Condition monitoring system, condition monitoring unit and method for monitoring a condition of a bearing unit for a vehicle

Abstract

A condition monitoring system for bearing units for vehicles, the system including at least one condition monitoring unit for measuring at least one operating parameter of one bearing unit and a control unit for receiving and processing signals obtained from the condition monitoring unit. The system additionally includes a circuit for detecting a geographic position, wherein the condition monitoring unit is configured to be at least one of activated and deactivated depending on the detected geographic position.

Claims

1. A condition monitoring system for bearing units for vehicles, the system comprising: at least one condition monitoring unit for measuring at least one operating parameter of one bearing unit; a control unit for receiving and processing signals obtained from the condition monitoring unit; a trigger planner for setting trigger points for activating and deactivating the at least one condition monitoring unit; and a circuit for detecting a geographic position of the vehicle, wherein the condition monitoring unit is activated and deactivated depending on the geographic position and a travelling direction of the vehicles with respect to the trigger points.

2. The condition monitoring system according to claim 1, the control unit further comprising a memory for storing route data of the vehicle, the route data including a plurality of possible route sections along which the vehicle can travel, wherein the control unit is configured to activate the condition monitoring unit when the vehicle is travelling in one route section out of a predetermined set of route sections and to deactivate the condition monitoring unit in route sections not included in the predetermined set of route sections.

3. The condition monitoring system according claim 1, the control unit further comprising a memory for storing route data of the vehicle, the route data including a plurality of possible route sections along which the vehicle can travel, wherein the control unit is configured to evaluate at least one characteristic of the route sections of the route data and to activate the condition monitoring unit when the vehicle is travelling in a route section with characteristics meeting at least one predetermined criterion and to deactivate the condition monitoring unit in route sections not meeting the at least one predetermined criterion.

4. The condition monitoring system according to claim 1, the control unit further comprising a memory for storing at least one radius and coordinates of a plurality of trigger points, wherein the control unit is configured to at least one of activate and deactivate the condition monitoring unit when the distance between at least one of the plurality of trigger points and the geographic position is smaller than the radius.

5. The condition monitoring system according to claim 1, wherein the memory is configured to store a travelling direction in relation with at least one of a plurality of trigger points, wherein control unit is configured to activate and/or deactivate the condition monitoring unit when the distance between at least one of the plurality of trigger points and the geographic position is smaller than the radius and when further the travelling direction of the vehicle matches the travelling direction stored in relation to said at least one waypoint.

6. The condition monitoring system according to claim 1, the circuit for detecting the geographic position includes a circuit for receiving signals of satellites of a global positioning system.

7. The condition monitoring system according to claim 1, wherein the condition monitoring unit is configured to communicate with the control unit in a wireless way.

8. The condition monitoring system according to claim 1, wherein the circuit for detecting a geographic position is part of the condition monitoring unit attached to the bearing unit.

9. The condition monitoring system according to claim 1, wherein the circuit for detecting a geographic position is part of the control unit of the vehicle.

10. The condition monitoring system according to claim 1, wherein the condition monitoring unit is configured to be attached to a hub unit of a train, wherein the control unit is configured to monitor the condition of a plurality of hub units of the train.

11. The condition monitoring system according to claim 1, wherein the control unit is configured to trigger simultaneous measurements across multiple condition monitoring units at a given geographical location.

12. The condition monitoring system according to claim 1, wherein the control unit is configured to use the data collected by the condition monitoring units for the purpose of measuring track quality as a tool for infrastructure monitoring.

13. The condition monitoring system according to claim 1, wherein the trigger planer activates and deactivates the condition monitoring unit based on a data structure comprising the geographic position, the travelling direction, upper and lower speed limits, and a radius.

14. The condition monitoring system according to claim 1, wherein the trigger planer activates an alarm when the vehicles pass in one of two possible directions on a track and when a speed of the vehicles is in within a range suitable for obtaining measurements of high quality.

15. At least one condition monitoring unit comprising: a controller configured to operate in an energy saving sleep mode and in an active mode, wherein the controller comprises a trigger planner for setting trigger points for activating and deactivating the at least one condition monitoring unit, wherein at least some of the parameters being monitored in the active mode are not monitored in the sleep mode, wherein the controller is configured to switch the at least one condition monitoring unit from the sleep mode to the active mode and from the active mode into the sleep mode based on one or more signals received by the controller from a control unit of a condition monitoring system operating within a vehicle, wherein the condition monitoring unit is activated and deactivated depending on a detected geographic position and a travelling direction of the vehicles with respect to the trigger points.

16. The at least one condition monitoring unit according to claim 15, wherein the controller is configured to switch the at least one condition monitoring unit from the sleep mode to the active mode upon receipt of a wake-up signal of the one or more signals from the control unit and to switch the at least one condition monitoring unit from the active mode into the sleep mode upon receipt of a sleep signal of the one or more signals from the control unit.

17. A method for monitoring a condition of a bearing unit for a vehicle comprising at least one condition monitoring unit for measuring at least one operating parameter of one bearing unit, a trigger planner for setting trigger points for activating and deactivating the at least one condition monitoring unit, and a control unit for receiving and processing signals obtained from the condition monitoring unit, the method comprising: detecting a geographic position and a travelling direction of the vehicle; and activating and deactivating the condition monitoring unit in accordance with the geographic position and the travelling direction with respect to the trigger points.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a schematic representation of a train including a condition monitoring system for bearing units for vehicles according to the invention;

(2) FIG. 2 is system component diagram of the monitoring system according to the invention is illustrated; and

(3) FIG. 3 is a flow diagram representative of the waypoint alarm activity algorithm implemented in the GPS module for determining the waypoint arrivals for the waypoints.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) FIG. 1 is a schematic representation of a train including a condition monitoring system for bearing units for vehicles according to the invention. The system comprises multiple condition monitoring units 10—one for each wheel of the train—for measuring at least one operating parameter of one bearing unit of a train axle box. The condition monitoring units 10 are formed as wireless sensor nodes attached to or embedded into the end plate of a double row roller bearing assembly of the hub (not shown). The measured operating parameters include vibrations, acoustic emissions and temperature of the bearing and the condition monitoring units 10 include corresponding sensors 12 respectively.

(5) A system concentrator serving as a control unit 18 for receiving and processing signals obtained from the condition monitoring unit 10 is provided in a locomotive of the train. The control unit 18 is essentially a personal computer equipped with software for controlling and monitoring various mechanical devices of the train and for issuing warning signals in cases where damages are detected or likely to occur based on the signals received from the condition monitoring units 10.

(6) The communication between the control unit 18 and the condition monitoring units 10 is at least partially wireless using antennae 17a. If necessary, each of the wagons is provided or some of the wagons are provided with a remote network manager 15 serving as a wireless network manager, a power supply manager for the units 10 and as a wireless network extender. The wireless network can be a single-band 2.4 GHz network or a dual band 2.4 GHz and 5 GhHz network. The skilled person may use other communication frequencies or protocols including different protocols for the backbone and for the communication between extenders and the units 10 depending on the circumstances.

(7) The control unit 18 is further equipped with a GPS antenna 17c and with an antenna 17b for a mobile communication interface using e.g. a GSM, GPRS, UMTS, LTE or HSDPA standard.

(8) In the embodiment of FIG. 1, the control unit 18 comprises a GPS receiver 19 receiving positioning signals from a system of satellites 30 as means for detecting a geographic position. The system is configured such that the condition monitoring units 10 are activated and/or deactivated depending on the detected geographic position as further explained below.

(9) A system component diagram of the monitoring system according to the invention is illustrated in FIG. 2.

(10) The condition monitoring units 10 are provided with a controller 14 and a transmitter 16 for wireless communication and with batteries powering the sensors, the controller 14 and the transmitter 16.

(11) The control unit 18 is equipped with a memory 20 for storing route data of the vehicle as well as other data including sensor data captured by the sensors 12. In the embodiment were the vehicle is a train, the route data is a map of a railway network. In other embodiments, the route data may be a collection or a database of waypoints. The railway network is composed of a plurality of sections or links stored in the database in the memory 20 in combination with parameters describing properties of the section such as a slope, average curvature, and maximum allowable travelling speed. The database in the memory 20 includes a plurality of possible route sections along which the vehicle can travel.

(12) A trigger planner 22 is configured to set trigger points for activating the condition monitoring units 10 with the sensors 12 in suitable sections of the track. Deactivation trigger points can be set by the trigger planner 22 as well. In an alternative embodiment, the condition monitoring units 10 can be deactivated when a predetermined time has elapsed. The trigger planner 22 can be part of the control unit 18 or of a remote server sending the trigger points to the control unit 18 using the mobile communication interface.

(13) Each of the trigger points is a data structure comprising not only the GPS coordinates but a further optional field indicating the travelling direction of the train in which the monitoring shall be triggered. Further, the data structure may comprise fields for upper and lower speed limits and, in one embodiment of the invention, for a radius, i.e. a minimum distance to the GPS coordinates required to trigger the waypoint alarm. Accordingly, the system can be configured such that the alarm is not triggered every time the train passes the waypoint but rather when the train passes in one of the two possible directions on a track and when the speed is in a desired range suitable for obtaining measurements of high quality.

(14) In the embodiment of the figures, the trigger planner 22 is a GUI Application for planning the data collection waypoints on the train's route. These may in particular include actual co-ordinates on a straight path where the speed is known to be constant. The trigger planner 22 in the embodiment provides a KML (Keyhole Markup Language) file or other kind of standard file format (e.g. GML) which is a standard for GIS data used by various map providers. This generic file can be used by a server of the condition monitoring system to download and use the waypoints or trigger points, which are stored in a trigger plan database 23.

(15) The trigger points are starting points of route sections which are part of a set of predetermined route sections in which the data acquisition by the condition monitoring units 10 shall be activated.

(16) The control unit 18 is configured to activate the condition monitoring unit 10 by sending a wakeup signal when the train passes a trigger point, i.e. enters a new route section included in the predetermined set of route sections. When the train passes a deactivating trigger point, i.e. leaves the route section for which the measurement shall be performed, the control unit 18 deactivates the condition monitoring units 10 by sending a sleep signal.

(17) After completion of the measurement, the measured data are stored in the memory 20 and sent to a remote condition monitoring server using the mobile communication interface of the control unit 18.

(18) In a preferred embodiment of the invention, the GPS module 27 is implemented as a library or a GPS processing thread in the control unit 18. It will have the required functionality of GIS Data acquisition from the Global Navigation Satellite System (GNSS) receiver 19. A thread in the control unit 18 loads the software module and starts GPS message interpretation. This thread is managed by the option setup in the server manager of the control unit 18. If the GPS option is selected and the appropriate KML data is loaded, the thread starts.

(19) On start, the GPS module 27 automatically connects to the GPS devices and detects connected emulators. Then, the GPS system listens and interprets messages for Position, Speed, and Direction encoded according to the standards set by the national marine electronics association (NMEA). Then, the in-memory trigger plan database 23 with the collection of waypoints in the memory 20 is updated using the data received from the trigger planner 22. Based on the position, the GPS system determines a waypoint arrival for each of the provided waypoints and notifies the clients when the waypoint is reached.

(20) The system further comprises a server manager application 21 providing configuration data, a collector application 24 for triggering measurements manually, a device manager application 25 for managing the settings of the units 10 on the wheels and a communication service 26.

(21) Optionally, the GPS system watches for speed changes beyond tolerance limits (if provided) and notifies changes. To this end, the NMEA messages are repeatedly received and processed until a Stop message is received. On Stop, the necessary clean-up is performed.

(22) A more detailed illustration of the waypoint alarm activity algorithm implemented in the GPS module 27 determining the waypoint arrivals for the waypoints is illustrated in FIG. 3. The GPS module starts and it works in 2 parallel paths. The waypoint processing is illustrated on the left-hand side in FIG. 3 and the event processing is illustrated on the right-hand side in FIG. 3. In the waypoint processing, on each receipt of position data from the GPS receiver 19 in a step 301, a check is made in a step 302 if any waypoints are in a pre-configured search radius of the current position. The pre-configured search radius may be set depending on the position and/or depending on the monitoring task.

(23) If there are any waypoints within the search radius, the direction variable stored in relation to each of them is checked match the direction of the vehicle in a step 303. If the direction is matched, the speed is checked in a step 304. When the speed is greater than or equal to the pre-configured value, the event processing path is invoked to raise a waypoint alarm in a step 305. The current position, details of the waypoint and the speed of travel are included as part of the alarm message. The subscriber to this alarm is control unit 18, which communicates to the sensor nodes 10 to perform data collection using the interface 26.

(24) In embodiments where a radius specific to a waypoint is set, the latter should be set smaller than the search radius and the waypoint alarm should be triggered only when the distance to the waypoint is within both the search radius and the waypoint-specific radius. Once a waypoint alarm has been generated, the waypoint is marked as processed.

(25) The radius avoids missing triggering at waypoints and it also makes the placement of waypoints much easier as the placement need not be 100% accurate. The receivers have inaccuracies due to GPS signal reflections and sometimes are slightly inaccurate.

(26) The trigger radius the placement of a boundary around a waypoint. It can be used e.g. in case where the waypoint some meters away from the rail track and not directly on it. The user can specify that if the receiver is within 100 m or any other suitable distance of any waypoint it should trigger. It could also useful when the user wishes to trigger at very specific point on a track, perhaps for track quality assessment. This could be achieved by setting the radius to be smaller.

(27) An alternative method of triggering measurements is facilitated by the system where a precise network time is specified for the measurement commencement time. The system application software monitors positional data which is constantly provided by the GPS module and estimates the time it will take to reach the waypoint location. At a time prior to reaching the waypoint the system application software issues a broadcast message over TCP/IP to the gateway manager(s) to instruct the nodes to trigger at a given network time in the future. When this time is reached each node performs a measurement, and the data is stored internally along with the time at which it was instructed to record the dataset.

(28) In a further embodiment of the invention, the control unit 18 does not rely on predetermined indications in the map data but rather the control unit 18 evaluates on-line based on the route data whether a route section to follow is likely to meet predetermined criteria using the stored characteristics of the route sections of the route data. The control unit 18 then activates the condition monitoring units 10 when the vehicle is travelling in a route section with characteristics meeting the criterion and to deactivate the condition monitoring unit 10 in route sections not meeting predetermined criterion. The activation and deactivation may further be dependent on other parameters such as travelling speed, outside temperature and elapsed time since the last activation.

(29) As already mentioned earlier, condition monitoring unit 10 for use in the condition monitoring system as described above includes a controller 14 configured to operate in an energy saving sleep mode and in an active mode. The controller 14 is configured to switch the condition monitoring unit 10 from the sleep mode to the active mode and from the active mode into the sleep mode based on signals received by the controller 14 via the transmitter 16 form the control unit 18. More specifically, the controller 14 is configured to switch the condition monitoring unit 10 from the sleep mode to the active mode upon receipt of a wake-up signal from a control unit 18 and to switch the condition monitoring unit 10 from the active mode into the sleep mode upon receipt of a sleep signal from the control unit 18.

(30) The above system implements a method for monitoring a condition of a bearing unit for a vehicle using at least one condition monitoring unit 10 for measuring at least one operating parameter of one bearing unit and a control unit 18 for receiving and processing signals obtained from the condition monitoring unit 10, wherein a geographic position of the vehicle is detected and wherein the condition monitoring unit 10 activated and/or deactivated depending on the detected geographic position.

(31) A further aspect of the invention relates to a method of triggering simultaneous measurements across multiple nodes at a given geographical location is desirable in order to discount the influence that track conditions may have on the measurements collected by sensors. In the case of long trains, the geographic location of the control unit 10 may substantially differ from the geographic location of a particular axle box. This helps ensuring that measurement quality remains consistent across all sensors. GPS coupled with a time synchronized sensor network can also be used to provide such a feature.

(32) A further aspect of the invention relates to the use of the system as specified above for the purpose of measuring track quality as a tool for infrastructure monitoring.

(33) When considering the example of a train presented above, waypoint co-ordinates are pre-logged in a database using a GUI trigger planner 22 application in the central control unit 18 as the central hub which manages the monitoring system operation.

(34) A hardware GNSS receiver module receives GIS signals from multiple satellites 30 and converts the signals into NMEA formatted messages for the GPS module which continually provides application software with location information including longitude and latitude data which the PC application can use to determine the approximate distance (and time) to the target waypoint.

(35) Upon reaching the location of the waypoint, the GPS module creates an exception message and determines that various parameters are met before proceeding further including ascertaining that the train is traveling within an acceptable speed band configured in the system and that the speed itself is not changing within a specified tolerance. If these conditions are accepted the system software proceeds to flag an exception and trigger a broadcast message to all nodes on the network. This transaction involves the transmission of a message over TCP/IP to all gateway managers on the network. Upon reception, each gateway manager forwards the broadcast message to the condition monitoring units 10 as the sensor nodes over wireless.

(36) When each condition monitoring unit 10 receives the message, it instigates a data capture, powering on acquisition circuitry for a period before storing the recorded data and shutting the circuitry off. Data may be offloaded directly after the capture or at a later time. The node then re-enters a low power state until requested to perform another measurement or task by the central control unit 18.

(37) In the case where manual measurements are requested, the system does not require GPS data. If the GPS is not being used, the default speed and null position values are used. In case of GPS availability, the speed and position are acquired from the GPS Module. Then a broadcast message is sent. Once the condition monitoring unit 10 receives the broadcast command message, it shall perform the necessary sampling according to the preconfigured setup and advised speed.

(38) The application software in the control unit 18 maintains a dynamic table in the database to coordinate the data received as a response to the broadcast command. This is done to prevent data loss during power outages or connectivity issues. The dynamic data needs to be flushed at predetermined intervals.

(39) As an optional feature, speed changes are constantly reported by the GPS module and if the speed changed event is handled the database is updated accordingly.

(40) When the overall data is received, the date/time and speed are compared with the database and for any speed changes. If the speed has remained constant the sample is logged and the waveform is requested. If any speed changed value exceeding a threshold value is observed, the sample is rendered invalid and not stored in the database.

(41) On reaching this waypoint, the condition monitoring units 10 are triggered to ‘wake up’ by the control unit 18 and begin operating. The process used by the trigger planner 22 to achieve this firstly determines a suitable waypoint location based on the speed, location and track conditions then inputting the waypoint parameter details into an on-train software running on the control unit 18. Depending on the data input by the trigger planner 22, there will be one or many periods of operation over the train's route.

(42) Wireless sensor systems associated with monitoring wheel bearings normally have means of detecting rotational speed of the wheel and consequently have a degree of resilience to speed variations.

(43) While sensor systems with wheel rotation detection may not require velocity information on straight lengths of track, embodiments using condition monitoring units 10 without rotation detection may benefit from GPS generated data for speed calculations. A simple solution only requires start and end points either coupled with time data from the GPS system, or using the wireless sensor system clock, but system lag from GPS can cause issues especially when acceleration information is required.

(44) In further embodiments of the invention the condition monitoring system may include an INS (Inertial Navigation System). Further, it is possible to equip the condition monitoring units 10 with a 3 or 6 axes accelerometer or gyroscope and to use the data measured by these devices in processing the waveforms and/or in judging the reliability of the data. This would enable improved control of the sensor system and assist with data processing by providing additional environmental information by enabling incorporation of some track related variation in addition to accurate acceleration measurements.

(45) Taking such factors into consideration assists in maintaining consistency of the conditions under which monitoring is conducted. It could also prove useful when monitoring on curved sections of track by providing angular acceleration and velocity readings. After all, these same principals of operation would apply not simply for a straight piece of track, but for any section of track the train travels over and, for example, monitoring bearings under maximum load can provide useful information.