Ignition control and diagnostics using ignition coil measurements

Abstract

A system and method for controlling an ignition system. An ignition coil assembly has an ignition transformer with primary windings and secondary windings, the secondary windings having a length between two ends. The ignition coil assembly has a measuring device adjacent the length of the secondary windings. A control unit is adapted to regulate timing of primary drive pulses to the ignition transformer for generating a spark at a spark apparatus to ignite a fuel-air mixture in an engine cylinder. The timing is based at least in part on measurements made using the measuring device.

Description

TITLEIGNITION CONTROL AND DIAGNOSTICS USING IGNITION COIL MEASUREMENTSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This International Application claims the benefit of U.S.Provisional Application No. 63 / 719,159 filed November 12, 2024, the disclosure of which is expressly incorporated by reference herein in its entirety.FIELD

[0002] The present teachings relate generally to power electronics and, more particularly, to ignition systems that may be used with combustion engines.BACKGROUND

[0003] In general, an ignition system generates a high voltage that is sent to a spark plug to create a spark, as is appreciated by one skilled in the art. The spark in turn ignites a fuel-air mixture in an engine's combustion chamber(s) to drive the engine. The ignition coil (also referred to as ignition transformer) typically produces the high voltage.

[0004] U.S. Pat. No. 5,623,209, entitled “Diagnostic system for capacitive discharge ignition system”, discloses an indirect breakdown voltage indicator.{P7501506846067. DOCX}

[0005] U.S. Pat. No. 5,208,540, entitled “Ignition performance monitor and monitoring method for capacitive discharge ignition systems”, discloses an indirect breakdown voltage indicator.

[0006] U.S. Pat. No. 6,283,103, entitled “Methods and apparatus for controlling spark duration in an internal combustion engine”, discloses an indirect indicator of some conditions.

[0007] U.S. Pat. No. 8,978,632, entitled “Ion sensing method for capacitive discharge ignition”, discloses an indirect combustion indicator.

[0008] US Pat. No. 7,401,603 (“the ‘603 Patent”), entitled “High tension capacitive discharge ignition with reinforcing triggering pulses”, discloses an indirect secondary voltage indicator and timed pulses to increase efficiency of an ignition system. The ‘603 Patent is incorporated by reference in its entirety.

[0009] U.S. Pat. No. 9,429,132, entitled “Capacitive ignition system with ion-sensing and suppression of AC ringing”, discloses an indirect combustion indicator. It uses some unclear language, stating DC current “causes the ringing of the secondary voltage.” As shown in the ‘603 patent and confirmed herein, secondary voltage ringing continues during a spark event.

[0010] While prior systems may seek to improve engine efficiency, they lack ability to directly measure what is happening inside of an ignition coil. Therefore, it would be beneficial to have an alternative system and method for ignition control and diagnostics using ignition coil measurements.SUMMARY

[0011] The needs set forth herein as well as further and other needs and advantages are addressed by the present embodiments, which illustrate solutions and advantages described below.{P7501506846067. DOCX}

[0012] One embodiment of a system according to the present teachings includes, but is not limited to, an ignition system. An ignition coil assembly has an ignition transformer with primary windings and secondary windings, the secondary windings having a length between two ends, and a measuring device adjacent the length of the secondary windings. A control unit is adapted to regulate timing of primary drive pulses to the ignition transformer for generating a spark at a spark apparatus to ignite a fuel-air mixture in an engine cylinder. The timing is based at least in part on measurements made using the measuring device.

[0013] In one embodiment, the measuring device measures an internal secondary voltage of the ignition coil assembly during a spark event.

[0014] In one embodiment, the measuring device directly contacts the secondary windings.

[0015] In one embodiment, the measuring device comprises a wire connected to the secondary windings.

[0016] In one embodiment, the measuring device does not directly contact the secondary windings.

[0017] In one embodiment, the measuring device comprises a sense tape.

[0018] In one embodiment, the coil assembly comprises a sensor for measuring signals received from the measuring device.

[0019] In one embodiment, the control unit comprises a sensor for measuring signals received from the measuring device.{P7501506846067. DOCX}

[0020] In one embodiment, the timing comprises sending one or more reinforcing pulses.

[0021] In one embodiment, the timing comprises a strength and / or a length of the one or more reinforcing pulses.

[0022] In one embodiment, the control unit uses an amplitude, a frequency, and / or a shape of an internal secondary voltage waveform to determine current operating conditions.

[0023] In one embodiment, the control unit uses the measuring device to determine a breakdown voltage, a secondary current, a spark plug condition, a secondary component capacitance, and / or a secondary fault condition.

[0024] One embodiment of a system according to the present teachings includes, but is not limited to, an engine system. It includes an engine and the ignition system according to the present teachings.

[0025] One embodiment of a system according to the present teachings includes, but is not limited to, an ignition coil assembly. An ignition transformer has primary windings and secondary windings, the secondary windings having a length between two ends. A measuring device is adjacent the length of the secondary windings. The ignition coil assembly is adapted to be in communication with a control unit, such that the control unit regulates ignition based at least in part on measurements made using the measuring device.

[0026] In one embodiment, the assembly further comprises a sensor for measuring signals received from the measuring device.{P7501506846067. DOCX}

[0027] Other embodiments of the system and method are described in detail below and are also part of the present teachings.

[0028] For a better understanding of the present embodiments, together with other and further aspects thereof, reference is made to the accompanying drawings and detailed description, and its scope will be pointed out in the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is an illustration of one embodiment of a system according to the present teachings.

[0030] FIG. 2 is another illustration of an embodiment of a system according to the present teachings.

[0031] FIG. 3 is an oscillogram of the internal secondary voltage according to the present teachings.

[0032] FIG. 4 is an oscillogram with open circuit waveforms from both the output and internal signal.

[0033] FIG. 5 is an oscillogram of internal secondary voltage, secondary voltage at the spark plug, secondary current, and primary pulses.

[0034] FIG. 6 is an illustration of another embodiment of a system according to the present teachings.

[0035] FIG. 7 is an oscillogram of a hard-wired internal sensor and a non-contact sensor.{P7501506846067. DOCX}

[0036] FIG. 8 is an illustration of another embodiment of non-contact sensing according to the present teachings.

[0037] FIG. 9 is an illustration of one embodiment of an engine control system according to the present teachings.DETAILED DESCRIPTION

[0038] The present teachings are described more fully hereinafter with reference to the accompanying drawings, in which the present embodiments are shown. The following description is presented for illustrative purposes only and the present teachings should not be limited to these embodiments. Any computer configuration and architecture satisfying the speed and interface requirements herein described may be suitable for implementing the system and method of the present embodiments.

[0039] In compliance with the statute, the present teachings have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the present teachings are not limited to the specific features shown and described, since the systems and methods herein disclosed comprise preferred forms of putting the present teachings into effect.

[0040] For purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description with unnecessary detail.

[0041] A “computing system” may provide functionality for the present teachings. The computing system may include software executing on{P7501506846067. DOCX}computer readable media that may be logically (but not necessarily physically) identified for particular functionality (e.g., functional modules). The computing system may include any number of computers / processors, which may communicate with each other over a network. The computing system may be in electronic communication with a datastore (e.g., database) that stores control and data information. Forms of computer readable media include, but are not limited to, disks, hard drives, random access memory, programmable read only memory, or any other medium from which a computer can read.

[0042] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. The use of “first”, “second,” etc. for different features / components of the present disclosure are only intended to distinguish the features / components from other similar features / components and not to impart any order or hierarchy to the features / components.

[0043] To aid the Patent Office and any readers of a patent issued on this application in interpreting the claims appended hereto, it is noted that none of the appended claims or claim elements are intended to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

[0044] Recitations of numerical ranges by endpoints include all numbers within that range (e.g., 1 to 5 includes 1 , 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Where a range of values is “greater than”, “less than”, etc., of a particular value, that value is included within the range.{P7501506846067. DOCX}

[0045] Any direction referred to herein, such as “top,” “bottom,” “left,” “right,” “upper,” “lower,” “above,” below,” and other directions and orientations are described herein for clarity in reference to the figures and are not to be limiting of an actual device or system or use of the device or system. Many of the devices, articles, or systems described herein may be used in a number of directions and orientations.

[0046] Any citation to a reference in this disclosure or during the prosecution thereof is made out of an abundance of caution. No citation (whether in an Information Disclosure Statement or otherwise) should be construed as an admission that the cited reference qualifies as prior art or comes from an area that is analogous or directly applicable to the present teachings.

[0047] The present teachings may be used to facilitate diagnostic capabilities of an ignition system using information available within the ignition coil (aka ignition transformer). This may include, for example, a direct measurement connection to the secondary winding somewhere other than at its the ends. In this way, the connection may be used to measure and / or monitor the internal secondary voltage during a spark event, away from its voltage clamping effect, although not limited thereto. The positioning of the connection may be determined by the desired goals of the measurement system.

[0048] As explained in the ‘603 patent, secondary voltage can be measured to time reinforcing pulses and produce a spark having a desired energy envelope. Pulses added on a waveform downswing may reinforce whereas pulses added on an upswing may dampen. The secondary voltage measurement has in the past been taken at the spark gap. However, voltage across the spark external to the coil serves to clamp the secondary voltage. A spark is essentially a Zener diode so that the secondary voltage cannot be{P7501506846067. DOCX}measured at the spark. So while it may be possible to visualize secondary voltage ringing during a spark event using the secondary current, the inability to directly measure secondary voltage can make timing (e.g., added primary drive pulses) more difficult.

[0049] In accordance with the present teachings, a measuring device (e.g., also referred to as a sensor, a wire, sense tape, etc.) may be positioned adjacent (e.g., connected) to the secondary winding somewhere other than at its the ends. This allows measurement of the secondary voltage inside the coil even during a spark event. The amplitude, frequency (or period), shape, etc. of the secondary voltage waveform can be used to determine current operating conditions, as is appreciated by one skilled in the art.

[0050] The measured data can be used to determine a number of things, such as breakdown voltage, secondary current, spark plug condition, secondary component capacitance, secondary fault conditions, etc. A system using such data can provide diagnostic alarms, take corrective actions (e.g., increase available energy, initiate preventive fault shutdown, etc.) to avoid system or engine damage, etc.

[0051] Referring now to FIG. 1, shown is an illustration of one embodiment of a system according to the present teachings. As shown, a wire may be connected to the secondary winding inside the ignition coil. This wire may be referred to as a signal wire that can identify secondary voltage ringing inside the coil, although not limited thereto.

[0052] While one possible position of the wire (i.e. , toward middle) is shown, the wire could be positioned closer to either end of the secondary winding. Changing the position may result in a change to the signal amplitude relative to the firing voltage.{P7501506846067. DOCX}

[0053] The present teachings may be employed in a similar fashion on other types of coil construction, such as paper layer coils or “pencil” coils, although not limited thereto.

[0054] Measurement of the internal secondary voltage waveform (e.g., during the spark event) may be used for diagnostic purposes. There may be a correlation of internal secondary voltage characteristics during a spark event to physical behaviors of the spark. There may also be a correlation of internal secondary voltage characteristics during a spark event to the primary winding measurement. One skilled in the art appreciates the various diagnostic applications for the present teachings.

[0055] Direct, accurate, and real-time measurement of actual spark conditions, breakdown voltage, secondary current, spark duration, spark reserve energy, etc., may be made by employing the present teachings. For example, current behavior may follow voltage behavior, so voltage measurement allows the ability to look ahead at future conditions.

[0056] Using a measuring device (e.g., wire) at the secondary windings may also eliminate the need for a separate secondary voltage sensing device (e.g., at the spark gap).

[0057] Referring now to FIG. 2, shown is another illustration of an embodiment of a system according to the present teachings. As shown, the wire may sense the voltage at an area between the ends of the secondary windings.

[0058] The wire (or other measuring device) may be positioned at position NST anywhere along the length of the secondary winding, where NST = Nsi + NS2. Positioning may depend upon the desired scaling of the signal voltage, where .01 NST < Ns2 < .99NST.{P7501506846067. DOCX}

[0059] The present teachings may be used as a design tool for optimizing simpler ignition systems or as an input into a more sophisticated systems with closed- or open-loop control. There are numerous applications as appreciated by one skilled in the art. Following are several non-limiting examples.

[0060] The present teachings may be used to monitor amplitude of internal secondary voltage ringing. The amplitude of ringing in a waveform of the internal secondary voltage may be both an indication of spark energy already delivered to the spark gap as well as energy left inside the coil for remaining spark duration. A lower amplitude ringing may show the spark is about to go out due to weak sustaining voltage / current. A higher amplitude ringing may show greater spark-sustaining energy reserve within the coil windings. Open circuit may be the condition where minimal spark energy is delivered.

[0061] The present teachings may be used for rapid predictive control of a spark. Amplitude of internal secondary voltage ringing is directly related to secondary current under Ohm’s law (V = IR, where \ / is voltage, I is current, and R is resistance). Since voltage leads current through the secondary winding, the secondary voltage may give an accurate estimation of the current which will follow if the spark conditions remain unchanged. As spark conditions change (e.g., spark channel stretches, etc.) the ringing may also change and the slope (e.g., derivative) of the change may reflect the changing condition.

[0062] The present teachings may be used to more precisely control a spark’s energy envelope (e.g., as discussed in ‘603 Patent). As ringing declines, the minimum spark current may be measured and controlled by reinforcing primary pulses. By use of a comparative control circuit (digital{P7501506846067. DOCX}and / or analog) looking at the amplitude of the internal secondary voltage, a desired secondary spark current profile can be achieved.

[0063] The present teachings may be used to monitor frequency change in the secondary voltage. Frequency change in the voltage ringing of an open circuit waveform may be inversely related to spark-sustaining voltage during a spark. Higher frequency may mean less remaining secondary capacitive charge in the end turns of the coil windings, which may indicate a lower spark voltage during the existing spark duration.

[0064] The present teachings may be used to monitor the shape of the secondary voltage ringing. The shape of the internal secondary voltage ringing may be used to estimate both spark channel length and conductivity, although not limited thereto.

[0065] The present teachings may be used to generate desired discharge wave shapes. Using a capacitive adder at certain points in the secondary winding an LRC structure may modify the resonant frequency of sections of the winding and may be used to generate desired discharge wave shapes. These may be used to extend duration, limit or enhance secondary current, and / or improve energy transfer efficiency, although not limited thereto. The shape of the winding distribution of wire turns can be used to add capacitance at desired positions within the winding without additional costs or materials. Accordingly, this could be used as a design tool for all types of high voltage oscillatory transformers in addition to more typical ignition coils.

[0066] The present teachings may be used to evaluate the magnetic behavior of a core di / dt to identify more information about the spark. This information may in turn be used to improve engine efficiency, although not limited thereto.{P7501506846067. DOCX}

[0067] The present teachings may be used to measure ringing back and forth between the primary and secondary. The greater the internal secondary voltage ringing, the greater the secondary current ringing at a higher frequency. As secondary voltage ringing declines, secondary current oscillations may be diminished. This may be due to the primary ringing back and forth with the secondary through mutual coupling. Positioning of the measuring device may indicate differences in measurement value and style.

[0068] Referring now to FIG. 3, shown is an oscillogram of the internal secondary voltage according to the present teachings. As shown, the internal secondary voltage still rings even when it is shorted at the spark gap due to the presence of a spark. The waveforms have no load other than a scope probe at 5,000 volts per division. The blue waveform shows a wired internal signal according to the present teachings. The yellow waveform shows coil output terminal voltage according to the prior art. When the spark is present the yellow waveform goes flat because the voltage is clamped, but the blue waveform still shows ringing. When the spark ends the yellow waveform shows the ringing again because the clamping effect has ended, as is appreciated by one skilled in the art.

[0069] Referring now to FIG. 4, shown is an oscillogram with open circuit waveforms from both the output and internal signal. As shown, there is no load other than a scope probe at 5,000 volts per division. The blue waveform is an internal signal. The yellow waveform is a coil output voltage signal. As shown, there are essentially no differences in the signals, as may be expected with no load on the coil.

[0070] Referring now to FIG. 5, shown is an oscillogram of internal secondary voltage, secondary voltage at the spark plug, secondary current, and primary pulses. The yellow waveform is secondary voltage at the spark. The green waveform is secondary current at the spark. The pink waveform is{P7501506846067. DOCX}internal secondary voltage. The purple waveform is primary drive pulses to the coil. As shown by the pink waveform, reinforcing pulses (e.g., on downcycles) increase secondary voltage and secondary current during a spark.

[0071] Referring now to FIG. 6, shown is an illustration of another embodiment of a system according to the present teachings. As shown, noncontact measurements of the internal secondary voltage may be employed, such as use of a sense tape, although not limited thereto. Such measuring devices may be used for other coil constructions such as paper layer coils, although not limited thereto.

[0072] A non-contact measuring device (e.g., capacitive sensor, etc.) may include foil tape or a wire laying along the secondary winding inside of the primary bobbin. One or more sensor processors (e.g., cap sensor) could also be embedded in the coil, such as in the primary bobbin, in order to receive and process signals from the measuring device / sensor. By adding straight sense wires or metal foil tape to a plastic primary bobbin the internal secondary voltage, spark breakdown, etc., could be sensed. Such a position in the bobbin may already be isolated for voltage.

[0073] In another example, the measuring device could be at the low end of the coil. In one embodiment, only two pieces of wire may be used in the bobbin, with one all the way to the HV end and the other part way up. Analyzing the difference between these signals may provide more information about the internal electrical characteristics of the coil. The positioning of the measuring device may also show differences in measurement value and style, although not limited thereto.

[0074] Referring now to FIG. 7, shown is an oscillogram of a hard-wired internal sensor and a non-contact sensor. As shown, there is no load other{P7501506846067. DOCX}than a scope probe. The non-contact sensor is at 50 volts while the others are at 5,000 volts per division. The yellow waveform is internal secondary voltage measured with a non-contact sensor. The red waveform is internal secondary voltage measured with a hard-wired sensor. The green waveform is secondary voltage measured at the spark plug. As shown, a non-contact sensor provides a similar waveform as the direct-contact sensor.

[0075] Referring now to FIG. 8, shown is an illustration of another embodiment of non-contact sensing according to the present teachings. As shown, a sensor may be used inside of the bobbin over a target bay. Use of a non-contact sensor may expand sensing options to sense the internal winding voltage and allow multiple winding voltages to be sensed simultaneously and compared for energy transfer calculations, although not limited thereto. One or more non-contact sensors (may be in addition to one or more contact sensors) may be positioned at any number of places to measure the internal secondary voltage or other electrical characteristics, as is appreciated by one skilled in the art.

[0076] Referring now to FIG. 9, shown is an illustration of one embodiment of an engine control system according to the present teachings. As shown, a control unit 900 may be in electronic communication with one or more ignition assemblies 904, 906. Each assembly may include a measuring device 904 (e.g., direct contact sensor(s), non-contact sensor(s), etc.) and an ignition coil 906. Communication between the central control unit 900 and measuring device 904, 904’, 904” may be performed over one or more communication links 902, 902’, 902”. Each assembly may send energy to a spark plug 908, 908’, 908”. The spark plugs may in turn drive crankshafts in an engine 910 (e.g., one or more spark plugs in each engine cylinder), as is appreciated by one skilled it the art.{P7501506846067. DOCX}

[0077] While the present teachings have been described above in terms of specific embodiments, it is to be understood that they are not limited to these disclosed embodiments. Many modifications and other embodiments will come to mind to those skilled in the art to which this pertains, and which are intended to be and are covered by both this disclosure and the appended claims. It is intended that the scope of the present teachings should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings.{P7501506846067. DOCX}

Claims

What is claimed is:

1. An ignition system, comprising:an ignition coil assembly having:an ignition transformer with primary windings and secondary windings, the secondary windings having a length between two ends;a measuring device adjacent the length of the secondary windings;a control unit adapted to regulate timing of primary drive pulses to the ignition transformer for generating a spark at a spark apparatus to ignite a fuel-air mixture in an engine cylinder;the timing based at least in part on measurements made using the measuring device.

2. The system of claim 1 , wherein the measuring device measures an internal secondary voltage of the ignition coil assembly during a spark event.

3. The system of claim 1 , wherein the measuring device directly contacts the secondary windings.

4. The system of claim 3, wherein the measuring device comprises a wire connected to the secondary windings.

5. The system of claim 1 , wherein the measuring device does not directly contact the secondary windings.

6. The system of claim 5, wherein the measuring device comprises a sense tape.

7. The system of claim 1 , wherein the coil assembly comprises a sensor for measuring signals received from the measuring device.{P7501506846067. DOCX}8. The system of claim 1 , wherein the control unit comprises a sensor for measuring signals received from the measuring device.

9. The system of claim 1 , wherein the timing comprises sending one or more reinforcing pulses.

10. The system of claim 9, wherein the timing comprises a strength and / or a length of the one or more reinforcing pulses.

11. The system of claim 1 , wherein the control unit uses an amplitude, a frequency, and / or a shape of an internal secondary voltage waveform to determine current operating conditions.

12. The system of claim 1 , wherein the control unit uses the measuring device to determine a breakdown voltage, a secondary current, a spark plug condition, a secondary component capacitance, and / or a secondary fault condition.

13. An engine system, comprising:an engine;the ignition system of claim 1.

14. An ignition coil assembly, comprising:an ignition transformer with primary windings and secondary windings, the secondary windings having a length between two ends;a measuring device adjacent the length of the secondary windings; the ignition coil assembly adapted to be in communication with a control unit, such that the control unit regulates timing of primary drive pulses based at least in part on measurements made using the measuring device.{P7501506846067. DOCX}15. The assembly of claim 14, further comprising a sensor for measuring signals received from the measuring device.{P7501506846067. DOCX}

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