Abstract:
A brake torque inspection method to a device having a drive machine and a driven component operatively connected to the drive machine is disclosed. The method comprises applying a brake to the driven component, and using a torque wrench at a shaft of the drive machine to determine the brake torque.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a 35 U.S.C. §371 US National Stage filing of International Patent Application No. PCT/CN2012/078342 filed on Jul. 9, 2012. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates generally to passenger conveyors and, more particularly, to methods for brake torque inspection. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    Modern buildings may include different types of passenger conveyors, namely, elevators, escalators and moving walkways. These devices have made moving within large buildings such as skyscrapers, airports and shopping malls faster, easier and more efficient. 
         [0004]    Escalators and moving walkways may occasionally need to be stopped for maintenance. When an escalator or moving walkway is stopped, two things must occur. First, the motor powering the escalator or walkway, typically a powerful electrical motor, is deactivated. Second, at essentially the same time, a primary brake is applied to prevent movement of the escalator or walkway until it is reactivated for use. Because of the importance of proper braking, it is typical to equip passenger conveyors with a second braking system to compliment the primary braking system, namely, an auxiliary braking system. 
         [0005]    While the primary brake is typically located in the drive system and is used for routine stopping and holding of escalators, the auxiliary brake is an additional safety brake, usually found in the main drive assembly in the upper landing area. Auxiliary brakes are activated in accordance with local safety codes when conditions warrant. Both braking systems require periodic inspection, repair, and maintenance. 
         [0006]    Conventionally, to inspect the brake torque of the auxiliary braking system, significant weight is placed on the steps of the escalator, which is then operated under normal conditions. Next, the brakes of the escalator are set, and the maintenance operators observe whether or not the auxiliary braking system can stop the required weight load on the escalator. From there, they can establish whether the auxiliary braking system meets the standard braking torque value required by local safety codes based on the weight of the load and function of the auxiliary brakes. This conventional method, however, requires a considerable amount of manpower, as well as time, to physically lift, load and unload the heavy weights. 
         [0007]    Thus, there exists a need for a simplified, efficient and reliable brake torque inspection method for escalator systems. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    In an exemplary embodiment, a brake torque inspection method to a device having a drive machine and a driven component operatively connected to the drive machine is disclosed. The method may comprise applying a brake to the driven component, and using a torque wrench at a shaft of the drive machine to determine the brake torque. 
         [0009]    The drive machine may have a motor shaft and an output shaft. The method may further comprise using the torque wrench at the motor shaft to determine the torque at the drive machine. The method may further comprise using the torque wrench at the output shaft to determine the torque at the drive machine. The method may further comprise multiplying the obtained torque measurement at the motor by a transmission ratio to determine the brake torque. Further, the method may comprise comparing the determined brake torque to a minimum amount of brake torque required by local safety codes for a passenger conveyor. The brake and the drive machine may be components of a passenger conveyor. The transmission ratio may depend on at least one transmission element configured to transfer power from the drive machine to a main drive shaft, the at least one transmission element comprising a gearbox, machine drive sprocket, main drive chain, and main drive sprocket. The method may further comprise applying a predetermined torque value by the torque wrench to the shaft to determine if the predetermined torque will cause the shaft to turn, wherein the predetermined torque value is calculated from multiplying a minimum amount of brake torque required by local safety codes for a passenger conveyor by a transmission ratio. 
         [0010]    In another exemplary embodiment, a method for inspecting the brake torque in a passenger conveyor is disclosed. The method may comprise setting an auxiliary brake of a passenger conveyor in a braking position, the auxiliary brake being operatively associated to a drive machine of the passenger conveyor. The method may further comprise applying a torque wrench to the drive machine to determine the brake torque. 
         [0011]    The braking position may be a position in which the auxiliary brake stops the passenger conveyor from moving. The drive machine may include a motor shaft, and the torque wrench may be applied to the motor shaft of the drive machine. The torque wrench may be adapted to engage with an end of the motor shaft at the top of a motor of the drive machine. The drive machine may include an output shaft, and the torque wrench may be applied to the output shaft of the drive machine. A torque at the drive machine may be determined by applying the torque wrench to the drive machine. The method may further comprise multiplying the torque at the drive machine by a transmission ratio to determine the brake torque. The transmission ratio may depend on at least one transmission element configured to transfer power from the drive machine to a main drive shaft of the passenger conveyor, the at least one transmission element comprising a gearbox, machine drive sprocket, main drive chain, and main drive sprocket. The auxiliary brake may be configured to stop the main drive shaft of the passenger conveyor. The method may further comprise comparing the determined brake torque to a minimum amount of brake torque required by local safety codes. The method may further comprise applying a predetermined torque value by the torque wrench to the shaft to determine if the predetermined torque will cause the shaft to turn, wherein the predetermined torque value is calculated from multiplying a minimum amount of brake torque required by local safety codes for a passenger conveyor by a transmission ratio. 
         [0012]    In yet another exemplary embodiment, a method for testing brake torque in a passenger conveyor is also disclosed. The method may comprise providing a passenger conveyor with a brake, a main drive shaft, and a drive machine. The method may further comprise applying the brake to the main drive shaft and using a torque wrench at the drive machine to test the brake torque, the drive machine being operatively configured to move the main drive shaft. 
         [0013]    A drive machine torque may be determined by the torque wrench. The method may further comprise multiplying the drive machine torque by a transmission ratio to determine the brake torque. The method may further comprise comparing the determined brake torque to an acceptable value of brake torque for the passenger conveyor required by local safety codes. The method may further comprise applying a predetermined torque value by the torque wrench to the shaft to determine if the predetermined torque will cause the shaft to turn, wherein the predetermined torque value is calculated from multiplying a minimum amount of brake torque required by local safety codes for a passenger conveyor by a transmission ratio. The drive machine may include a motor shaft and an output shaft, and the torque wrench may be applied to either the motor shaft or the output shaft. The passenger conveyor may comprise an escalator, a moving walkway, or an elevator. 
         [0014]    These and other aspects and features of the invention will become more readily apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings. Although various features are disclosed in relation to specific exemplary embodiments of the invention, it is understood that different embodiments of the invention are not mutually exclusive, and the various features may be combined with each other, or used alone, with any of the various exemplary embodiments of the invention without departing from the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic side view of an escalator, which may employ the teachings of the present invention; 
           [0016]      FIG. 2  is a partial perspective view of the upper landing of the escalator of  FIG. 1 ; 
           [0017]      FIG. 3  is a perspective view of the machine of the escalator of  FIG. 1 ; 
           [0018]      FIG. 4  is another partial perspective view of the upper landing of the escalator of  FIG. 1 ; 
           [0019]      FIG. 5  is a partial perspective view of an upper landing of an escalator showing the application of a torque wrench to the motor, according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 6  is a flowchart outlining a brake torque inspection method according to an exemplary embodiment of the present invention; and 
           [0021]      FIG. 7  is a top view of torque wrench being applied to a motor, according to an exemplary embodiment of the present invention. 
       
    
    
       [0022]    While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof will be shown and described below in detail. The invention is not limited to the specific embodiments disclosed, but instead includes all modifications, alternative constructions, and equivalents thereof. 
       DETAILED DESCRIPTION 
       [0023]    Although described in detail below as relating to an escalator, it will be understood that the brake torque inspection method disclosed herein may relate to any passenger conveyer, such as, including but not limited to, a moving walkway or elevator without departing from the scope of the invention. Furthermore, the disclosed brake torque inspection method may also apply to any braking system with an associated motor. 
         [0024]    Turning now to  FIG. 1 , the schematic side view of an escalator  10  is shown. The escalator  10  includes a frame or truss  12 , which extends from a lower elevation first end  14  to a higher elevation second end  16 . The first end  14  and second end  16  are parallel to one another and are connected by an inclined midsection  18 . The escalator  10  extends from a lower landing  20  to an upper landing  22 . 
         [0025]    The upper landing  22  houses a main drive shaft  24  ( FIG. 2 ), which drives steps  26  and handrail  28 . The main drive shaft  24  is powered by a drive machine  30 , which provides the motive force for the escalator  10 . As shown best in  FIG. 3 , the drive machine  30  may comprise an electric motor  32 , a motor shaft  38 , a machine brake  34 , a gearbox  36 , and an output shaft (not shown). The motor  32  of the drive machine  30  converts electrical energy into mechanical energy, which is translated to the gearbox  36  through the motor shaft  38 . Situated between the motor  32  and gearbox  36 , the machine brake  34  provides braking action to the motor  32 . The gearbox  36  increases the torque from the motor shaft  38  and transmits that increased torque to a machine drive sprocket  40  through the output shaft. It will be understood that the drive machine may also be gearless without departing from the scope of the invention. As shown best in  FIG. 4 , a main drive chain  42  transfers the torque from the machine drive sprocket  40  to a main drive sprocket  44 , which is coupled to the main drive shaft  24 . The relative diameters of the machine drive sprocket and the main drive sprocket further increase the transmission ratio between the drive machine and the main drive shaft. 
         [0026]    Turning now to  FIG. 5 , to stop the escalator  10 , a main drive shaft brake and/or an auxiliary brake  46  is applied to the main drive shaft  24 . The main drive shaft brake is used in normal operation, while the auxiliary brake  46  is used as a redundant brake in the even there is a failure in the main drive system. The auxiliary brake  46  exerts a frictional force on a brake disk  48 , which is affixed to the main drive shaft  24 , causing the main drive shaft  24  to stop moving. The auxiliary brake  46  should be able to apply a minimum amount of brake torque to the main drive shaft  24  to ensure that the auxiliary brake  46  is working sufficiently for the safety of passengers riding on the escalator  10 . Local safety codes mandate what the required minimum amount of brake torque is, depending on the design and dimensions of the escalator  10 , and typically mandate periodic testing to ensure compliance with the safety code. 
         [0027]    According to an exemplary embodiment of the present invention, a torque wrench  50  may be applied to the drive machine  30  to test the brake torque of the auxiliary brake  46 . The flowchart in  FIG. 6  illustrates an exemplary method  60  for inspecting brake torque. At first step  62 , the auxiliary brake  46  is applied or set in the braking position. The braking position is the position in which the auxiliary brake  46  stops the main drive shaft  24  and escalator  10  from moving. 
         [0028]    Once the auxiliary brake  46  is applied, at step  64 , the torque wrench  50  may be used at the drive machine  30  to measure the brake torque. As shown best in  FIG. 7 , the torque wrench  50  may be adapted to engage with an end  52  of the motor shaft  38  at a top  54  of the motor  32  of the drive machine  30 . The torque wrench  50  may be in the form of a socket wrench and may be configured to measure the torque applied to the drive machine  30 . By using the torque wrench  50  to rotate the motor  32  about its central axis A ( FIG. 5 ), a drive machine torque may be determined. For example, an operator may apply torque on the motor shaft  38  of the motor  32  in the direction of arrow  56  shown in  FIG. 5 , until the auxiliary brake  46  can no longer stop the main drive shaft  24  from moving. Alternatively, the operator may also apply the torque wrench at the output shaft of the gearbox  36  to determine the drive machine torque. The operator may then record the drive machine torque measurement on the torque wrench  50  at this moment. The moment at which the auxiliary brake  46  can no longer stop the movement of the main drive shaft  24  when torque is applied at the drive machine  30  determines the full load brake torque of the auxiliary brake  46 . 
         [0029]    Referring back to  FIG. 6 , at step  66 , the determined drive machine torque may be multiplied by a transmission ratio to determine the full load brake torque, or the torque at which the auxiliary brake  46  can no longer stop the main drive shaft  24  from moving. The transmission ratio is the ratio of the brake torque at the auxiliary brake  46  to the torque at the drive machine  30 . The transmission ratio may depend on at least one transmission element configured to transfer power from the drive machine  30  to the main drive shaft  24 . For example, the transmission elements may include the motor shaft  38 , gearbox  36 , machine drive sprocket  40 , main drive chain  42 , and main drive sprocket  44  of the escalator  10 . At step  68 , the determined brake torque may then be compared to a value for the minimum amount of brake torque required by local safety codes to see whether or not the safety requirements for the auxiliary brake  46  of the escalator  10  are met. 
         [0030]    In an alternative embodiment, a minimum required motor torque value may be calculated based on the minimum brake torque value mandated by local safety codes. For example, the minimum required brake torque value may be divided by the escalator&#39;s  10  transmission ratio to determine the minimum required motor torque value. The motor torque measurement obtained at step  66  may then be compared to the minimum required motor torque value to see whether or not the safety requirements for the auxiliary brake  46  of the escalator are met. 
         [0031]    In another alternative embodiment, a predetermined torque value may be applied by the torque wrench  50  to either the motor shaft  38  or the output shaft of the drive machine  30  to determine if the predetermined torque will cause the motor shaft  38  or output shaft to turn. The predetermined torque value may be calculated from multiplying a minimum amount of brake torque required by local safety codes for a passenger conveyor by a transmission ratio. After the torque wrench  50  is set to the predetermined torque value, the torque wrench  50  may then be applied to the motor shaft  38  or output shaft to determine if the minimum torque will overcome the brake force and cause the motor shaft  38  to turn. If the torque wrench  50  turns the motor shaft  38  or output shaft, this signifies that the brake torque of the escalator auxiliary brake  46  is not set high enough. If the torque wrench  50  does not turn the motor shaft  38  or output shaft, this signifies that the brake torque at least meets the minimum safety requirements. In this way, the brake torque value is determined as a minimum brake torque value rather than an absolute brake torque value, wherein such determination may be sufficient to demonstrate compliance with requirements for the device. 
       INDUSTRIAL APPLICABILITY 
       [0032]    The brake torque inspection method disclosed herein may be used in a wide range of industrial or commercial applications, such as in escalator systems. By using the disclosed method, the full load brake torque of a braking system can be inspected, thereby ensuring passenger safety and ride quality of the escalator system. 
         [0033]    Furthermore, the disclosed method provides a simplified, inexpensive, efficient and reliable way to inspect brake torque. By applying a torque wrench at the drive machine, brake torque inspection of escalator systems can be quickly and easily accomplished by a single operator. Thus, compared to the conventional brake torque inspection method of loading the escalator steps with a heavy and large weight load, many time, labor, and cost-saving advantages are provided by the present invention. 
         [0034]    While the foregoing detailed description has been given and provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments, but that the same are provided simply for enablement and best mode purposes. The breadth and spirit of the present disclosure is broader than the embodiments specifically disclosed and encompassed within the claims appended hereto. 
         [0035]    While some features are described in conjunction with certain specific embodiments of the invention, these features are not limited to use with only the embodiment with which they are described, but instead may be used together with or separate from, other features disclosed in conjunction with alternate embodiments of the invention.