Patent Application
20170314524
The present disclosure relates generally to a technique for monitoring sparkplug health, and more particularly to detecting a timing of spark production by way of sensing an electrical property in a primary ignition circuit.
A variety of engine performance monitoring and diagnostic routines have been proposed over the years. Most modern engines, and machines generally, have routine maintenance schedules where the engine or machine is brought in for service and various parts are tested, cleaned, inspected, repaired, and potentially replaced. On-board diagnostics and the like can enable operators and owners to be easily alerted to needed servicing prior to the next scheduled maintenance. Such diagnostics can also be of value in the validation of changed specifications or in analysis as to whether service intervals are in fact optimally scheduled.
Those skilled in the art will be familiar with the general desirability of scheduling routine maintenance relatively infrequently. In other words, since an engine is removed from service for a time whenever maintenance is needed, certain operations where the engine is ordinarily used may need to be idled or may otherwise be inconvenienced. Moreover, owners typically desire their machines to be operating as much of the time as is practicable. A typical example is an electrical power genset which can operate most of the hours of the day or continuously, but must be taken off-line for inspection and/or replacement of many different components. To be conservative, manufacturers typically schedule routine maintenance relatively frequently so as to prevent otherwise avoidable unscheduled downtime when unexpected breakdowns or the like occur. Improved diagnostics can improve engineers' understanding of when service is really needed, and can better warn operators and owners when something appears to be amiss outside of routine maintenance schedules. In the case of certain components and subsystems, such as engine electrical systems used in spark-ignited engines, it can be desirable to understand when sparkplug failure is expected prior to such failure actually occurring. Commonly owned United States Patent Application Publication No. 2015/0340846 to Schultz et al. is directed to a detection system for determining spark voltage. For example, Schultz et al. is directed to detecting a spark time based on a signal indicating that a voltage, on a low side of a primary coil, exceeds a threshold.
In one aspect, a method of determining sparkplug health in an engine ignition system includes energizing a primary ignition circuit so as to inductively energize a secondary ignition circuit to produce a spark between electrodes in a sparkplug coupled with the energized secondary ignition circuit, and sensing an electrical property of the primary ignition circuit that varies based on the production of the spark. The method still further includes flagging the sparkplug for service based on a pattern of varying of the electrical property, the pattern being indicative of a timing of the spark production.
In another aspect, an engine ignition control system includes primary ignition circuitry having an electrical input configured to couple with an electrical energy supply, and electrical outputs configured to energize secondary ignition circuitry for a sparkplug. The system further includes sensing circuitry coupled with the primary ignition circuitry and configured to sense an electrical property therein that varies based on production of a spark between electrodes of the sparkplug when the secondary ignition circuitry is energized. The system still further includes a control device coupled with the sensing circuitry and configured to produce a control signal indicative indicative of an aging state of the sparkplug based on a pattern of varying of the sensed electrical property, the pattern being indicative of a timing of the spark production.
In still another aspect, an engine ignition system includes a fluid conduit configured to convey a mixture of a fuel and air for combustion, and a sparkplug including electrodes forming a spark gap positioned within the fluid conduit. The system further includes an ignition control system including primary ignition circuitry, secondary ignition circuitry coupled with the electrodes, and sensing circuitry coupled with the primary ignition circuitry and configured to sense an electrical property of the primary ignition circuitry that varies based on production of a spark between the electrodes. The ignition control system still further includes a control device coupled with the sensing circuitry, and the control device being configured to determine a timing of the production of the spark based on a pattern of varying of the sensed electrical property.
Referring to
In some implementations, engine 10 is a gaseous fuel spark-ignited engine where an ignition system 30 (or “system 30”) of the gaseous fuel spark-ignited engine includes intake runner 32, a fuel injector 34, a gaseous fuel supply 36 containing compressed or liquefied natural gas, for instance, and a sparkplug 46. Each of a plurality of cylinders of engine 10 could be equipped analogously to cylinder 14, as depicted in
Referring also now to
It will be recalled that control system 40 is configured to determine time to spark of sparkplug 46. To this end, control system 40 further includes sensing circuitry 60 coupled with primary ignition circuitry 42 and configured to sense an electrical property of primary ignition circuitry 42 that varies in response to production of a spark between electrodes 47. In some implementations, the sensed electrical property is electrical current, sensed on a low side of primary ignition circuitry 42. A current sense resistor 62 is coupled with electrical output 56, and sensing circuitry 60 may be connected to opposite sides of current sense resistor 62. Referring also now to
It will be recalled that the sensed electrical property varies based on production of a spark (or spark production) between electrodes 47. The manner in which the sensed electrical property varies can be indicative of characteristics of the spark production. In particular, a pattern of the varying in the sensed electrical property can be indicative of a timing of the spark production. Thus, by monitoring the sensed electrical property, a timing of spark production can be determined, which in turn can be indicative of an aging state of sparkplug 46. As a sparkplug ages a time duration required to generate a spark at least under consistent operational conditions can increase. Thus, older sparkplugs, or sparkplugs having been subjected to a relatively greater number of operating cycles, can take longer to spark, and in some instance require a higher voltage to spark, than relatively newer sparkplugs or sparkplugs having been subjected to a relatively lesser number of operating cycles.
Control device 48 may be coupled with sensing circuitry 60 and configured to produce a control signal indicative of an aging state of sparkplug 46 based on a pattern of the varying of the sensed electrical property that is indicative of a timing of spark production. Control device 48 may be or include a field programmable gate array (FPGA) in one embodiment, but could include another computing or calculation device in other embodiments. Control device 48 could also include multiple devices such as an FPGA configured to execute certain logic functions and also a microprocessor configured to execute other logic functions in the operation of control system 40. It should be appreciated that control system 40 might broadly produce a signal that is indicative of a timing of spark production, and be further configured to process that timing of spark production information so as to determine a time to spark. The time to spark can be understood as a time duration between energizing primary ignition circuitry 42 to a time of the spark production. Control device 48 may be further configured to clock a time duration from energizing primary ignition circuitry 42 to the spark production, and to produce the control signal based on the clocked time duration. For instance, control device 48 may be configured to control switching elements (not numbered) in the nature of transistor switches in ignition circuitry 42 so as to selectively connect and disconnect primary ignition coil 43 from an electrical energy supply, and also to selectively connect and disconnect sense resistor 62 and sensing circuitry 60.
The control signal indicative of aging state can be understood as a signal that is indicative of whether a sparkplug is a certain portion through an expected service life (e.g. 50% of the way through an expected service life, 25% of the way through an expected service life, or 99% of the way through an expected service life). Correlation between a time to spark and an aging state can be determined empirically for any given system or class of systems. The actual determination for purposes of producing the control signal can include comparing a time to spark with a plurality of stored times indicative of a plurality of different aging states. The comparison could be performed by control device 48/FPGA or by another computing device running application software for engine operation, for example. In some implementations, control device 48 may be further configured to set a flag for servicing sparkplug 46 based on the control signal. The flag may include one or more bits of information that indicates a first aging state of a given sparkplug (the sparkplug need not be replaced) or a second aging state of the given sparkplug (the sparkplug needs to be replaced or is old). In some implementations, different flags could be set depending upon where in a service life a particular sparkplug is deemed to be. For example, a first flag could be set at a 25% aging state, a second flag set at a 75% aging state, and a third flag set at a 90% aging state. When brought in service a technician could examine the flags and determine whether sparkplug replacement is appropriate, or critical, in parallel with the setting of the flag, control device 48 could activate alert 80, such as by illuminating a check engine light or recording in computer readable memory an aging state of sparkplug 56. In still other instances, it might be desirable to transmit a wireless signal indicative of aging state to a fleet manager or another centralized control and/or monitoring station for a fleet of machines of which engine 10 is a part.
Referring now also to
From
From the foregoing description it will be understood that a pattern of varying of electrical current can be exploited according to the present disclosure for on-board sparkplug diagnostics. In addition to or as an alternative to detecting an inflection point, other embodiments where other characteristics such as potentially a slope or change in slope could be used to detect spark production or anticipated spark production. Moreover, while the present description focuses on a single instance of spark production it should be appreciated that practical implementations of the present disclosure will commonly include diagnostics that evaluate time to spark or other properties over numerous operating cycles, perhaps thousands, millions or even billions of instances of spark production, to detect when a sparkplug needs to be serviced.
Referring to the drawings generally, but in particular now to
From block 250 the logic may advance to block 270 to compare the time to spark with a stored time. As described above, a time known to be associated with a 50%, 75%, 90%, or any other arbitrarily selected aging state of a sparkplug between being first placed in service and an expected failure time or scheduled replacement might be selected. The relationship between such aging states and a time to spark can be empirically determined by way of testing and/or extrapolating, or even potentially by way of modeling. Control device 48 may be configured to clock the time from start of current in primary circuitry 42 to the time of spark as described herein. From block 270 the logic may advance to block 280 to query whether the time to spark is greater than a threshold time. If no, the logic may exit at block 290. If yes, the logic may advance to block 300 to set a flag for service and/or activate alert 80. The logic may FINISH at block 310.
While a relationship between a time to spark and sparkplug aging state has been previously recognized, existing strategies for spark time detection suffer from a number of shortcomings with respect to certain applications. On the one hand, the electrical properties in primary ignition circuitry that are affected by sparking on the secondary side are not readily evident and variations therein may be relatively subtle. Moreover, while certain techniques have been proposed that relate to measuring electrical properties such as voltage and/or current on the secondary side, such an approach would require additional hardware over and above the sensing and testing circuitry that is already resident on many engines. Since the present strategy does not require sensing or monitoring of the secondary circuit no additional hardware apart from what can be integrated in control module 50 is needed.
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon examination of the attached drawings and appended claims.
