Patent Publication Number: US-11643301-B2

Title: System and method for monitoring sheave bearing condition

Description:
TECHNICAL FIELD 
     This disclosure relates to a system and method for monitoring a sheave bearing condition, and in particular relates to passenger conveyer systems, such as elevator systems, employing the system and method. 
     BACKGROUND 
     Passenger conveyer systems such as elevator systems generally include a motor, drive shaft, and brake system. In the context of an elevator system, the motor, drive shaft, and brake system control movement of an elevator car within a hoistway. Specifically, an elevator car and a counterweight are typically suspended from one or more suspension members, such as belts or ropes, wrapped around the drive shaft. The suspension members are also typically wrapped around one or more sheaves, which in turn are configured to rotate on bearings known as sheave bearings. 
     SUMMARY 
     A passenger conveyer system according to an exemplary aspect of the present disclosure includes, among other things, a suspension member and a sheave configured to rotate on a bearing. The suspension member is wrapped around at least a portion of the sheave. Further, the system includes a sensor mounted adjacent an end of the suspension member, and a controller configured to determine a condition of the bearing based on an output of the sensor. 
     In a further non-limiting embodiment of the foregoing passenger conveyer system, the system includes an elevator car and a counterweight. Further, the sheave is mounted adjacent one of the elevator car and the counterweight. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the sheave is a first sheave configured to rotate on a first bearing and mounted adjacent the elevator car, the passenger conveyer system includes a second sheave configured to rotate on a second bearing, the second sheave is mounted adjacent the counterweight, and the suspension member is wrapped around at least a portion of the first and second sheaves. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the sensor is a first sensor mounted adjacent a first end of the suspension member, and the passenger conveyer system includes a second sensor mounted adjacent a second end of the suspension member opposite the first end. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the first end of the suspension member is an end of a segment of the suspension member extending directly to the first sheave, and the second end of the suspension member is an end of a segment of the suspension member extending directly to the second sheave. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller is configured to determine a condition of the first bearing based on an output of the first sensor, and the controller is configured to determine a condition of the second bearing based on an output of the second sensor. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the sensor is an accelerometer. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller is configured to identify a potential impaired condition of the bearing when the output of the sensor exceeds a threshold. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller applies a filter to the output of the sensor to reject portions of the output unlikely to be indicative of the potential impaired condition. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the threshold is a threshold in at least one of a time domain and a frequency domain, and the controller is configured to identify the potential impaired condition based on an amplitude of an output of the sensor exceeding the threshold in a time domain or a frequency domain. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller determines an RMS acceleration based on the output and compares the RMS acceleration to the threshold. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller is configured to transform an output of the sensor from the time domain to the frequency domain. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller is configured to identify a plurality of different potential impaired conditions of the bearing when the output of the sensor exceeds a threshold corresponding to a respective one of the plurality of different potential impaired conditions. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the plurality of different potential impaired conditions include potential impairments of a ball of the bearing, a cage of the bearing, an outer race of the bearing, and an inner race of the bearing. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the system includes a drive shaft, and the sensor is not mounted adjacent a segment of the suspension member leading directly to the drive shaft. 
     In a further non-limiting embodiment of any of the foregoing passenger conveyer systems, the controller is configured to cause a prompt to be issued in response to the potential impaired condition being identified. 
     A method according to an exemplary aspect of the present disclosure includes, among other things, identifying a potential impaired condition of a bearing of a sheave based on an output of a sensor mounted adjacent an end of a suspension member. The sheave is mounted adjacent one of an elevator car and a counterweight. 
     In a further non-limiting embodiment of the foregoing method, the method includes identifying a potential impaired condition of a first bearing of a first sheave mounted adjacent the elevator car based on an output of a first sensor mounted adjacent a first end of the suspension member adjacent a segment of the suspension member leading directly from the first end to the first sheave. The method further includes identifying a potential impaired condition of a second bearing of a second sheave mounted adjacent the counterweight based on an output of a second sensor mounted adjacent a second end of the suspension member adjacent a segment of the suspension member leading directly from the second end to the second sheave. 
     In a further non-limiting embodiment of any of the foregoing methods, the identifying step includes identifying at least one of an impairment of a ball of the bearing, a cage of the bearing, an outer race of the bearing, and an inner race of the bearing. 
     In a further non-limiting embodiment of any of the foregoing methods, the identifying step includes determining that the output of the sensor exceeded a threshold in at least one of a time domain and a frequency domain. 
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically illustrates an example passenger conveyer system. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to a system and method for monitoring a sheave bearing condition, and in particular relates to passenger conveyer systems, such as elevator systems, employing the system and method. An example passenger conveyer system includes a suspension member, and a sheave configured to rotate on a bearing. The suspension member is wrapped around at least a portion of the sheave. Further, the system includes a sensor mounted adjacent an end of the suspension member, and a controller configured to determine a condition of the bearing based on an output of the sensor. This disclosure enables real-time monitoring, possibly at a remote location (i.e., not on site), of the condition of the sheave bearing, which permits one to perform condition-based maintenance of the sheave bearing as opposed to solely performing periodic inspections of the sheave bearing. Further, this disclosure is relatively easily incorporated into an existing elevator system, meaning that this disclosure may be used to retrofit existing elevator systems with a real-time sheave bearing monitoring feature. These and other benefits will be appreciated from the following written description. 
       FIG.  1    schematically illustrates an example passenger conveyer system  10 . In  FIG.  1   , the passenger conveyer system  10  is an elevator system, however this disclosure may be extended to other passenger conveyer systems such as escalators. 
     The passenger conveyer system  10  includes an elevator car  12  configured to travel in a hoistway. Travel of the elevator car  12  is governed, in this example, by a drive system  14  including an electric motor, a drive shaft  16  mechanically connected to the electric motor, and one or more brakes. The drive shaft  16  may be mounted in the hoistway or outside the hoistway in a machine room, as examples. 
     The elevator car  12  and a counterweight  18  are suspended from a suspension member  20 , such as a belts or rope, wrapped at least partially around the drive shaft  16 . Thus, when the drive shaft  16  rotates, the elevator car  12  moves vertically up or down within the hoistway depending upon the direction of rotation of the drive shaft  16 . While only one suspension member  20  is shown in  FIG.  1   , it should be understood that the elevator car  12  and counterweight  18  may be suspended from multiple suspension members. 
     The suspension member  20  extends between a first end  22  and a second end  24 . In this example, the first end  22  and second end  24  of the suspension member  20  are attached to respective first and second terminations  26 ,  28 , which may include wedge sockets, swaged terminals, ferrules and thimbles, or other known types of terminations for elevator suspension members. Reference herein to an end of the suspension member  20  includes the ends  22 ,  24  and the terminations  26 ,  28 . The ends  22 ,  24  and terminations  26 ,  28  may be relatively close to one another and may be arranged adjacent one another in a machine room, for example. 
     The suspension member  20  in this example includes a first segment  30  extending directly from the first end  22  to a first sheave  32 , which is mounted to the elevator car  12  and is configured to rotate on (i.e., spin on) a first bearing  34 . The term directly is used mean that there are no intervening sheaves, for example, between the first end  22  and the first sheave  32  along the segment  30 . The first sheave  32  is configured to travel with the elevator car  12  as it moves within a hoistway during operation of the passenger conveyer system  10 . 
     In this example, the first bearing  34  includes an inner race, an outer race, a cage, and a plurality of rolling elements such as balls. The suspension member  20  is wrapped around at least a portion of the first sheave  32 . While only one first sheave  32  is shown, there may be multiple first sheaves mounted to the elevator car  12 . 
     The suspension member  20  includes a second segment  36  extending directly from the first sheave  32  to a second sheave  38 , a third segment  40  extending directly from the second sheave  38  to the drive shaft  16 , and a fourth segment  42  extending directly from the drive shaft  16  to a third sheave  44 . A fifth segment  46  of the suspension member  20  extends directly from the third sheave  44  to a fourth sheave  48  mounted to the counterweight  18 . A sixth segment  50  of the suspension member  20  extends directly from the fourth sheave  48  to the second end  24 . The fourth sheave  48  is configured to travel with the counterweight  18  as it moves during operation of the passenger conveyer system  10 . As with the first sheave  32 , the suspension member  20  is wrapped at least partially around each of the sheaves  38 ,  44 ,  48  and the drive shaft  16 . 
     The term segment as used relative to the segments  30 ,  36 ,  40 ,  42 ,  46 , and  50  is used to refer to segments of the overall length of the suspension member  20  between adjacent ends and/or sheaves. A distance between adjacent ends and/or sheaves may change during operation of the passenger conveyer system  10 . While the suspension member  20  is arranged such that it exhibits six segments in this example, it should be understood that this disclosure extends to other arrangements including additional or fewer sheaves and additional or fewer segments. Further, while the drive shaft  16  is shown in a particular location, the drive shaft  16  could be located elsewhere along the suspension member  20 . The terms “first,” “second,” “third,” etc., as used herein relative to the sheaves and segments is arbitrary and used for purposes of explanation only. 
     The sheaves discussed above may each be configured to rotate on a bearing configured similar to the bearing  34 . For instance, the sheave  48  is configured to rotate on a bearing  52  including an inner race, an outer race, a cage, and a plurality of rolling elements such as balls. The bearings  34 ,  52  may be referred to as sheave bearings, or bearings of the sheave. The bearings  34 ,  52  may each include one or more bearings, such as a set of two bearings. 
     This disclosure is configured to monitor a condition, namely a health condition, of the bearings in the passenger conveyer system  10 . In particular, this disclosure is configured to monitor the condition of the bearings  34 ,  52  to identify potential impaired conditions of the bearings  34 ,  52 . The term potential impaired condition is used herein to refer to conditions where a condition of a bearing has possibly reduced in quality relative to a normal operating condition and which may result in reduced ride quality. The term potential impaired condition is inclusive of conditions where the bearing has actually been damaged or the operation of the bearing is actually impaired from wear or a defect, but also includes conditions where the bearing is not damaged but may possibly be impaired. The potential impaired condition of the bearing could be caused by another component, such as the adjacent sheave or an interaction between the sheave and the suspension member. In response to a potential impaired condition, an inspection of the bearing may be performed and it may be determined that there is no issue with the bearing, that the bearing or another component requires service, or that the bearing or another component must be replaced. 
     In  FIG.  1   , a first sensor  54  is mounted adjacent the first end  22 , and in particular is directly attached to the first termination  26 . A second sensor  56  is mounted adjacent the second end  24 , and in particular is directly attached to the second termination  28 . The first and second sensors  54 ,  56  are accelerometers in this example and are configured to generate outputs indicative of a condition of the bearings  34 ,  52 . In particular, the first and second sensors  54 ,  56  are configured to generate outputs indicative of a vibration in a respective segment  30 ,  50  of the suspension member  20 . 
     While two sensors  54 ,  56  are shown in  FIG.  1   , this disclosure extends to passenger conveyer systems including one or more sensors. For instance, the passenger conveyer system  10  may include one or both of the sensors  54 ,  56 . 
     The first and second sensors  54 ,  56  are electronically connected to a controller  58 . The controller  58  is shown schematically in  FIG.  1   . The controller  58  includes electronics, software, or both, to perform the functions described herein. In one non-limiting embodiment, the controller  58  is an elevator drive controller. Although it is shown as a single device, the controller  58  may include multiple controllers in the form of multiple hardware devices, or multiple software controllers within one or more hardware devices. The controller area network  60  allows the controller  58  to communicate with various components, namely the first and second sensors  54 ,  56 , of the passenger conveyer system  10  by wired and/or wireless electronic connections. 
     The controller  58  is configured to determine a condition of the bearings  34 ,  52  based on respective outputs of the first and second sensors  54 ,  56 . The controller  58  could alternatively or additionally be configured to detect noise from a sheave-suspension member interaction based on the outputs of the sensor  54 ,  56 . By arranging the first and second sensors  54 ,  56  adjacent respective first and second ends  22 ,  24 , noise from other components of the passenger conveyer system  10 , such as the drive shaft  16 , is reduced. The first and second sensors  54 ,  56  are not mounted adjacent segments of the suspension member  20  leading directly to the drive shaft  16 , such as segments  40  or  42 . In this way, the output of the first and second sensors  54 ,  56  is representative of the vibration in the respective segment  30 ,  50 , which in turn may be interpreted by the controller  58  as a condition of the respective bearing  34 ,  52 . 
     The first and second sensors  54 ,  56  are accelerometers and are configured to measure vibration. In this example, the first and second sensors  54 ,  56  are configured to generate an output signal having an amplitude indicative of the acceleration of the respective segments  30 ,  50 . The controller  58  is configured to identify a potential impaired condition of a respective one of the first and second bearings  34 ,  52  when the output of the respective first and second sensor  54 ,  56  exceeds a threshold. 
     The threshold may be a predetermined threshold known to correspond to a potential impaired condition. The controller  58  may consider a plurality of different thresholds in parallel. The different thresholds may correspond to different potential impaired conditions of the bearings  34 ,  52 . In particular, there may be different thresholds corresponding to a potential impaired condition of the inner race, outer race, cage, and rolling elements. 
     If the output meets or exceeds one of the thresholds, the controller  58  identifies a potential impaired condition. In response to that determination, the controller  58  may send a signal or issue a prompt to maintenance personnel. If known, the prompt may also indicate that the potential impaired condition applies to a particular component (i.e., the inner race, outer race, cage, or rolling elements) of a particular bearing (i.e., bearing  34  or  52 ). The controller  58  may also shut down operation of the passenger conveyer system  10  until an inspection is performed in some examples. 
     In order to determine whether a threshold has been met or exceeded, the controller  58  may analyze the outputs of the first and second sensors  54 ,  56  using a conventional analysis and/or an envelope analysis. Performing redundant analyses may give additional confidence to the determination that there is a potential impaired condition of a bearing. That said, this disclosure is not limited to redundant analyses, and the outputs of the first and second sensors  54 ,  56  may be analyzed using one analytical technique. 
     In a conventional analysis, the controller  58  compares the output of the first and second sensors  54 ,  56  in one or both of a time domain and a frequency domain to one or more of the predetermined thresholds. In the time domain, the controller  58  may compare a root mean square (RMS) acceleration, which is the average of the time-varying acceleration data over a particular time window. If the RMS acceleration, as reported by a particular one of the first and second sensors  54 ,  56 , exceeds a threshold, then the controller  58  identifies a potential impaired condition of the respective bearing  34 ,  52 . 
     The controller  58  may also analyze the outputs of the first and second sensors  54 ,  56  by transforming them to the frequency domain and comparing the outputs to thresholds known to correspond to potential impaired conditions at certain frequencies. Again, if one or more of the thresholds is exceeded, a potential impaired condition is identified. In one example, analyzing the outputs of the first and second sensors  54 ,  56  in the frequency domain enables the controller  58  to identify potential impaired conditions associated with the individual components of the bearings  34 ,  52 . For instance, unduly large amplitudes at a certain frequency may be associated with a cage defect, while an unduly large amplitude at another frequency may be associated with a rolling element defect. 
     In an envelope analysis, the controller  58  may process the output signals from the first and second sensors  54 ,  56  and use the processed signals to determine whether there is a potential impaired condition. In one example, the controller  58  applies a filter, such as a band-pass filter, to the output of the first and second sensors  54 ,  56  so that the frequencies known to correspond and show sensitivity to bearing degradation are allowed to pass. In a further example, the filer rejects portions of the outputs unlikely to be indicative of the potential impaired condition of the bearings  34 ,  52 . For instance, if a frequency of the drive shaft  16  during operation is known, the controller  58  may filter out that frequency. The controller  58  may consider whether the output of the processed and/or filtered signal exceeds one or more thresholds in the time domain and/or the frequency domain. The controller  58 , in particular, may consider whether an RMS acceleration of the filtered signal exceeds a threshold in the time domain and/or consider whether the amplitude of the filtered signal exceeds one or more thresholds at certain frequencies in the frequency domain. 
     It should be understood that terms such as “generally,” “substantially,” and “about” are not intended to be boundaryless terms, and should be interpreted consistent with the way one skilled in the art would interpret those terms. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. In addition, the various FIGS. accompanying this disclosure are not necessarily to scale, and some features may be exaggerated or minimized to show certain details of a particular component or arrangement. 
     One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.