FIELD OF THE DISCLOSURE

[0001] The present disclosure generally relates to frictionless brakes, and more particularly, to permanent magnet biased braking devices for use with elevators.

BACKGROUND OF THE DISCLOSURE

[0002] Gearless machines such as elevators or other belt-driven systems typically employ a mechanical or electromechanical braking system to stop or temporarily hold a particular motion. Electromechanical brakes of elevators, for instance, generally employ a clutch-type braking mechanism for supplying a holding or braking torque that is sufficient for slowing or holding an elevator car at a fixed position. The braking torque supplied by clutch-type brakes is mechanically produced by the friction that is generated between a rotating brake disk that is rigidly attached to a machine shaft and a set of friction pads that is releasably placed in contact with a surface of the brake disk. The engagement or disengagement of the friction pads is electromechanically controlled by a brake coil. Moreover, when the brake coil is activated, a magnetic attraction between the armature plates and an electromagnetic core causes the friction pads to disengage from the surface of the brake disk. When the brake coil is deactivated, springs that engage the armature plates urge the armature plates into engagement with the surface of the brake disk. Although such clutch-type brakes have been proven to be effective and are still widely used today in various gearless applications such as elevators, and the like, they still have room for improvement.

[0003] Due to its dependency on friction, clutch-type brakes are generally noisy. The braking performance is also dependent on environmental factors, such as temperature, humidity, and the like. For instance, in moist environments, the friction paths of clutch- type brakes tend to become sticky. Furthermore, the range of braking torque that a specific clutch-type brake can variably apply is relatively narrow. For example, a clutch- type brake cannot provide enhanced or sufficiently more stopping power for emergency stops, or the like. Conversely, a clutch-type brake cannot provide reduced stopping power for normal stops than with emergency stops. A typical clutch- type brake is limited to its rated torque which is further dictated by the invariable mechanical limits of the brake, material composition of its friction pads, and the like. Accordingly, it follows that clutch-type brakes offer less overall control or variation of the braking torque.

[0004] Other drawbacks associated with clutch-type brakes pertain to the

manufacturing, installation and maintenance thereof. For instance, manufacturing and installing a clutch-type brake onto the frame and shaft of an elevator is substantially complex and costly. Correspondingly, making adjustments to a pre-existing clutch-type braking system is also costly and difficult to perform. Regardless of the degree of maintenance performed, however, long-term use of clutch-type brakes typically result in burnished surfaces on bearing frames, splinted shaft ends, and the like. Furthermore, the very nature of clutch-type brakes calls for a substantial number of moving parts and components, which indicates yet another area having room for improvements. For instance, clutch-type brakes as applied to elevators may require several mechanical springs, O-rings, guiding pins, and the like.

[0005] Clutch-type brakes also require proximity sensors, micro-switches, or the like, to indicate the status of the brake or to provide feedback of the performance of the brake. Furthermore, the pure mechanical nature of clutch-type brakes makes it difficult to integrate the brake with any other useful controls or functions, such as speed detection, position detection, rescue encoding, or any other subsystem functions.

SUMMARY OF THE DISCLOSURE

[0006] In accordance with one aspect of the disclosure, a brake for applying torque upon a rotational component is provided. The brake comprises a first flange and a second flange, wherein each of the first and second flanges respectively provides first and second sets of poles extending therefrom. The second flange is coupled to the rotatable component and disposed proximate to the first flange such that the second set of poles is disposed in close proximity to the first set of poles. The brake also comprises a ring assembly that is disposed between the first and second flanges. The ring assembly includes a permanent magnet ring, one or more magnetic cores and a brake coil.

[0007] In accordance with another aspect of the disclosure, a brake for applying holding and stopping torques upon a machine shaft is provided. The brake comprises a first flange and a second flange, wherein each of the first and second flanges respectively provides first and second sets of poles extending therefrom. The second flange is coaxially disposed proximate to the first flange such that the second set of poles is rotatably disposed in close proximity to the first set of poles. The second flange is rigidly and axially coupled to the machine shaft. The brake also comprises an internal core ring assembly that is concentrically disposed between the first and second flanges. The internal core ring assembly includes a permanent magnet ring, one or more magnetic cores and a brake coil. The brake also includes a control circuit that is in electrical communication with the brake coil and configured to selectively control a direction and a magnitude of a coil current flowing through the brake coil. [0008] In accordance with yet another aspect of the disclosure, a machine having a first component and a second component is provided. The second component of the machine is rotatable relative to the first component. The machine further comprises first and second flanges, wherein each of the first and second flanges respectively provides first and second sets of poles that extend therefrom. The second flange is coupled to the second component and is disposed proximate to the first flange such that the second set of poles is disposed in close proximity to the first set of poles. The machine also comprises a ring assembly that is disposed between the first and second flanges. The ring assembly includes a permanent magnet ring, one or more magnetic cores and a brake coil.

[0009] These and other aspects of this disclosure will become more readily apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a partial perspective view of an elevator system constructed in accordance with the teachings of the disclosure;

[0011] FIG. 2 is a partial perspective view of an exemplary brake as applied to a gearless machine of the elevator system of FIG. 1 ;

[0012] FIG. 3 is another partial perspective view of the brake of FIG. 2;

[0013] FIG. 4 illustrates additional views of the brake of FIG. 2;

[0014] FIG. 5 illustrates a partial exploded view of the brake of FIG. 2;

[0015] FIG. 6 is a partial cross-sectional view of the brake of FIG. 2 in an engaged state; [0016] FIG. 7 is a partial cross-sectional view of the brake of FIG. 2 in a disengaged state;

[0017] FIG. 8 is a schematic of an exemplary control circuit for the brake of FIG. 2;

[0018] FIG. 9 illustrates various views of an exemplary shroud for the brake of FIG. 2;

[0019] FIG. 10 is a cross-sectional view of another exemplary brake;

[0020] FIG. 11 is a partial cross-sectional view of the brake of FIG. 10 in an engaged state;

[0021] FIG. 12 is a partial cross-sectional view of the brake of FIG. 10 in a disengaged state;

[0022] FIG. 13 is a cross-sectional view of yet another exemplary brake;

[0023] FIG. 14 is a partial cross-section view of the brake of FIG. 13;

[0024] FIG. 15 is a partial cross-sectional view of the brake of FIG. 13 in an engaged state; and

[0025] FIG. 16 is a partial cross-sectional view of the brake of FIG. 13 in a disengaged state.

[0026] While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to be limited to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling with the spirit and scope of the present disclosure. DETAILED DESCRIPTION

[0027] Referring now to FIG. 1 , an elevator system 20 is shown in schematic fashion. It is to be understood that the version of the elevator 20 shown in FIG. 1 is for illustrative purposes only and to present background for the various components of a general elevator system.

[0028] As shown in FIG. 1, the elevator system 20 may include a hoistway 22 provided vertically within a multi-story building 24. Typically, the hoistway 22 could be a hollow shaft provided within a central portion of the building 24 with multiple hoistways being provided if the building is of sufficient size and includes multiple elevators. Extending substantially the length of the hoistway 22 may be rails 26 and 28. An elevator car 30 may be slidably mounted on a pair of rails 26 (only one rail 26 shown in FIG. 1 for clarity) and a counterweight 32 may be slidably mounted on a pair of rails 28 (only one rail 28 shown in FIG. 1 for clarity). While not depicted in detail in FIG. 1, one of ordinary skill in the art will understand that both the car 30 and counterweight 32 could include roller mounts 34, bearings, or the like for smooth motion along the rails 26 and 28. The roller mounts, bearings, or the like may also be slidably mounted to the rails 26 and 28 in a secure fashion.

[0029] In order to move the car 30 and thus the passengers and/or cargo loaded thereon, a motor 36 may be provided typically at the top of hoistway 22. Electrically coupled to the motor 36 may be an electronic controller 38 which in turn may be electrically coupled to a plurality of operator interfaces 40 provided on each floor to call the elevator car 30, as well as operator interfaces 42 provided on each car 30 to allow the passengers thereof to dictate the direction of the car 30. A safety chain circuit 44, as well as a power supply 46, may also be electrically coupled to the electronic controller 38. Mechanically extending from the motor 36 may be a drive shaft 48, which in turn may be operatively coupled to a traction sheave 50, and further may extend to operatively couple to a braking system 52. The braking system 52 may also be electrically coupled to the electronic controller 38. Trained around the sheave 50 may be a tension member 54, such as a round rope or a flat belt. The tension member 54 may be in turn operatively coupled to counterweight 32 and car 30 in any suitable roping arrangement. Of course, multiple different embodiments or arrangements of these components are possible with a typical system including multiple tension members 54 as well as various arrangements for the motor 36 and the sheaves 50 of the elevator system 20.

[0030] Turning to FIGS. 2 and 3, an exemplary variable reluctance brake 110 that may be used in conjunction with the braking system 52 of the elevator system 20 of FIG. 1 is provided. As shown, the variable reluctance brake 110 may essentially include a first flange 112 and a second flange 114, wherein each flange 112, 114 may be formed of ferromagnetic material, such as steel, or the like. The second flange 114 may be axially aligned with and rotatably movable relative to the first flange 112. The first flange 112 may be coupled to a stationary component of a machine 115, such as a machine frame 116, or the like, of a gearless machine of an elevator system 20. A non-magnetic separator 118 may also be disposed between a surface of the first flange 112 and the machine frame 116. The second flange 114 may be coupled to a rotatable component of a machine 115, such as a machine shaft 120, drive shaft 48, or the like, of an elevator system 20. The machine shaft 120 may be configured to be rotatable relative to the machine frame 116 via a machine bearing 121, or the like, disposed therebetween. In alternative embodiments, the first flange 112 may be rotatable while the second flange 114 may be stationary. [0031] Still referring to FIGS. 2 and 3, the first flange 112 may include a first set of poles 122 that may be evenly spaced and radially distributed thereabout. The first set of poles 122 may be configured to perpendicularly extend away from a plane of the first flange 112 and/or may have a claw shape. Similarly, the second flange 114 may include a second set of poles 124 that may be evenly spaced and radially distributed thereabout. The second set of poles 124 may also be configured to perpendicularly extend away from a plane of the second flange 114, and/or may have a claw shape. In a completed assembly, the open ends of each of the first and second flanges 112, 114 may be axially and concentrically joined so as to essentially form a partial enclosure or void

therebetween. The poles 122, 124 may be sized such that the second set of poles 124 concentrically and rotatably fit within the first set of poles 122. The first and second flanges 112, 114 may be sized such that the second set of poles 124 rotate in substantial close proximity to, but not in direct contact with, the first set of poles 122. Alternatively, the second set of poles 124 may be sized so as to concentrically and rotatably fit around the first set of poles 122. Moreover, each set of poles 122, 124 may be similarly sized and evenly spaced such that in the completely stopped or engaged state, shown for example in FIGS. 2 and 3, any two corresponding set of poles 122, 124 are in a completely overlapping and aligned position with one another. In alternative

embodiments, the thickness of the first set of poles 122 may be larger, or smaller, than the corresponding second set of poles 124. In still further alternative embodiments, the first and second flanges 112, 114 may be substituted with cylindrical drums, sprocket disks, or the like, without straying from the teachings of the disclosure.

[0032] Turning now to FIGS. 4 and 5, the brake 110 of FIGS. 1 and 2 may be provided with a ring assembly 125 having at least one axially magnetized permanent magnet ring 126, one or more magnetic cores 128 and a winding or brake coil 130. The ring assembly 125 may be referred to as an internal core ring assembly 125 since it may be

concentrically disposed between the first and second flanges 112, 114 and/or may reside within the enclosure formed by the claw poles 122, 124. Specifically, one or more magnetic cores 128 may be formed of ferromagnetic rings, such as steel, or the like, and may be employed to at least partially abut and radially surround the permanent magnet ring 126. The permanent magnet ring 126 may be configured to abut the first flange 112 or be disposed in close proximity thereof. The brake coil 130 may include a winding of wires, or the like, which provides for current flow therethrough, and further, may be configured to encircle the permanent magnet ring 126 as well as the magnetic cores 128. The brake coil 130 may also be positioned in close proximity to, but not in direct contact with, the first and second sets of claw poles 122, 124. Additionally, one or more nonmagnetic spacers or control gaps 132 may be used to separate the one or more magnetic cores 128. Furthermore, the brake 110 may be configured such that a radial air gap 133 exists between the second flange 114 and the internal core ring assembly 125 so as to allow for undisturbed rotation of the second flange 114 and to facilitate the flow of magnetic flux therethrough. Moreover, each of the components of the brake 110 may be fabricated using simplified low cost methods. For example, the flanges 112, 114 and the magnetic cores 128 may be manufactured by cutting, pressing and/or forging thick sheets of ferromagnetic steel, while the non-magnetic separator 118 and control gaps 132 may be cut from non- ferromagnetic materials, such as non-ferromagnetic steel including stainless steel, aluminum, or the like.

[0033] In an engaged or first state, as shown in FIG. 6, the brake 110 may be configured to apply a predetermined or rated braking torque to a second flange 114 and a corresponding machine shaft 120. The individual components of the brake 110 may be configured such that, by default, a magnetic field or attraction is formed between the first and second sets of claw poles 122, 124. For example, magnetic flux may be provided by the permanent magnet ring 126, and further, maintained through select ferromagnetic steel portions of the brake 110, for instance, the magnetic cores 128, flanges 112, 114 and respective sets of claw poles 122, 124. In this example, the magnetic flux may flow from the permanent magnet ring 126 and through the first flange 112, through the first set of claw poles 122, over a working air gap 136 and through the second set of claw poles 124. From the second set of claw poles 124, the magnetic flux may flow through the second flange 114, over the radial air gap 133 and through the magnetic cores 128. As shown in FIG. 6, the magnetic flux may be routed around a cross-section of the brake coil 130 when there is no current flowing through the brake coil 130. The flow of magnetic flux between each pair of corresponding claw poles 122, 124 may bias each of the rotatable second set of claw poles 124 to be aligned and held proximate to a corresponding stationary claw pole 122 belonging to the first flange 112. As a result, the second flange 114, and thus the machine shaft 120 coupled thereto, may be prevented from rotating relative to the first flange 112.

[0034] When the loading torque, or the torque associated with the loading of an associated elevator car 30, or the like, is equal to zero, the first and second sets of claw poles 122, 124 of the variable magnetic reluctance brake 110 may be in full angular alignment. Under some load, however, the second flange 114 may begin to angularly creep away from perfect alignment. The holding position may be maintained by the brake 110 until misalignment between the first and second sets of claw poles 122, 124 reaches an upper limit, for example, approximately one-fourth of the radial distance between claw poles 122, 124. The rated holding torque of the brake 110 may be preconfigured to allow for such degrees of misalignment. If the loading torque exceeds the rated value, the brake 110 may lose its holding capacity, and the second flange 114 may begin to rotate, or angularly jump from one aligned claw pole position to the next in a cogging fashion. The angular spacing of the respective claw poles 122, 124 of the first and second flanges 112, 114 may thus be defined by the maximum misalignment that is allowed for any particular application. For example, the angular spacing of the claw poles 122, 124 may be dependent upon the characteristics of the associated elevator car 30 being suspended, for example, by ropes or flat belts 54, from an elevator machine 20, hallway floors, and the like. A misalignment of approximately one-fourth of the radial distance between claw poles 122, 124, which may be greater than what is currently required by existing elevator systems 20, may be sufficient so as to prevent any substantial misalignment between an elevator car 30 and the associated hallway floors.

[0035] In a disengaged or second state, as shown in FIG. 7, an electrical current, for example, I _co a, may be supplied through the brake coil 130 surrounding the permanent magnet ring 126 and magnetic cores 128. The amount of coil current 7 _co n provided through the brake coil 130 may be configured to correspond to a rated DC current so as to generate an electromagnetic field to oppose the magnetic field created by the permanent magnet ring 126. For example, the electromagnetic field may serve to isolate the magnetic flux to the permanent magnet ring 126, magnetic cores 128 and the first flange 112, as shown in FIG. 7, and essentially neutralize any magnetic flux existing through each pair of corresponding claw poles 122, 124. Accordingly, the magnetic attraction between the first and second sets of claw poles 122, 124 may be eliminated and the second flange 114, as well as the machine shaft 120 associated therewith, may be free to rotate. To apply subsequent braking, the coil current 7 _co n may be substantially reduced or completely ceased so as to allow the magnetic field between the claw poles 122, 124 to force the second flange 114 back into alignment.

[0036] The brake 110 may also be configured with means for enhancing braking torque, or applying substantially more braking torque than the nominal or rated braking torque. Such braking torque enhancements may be used with, for instance, emergency stops, or the like, but is not limited thereto. In a first example, the braking torque may be enhanced by reversing the polarity of the voltage supplied to the brake 110, or more particularly, by reversing the direction of the coil current 7 _co n. Reversing the direction of the coil current / _co ii may generate an electromagnetic field which assists rather than neutralizes the magnetic field generated by the permanent magnet ring 126. Accordingly, reversing the current 7 _co n through the brake coil 130 may serve to increase the magnetic flux through the respective claw poles 122, 124, and thus, to enhance the effective braking torque of the brake 110.

[0037] Such reversals may be initiated in response to input by a user requesting an emergency stop, or the like, or may be executed using a control circuit 138, as shown in the particular example of FIG. 8. The control circuit 138 may be disposed in electrical communication between the brake 110 and a brushless permanent magnet motor 140 that is further coupled to a drive module 141 of a gearless machine of, for example, an elevator system 20. The control circuit 138 may comprise a series of switches SI, S2, relays, or the like, that are selectively configured to instantaneously reverse the polarity of the voltage supplied to the brake coil 130. The control circuit 138 may also provide a rectifier bridge 142, or the like, that is configured to further increase the effective braking torque during emergency stops by employing back-electromotive force, or back-EMF, generated by the permanent magnet motor 140. The rectifier bridge 142 may be electrically coupled to two or more phases of the permanent magnet motor 140 and in proper polarity with the brake coil 130 of the brake 110. As such, when an emergency stop is engaged, the effective braking torque may comprise both the torque component that is generated by the permanent magnet motor 140 and the enhanced torque component generated by the brake 110. Both components of the braking torque may be applied until a rotor 144 of the permanent magnet motor 140 stops rotating. As the back-EMF is proportional to the rotational velocity of the rotor 144, any torque component depending thereupon may be eliminated once the rotor 144 slows to a complete stop.

[0038] Emergency or enhanced stopping of the brake 110 may also be achieved through the use of a shroud 146, as shown for example in FIG. 9. A shroud 146 may include a plurality of fillers 148 configured to be coupled to or axially inserted into the corresponding spaces between first and/or second sets of claw poles 122, 124. Shrouds 146 may be formed of a non-ferromagnetic and electrically conductive material, such as aluminum, or the like. The dynamic stopping torque may be provided when the magnetic field formed between the claw poles 122, 124 interact with eddy currents which may form within the body of the one or more electrically conductive shrouds 146. The strength of the magnetic field between the claw poles 122, 124 may range from a maximum value, as measured from directly under one stationary claw pole 122, to a minimum value, as measured between two adjacent stationary claw poles 122. The circulation and excitation of eddy currents may be caused by the movement of the electrically conductive shroud 146 through the alternating magnetic fields formed between the claw poles 122, 124. Furthermore, during high speed rotations of a second flange 114, unfilled spaces between the first and second respective sets of claw poles 122, 124 may cause significant air disturbance as well as substantial acoustic noise. Such disturbances and noise may be significantly reduced by incorporating the shroud 146 and/or fillers 148 of FIG. 9. In some embodiments, one shroud 146 may be provided to only one of the first and second flanges 112, 114. In alternative embodiments, one shroud 146 may be provided to each of the first and second flanges 112, 114 so as to increase the stopping capabilities of the brake 110. In still further alternatives, fillers 148 may be individually provided between each of the claw poles 122, 124 of the first and/or second flanges 112, 114 without the shroud 146. Additionally, while the embodiment of FIG. 9 may illustrate the shroud 146 and fillers 148 as applied to the brake 110 of FIGS. 2-5, it is understood that such shrouds 146 and fillers 148 may be adapted for use with any other variable reluctance brake, such as brakes 110a, 110b disclosed in FIGS. 10-16 of this disclosure. For example, a plurality of fillers 148 may be adapted to fill the spaces between the claw poles 124a, 124b belonging to the second flanges 114a, 114b of FIGS. 10-16.

[0039] Referring now to FIGS. 10-12, another exemplary variable reluctance brake 110a is provided. As in the previous embodiments, the brake 110a may include at least a first flange 112a and a second flange 114a, wherein the first flange 112a may be stationary and the second flange 114a may be rotatably movable relative to the first flange 112a. Each of the first and second flanges 112a, 114a may also provide respective first and second sets of claw poles 122a, 124a which extend perpendicularly therefrom. In contrast to the first and second flanges 112, 114 of FIGS. 2 and 3, each of the first and second flanges 112a, 114a of FIGS. 10-12 may be a dual-layer or double salient flange configured to enhance the reluctance forces or holding torque thereof. More specifically, each of the first and second flanges 112a, 114a may comprise two or more layers of a ferromagnetic material, such as steel, or the like, so as to improve the flow of magnetic flux therethrough.

[0040] As shown in FIGS. 10-12, the two joined layers of the first flange 112a may be configured to separate at the edges so as to form two layers, for example, inner and outer layers, of claw poles 122a. The space between the inner and outer layers of the first set of claw poles 122a may be sized to concentrically and rotatably receive the joined layers of the second set of claw poles 124a of the second flange 114a. As in previous

embodiments, the first and second sets of claw poles 122a, 124a may be equally sized and distributed such that during a complete stop, any two corresponding claw poles 122a, 124a are in complete alignment with one another. In alternative embodiments, the layers of the first set of claw poles 122a may be joined and received within a separation formed between inner and outer layers of the second set of claw poles 124a.

[0041] Still referring to FIGS. 10-12, the brake 110a may also be provided with an internal core ring assembly 125 a including at least one axially magnetized permanent magnet ring 126a, one or more magnetic cores 128a and a brake coil 130a concentrically disposed between the first and second flanges 112a, 114a. Specifically, one or more magnetic cores 128a may be formed of ferromagnetic rings, made of steel, or the like, and may be employed to at least partially abut and radially surround the permanent magnet ring 126a. The permanent magnet ring 126a may be configured to abut the first flange 112a or be disposed in close proximity thereof. The brake coil 130a may include a winding of wires, or the like, which provides for current flow therethrough, and further, may be configured to encircle the permanent magnet ring 126a as well as the magnetic cores 128a. The brake coil 130a may also be positioned in close proximity to but not in direct contact with the first and second sets of claw poles 122a, 124a. Additionally, one or more control gaps or non-magnetic spacers 132a may be used to separate the one or more magnetic cores 128a. Furthermore, the brake 110a may be configured with an axial air gap 134 disposed between the second flange 114a and the internal core ring assembly 125a so as to allow for undisturbed rotation of the second flange 114a.

[0042] In some embodiments, as in the brake 110 of FIGS. 2-7, the magnetic flux may flow into the internal core ring assembly 125 in an axial direction, wherein the magnetic flux flows through a laterally disposed clearance or radial air gap 133. In contrast, the magnetic flux within the brake 110a of FIGS. 11 and 12 may be routed from the permanent magnet ring 126a, through the inner and outer layers of the first set of claw poles 122a, over working air gaps 136a, through the layers of the second set of claw poles 124a, through the body of the rotatable second flange 114a, through an axial clearance or axial air gap 134, through the magnetic cores 128a and back into the permanent magnet ring 126a. As such, the actual flow of the magnetic flux within the brake 110a of FIGS. 10-12 may essentially enter the internal core ring assembly 125a in a radial rather than an axial direction. The resulting radial force associated with each corresponding pair of claw poles 122a, 124a may be equally distributed and balanced about the circumference of the second flange 114a. Accordingly, any undesired net axial force acting upon the rotatable second flange 114a, or transmitted to the associated machine frame 116, shaft 120 and bearing 121, may be eliminated. Such configurations may serve to prevent any excessive axial preload on the associated bearing 121.

[0043] In an engaged or first state, as shown in FIG. 11 , the brake 110a may apply a braking torque to the rotatable second flange 114a and a corresponding machine shaft 120. As in the previous embodiments, the individual components of the brake 110a may be configured such that, by default, a magnetic field or attraction is formed between the first and second sets of claw poles 122a, 124a. The magnetic flux may be provided by the permanent magnet ring 126a, and further, maintained through select ferromagnetic steel portions of the brake 110a, such as the magnetic cores 128a, flanges 112a, 114a and respective claw poles 122a, 124a. For example, the magnetic flux may flow from the permanent magnet ring 126a, through the first flange 112a, through the first set of claw poles 122a, over working air gaps 136a and through the second set of claw poles 124a. From the second set of claw poles 124a, the magnetic flux may flow through the second flange 114a, over an axial air gap 134 and through the magnetic cores 128a. As shown in FIG. 11, the magnetic flux may be routed around a respective cross-section of the brake coil 130a when there is no current flowing through the brake coil 130a. The flow of magnetic flux between each pair of corresponding claw poles 122a, 124a may bias each of the rotatable claw poles 124a of the second flange 114a to be held in alignment with a corresponding claw pole 122a belonging to the first flange 112a. Thus, during the engaged state, the second flange 114a, and thus an associated machine shaft 120, may be prevented from rotating relative to the first flange 112a.

[0044] In a disengaged or second state, as shown in FIG. 12, an electrical current may be supplied through the brake coil 130a surrounding the permanent magnet ring 126a and magnetic cores 128a. The coil current through the brake coil 130a may serve to generate an electromagnetic field configured to oppose the magnetic field created by the permanent magnet ring 126a. More specifically, the electromagnetic field may serve to isolate the magnetic flux to the permanent magnet ring 126a, magnetic cores 128a and the first flange 112a, and essentially neutralize any magnetic flux existing through each pair of corresponding claw poles 122a, 124a. Accordingly, the magnetic attraction between the first and second sets of claw poles 122a, 124a may be eliminated and the second flange 114a, as well as an associated machine shaft 120, may be free to rotate. To apply subsequent braking, the coil current may be ceased such that the magnetic field between the claw poles 122a, 124a force the second flange 114a back into alignment.

[0045] Turning now to FIGS. 13 and 14, another exemplary variable reluctance brake 110b is provided. As in previous embodiments, the brake 110b may include first and second flanges 112b, 114b formed of ferromagnetic material, such as steel, or the like, wherein the first flange 112b may be stationary and the second flange 114b may be rotatably movable relative to the first flange 112b. Each of the first and second flanges 112b, 114b may also include respective first and second sets of claw poles 122b, 124b which extend perpendicularly therefrom. In contrast with previous embodiments, the first flange 112b of FIGS. 13 and 14 may be provided with an opposing stationary sub-flange 150 also formed of ferromagnetic material, such as steel, or the like, and having a subset of poles 152, in the form of claws, or the like, extending perpendicularly therefrom. In particular, the diameter of the sub-flange 150 may be sized to be smaller than that of the first flange 112b so as to concentrically fit within and axially abut the inner portion of the first flange 112b. The subset of claw poles 152 of the sub-flange 150 may be radially separated from the first set of claw poles 122b so as to provide the second set of claw poles 124b with room to rotate therebetween. The first and second sets of claw poles 122b, 124b may be similarly sized and equally distributed such that in a completely engaged state, any two corresponding claw poles 122b, 124b are in complete alignment with one another. The sub-flange 150 may be configured to isolate the flow of magnetic flux through the claw poles 124b of the rotatable second flange 114b and to minimize any flow of magnetic flux through the body thereof. [0046] As shown in FIGS. 15 and 16, an internal core ring assembly 125b of the brake 110b may be disposed within the void between the first flange 112b and the opposing sub-flange 150. The internal core ring assembly 125b may include at least one axially magnetized permanent magnet ring 126b, one or more magnetic cores 128b and a brake coil 130b concentrically disposed between the first flange 112b and the sub-flange 150. More specifically, one or more magnetic cores 128b may be formed of ferromagnetic rings made from steel, or the like, and may be employed to at least partially abut and radially surround the permanent magnet ring 126b. The permanent magnet ring 126b may be configured to abut the first flange 112b or be disposed in close proximity thereof. The brake coil 130b may be a winding of wires, or the like, which provides for current flow therethrough. The brake coil 130b may further be configured to encircle the permanent magnet ring 126b and radially abut the inner edge of the subset of claw poles 152. Additionally, one or more non-magnetic spacers or control gaps 132b may be used to separate the one or more magnetic cores 128b. The brake 110b may also be configured such that a radial air gap 135 exists between the second flange 114b and the sub-flange 150 so as to allow for undisturbed rotation of the second flange 114b.

[0047] In an engaged or first state, as shown in FIG. 15, the brake 110b may be configured to apply a predetermined braking torque to the rotatable second flange 114b and a corresponding machine shaft 120. As in previous embodiments, the individual components of the brake 110b may be configured such that, by default, a magnetic field or attraction is formed between the first and second sets of claw poles 122b, 124b. In contrast with previous embodiments, the magnetic flux may be configured to return through the stationary subset of claw poles 152 and associated sub-flange 150 so as to concentrate the magnetic flux flow to the second set of claw poles 124b, and further, to minimize any magnetic flux from flowing through the body of the second flange 114b. More specifically, the magnetic flux may flow from the permanent magnet ring 126b, through the first flange 112b, through the first set of claw poles 122b, over working air gaps 136b, through the second set of claw poles 124b, over additional working air gaps 136b, through the subset of claw poles 152, through the sub-flange 150 and through the magnetic cores 128b. Such isolation of the magnetic flux to the claw poles 122b, 124b, 152 may serve to maximize the magnetic attraction thereof, and thus, improve the overall braking ability of the brake 110b. As shown, the magnetic flux may also be routed around a cross-section of the brake coil 130b when there is no current flowing through the brake coil 130b. The flow of magnetic flux between each pair of corresponding claw poles 122b, 124b may bias each of the rotatable claw poles 124b of the second flange 114b to be held in alignment with a corresponding claw pole 122b belonging to the first flange 112b. As a result, during the engaged state, the second flange 114b, and thus, an associated machine shaft 120, may be prevented from rotating relative to the first flange 112b.

[0048] In a disengaged or second state, as shown in FIG. 16, an electrical current may be supplied through the brake coil 130b surrounding the permanent magnet ring 126b and magnetic cores 128b. The amount of current provided through the brake coil 130b may generate an electromagnetic field which opposes and essentially neutralizes the magnetic field created by the permanent magnet ring 126b. Accordingly, the magnetic attraction between the first and second sets of claw poles 122b, 124b may be eliminated and the second flange 114b, as well as an associated machine shaft 120, may be free to rotate. To apply subsequent braking, the coil current may be substantially reduced or completely ceased so as to allow the magnetic field between the claw poles 122b, 124b to force the second flange 114b back into alignment.

[0049] Based on the foregoing, it can be seen that the present disclosure may provide a brake for machines, such as gearless machines for elevator systems. The present disclosure provides a permanent magnet biased frictionless brake.

[0050] While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure.