50  is extended, the guard  60  may contact the rail  40  to prevent the primary magnet  50  from impacting the rail  40 . To assist in smoothly transitioning across the rail  40 , the guard  60  may have a trapezoidal shaped portion that extends through the opening  46  at least at the working position. This shape allows the guard  60  and the friction force provider  30  to translate across and bumps or other features of the rail  40  without creating unnecessary strain on the friction force provider. The guard  60  may be formed of a magnetically sensitive material to convey the magnetic field from the primary magnet  50  to the rail  40 . However, other materials are also possible. 
     Friction Force Provider with External Triggering Mechanism 
     In the following embodiments, the ESA  20  further includes a triggering mechanism  51  that is provided as a separate component from the FFP  30 . As illustrated in  FIGS. 9 and 10 , the FFP  30  of this embodiment includes a spring  62  positioned within the housing  42  at the second end  48 . The spring  62  works to bias the primary magnet  50  towards the opening  46  at the first end  44  of the housing  42 . To counter the spring  62  and retain the primary magnet  50  in the housing  42  in the armed position, a latch  64  is provided. This latch  64  may take many forms, and should not be considered as limited to just the form illustrated in the presented figures. When triggered, the latch  64  releases the primary magnet  50 , allowing the spring  62  to move the primary magnet  50  to a position where the magnetic flux of the primary magnet  50  can be closed through the rail  40 . 
     A filler  65  may be mounted with the primary magnet  50 , as illustrated in  FIG. 10 . This filler may be made of a magnetically sensitive material, such as steel for example, but other materials are also possible. This filler  65  may occupy any intervening space surrounding the primary magnet  50  within the housing  42 . 
     As can be seen in  FIG. 11 , the triggering mechanism  51  of this embodiment may include a trigger housing  66  having a first end  68  defining an opening  70  and an opposed second end  72 . A holding plate  54  is mounted in a stationary position within the trigger housing  66 . An electro-magnetic coil  52  and a trigger magnet  76  may also be mounted within the trigger housing  66 . In the embodiment illustrated in  FIG. 11 , the coil  52  is mounted in a stationary position at the first end  68 , the holding plate  54  is mounted in a stationary position at the second end  72 , and the trigger magnet  76  is moveably mounted between the coil  52  and holding plate  54 , having an armed position and a working position. The illustrated configuration is only one possible configuration, and others also exist. For example, configurations similar to those of the FFP  30  presented above, where the coil  52  separates the primary magnet  50  and holding plate  54  are also possible. The coil  52  may define a passage  74  in communication with the opening  70  of the trigger housing  66 . A pin  78  is also moveably mounted with the trigger magnet  76 . In the illustrated embodiment the pin  78  is positioned within the trigger housing  66  and through the passage  74  and in the working position, the pin  78  moves through the opening  70  to release the latch  64  of the FFP  30 . In other embodiments, the pin  78  may also extend beyond the housing  66  or be held outside of the housing  66  altogether 
     In the armed position of the illustrated embodiment, the trigger magnet  76  closes its magnetic flux through the holding plate  54  retaining the trigger magnet  76  in this position. This position also sets the pin  78  in a position where the pin  78  does not release the latch  64 . To initiate a transition from the armed to the working position, in the trigger mechanism  51  an electrical signal is transmitted, such as from the optical speed sensor, through the coil  52  to generate a magnetic field and attract the trigger magnet  76 . This attraction pulls the trigger magnet  76  away from the holding plate  54  and towards the first end  68  until the trigger magnet  76  closes its flux through the coil  52 . Once in this working position, the trigger magnet  76  remains in this position without a supply of electricity for an indefinite period of time until reset through either mechanical or electrical means. 
     The movement to the working position also moves the pin  78 . As the pin  78  moves, it releases the latch  64 , allowing the springs  62  to push the primary magnet  50  from the armed position to the working position. The pin  78  is then held in the working position by the trigger magnet  76 , and is reset to its armed position when the trigger magnet  76  returns to its armed position. The primary magnet  50 , on the other hand, will remain in the working position through magnetic attraction to the rail  40  until physically disengaged and reset along with the latch  64  and triggering mechanism  51 . 
     In another embodiment presented in  FIG. 12 , the FFP  30  may only include the braking pad  54 , spring  62 , and latch  64 . In this embodiment, the latch  64  retains the spring  62  and braking pad  54  in the armed position. Upon activation, the triggering mechanism  51  releases the latch  64  which releases the spring  62  and braking pad  54 . This allows the spring to expand and push the braking pad  54  into contact with the rail  40  to create a frictional force in the working position. Once in the working position, the spring  62  and braking pad  54  may be held there indefinitely through the force of the spring  62  without use of electricity, and must be physically reset to be returned to the armed position. 
     INDUSTRIAL APPLICABILITY 
     From the foregoing, it can be seen that the technology disclosed herein has industrial applicability in a variety of setting such as, but not limited to, applying a force to an elevator rail to engage an emergency braking system. More specifically, the presented force provider utilizes combinations of permanent magnets, electromagnetic coils, and springs to apply a force to a rail. This force provider has fewer components than prior art force providers and requires a relatively small one-time electrical signal to activate and no electricity to maintain the force provider in both the armed and working positions. A traditional governor is also not needed, eliminating complexity in the elevator system and reducing part count. Further, the proposed friction force provider and triggering mechanism are bi-stable and remain in the armed position and the working position indefinitely without a source of power. 
     While the present disclosure has been made in reference to an elevator, and specifically to an electrical safety system, one skilled in the art will understand that the teachings herein can be used in other applications as well. For example, the presented teachings may be used to construct a force provider for any application that requires little energy to activate and reset and no energy to maintain in both the armed and working positions. Said force provider can also be implemented where the force provider must be locked in both the armed and working positions. It is therefore intended that the scope of the invention not be limited by the embodiments presented herein as the best mode for carrying out the invention, but that the invention include all equivalents falling within the spirit and scope of the appended claims as well.