Patent Description:
Mitigation of vibrations and other loading phenomena in all manner of machinery is an ongoing challenge. Machine systems can experience a great variety of externally and internally originating vibrations, shocks, and other harsh service conditions. With rotating machinery it is often desirable to dampen torsional loads and vibrations. In the case of an engine crankshaft, for example, the crankshaft does not rotate at a constant speed, but is instead rapidly accelerated and decelerated in response to combustion in the engine cylinders, compression of gases for combustion, exhaust, opening of valves, application of external loads, and still other phenomena. In this dynamic environment, torsional loads can be additive, subtractive, or create resonances that can damage the engine crankshaft or degrade performance of the engine or associated systems over time.

It is common in modern machine systems, where dampening of torsional loads is desired, to employ a torsional damper. In the case of certain engine systems the torsional damper can include a viscous torsional damper having a rotatable mass in contact with a relatively highly viscous fluid, providing inertia that can reduce or eliminate the occurrence or intensity of problematic torsional loads. Torsional dampers of any type can experience performance degradation or failure over time. One strategy for diagnosing torsional damper condition is set forth in <CIT> where a drivetrain having a driveshaft is equipped with a torsional vibration damper. The diagnostic strategy proposes capturing a reference vibration signal of the driveshaft in a reference state, capturing an operating vibration signal of the driveshaft in an operating state deviating from the reference state, and comparing the reference vibration and operating vibration signals. While the strategy set forth in the '<NUM> patent may have certain applications, the technique appears to require dedicated additional hardware and is relatively complex.

<CIT> describes a monitoring system and a method for monitoring torsional vibration dampers. The method include acquiring data corresponding to the free end of the shaft which torsional vibration damper is coupled, acquiring data corresponding to the thermal state of the damper and monitoring the shaft damper operation by processing the acquired data and comparing the process data of the pre-determined threshold values.

In one aspect, a method for prognostic warning of damper damage in a machine system includes monitoring a machine operating parameter that is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on a crankshaft in the machine system having a viscous torsional damper coupled therewith. The method further includes monitoring a temperature parameter. The method still further includes populating an operating history of the machine system, based on the monitored machine operating parameter and the monitored temperature parameter, calculating a damper damage term based on the populated operating history, and triggering a damper damage warning based on the calculated damper damage term. The monitoring of the machine operating parameter includes monitoring a load factor of an internal combustion engine in the machine system; the monitoring of the temperature parameter includes monitoring an ambient temperature; and the populating of the operating history further includes populating a plurality of bins with clocked operating times of the machine system at different combinations of load factor and temperature.

In another aspect, a machine system includes a machine having a crankshaft supported for rotation in a housing, and a viscous torsional damper coupled with the crankshaft. The machine system further includes a damper damage warning system having a warning device, and an electronic control unit in communication with the warning device. The electronic control unit is structured to monitor a machine operating parameter that is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on the crankshaft, and to monitor a temperature parameter. The electronic control unit is further structured to populate an operating history of the machine system based on the monitored machine operating parameter and the monitored temperature parameter. The electronic control unit is further structured to calculate a damper damage term based on the monitored machine operating parameter and the monitored temperature parameter, and to command activation of the warning device, based on the calculated damper damage term.

The machine system still further includes that the monitoring of the machine operating parameter includes monitoring a load factor of an internal combustion engine in the machine system; the monitoring of the temperature parameter includes monitoring an ambient temperature; and the populating of the operating history further includes populating a plurality of bins with clocked operating times of the machine system at different combinations of load factor and temperature.

In still another aspect, an engine control system includes an electronic control unit structured to receive engine operating data for an engine operating parameter that is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on a crankshaft in an internal combustion engine, and to receive temperature data for a temperature parameter. The electronic control unit is further structured to populate an engine operating history based on the data for the engine operating parameter and the data for the temperature parameter, and to calculate a damper damage term based on the populated engine operating history. The electronic control unit is further structured to compare the calculated damper damage term to a stored threshold term, and to command activation of a damper damage warning device based on the comparison of the calculated damper damage term to the stored threshold term. The machine operating parameter includes a load factor of an internal combustion engine in the machine system; the temperature parameter includes an ambient temperature; and the populating of the operating history further includes populating a plurality of bins with clocked operating times of the machine system at different combinations of load factor and temperature. The engine control system still further includes that the monitoring of the machine operating parameter includes monitoring a load factor of an internal combustion engine in the machine system; the monitoring of the temperature parameter includes monitoring an ambient temperature; and the populating of the operating history further includes populating a plurality of bins with clocked operating times of the machine system at different combinations of load factor and temperature.

Referring to <FIG>, there is shown a machine system <NUM> including a machine <NUM>, shown in the context of an internal combustion engine. Machine <NUM> (hereinafter "engine <NUM>") may include a compression ignition internal combustion engine, such as a diesel engine having a housing <NUM> with a plurality of cylinders <NUM> formed therein. Cylinders <NUM> may each be equipped with a piston <NUM> movable between a top dead center position and a bottom dead center position in a conventional four-stroke engine cycle. Engine <NUM> also includes a crankshaft <NUM> supported for rotation in housing <NUM>. Engine <NUM> may be operable to power an electrical generator <NUM> to provide electrical power for supplying to a grid, or for operating drive motors in a vehicle, or for still other purposes such as operating a pump, a compressor, or industrial apparatus.

Engine <NUM> could be coupled with driven machinery other than an electrical generator in other instances. Engine <NUM> also includes a drive pulley <NUM> rotated by way of rotation of crankshaft <NUM> to operate a driven pulley <NUM> by way of a belt <NUM>. Rotation of driven pulley <NUM> can rotate an output shaft <NUM> that operates equipment associated with engine <NUM> such as a transmission pump, a hydraulic pump, a compressor, a camshaft, or still other types of equipment. Rather than a pulley system, engine <NUM> might be equipped with a geartrain, or still another rotated system. Engine <NUM> also includes a viscous torsional damper <NUM> coupled with crankshaft <NUM>. Damper <NUM> may include a housing <NUM>, an inertia ring <NUM> structured to rotate within housing <NUM>, and a fluid space <NUM> that contains a viscous fluid for communicating rotation between housing <NUM> and inertia ring <NUM> in a generally known manner. Damper <NUM> could include still other components such as bearings of a variety of types.

As suggested above, in certain internal combustion engines, and notably four-stroke piston diesel engines, crankshaft rotation may be non-uniform and dynamic due to the different piston strokes of numerous pistons, including suction, compression, power, and exhaust. In addition to the varying forces communicated between the pistons and the crankshaft, firing order of the individual cylinders can dictate that the crankshaft is continuously accelerated and decelerated. It is generally desirable to prevent passing on of these rotational irregularities and vibrations to a belt drive system, a geartrain, or other driven equipment.

In machine system <NUM> damper <NUM> is used for mitigating the various torsional vibrations and loads that can be experienced by crankshaft <NUM>. Damper <NUM> can thus be exposed to relatively high levels of mechanical stress and strain, including shearing forces on the viscous damping fluid. When a damper in a machine system such as an engine system becomes worn, due at least in part to degradation of the damping fluid, increased engine noise, reduced comfort in a vehicular application, or other phenomena can be observed. Compliance with service and replacement intervals as well as regular inspection can assist in ensuring desired torsional damper functioning.

Nevertheless, damper service life can be unpredictable based on variable factors. Where an engine is used to operate an electrical generator, for example, in a standby generator set application, the challenges can be more acute since standby generator sets may be run at various loads depending on load requirements and used in diverse locations exposed to relatively extreme temperatures and temperature changes. The present disclosure provides a strategy for prognostic warning of damper damage in machine system <NUM>.

To this end, machine system <NUM> further includes a damper damage warning system or control system <NUM>. Control system <NUM> may be an on-board engine control system, or a separate control system, having an electronic control unit <NUM> structured to receive engine operating data for an engine operating parameter that is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on crankshaft <NUM> in engine <NUM>. Electronic control unit <NUM> may further be structured to receive temperature data for a temperature parameter.

Control system <NUM> can monitor the machine operating parameter, monitor the temperature parameter, and populate an operating history of machine system <NUM> based on the monitored machine operating parameter and the monitored temperature parameter. Electronic control unit <NUM> may further calculate a damper damage term based on the populated operating history, and compare the calculated damper damage term to a stored threshold term. The damper damage term may be a quantitative or qualitative numerical value that is associated with a relative degree of wear or performance degradation of a viscous damper.

The threshold value can be a numerical value, that has been determined to be associated with a relative degree of wear or performance degradation that justifies warning an operator that further operation of machine system <NUM> should be suspended or modified until such time as damper <NUM> can be replaced. The threshold term could be a value which, if equaled or exceeded by the damper damage term, for example, justifies engine shutdown, derating, or operating the machine only in a limp home mode. The threshold term could be determined empirically, or by simulation potentially, for an individual engine or a class of similar engines. Comparing the damper damage term with the threshold term can include a greater-than-or-equal-to comparison, a less-than-or-equal-to-comparison, or via other similar comparison. Based upon the comparison of the calculated damper damage term to a stored threshold term, electronic control unit <NUM> may command activation of a damper damage warning device <NUM> in control system <NUM>.

As noted above the monitored machine operating parameter is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on crankshaft <NUM>. The term linked with means directly or indirectly indicative of, approximating, or associated with. The machine operating parameter includes a load factor of engine <NUM>, which can generally be understood as an engine load proportion of a rated engine load. It has been observed that vibration or torsional load amplitude may be greater at certain engine load factor levels than at other engine load factor levels. Certain frequencies, including resonance frequencies, may also tend to be observed more at certain load factor levels than at others. Linking of engine load factor with direction, amplitude, or frequency of torsional loads on crankshaft can be determined empirically, or by simulation potentially, for a class of similar engines or an individual engine. Other parameters having a known, determinable, or estimable relationship with engine load could be targeted for monitoring the engine operating parameter in an analogous fashion. Accordingly, by monitoring load factor, electronic control unit <NUM> can gather information about present operating state of engine <NUM> that can be understood as more or less likely to be associated with undesired or problematic torsional loads, which in turn are associated with relatively greater wear on damper <NUM>. The monitored temperature parameter includes a monitored ambient temperature.

Control system <NUM> may also be equipped with an engine sensor <NUM> for producing the engine operating data for the engine operating parameter. Engine sensor <NUM> could include one or more sensors which alone or together can monitor one or more parameters indicative of engine load. As engine load cannot be sensed directly, engine sensor <NUM> can include one or more of a mass flow sensor in an engine air intake system (not shown), a fueling sensor, an engine speed sensor, a torque sensor, a temperature sensor, or still others. A virtual engine load sensor as is known in the art could be used.

Control system <NUM> may also be equipped with a temperature sensor <NUM>, which can be an ambient temperature sensor exposed to the ambient environment outside of engine <NUM>. Control system <NUM> also includes warning device <NUM> with which electronic control unit <NUM> is in communication. Warning device <NUM> may include an operator warning light, such as a check engine light, or another operator-perceptible warning device such as a speaker or buzzer. Warning device <NUM> could be positioned in an operator cab in a mobile vehicular application. Warning device <NUM> could also include an illuminable indicator or icon on a control pad or even on a graphical user interface. In still another embodiment, a damper damage warning could be logged in a memory and retrieved or observed using a service tool by a technician. As noted above, electronic control unit <NUM> may trigger and output a damper damage warning signal based on a calculated damper damage term. Triggering the damper damage warning can include commanding activation of warning device <NUM>, as further discussed herein.

Referring now also to <FIG>, there is shown a functional block diagram of electronic control unit <NUM> illustrating additional details. Electronic control unit <NUM> can include an input/output interface <NUM>, and at least one processor <NUM>. Processor <NUM> may be any suitable processor such as a microprocessor, a microcontroller, or a field programmable gate array (FPGA). Electronic control unit <NUM> also includes a memory <NUM>. Memory <NUM> can be any suitable computer readable memory such as RAM, ROM, SDRAM, EEPROM, flash, a hard drive, or still another. Memory <NUM> stores computer executable program instructions which, upon execution by processor <NUM>, can perform the prognostic warning strategy discussed herein.

In one implementation, electronic control unit <NUM> includes an engine control unit structured to execute not only the prognostic warning logic of the present disclosure, but also standard engine control functions. To this end, memory <NUM> may store engine control software <NUM> and a variety of engine maps <NUM>. Also depicted in <FIG> are engine/operator inputs <NUM> that may be received by electronic control unit <NUM> and include any of a great variety of parameters such as rotational speeds, pressures, temperatures, and still others that are monitored during operation of engine <NUM>. Operator inputs such as speed requests, fueling requests, or other similar parameters may also be included in inputs <NUM>. Processor <NUM> may receive inputs <NUM> and, by executing engine control software <NUM>, produce engine control commands <NUM>. Memory <NUM> may also store damper damage warning software <NUM>, and a damage fraction map <NUM> further discussed herein.

Also depicted in <FIG> is an engine load input <NUM> and a temperature input <NUM>. Engine load input <NUM> can directly or indirectly indicate, or include data associated with, engine load, as discussed herein, and could include a signal from engine sensor <NUM>. Engine load input <NUM> can, potentially with other information, be used to determine present engine load factor. Temperature input <NUM> can include a signal from temperature sensor <NUM>. Based upon engine load input <NUM> and temperature input <NUM> processor <NUM>, by executing damper damage warning software <NUM>, can produce a warning command <NUM> to activate warning device <NUM>.

Referring to <FIG>, there is shown a table <NUM> of software control functions according to the present disclosure. A plurality of cells <NUM> in a first table can be populated, by electronic control unit <NUM>, to reflect an operational history of machine system <NUM>. Cells <NUM> represent bins that are populated with clocked operating times of machine system <NUM>. It can be noted that cells <NUM> are segregated by temperature, with a left column of cells representing combinations of load factor and temperature less than "X" °C, and a right column of cells representing combinations of load factor and temperatures above X °C. In one embodiment of the disclosed concepts X°C might be equal to about <NUM> ambient temperature.

As further discussed below, operating hours of engine <NUM> per each combination of load factor and temperature are logged, for instance at a task rate of <NUM> second. Also shown in table <NUM> are a plurality of cells <NUM> that represent calculations of damage per bin, again segregated by temperature and load factor corresponding to cells <NUM>. In the <FIG> illustration, since no information has yet been stored in cells <NUM>, total engine hours shown is zero. Similarly, a Sum of Damage shown at <NUM> is also zero. An event shown at <NUM> indicates that No Warning is displayed at this point in time. As will be further apparent from the following description, as machine system <NUM> is operated, engine operating time per bin, such as in seconds, can be logged, damage per bin calculated, a Sum of Damage or total damage calculated, and potentially other processing steps executed to determine whether an event satisfying a condition leading to Warning indication has occurred, or whether an event satisfying a condition leading to No Warning indication has occurred.

It will also be recalled that electronic control unit <NUM> calculates a damper damage term based on the populated operating history. The damper damage term can include a damper total damage term. In other words, a total damage term can be calculated that reflects the relative wear that damper <NUM> has likely experienced, or a level of performance degradation that has likely occurred, based on the manner in which machine system <NUM> has been operated and based on the conditions under which the machine is operated. It will also be recalled that certain combinations of load factor, temperature and/or potentially other factors are expected to have a relatively greater impact on damper life. For this reason, electronic control unit <NUM> may calculate the damper total damage term based on a weighted cumulation of operating times for machine system <NUM> for each of the plurality of bins. Operation for a given time in some bins can be expected to affect damper life relatively more or less than operation for the given time in other bins, with the operating time per bin being weighted accordingly. Where operation in one bin is associated with relatively greater damage than another bin, the first bin may be weighted more heavily, for example. It will also be recalled that memory <NUM> may store a damage fraction map <NUM>.

Damage fraction map <NUM> may include stored damage fraction terms, determined empirically, for each of the plurality of bins. Processor <NUM> can read the stored damage fraction terms for calculating damage amounts per bin, such as by multiplying an operating time per bin by the damage fraction term or "damper life weighing term" in the equation below. One example calculation could include multiplying <NUM> hours above <NUM> operating time at <NUM>-<NUM> load factor % by a damper life weighting term of <NUM> to produce a damage amount for the given bin of <NUM>. Another example might be multiplying <NUM> hours operating time, below <NUM>, at <NUM>-<NUM> load factor % by a damper life weighting term of <NUM> to produce a damage amount for the given bin of <NUM>. These numbers are merely to illustrate an example. Calculation of total damage can include calculating a damper total damage term based on a weighted cumulation of the operating times for each of the plurality of bins. One example calculation of the damper total damage term includes calculating the damper total damage term by way of the equation: <MAT> Where:.

Referring now to <FIG>, there is shown a flowchart <NUM> illustrating example logic flow, according to one embodiment of the disclosed concepts. Flowchart <NUM> commences at a block <NUM> to query whether engine <NUM> is operating? If engine <NUM> is not operating, then the logic can advance to Exit at a block <NUM>. Alternatively, if engine <NUM> is running, the logic advances to a block <NUM> to determine whether damper damage warning strategy is enabled. If the warning strategy is not enabled, the logic advances to Exit at a block <NUM>. However, if the warning strategy is enabled, the logic advances to a block <NUM> to increment a timer. In one implementation, electronic control unit <NUM> can perform several functions relating to damper damage assessment in time intervals of one second, although the present disclosure is not thereby limited.

From block <NUM> the logic advances to block <NUM> to clock engine operating seconds per bin. Again, a different time interval might be used for clocking engine operations. It will be recalled that engine operating seconds per bin can include engine operating seconds for each of a plurality of combinations of engine load factor and ambient temperature, consistent with the illustration in <FIG>, or using other combinations of load factor, temperature, or other factors. Temperature data as discussed herein is input to the logic flow at a block <NUM>, and engine operating data as discussed herein is input to the logic flow at a block <NUM>.

From block <NUM> the logic advances to a block <NUM> to calculate damage per bin, as discussed herein. From block <NUM> the logic advances to a block <NUM> to calculate cumulated damage for all bins, such as by way of the equation set forth herein. From block <NUM> the logic advances to a block <NUM> to query if the total damage (TD) is greater than a threshold. Block <NUM> can include comparing the damper damage term to a stored threshold term, also as discussed herein. If TD is greater than the threshold, then the logic advances to a block <NUM> to command activation of the warning device, for example illuminating a light, sounding an alarm, or sending a text message to an operator's mobile device, and the like. From block <NUM> the logic advances to a block <NUM> to Exit. If TD is less than or equal to the threshold, the logic can return to block <NUM> to again increment the timer. The present strategy can also include storing engine operation seconds per bin at a block <NUM>, for long term storage on at least one of memory <NUM>, a local drive, a remote drive, and the like. Storing engine operation seconds per bin at block <NUM> can enable transferring the previously logged operational history data to a replacement electronic control unit. A new or replacement electronic control unit is often cloned for installation in an engine. That way, the cumulative damper damage can be incorporated for consideration even when the electronic control unit in a machine system is replaced, but a torsional damper that has not yet reached the end of its service life is not replaced.

The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure as defined in the claims.

Claim 1:
A method for prognostic warning of damper damage in a machine system (<NUM>) comprising:
monitoring a machine operating parameter that is linked with at least one of an amplitude, a frequency, or a direction of torsional loads on a crankshaft (<NUM>) in the machine system (<NUM>) having a viscous torsional damper (<NUM>) coupled therewith;
monitoring a temperature parameter;
populating an operating history of the machine system (<NUM>) based on the monitored machine operating parameter and the monitored temperature parameter;
calculating a damper damage term based on the populated operating history; and
triggering a damper damage warning based on the calculated damper damage term;
characterised in that the monitoring of the machine operating parameter includes monitoring a load factor of an internal combustion engine (<NUM>) in the machine system (<NUM>);
the monitoring of the temperature parameter includes monitoring an ambient temperature; and
the populating of the operating history further includes populating a plurality of bins with clocked operating times of the machine system (<NUM>) at different combinations of load factor and temperature.