Method and system for monitoring an injector valve

Abstract

A method for controlling a fuel injector includes applying an overflow valve current, applying a control valve current, the control valve and the overflow valve including components electrically connected to each other, and detecting a timing for the overflow valve to return to an open position based on a sensed overflow valve current. The method further includes detecting a timing for the control valve to return to a stationary position based on a sensed control valve current, the sensed overflow valve current and the sensed control valve current being included in corresponding follow-through currents that at least partially overlap each other, adjusting the overflow valve current applied during injection based on the detected overflow valve return timing, and adjusting the control valve current applied during injection based on the detected control valve return timing.

Description

Technical Field

[0001] The present invention generally relates to systems for internal combustion engines, and more specifically to methods and systems for detecting valve movement in fuel injectors of internal combustion engine systems. Background Technology

[0002] Internal combustion engines include electronic controllers that monitor and control various aspects of engine operation, including the timing and amount of fuel injection. To precisely control fuel injection, some engine systems include controllers that monitor the positions of multiple electronically controlled solenoid valves. This monitoring is performed by analyzing the current generated as the valves move between different positions. However, due to the proximity of these valves, electrical crosstalk can occur. This crosstalk can prevent the controller from monitoring the valve states and from adjusting the control signals used for the fuel injectors to compensate for changes in the injector's performance characteristics.

[0003] U.S. Patent No. 10,060,399 ('399 Patent) to Namuduri et al. discloses a start-up controller for a fuel injector. The controller described in '399 Patent receives feedback signals from the fuel injector, such as flux linkage, voltage, and current. A control module can modify the fuel injector signals for injection events based on this feedback. While the controller and fuel injector described in '399 Patent may be useful in certain situations, they may not provide useful feedback in injector systems where two or more electrical components associated with the fuel injector are affected by crosstalk.

[0004] The disclosed systems and methods can solve one or more of the problems described above and / or other problems in the art. However, the scope of the invention is defined by the appended claims, and not by its ability to solve any particular problem. Summary of the Invention

[0005] In one aspect, a method for controlling a fuel injector in an engine system may include applying an overflow valve current to move the overflow valve of the fuel injector to a closed position, applying a control valve current to move the control valve of the fuel injector to an injection position, the control valve and the overflow valve including components electrically connected to each other, and detecting timing for the overflow valve to return to the open position based on a sensed overflow valve current. The method may further include detecting timing for the control valve to return to a stationary position based on a sensed control valve current, the sensed overflow valve current and the sensed control valve current being included in corresponding follow-through currents that at least partially overlap each other, adjusting the overflow valve current applied during injection based on the detected overflow valve return timing, and adjusting the control valve current applied during injection based on the detected control valve return timing.

[0006] In another aspect, a method for controlling a fuel injector in an engine system, the fuel injector including a first solenoid actuation valve and a second solenoid actuation valve electrically connected to the first solenoid actuation valve, the second solenoid actuation valve having a shorter return time from an actuated position to a stationary position compared to the first solenoid actuation valve, the method may include applying a current to a first solenoid of the first solenoid actuation valve and applying a current to a second solenoid of the second solenoid actuation valve. The method may further include measuring the return timing of at least one of the first solenoid actuation valve or the second solenoid actuation valve and executing a measurement strategy including one or more of the following: causing a first freewheeling current of the first solenoid actuation valve to begin increasing at a timing approximately the same as a second freewheeling current of the second solenoid actuation valve; ignoring a first current peak of the first solenoid actuation valve; or imposing a limit on the regulation of the current applied to the first solenoid, the current applied to the second solenoid, or both.

[0007] In another aspect, a fuel injection control system may include at least one power source and a fuel injector, the fuel injector including an overflow valve biased toward an open position and including an overflow valve solenoid and a control valve biased toward a rest position and including a control valve solenoid electrically connected to the control valve solenoid. The fuel injection control system may also include a controller configured to apply an overflow valve current to move the overflow valve of the fuel injector to a closed position, apply a control valve current to move the control valve of the fuel injector to an injection position, the control valve and the overflow valve including components electrically connected to each other, and detect timing of the overflow valve returning to the open position. The controller may also be configured to detect timing of the control valve returning to the rest position, apply strategies to allow detection of the overflow valve return timing based on inductively sensed overflow valve current and detection of the control valve return timing based on inductively sensed control valve current, and adjust at least one of the overflow valve current applied during injection or the control valve current applied during injection. Attached Figure Description

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the specification, serve to explain the principles of the disclosed embodiments.

[0009] Figure 1 This is a partial schematic cross-sectional view of the fuel injector of a fuel injection system according to various aspects of the present invention.

[0010] Figure 2 yes Figure 1 A block diagram of an exemplary engine control module for a fuel injection system.

[0011] Figure 3 It is shown Figure 1 A diagram illustrating exemplary operation of a fuel injection system.

[0012] Figure 4 It is shown Figure 1 A diagram illustrating exemplary operation of a fuel injection system.

[0013] Figure 5 It is shown Figure 1 A diagram illustrating exemplary operation of a fuel injection system.

[0014] Figure 6 It is shown Figure 1 A diagram illustrating exemplary operation of a fuel injection system.

[0015] Figure 7 This is a flowchart of a method for controlling a fuel injector in an engine system according to an aspect of the present invention. Detailed Implementation

[0016] The foregoing general description and the following detailed description are merely exemplary and illustrative and do not limit the claimed features. As used herein, the terms “comprising,” “including,” “having,” “containing,” or other variations thereof are intended to cover non-exclusive inclusions, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, in this invention, relative terms (e.g., “about,” “substantially,” “usually,” and “approximately,” etc.) are used to indicate possible variations of ±10% in the stated values.

[0017] Figure 1 This is a cross-sectional view illustrating a fuel injection system 10 according to an aspect of the invention, including a fuel injector 12. The fuel injection system 10 may be a component of an internal combustion engine system and may include the fuel injector 12, one or more power sources, and a controller, such as an electronic control module (ECM) 80, configured to supply electrical power to the fuel injector 12. The fuel injector 12 may be a mechanically actuated, electronically controlled unit injector including an injector body 11 housing a plurality of electronically controlled valves that cooperate to inject fuel. The fuel injector 12 may also include a series of channels for supplying, returning, and injecting fuel. A fuel reservoir or pressure chamber 17 may receive fuel from a fuel source. The fuel within the pressure chamber 17 may be pressurized by a cam-actuated piston (not shown) to supply pressurized fuel to a check valve 40. In addition to the check valve 40, the fuel injector 12 may include one or more electronically controlled valves, such as an overflow valve 20, and control valves, such as a direct-operated control (DOC) valve 30.

[0018] The relief valve 20 can be a normally open valve, comprising a relief solenoid 21, a relief armature 23, a relief valve component 25, and a relief valve seat 29. When the relief valve 20 is in the stationary or open position ( Figure 1 When positioned as shown, the relief valve component 25 can be located away from the seat 29 to allow communication between the relief passage 22 and the fuel return passage 13, thereby reducing pressure and allowing fuel to be discharged from the injector 12. When actuated or closed, the relief valve component 25 can rest on the relief valve seat 29 and prevent fuel from entering the fuel return passage 13. This actuation position of the relief valve 20 can be associated with fuel injection.

[0019] DOC valve 30 can be a normally closed valve, comprising DOC solenoid 31, DOC armature 33, DOC valve component 35, and DOC valve seat 36. Figure 1 In the first position (referred to herein as the rest position or closed position) of the DOC valve 30, the DOC valve member 35 is positioned to allow communication between the control chamber 42 and the pressure connection channel 32. When in this closed position, the DOC valve member 35 rests on the DOC valve seat 36 and prevents communication between the control chamber 42 and the low-pressure fuel passage pressure connection channel 38, placing the control chamber 42 in a pressurized state that prevents movement of the check valve member 45. The DOC valve member 35 can be biased toward this closed position by a spring member. In the second position (referred herein as the actuated position or open position), the DOC valve member 35 can block communication between the control chamber 42 and the pressure fuel passage 32, and can allow communication between the control chamber 42 and the low-pressure passage 38, thereby releasing pressure in the control chamber 42. The actuated or open position of the DOC valve 30 can be associated with fuel injection.

[0020] Overflow solenoid 21 and DOC solenoid 31 may be positioned close to each other such that these solenoids are electrically connected to each other. As used herein, the phrases “electrically connected” and “electrically coupled” refer to components that, under at least some conditions, transfer electrical energy to each other to generate crosstalk. For example, a change in current in one of solenoids 21 and 31 can induce a voltage and generate a measurable current in the other solenoid. For example, solenoids 21 and 31 may be induced to be connected to each other.

[0021] Check valve 40 may be a one-way needle valve including check valve component 45, when in Figure 1In the closed position, check valve member 45 prevents communication between check valve chamber 90 and injection orifice 98. In the open position, communication between check valve chamber 90 and injection orifice 98 is allowed, thus allowing fuel injection. Spring member 48 may bias check valve member 45 toward the closed position. Additionally, check valve member 45 may remain in the closed position when control chamber 42 is in communication with pressure connection channel 32. Needle valve member 45 may be configured to move from the closed position to the open position when DOC valve 30 is in the open or actuated position. For example, when relief valve 20 is closed and DOC valve 30 is open, control chamber 42 may be at a lower pressure than the pressure within check valve chamber 90, thus allowing pressurized fuel within check valve chamber 90 to resist the biasing force of spring member 48 and be injected through orifice 98.

[0022] ECM 80 can be configured to receive sensed inputs and generate commands or other signals to control the operation of a plurality of fuel injectors 12 of the fuel injection system 10, each fuel injector 12 including valves 20, 30, and 40. ECM 80 may include a single microprocessor or multiple microprocessors that receive inputs and issue control signals, including applying electrical energy to solenoids 21 and 31. ECM 80 may include a power source (e.g., a battery) electrically connected to solenoids 21 and 31 and may output commands to separate control circuitry, including circuitry for increasing the voltage of the electrical energy applied to solenoids 21 and 31. ECM 80 can be configured to control the application of electrical energy and thus current to solenoids 21 and 31. For example, ECM 80 may issue commands to selectively energize solenoids 21 and 31 with electricity and may control circuitry configured to de-energize solenoids 21 and 31 and control the rate of decay of the electrical energy stored in solenoids 21 and 31. ECM 80 may include memory, auxiliary storage devices, a processor such as a central processing unit, or any other means for performing tasks consistent with the present invention. The memory or auxiliary storage devices associated with ECM 80 may store data and software to allow ECM 80 to perform its functions, including those described below regarding method 700. Figure 7 The functions described herein. In particular, data and software in memory or auxiliary storage devices can allow the ECM 80 to perform any of the valve return timing, signal analysis, and adaptive injector control functions described herein. Many commercially available microprocessors can be configured to perform the functions of the ECM 80. Various other known circuits can be associated with the ECM 80, including signal conditioning circuits, communication circuits, and other suitable circuits.

[0023] Figure 2An exemplary configuration of ECM 80 is shown. In at least some aspects, ECM 80 may receive input 200, including detected values, calculated values, or both. ECM 80 may provide one or more regulated relief valve waveforms 280 and / or regulated DOC valve waveforms 290 as output 270. Waveforms 280 and 290 may correspond to control signals generated by ECM 80 to apply electrical energy to solenoids 21 and 31, respectively.

[0024] The relief valve return time 202 can be a signal indicating the timing of the return of the relief valve member 25 to the resting position where the relief valve 20 is open. This signal can be generated and identified, for example, near the end of an injection event after the time when the relief valve 20 is closed to facilitate fuel pressurization and injection. The control valve return time 204 can be a signal indicating the timing of the return of the control valve member 35 to a resting or closed position after being actuated to inject fuel. Return times 202 and 204 can be analyzed by the ECM 80 to determine each return timing by evaluating the current levels in solenoids 21 and 31, as described below. In one aspect, return times 202 and 204 can be measured during a single injection event. For example, return times 202 and 204 can each correspond to the end of an injection, or the time immediately following an injection and before a subsequent injection. Engine condition 206 can correspond to one or more signals indicating engine parameters, such as engine speed, required engine output, or other factors that the ECM 80 can determine based on these parameters, including quantities and timings associated with fuel injection. Engine condition 206 may include one or more sensed conditions (e.g., engine speed) and one or more conditions calculated by ECM 80 or another control unit (e.g., desired fuel injection quantity).

[0025] Output 270 may correspond to a control signal used to provide electrical power to solenoids 21 and 31 to operate relief valve 20 and DOC valve 30. The regulated relief valve waveform 280 may include a control signal for energizing solenoid 21 and positioning relief valve 20 in the closed position for a desired time period. The regulated control valve waveform 290 may include a control signal for energizing solenoid 31 and positioning DOC valve 30 in the open position for a desired time period. The control signals for the regulated relief valve waveform 280 and the regulated control valve waveform 290 may be modified based on detected times 202 and 204. Return times 202 and / or 204 may be identified via analysis performed by ECM 80 using at least one delay map 230, measurement window 240, or adjustment limit 250. Once analyzed by ECM 80, return times 202 and / or 204 can be compared with corresponding expected return times. Expected valve return times can be determined by retrieving values ​​from valve return time map 260 based on the current engine condition 206.

[0026] Specifically, ECM 80 may include one or more delay maps 230 storing information representing the movement of the relief valve 20. The information stored in the delay maps 230 may include one or more times when the valve of injector 12 will begin to return from the actuated position to the rest position once current is no longer applied to the solenoid associated with the valve. Thus, the delay map 230 may represent a time quantity or delay between a first time and a second time, at which current is no longer applied from the energy source, and at the second time when the freewheeling current is first enabled and monitored. In at least some aspects, this second time may occur after the movement of the valve from the actuated position to the rest position has begun. The information stored in the delay map 230 may be based on the expected performance of the relief valve 20, the DOC valve 30, or both. Specifically, the delay map 230 may include information indicating which valve is expected to return from the actuated position more quickly.

[0027] Measurement window 240 can represent the time period during which the ECM 80 analyzes whether a pattern exists in the follow current that is associated with the current induced by the return of the relief valve 20 and / or the DOC valve 30 to the rest position. Measurement window 240 may include one or more time periods during which the ECM 80 analyzes the current indicating the pattern the valve is returning to. Measurement window 240 may also include one or more time periods during which the ECM 80 ignores the current pattern.

[0028] Adjustment limit 250 may include information corresponding to a limitation imposed on the regulation of the current waveform of relief valve 20 and / or DOC valve 30. ECM 80 may access adjustment limit 250 to determine the maximum permissible regulation achieved by the regulated relief valve waveform 280, the regulated control valve waveform 290, or both. In particular, adjustment limit 250 may represent the latest time at which current can be applied, the earliest time at which current can be withdrawn, or both.

[0029] Valve return time mapping 260 may include information indicating the expected timing of the return of relief valve component 25 or DOC valve component 35 to a rest position after actuation. First mapping 260 may allow ECM 80 to retrieve the expected or desired return time of relief valve 20 for a set of mapping inputs, while second mapping 260 may allow ECM 80 to retrieve the expected or desired return time of DOC valve 30 for a corresponding set of mapping inputs. Inputs to mapping 260 may include, for example, engine condition 206, the instantaneous level of current applied to solenoid 21 or 31 when electrical power is no longer supplied to the solenoid, the cumulative amount of current applied to solenoid 21 or 31 during at least a portion of injection, or the voltage of the power source supplying current to solenoid 21 or 31.

[0030] Industrial applicability

[0031] The fuel injection system 10 can be used with any suitable machine, vehicle, or other device or system including an internal combustion engine having one or more fuel injectors with electronically controlled valves. In particular, the fuel injection system 10 can be used in any internal combustion engine system where it is desirable to detect the timing of the electronically controlled valve components reaching a rest position after actuation. The fuel injection system 10 can be used in systems comprising two or more electrically connected solenoid-actuated valves and can be configured to detect the return timing of each of these valves in a single fuel injection event.

[0032] Figure 3-6 This is a graph illustrating exemplary waveforms of the currents within the overflow solenoid 21 and the DOC solenoid 31 relative to time. The ECM 80 can monitor these currents to identify the return times of the overflow valve 20 and the DOC valve 30. Specifically, the ECM 80 can perform pattern analysis on the freewheeling currents generated via solenoids 21 and / or 31 to identify peaks in these currents that can indicate the timing of the return of the overflow valve 20 and the DOC valve 30 to their respective rest positions. In at least some respects, the monitored freewheeling overflow and control valve currents can at least partially overlap with each other. Figure 3-6 ).

[0033] Reference Figure 3 The relief valve current 300 can be applied to hold the relief valve 20 in the closed position by utilizing the electromotive force generated on the relief armature 23 using the relief solenoid 21. The DOC valve current 350 can be applied to hold the DOC valve 30 in the open position by applying current to the DOC solenoid 31. The relief valve current 300 can be applied until a time coincides with the current consumption 302. At a later time, indicated by time 304, a freewheeling state can be enabled to facilitate the detection of the freewheeling current 306. This freewheeling current 306 may include an induced current component generated by the movement of the relief valve member 25 and the armature 23. For example, this movement can generate an induced current when the electromotive force generated by the solenoid 21 has dissipated to the amount that allows the relief valve member 25 to begin returning from the relief valve seat 29 to the rest position.

[0034] Current 306 may also include crosstalk effects from the current 350 applied to the DOC valve 30. For example, when current 306 is monitored by ECM 80, variations in the DOC valve current 350 can introduce noise that increases or decreases the level of the freewheeling current 306. For instance, the effect of the DOC current waveform 350 may tend to increase current 306, thereby introducing a first current peak 308 that occurs before the actual time it takes for the relief valve 30 to return to its resting position. Since ECM 80 can monitor current 306 for current peaks that indicate the return time of the relief valve 30, ECM 80 can associate peak 308 with that return time, rather than aligning a second current peak 310 with the actual return time of the relief valve 20. In some cases, peak 308 may have approximately the same or greater amplitude as peak 310, which can further interfere with the identification of the actual return time of the relief valve 20.

[0035] DOC valve current 350 can be applied until the electrical energy is recovered at recovery time 360 ​​352. Similar to relief valve member 25, DOC valve member 35 can begin to return to its rest position once the electromotive force dissipates. When DOC valve member 35 returns to its rest position, this movement can induce a current that contributes to the current 354 monitored starting at time 322. The monitored current 354 may include a current peak 356 due to the current induced when DOC valve member 35 reaches its rest position. The freewheeling current 354 may at least partially overlap with the freewheeling current 306.

[0036] Continue to refer to Figure 3 As a first exemplary strategy, the ECM 80 can adjust the timing of activating the circuit 300 used to monitor the relief valve current to reduce the impact of the DOC valve current 350 on the sensed relief valve current. For example, the time for monitoring the relief valve current 300 by enabling the freewheeling state can be extended to a second or adjusted time 322. As in the example shown, the initial rise of the freewheeling current can be delayed by an amount of time such that the freewheeling currents used for the relief valve and the DOC valve begin to rise at approximately the same time (time 322).

[0037] Monitoring the DOC valve current in freewheeling mode can begin after a delay of 340, which can be used to determine time 322. The delay value 340 can be determined based on the current engine condition 206. Figure 2One or more delay maps 230 are queried to retrieve the information. Therefore, for both the relief valve and the DOC valve, the timing for enabling freewheeling can be the same, or it can be offset by a predetermined amount to start at a similar time. This strategy can reduce or eliminate the impact of the DOC valve current 350 on the relief valve current 300. For example, as shown by the dashed line of the relief valve current 300, the freewheeling current 324 can be detected by the ECM 80, allowing the ECM 80 to identify the peak value 326 corresponding to the actual timing of the relief valve 25 returning to its resting position.

[0038] Figure 4 This includes a relief valve current 400 and a DOC valve current 450 for actuating and monitoring valves 20 and 30. The relief valve current 400 may include a freewheeling current 402 with peak values ​​404 and 406, which is measured by the ECM 80 via a freewheeling circuit communicating with the relief solenoid 21. This freewheeling current may include a current component introduced by the DOC valve current 450. The dashed portion of the relief valve current 400 represents a freewheeling current 432 that more closely corresponds to the actual movement of the relief valve member 25. Therefore, the arrival time of the relief valve 25 may result in a current peak 434. The current 402 measured by the ECM 80 may be greater than the current 432 due to the activation of the freewheeling to monitor the induced current and the effects of crosstalk from the DOC valve 30. The DOC valve current 450 may include a freewheeling current 482 with a peak value 484 corresponding to the arrival time of the DOC valve member 35 reaching its rest position.

[0039] As a second exemplary strategy for monitoring the current associated with relief valve 20, DOC valve 30, or both, ECM 80 may apply one or more monitoring windows during which freewheeling current is monitored for patterns indicating valve return timing (e.g., current peaks introduced by induced current). This second strategy may include one or more windows during which patterns such as current peaks in the freewheeling current are ignored. ECM 80 may ignore current peaks occurring outside monitoring window 420. For example, peak 404 occurring outside monitoring window 420 during pre-monitoring window 410 may be ignored. Similarly, peaks or other patterns (if present) may be ignored during pre-monitoring window 460 applied to the analysis of DOC valve current 450.

[0040] Pre-monitoring windows 410 and 460 can be different for different valves of injector 12, such as Figure 4 As shown. Similarly, monitoring windows 420 and 470 can be different for different valves of injector 12. In some respects, valves that tend to return faster (e.g., DOC valve 30) may have a longer monitoring window 470 than valves that return more slowly (e.g., relief valve 20). Information about these return times or delays can be retrieved from delay map 230.

[0041] If needed, ECM 80 can be configured to modify the windows used to monitor the induced current of relief valve 20 and / or DOC valve 30. For example, when ECM 80 determines that crosstalk is more likely to occur (e.g., based on engine condition 206), ECM 80 can reduce the duration of monitoring windows 420 and 470.

[0042] Figure 5 Exemplary waveforms of the relief valve current 500 and the DOC valve current 550 for actuating and monitoring valves 20 and 30 are shown. The relief valve current 500 may include a freewheeling current 502 having a peak value 504 caused by the induced current corresponding to the relief valve member 25. The DOC valve current 550 may be applied as an unregulated DOC valve waveform 552 or a regulated DOC valve waveform 562. The unregulated DOC valve waveform 552 may be applied by interrupting the application of electrical energy to the DOC solenoid 31 at an unregulated time 582. The freewheeling current 554, and in particular the freewheeling current peak value 556, may correspond to the current caused by the movement of the DOC valve 30 when electrical energy is withdrawn at time 582.

[0043] To compensate for performance variations in the DOC valve 30 and / or changes in engine condition 206, the ECM 80 can adjust the timing of the DOC current 550, thereby producing a regulated DOC valve waveform 562. For example, it may be desirable to delay the recovery or dissipation of energy supplied to the DOC solenoid 31 until the adjustment time 584 by continuously applying electrical energy for delay 580. This may result in the freewheeling current 564 having a peak value 566.

[0044] In some respects, ECM 80 may impose limits on the maximum amount by which the DOC current 550 can be extended or the latest point in time at which the DOC current 550 can be applied. This limitation may, for example, prevent the application of a high-level DOC current 550 at a timing point that would overlap with peak 504, or prevent the application of current for a predetermined period prior to peak 504. Figure 5 In the example shown, this limitation can correspond to time 584. Therefore, the DOC current 550 can be prevented from interfering with the detection of the current peak 504 caused by the induced current included in the freewheeling current 502.

[0045] Figure 6Exemplary waveforms of the relief valve current 600 and the DOC valve current 650 according to another example of the third strategy are shown. The relief valve current 600 may include a high current level 602, which is applied for a desired time to keep the relief valve 20 closed. The relief valve current 600 may also include an induced current peak 606 included in the freewheeling current 604. The DOC valve current 650 may be applied as an unregulated DOC valve waveform 652 or a regulated DOC valve waveform 662. Referring to the unregulated DOC valve waveform 652, electrical energy may be applied until an unregulated timing 684. Once the electrical energy is dissipated after the unregulated timing 684, the return movement of the DOC valve member 35 may generate an induced current peak 656 included in the freewheeling current 654.

[0046] ECM 80 can adjust the timing of DOC current 650, for example, to inject a desired amount of fuel. For example, ECM 80 can determine the amount of time the energy source needs to reduce the current applied to DOC solenoid 31, for example, by applying a regulated DOC valve waveform 662, in which no electrical energy is applied and / or consumed at an earlier timing 682. The regulated DOC valve waveform 662 can result in a freewheeling current 664 with a peak value 666.

[0047] As part of a third strategy, ECM 80 can limit the maximum amount by which the DOC current 650 can be advanced (e.g., advanced by 680). For example, this limitation can prevent the application of a high current level 602 at a timing that would overlap with peak 666. Therefore, crosstalk or other noise that would prevent the detection of peak 666 can be avoided, thus facilitating the measurement of the valve return timing of DOC valve 30. Figure 6 In the example, this limit could correspond to time 682.

[0048] Figure 7 This is a flowchart illustrating a method 700 for controlling one or more fuel injectors 12 of an engine system that may include a fuel injection system 10. Method 700 can be repeatedly executed during engine operation to progressively issue commands to one or more valves of the injectors 12 to compensate for changing conditions. Method 700 may, for example, include applying one or more of the strategies described above to detect the return timing of the relief valve 20, the DOC valve 30, or both, even when the follow current associated with valves 20 and 30 overlaps with each other in time. Based on the detected return timing, the waveforms of the relief valve 20 and / or the DOC valve 30 can be adjusted to facilitate precise control of the injectors 12 when the performance of one or more valves of the injectors 12 changes, for example, due to wear.

[0049] In step 702, current may be applied to solenoid 21 to close relief valve 20. Similarly, in step 704, ECM 80 may control the application of current to open DOC valve 30. Steps 702 and 704 may include applying current to each valve 20 and 30 until a desired timing.

[0050] During step 706, ECM 80 may apply a first strategy, a second strategy, a third strategy, or any combination thereof to facilitate the measurement and monitoring of freewheeling current. This freewheeling current may include the current caused by the return of relief valve 20 and the current caused by the return of DOC valve 30. These freewheeling currents may occur at timings that at least partially overlap with each other. For example, in the first strategy, the timing of monitoring the freewheeling current in the first valve may be delayed or alternatively advanced. This can be implemented such that the first valve (which may be a valve that returns more slowly (e.g., relief valve 20)) will experience an initial increase in freewheeling current at approximately the same time as enabling freewheeling current for a faster valve (e.g., DOC valve 30). This can, for example, ensure that the dwell time after the application of electrical energy is within an acceptable window for both valves. A second strategy, which may be performed alone or in combination with the first or third strategy, may include the use of one or more pre-monitoring windows and one or more monitoring windows, as described above. A third strategy, which may be performed alone or in combination with the first or second strategy, may include imposing one or more limits on the amount of current regulated for relief valve 20, DOC valve 30, or both.

[0051] Step 708 may include detecting the return timing of the relief valve 20 and the DOC valve 30 while executing one or more of the strategies applied during step 706. This prevents crosstalk from interfering with the detection of the valve return timing 202 of the relief valve 20 and the valve return timing 204 of the DOC valve 30. For a single fuel injection, both valve return times can be detected.

[0052] In step 710, the ECM 80 may adjust at least one characteristic of the current applied for closing the relief valve 20, opening the DOC valve 30, or both. This may be performed, for example, based on a detected relief valve return timing 202 and a detected DOC valve return timing 204. The current characteristic may include, for example, the timing of starting to apply electrical energy, the timing of stopping to apply electrical energy, and / or the duration of applying electrical energy.

[0053] In some fuel injectors, obtaining measurements from two or more valves is useful. One or more strategies can be used to allow simultaneous valve monitoring, even when valve components are electrically connected. This simultaneous monitoring, which can be performed by detecting the valve return time during a single fuel injection, can help to accurately assess the actual operation of the fuel injector. By measuring the valve return time, the duration of the current applied during subsequent injections can be adjusted to minimize fuel delivery variability and increase control over the amount of fuel injected. Controlling the amount of fuel injected can help to inject the minimum amount of fuel, such as in ignition injections performed during the main injection or post-injections performed after the main injection. Precise injection of small amounts of fuel can improve emissions performance and reduce the amount and / or opacity of smoke produced by the engine.

[0054] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and systems without departing from the scope of the invention. Other embodiments of the methods and systems will become apparent to those skilled in the art upon consideration of the description and practice of the devices and systems disclosed herein. This specification and examples are intended to be considered merely exemplary, and the true scope of the invention is indicated by the appended claims and their equivalents.

Claims

1. A method for controlling a fuel injector in an engine system, the method comprising: Apply an overflow valve current to move the overflow valve of the fuel injector to the closed position; Apply current to the control valve to move the control valve of the fuel injector to the injection position, wherein the control valve and the relief valve include components electrically connected to each other; The timing for the overflow valve to return to the open position is based on the current detection of the overflow valve. The timing of the control valve returning to the stationary position is detected based on the sensing control valve current, wherein the sensing relief valve current and the sensing control valve current are included in corresponding freewheeling currents that at least partially overlap with each other. The overflow valve current applied during injection is adjusted based on the timed return of the overflow valve to the open position detected. as well as The control valve current applied during injection is adjusted based on the timed return of the detected control valve to the stationary position.

2. The method according to claim 1, wherein the timing of sensing the overflow valve current does not overlap with the timing of applying the control valve current.

3. The method of claim 2, wherein the overflow valve current and the control valve current are applied such that the freewheeling current starts simultaneously.

4. The method of claim 1, wherein a peak value of at least one of the inductive overflow valve current and the inductive control valve current appearing within the measurement window is detected.

5. The method of claim 4, wherein current peaks occurring outside the measurement window are ignored.

6. The method of claim 1, wherein the amount of time during which the relief valve current is regulated is limited to increase or decrease.

7. The method of claim 1, wherein the increase or decrease in the amount of time during which the control valve current is regulated is limited.

8. A fuel injection control system, comprising: At least one power source; Fuel injector, comprising: An overflow valve, the overflow valve being biased toward an open position and including an overflow valve solenoid; A control valve, the control valve being biased toward a rest position and including a control valve solenoid electrically connected to the relief valve solenoid; and The controller is configured as follows: Apply an overflow valve current to move the overflow valve of the fuel injector to the closed position; Apply current to the control valve to move the control valve of the fuel injector to the injection position; The timing for detecting the return of the overflow valve to the open position; The timing of the control valve returning to the stationary position is detected; Detection of timing for the return of the relief valve to the open position based on the sensing of the relief valve current and timing for the return of the control valve to the stationary position based on the sensing of the control valve current; and Adjust at least one of the overflow valve current applied during injection and the control valve current applied during injection.

9. The fuel injection control system of claim 8, wherein a peak value of at least one of the following occurring within the measurement window, comprising the inductive overflow valve current and the inductive control valve current, is detected.

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