Abstract:
There is provided a system for monitoring a replaceable unit. The system comprises a passive memory device attached to the replaceable unit forming part of an assembly such as an engine. The passive memory is for storing and for providing access to replaceable unit information comprising unit identification and usage information. The system may further comprise an event detector which may be embodied as an electronic engine controller (EEC) operatively connected to the engine, for accumulating the usage information related to the replaceable unit, and for communicating with the passive memory device to update the unit information stored in the passive memory device with the usage information.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates generally to the monitoring and maintenance of powered and non-powered replaceable units and machinery located within a large installation, such as an industrial manufacturing line, an aircraft, a ship or any type of vehicle. 
       BACKGROUND OF THE ART 
       [0002]    Various types of engines and systems need constant or periodic inspection and monitoring. In aircraft applications for example, an Electronic Engine Control (EEC) records and provides monitoring and maintenance data, which is transmitted to onboard Health Usage Monitoring Systems (HUMS) or Data Transmission Units (DTU). The monitoring and maintenance data may be further downloaded to portable maintenance monitoring equipment upon landing of the aircraft. The type of inspection and maintenance actions needed for each replaceable unit within the installation or vehicle requiring periodic maintenance may vary depending on their operation time and whether the replaceable unit was subjected to any stress occurring during a specific event. In addition, it is highly desirable that each maintenance and inspection action be kept up-to-date and that any technical information pertaining to each replaceable unit is made readily available. 
         [0003]    Accordingly, there is a need to provide an improved electronic-tag system and method for monitoring inspection, maintenance, and operation of each replaceable unit within a large installation such as an aircraft. 
       SUMMARY 
       [0004]    In one aspect, there is provided a system for monitoring a replaceable unit. The system comprises a passive memory device attached to the replaceable unit forming part of an assembly. The passive memory is for storing and for providing access to replaceable unit information comprising unit identification and usage information. The system further comprises an event detector operatively connected to the assembly, for accumulating the usage information related to the replaceable unit, and for communicating with the passive memory device to update the unit information stored in the passive memory device with the usage information. 
         [0005]    In another aspect, there is provided a system for monitoring a replaceable unit. The system comprises means for storing and for providing access to replaceable unit information. The means for storing is passive and further adapted to be attached to the replaceable unit. The replaceable unit forms part of an assembly, and the unit information comprises unit identification and usage information. The system further comprises means for accumulating the usage information related to the replaceable unit and for communicating with the passive memory device to update the unit information stored in the passive memory device with the usage information, the means being operatively connected to the assembly. 
         [0006]    In yet another aspect, there is provided a method for monitoring a replaceable unit. The method comprises: providing a passive memory device attached to the replaceable unit forming part of an assembly, the passive memory device being adapted to store and provide access to replaceable unit information comprising unit identification and usage information; providing an event detector operatively connected to the assembly; accumulating usage information related to the replaceable unit using data gathered from the event detector; and communicating the accumulated usage information to the passive memory device to update the unit information stored in the passive memory device with the usage information. 
         [0007]    Further details of these and other aspects of the present invention will be apparent from the detailed description and figures included below. 
         [0008]    In the present description, the expression “passive memory device” refers to a memory device containing no battery or internal power source to retain data. This definition is well accepted and known by those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Reference is now made to the accompanying figures, in which: 
           [0010]      FIG. 1  schematically illustrates a monitoring system; 
           [0011]      FIG. 2  schematically illustrates the monitoring system of  FIG. 1  within the context of an aircraft engine; 
           [0012]      FIG. 3  is a flowchart which illustrates a monitoring method in relation to the monitoring system of  FIGS. 1 and 2 ; 
           [0013]      FIG. 4  schematically illustrates an alternative version of the monitoring system of  FIGS. 1 and 2 ; and 
           [0014]      FIG. 5  schematically illustrates another alternative version of the monitoring system of  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  schematically illustrates a monitoring system  10  wherein a replaceable unit  12  has a passive memory device  13 , also known as a memory button or an electronic-tag. The replaceable unit  12  forms part of an assembly such as an engine, and is thus capable of being attached with other units forming the engine. The engine may be part of a larger assembly such as an industrial manufacturing line, an aircraft, a ship or any type of vehicle. The passive memory device  13  is further connected (either periodically or permanently) to a connecting device  14 , for establishing an electrical contact with the passive memory device  13  and for enabling the communication between the passive memory device  13  and an event detector herein illustrated as an electronic engine control (EEC) device  15 . An embodiment where the event detector forms part of the replaceable unit  12  is shown in  FIG. 4  and discussed below. The connecting device  14  is herein illustrated with two probes attached together via a communication channel enabling either electrical or wireless communication. 
         [0016]    The EEC device  15  is responsible for the control of the engine assembly. The EEC device  15  may have an elapsed time indicator (ETI) device  16 , a memory device  17  attached to the connecting device  14 , and a database  18 . 
         [0017]    The powerless memory device  13  has a non-volatile memory in which it is possible to record new data and access already stored data. Such data can be, for example, the replaceable unit&#39;s serial number or part number, a time since new or a time when replaced, a time since last maintenance (inspection or repair), and a time since overhaul or since last refurbishment. Other similar “times to” perform any type of action due on the unit can also be recorded. These times relate to usage information and are thus updated throughout the replaceable unit&#39;s lifecycle. The replaceable unit&#39;s technical information such as serial or part number usually remains fixed during the replaceable unit&#39;s entire functional life within the engine being monitored. The powerless memory device  13  can also be password protected and contain information such as the serial number of all the engines or the other units to which it has been connected in its lifecycle. Any other relevant maintenance information, such as maintenance due schedule and a maintenance history can also be recorded, accessed and updated in accordance with the monitoring system herein detailed. 
         [0018]    The connecting device  14  is characterized by having two probe-like devices engaged on each one of the two memory devices  13  and  17  of the replaceable unit  12  and the EEC device  15  respectively. The probe-like devices are capable of reading and writing to each of the two memory devices  13  and  17  via a direct electrical connection or a wireless connection. Hence, the connecting device  14  permits the communication between the replaceable unit&#39;s passive memory device  13  and the EEC device  15 . Communication between the two probe-like devices of the connecting device  14  can be achieved either through electrical wiring connections or through wireless communication. Alternatively, the connecting device  14  could simply be a connector. In the case where memory device  13  is passive, the connecting device  14  shall be powered from the EEC device  15  or the memory device  17  on the EEC. 
         [0019]    The EEC device  15  may be powered by the engine it controls. The EEC device  15  is capable of recording and detecting events concerning the engine in a database  18 . For example, when the engine is activated, a control event is recorded and an event signal is sent to the ETI device  16 . The EEC device  15  may be accessed by any user stations needing information on the control events and replaceable unit information. The EEC device  15  can be password protected. 
         [0020]    The ETI device  16  is a device capable of counting an elapsed time between two given events, upon receiving given event signals from the EEC  15  whenever given events occur. Once an elapsed time is determined between given events, it is sent to database  18  or to the memory device  17 , and subsequently to whichever passive memory device  13  of a replaceable unit is affected by such an event. 
         [0021]    Memory device  17  is similar to passive memory device  13 , although it is powered by the power of the EEC  15 , and therefore is not necessarily passive. 
         [0022]    Control events (or simply “events”) also can be, for example, the number of engine stalls, occurrences when the engine&#39;s temperature is not within a prescribed range, or any other event under the existing control of the EEC device  15  such as when weight is felt on the wheels (i.e., “weight-on-wheels”) in the case of an aircraft. 
         [0023]    A list of all the replaceable units  12  forming part of the engine being monitored and controlled by the EEC device  15  is stored in database  18 . A log of control events and activation history concerning each replaceable unit  12  is created and stored in database  18 . In other words, control event information and elapsed times for each event are recorded for the replaceable unit  12  being affected by the events. The information related to each replaceable unit  12  is periodically sent to its passive memory device  13  and stored there. 
         [0024]    For example, a start-up signal is sent to the ETI device  16  upon activation of the engine under the control of the EEC device  15 , and a shut-down signal is sent to the ETI device  16  when the engine is shut-down. The ETI device  16  counts the time between the reception of these two signals. An elapsed time corresponding to the engine&#39;s activation time or run-time is therefore measured. This elapsed time is recorded in the database  18  for each related replaceable unit  12 . The passive memory devices  13  of each replaceable unit  12  affected by the activation of the engine are updated with the recorded elapsed time. A total activation time for each replaceable unit  12  is thus stored in each of the passive memory devices  13 . Updates can be performed after each activation periods or during the activation time, as in a real-time fashion. Certain information stored on the passive memory devices  13  can always be found at a given memory address for example, such that specific information can be retrieved by accessing the given address. Information stored in a passive memory device  13  can be read or accessed by first energising the device  13  such that the desired information can be sent through the connecting device  14  to the requesting party. For example, the ECC device  15  can sequence a given pattern for reading or writing to each of the replaceable units  12  memory devices  13 . The sequence can vary according to specific information demands and update requirements. 
         [0025]    Similarly, the EEC device  15  can maintain a log of occurrences when a given parameter being monitored by the EEC device  15  exceeds a given threshold value. For example, each time the engine&#39;s temperature or pressure level exceeds a given safe temperature or pressure range, an event is recorded in database  18 . Other parameters may also be monitored, such as vibration levels, flow of air or a liquid, and voltages. The rate of change of the previously listed given parameters may also be considered as an event to be recorded. When an event is known to affect a given replaceable unit  12 , the log of events for the given replaceable unit  12  is updated with the information concerning the event. 
         [0026]    Still referring to  FIG. 1 , the EEC device  15  sets a flag or an alarm that maintenance is due on a specific replaceable unit whenever a comparison of the updated unit information with the maintenance schedule stored in a passive memory device reveals that maintenance is due. Similarly, whenever maintenance is performed on a given replaceable unit  12 , the EEC device  15  updates the time of the last maintenance stored in the passive memory device  13  of the corresponding replaceable unit. The time since the last maintenance is then updated each time the activation time is being updated. The time to a replaceable unit&#39;s overhaul and the time since a replaceable unit&#39;s overhaul are updated in a similar manner. 
         [0027]    Whenever a replaceable unit is replaced, the part number or serial number of the new replaceable unit, stored in the replaceable unit&#39;s passive memory device  13  is sent to the EEC device  15 . The EEC device  15  can thus also determine if the new replaceable unit being installed is compatible with the engine or the other replaceable units to which it is to be connected and with which they function by comparing the new part number or serial number stored in the new replaceable unit&#39;s passive memory device  13  with a compatibility list of the engine stored either database  18  or memory device  17 . 
         [0028]    Additionally, the passive memory device  13  of the replaceable unit  12  can be interrogated independently of the EEC device  15 , by any other reading device, and thus even when the unit  12  is removed from the engine or assembly. This allows for the reading or writing of related usage information wherever the replaceable unit is located. 
         [0029]      FIG. 2  schematically illustrates the monitoring system of  FIG. 1  within the context of an engine  19  installed in an aircraft having an aircraft body  20 . Replaceable units  12  can be mechanical parts, flight control units (FCU), engine pumps, any line replaceable units (LRUs), electrical wiring harnesses, and any other modules within the engine  19  and the rest of the aircraft&#39;s body  20 . The monitoring system illustrated is most valuable for non-powered replaceable units however. 
         [0030]      FIG. 3  is a flowchart which illustrates a monitoring method in relation to the monitoring system of  FIGS. 1 and 2 . In step  20 , the EEC device  15  reads unit information and maintenance due schedule previously stored in the replaceable unit&#39;s  12  passive memory device  13 . This step can be omitted and be part of step  25  below. 
         [0031]    In step  21 , the EEC device  15  accumulates usage information concerning replaceable units  12  forming part of an engine such as an aircraft engine  19  using control information related to the engine  19 . The accumulated usage information is stored in either or both database  18  and memory device  17  of the EEC device  15 , according to each replaceable unit  12  involved. 
         [0032]    In step  22 , the accumulated usage information is sent to each of the passive memory devices  13  of every replaceable unit  12  affected by the control information of the EEC device  15  via connecting devices  14 . 
         [0033]    In step  23 , the replaceable units&#39; passive memory devices  13  receive, via the connecting device  14 , the accumulated usage information. 
         [0034]    In step  24 , each of the passive memory devices  13  updates its stored replaceable unit information with the received accumulated usage information. 
         [0035]    In steps  25  to  27 , the EEC device  15  reads the updated replaceable unit information and the maintenance due schedule stored in each of the replaceable unit&#39;s passive memory devices  13  and compares them to determine whether maintenance is due or not. If maintenance is due, a flag or an alarm is turned on, or a data bit can be set or a signal can be sent to the EEC device  15 , such that proper actions may be taken by maintenance and inspection personnel. 
         [0036]      FIGS. 4 and 5  present alternative versions of the monitoring system as illustrated in FIGS. I and  2 , wherein the replaceable units  12  being adapted to provide power to their respective passive memory devices  13 , and record data related to events occurring internally or within their own body structure. 
         [0037]    More specifically,  FIG. 4  illustrates an alternative version of a replaceable unit  12  capable of generating enough power to energize on-board intelligent devices. A power generator  121  capable of generating power from the replaceable unit&#39;s own mechanical activity, or preferably from any environmental conditions, sends power to an internal event detector  122  and an elapsed time indicator (ETI) device  123 , also both located in the replaceable unit  12 . 
         [0038]    The environmental conditions used by the power generator  121  to generate power can be, for example, vibrations present when the replaceable unit is mechanically functioning, or when a nearby engine is activated. Other environmental factors such as pressure pulses and liquid flows can be used by the media power generator  121 . Such an internal power generation provides the ability to add intelligence and additional smart features to both the passive memory device  13  and the replaceable unit  12 . In this way, a replaceable unit  12  can independently monitor events occurring within its own structure and maintain a log of events stored within its own now power-enabled passive memory device  13 . In such a case, the EEC device  15  may not be needed. 
         [0039]    For example, a replaceable unit&#39;s self-generated power is used to power the timer of the ETI device  123 , the internal event detector  122 , and the passive memory device  13 . Sensors within the internal event detector  122  are thus capable of detecting events and take relevant measurements. The detected events and measurements are used to activate the ETI device  123  and in turn update replaceable unit information stored in the passive memory device  13 . The detected events and other measurements can also trigger counters to count occurrences of given events. 
         [0040]    For example, whenever an event occurs, a signal is sent to the ETI device  123 , such that an elapsed time can be measured, and a log of events according to their detailed measurements and times is created and stored in the passive memory device  13 . Other features such as logging a time of use, or a time when the replaceable unit is in function, detecting when a given parameter being measured exceeds a set threshold, detecting any undesirable agent or chemical compound contamination within the replaceable unit  12  can be achieved. Since the passive memory device  13  can use the self-generated power, the execution of small software routines stored within the memory device  13  by an on-board processor (not shown), is made possible. An alarm or data bit can thus be turned on by the replaceable unit  12  itself whenever a maintenance is due or, for example, whenever a given specific event or measurement occurs within the body of the replaceable unit  12 . 
         [0041]    Although not necessary due to internal self-monitoring capabilities as detailed above, the passive memory device  13  can send updated unit information such as the log of events and any alarm to the memory device  17  of a related EEC device  15  of an engine  19  (refer to  FIGS. 1 and 2 ) such that proper actions may be taken. Either one of the EEC  15  or the on-board processing power can prompt a user station to alert any personnel responsible of the equipment&#39;s proper functioning. 
         [0042]      FIG. 5  is similar to  FIG. 4 , although additional features are introduced. The internal event detector  122 , in addition to simply taking measurements to detect events, is adapted to acquire and record digital pictures (or images) of events, hardware or components located within the replaceable unit, and collect any other relevant measurements. The collected evidence is then stored in a storage device  1221  or directly in the memory device  13 . The evidence collected and stored is accessible via the memory device  13 . Actuators (not shown) can also be controlled by the onboard processing power capabilities of the replaceable unit  12  to enable the automatic performance of proper actions upon the recognition of an event. 
         [0043]    For example, when an event is detected by the internal event detector  122 , evidence is recorded and stored. An event start and an event stop signal are sent to the ETI device  123 . The ETI device  123  calculates an elapsed time during which the event occurs. The ETI device  123  then sends elapsed times to the passive memory device  13 , wherein a log of events is recorded. Evidence data can be accessed by the EEC device  15  of a related engine through the memory devices  13  and  17 , and through the connecting device  14  in order to determine whether an action should be performed or not. Alternatively, this decision can be taken by the replaceable unit&#39;s on-board processor. The on-board processor (not shown) can be in the ETI device  123 , internal event detector  122  or anywhere in the replaceable unit  12 . A diagnosis is subsequently generated by the processor and results from such event monitoring. The amount of wear and the verification of the replaceable unit&#39;s  12  general health can also be monitored 
         [0044]    In a situation where an action is required upon the detection of a given event, an “action required” signal generated by the processor or ETI device  123  is sent back to the internal event detector  122 . The power necessary to perform the “actions required” by actuators is provided by the on-board power generator  121 . Actions are performed by actuators, for example, which can perform basic maintenance tasks without the intervention of any personnel or maintenance crew. Actions may also be performed whenever the measure of the wear of a device within the replaceable unit  12  requires compensation for example. The actuators are also capable of moving components within the replaceable unit  12  or the replaceable unit  12  itself if required. Other actions, such as removing sludge build-ups or un-clogging on-board filters are also possible. Multiple event detecting devices located in a same replaceable unit  12  or in another replaceable unit  12  can communicate with each other, directly or via each unit&#39;s memory device  13 . This allows for the coordination of actions performed throughout the engine or installation. 
         [0045]    Those skilled in the art will recognize that several other monitoring or actuation options can be performed by the above-described system and method, and that the options herein describes are given as examples. It is thus understood that several other embodiments may be implemented and fall within the scope of the system and method herein described.