Power draw control for fuel injectors

Abstract

In one example, disclosed herein is a method for controlling a fuel injector of an engine system, the method comprising: based on engine operating conditions of the engine system, determining a pull-in duration of the fuel injector during which current is applied to move a valve member away from a rest position; applying a current to a valve solenoid to move the valve member of the fuel injector to a closed position for the determined pull-in duration; and after the determined pull-in duration, reducing the current applied to the valve solenoid to a holding level.

Description

Technical Field

[0001] The present disclosure relates generally to internal combustion engines and, more particularly, to methods and systems for controlling power draw of fuel injectors. Background Art

[0002] Internal combustion engines typically include an electronic controller that manages and / or monitors various aspects of the operation of the internal combustion engine. For example, in order to accurately control the timing and / or amount of fuel injected into the internal combustion engine by a fuel injector included in the internal combustion engine, the internal combustion engine system includes a controller that manages and / or monitors the position of one or more electronically controlled valves (e.g., solenoid valves) housed in the fuel injector. For efficiency, safety, or regulatory purposes, it is necessary to control or reduce the power drawn by the fuel injector on one or more power supplies that provide electrical energy to one or more electronically controlled valves. For example, if the power drawn by the fuel injector is not properly controlled or reduced, a tightly timed injection from the fuel injector may cause the power supply that provides electrical energy to one or more electronically controlled solenoids of the fuel injector to exceed its power limit.

[0003] U.S. Patent No. 6,571,773 to Yamakado et al. (the '773 patent) discloses a method for controlling a fuel injector that includes monitoring the current and / or voltage applied to a valve of the fuel injector. The controller described in the '773 patent monitors the voltage supplied to the fuel injector to maintain linearity of injection volume. However, the '773 patent does not disclose a method or system for mapping or controlling the power draw of the fuel injector.

[0004] The methods and systems of the present disclosure may solve one or more of the above problems and / or other problems in the art. However, the scope of protection provided by the present disclosure is defined by the appended claims, rather than by the ability to solve any specific problem. Summary of the Invention

[0005] In one aspect, a method for controlling a fuel injector of an engine system includes: determining an energization duration of the fuel injector during which current is applied to move a valve member away from a rest position based on an engine operating condition of the engine system; applying current to a valve solenoid to move the valve member of the fuel injector to a closed position for the determined energization duration; and reducing the current applied to the valve solenoid to a holding level after the determined energization duration.

[0006] On the other hand, a method for controlling a fuel injector of an engine system includes: for an injection event: based on an engagement duration map generated for the fuel injector, applying current to a valve solenoid to move a valve of the fuel injector to an actuated position for a second engagement duration, adjusting the start of the current for the second engagement duration based on the measured valve arrival time, and after the second engagement duration, reducing the current applied to the valve solenoid to a holding level.

[0007] On the other hand, an engine system may include at least one fuel injector and a controller that is operable to: determine an engagement duration of the fuel injector based on an engine operating condition of the engine system; apply current to a valve solenoid to move a valve of the fuel injector to an actuated position for the determined engagement duration; and reduce the current applied to the valve solenoid to a holding level after the determined engagement duration. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0009] Figure 1 depicts a schematic cross-sectional view of a fuel injector;

[0010] Figure 2 Depicts the Figure 1 A block diagram of an exemplary electronic control module for use with a fuel injector;

[0011] Figure 3 Depicted Figure 2 A diagram illustrating an exemplary pull-in duration map for an electronic control module;

[0012] Figure 4 depicts a graph representing a series of exemplary end-of-line (EOL) tests;

[0013] Figure 5 Depicted Figure 1 A diagram of an exemplary operation of a fuel injector;

[0014] Figure 6 Depicted Figure 1 a diagram of an exemplary operation of a fuel injector; and

[0015] Figure 7 A flow chart of a method for controlling a fuel injector is depicted. DETAILED DESCRIPTION

[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 "comprises," "comprising," "having," "containing," or other variations thereof are intended to encompass non-exclusive inclusions such that a process, method, article, or apparatus comprising a series of elements may include not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, in this disclosure, relative terms (such as, "approximately," "substantially," "generally," and "approximately," etc.) are used to indicate a possible variation of ±10% in the stated value. In this disclosure, the term "based on" or any other variation thereof is intended to encompass, for example, "based in part on," "based at least in part on," and "based entirely on."

[0017] Figure 1 A schematic cross-sectional view of a fuel injector 12 is illustrated. The fuel injector 12 may be a component of a fuel injection system 10, which may also include one or more power sources (e.g., one or more batteries, or one or more high-voltage power systems; not shown) and one or more controllers (e.g., an electronic control module or ECM 80). The fuel injection system 10 may be a component of an engine system (e.g., an internal combustion engine or ICE). The one or more controllers 80 of the fuel injection system 10 may be operable to cause the one or more power sources to provide electrical energy to one or more components of the fuel injector 12 (such as one or more solenoid valves). The components of the fuel injector 12 may be operable to cause the fuel injector 12 to inject fuel into another component of the engine system to which the fuel injector 12 is connected, such as a combustion chamber (not shown).

[0018] The fuel injector 12 may be a mechanically actuated, electronically controlled fuel injector in which fuel is pressurized by a cam (not shown) and injected based on a signal generated by the ECM 80. Figure 1 As illustrated, the fuel injector 12 may include an injector body 11. The injector body 11 may house various components of the fuel injector 12, such as a fuel reservoir 17, one or more valves (e.g., electronically controlled solenoid valves), such as a relief valve 20 and a control valve 30, and a series of passages for supplying, returning, and injecting fuel. The fuel reservoir 17 may receive fuel from a fuel source (not shown), which may be pressurized, such as by a cam-actuated piston (not shown), to provide pressurized fuel to a check valve 40. The operation of the check valve 40 may be managed by the relief valve 20 and the control valve 30.

[0019] The relief valve 20 may be a normally open valve including a relief valve solenoid 21, a relief valve armature 23, a relief valve member 25, and a relief valve seat 29. When the relief valve 20 is at rest (e.g., when the relief valve 20 is not actuated by electrical energy), the relief valve 20 is in an open or non-injection position, such as Figure 1 As illustrated. In the open position or non-injection position, the relief valve member 25 can be positioned away from the relief valve seat 29, thereby allowing communication between the relief passage 22 and the fuel return passage 13. In such a configuration, fuel is allowed to be discharged from the fuel injector 12, thereby reducing the pressure within the fuel injector 12 (e.g., the pressure within the fuel reservoir 17). The relief valve 20 can be biased toward the open position or non-injection position by a spring 24.

[0020] When the relief valve 20 is fully actuated (e.g., by electrical energy), the relief valve 20 is in a closed position. In the closed position, the relief valve member 25 can engage the relief valve seat 29, thereby preventing communication between the relief passage 22 and the fuel return passage 13. In such a configuration, fuel is not allowed to be discharged from the fuel injector 12, thereby causing the pressure within the fuel injector 12 (e.g., the pressure within the fuel reservoir 17) to increase. In some examples, the fuel injector 12 does not release fuel until the relief valve 20 is actuated to the closed position and the pressure within the fuel injector 12 has increased accordingly. Therefore, the actuated position or closed position of the relief valve 20 can be associated with the injection of fuel.

[0021] The control valve 30 may include a control valve solenoid 31, a control valve armature 33, a control valve member 35, and a control valve seat 36. When the control valve 30 is at rest (e.g., when the control valve 30 is not actuated by electrical energy), the control valve 30 is in a non-injection position, such as Figure 1 In the non-injection position, the control valve member 35 may be positioned so as to allow communication between the control chamber 42 and the high pressure connecting passage 32, as shown. Figure 1 In such a configuration, the control valve member 35 can engage the control valve seat 36 and prevent communication between the control chamber 42 and the low pressure connecting passage 38, thereby placing the control chamber 42 in a pressurized condition that prevents movement of the check valve member 45. The control valve 30 can be biased toward the non-injection position by the spring 24.

[0022] When the control valve 30 is fully actuated (e.g., by electrical energy), the control valve 30 is in the injection position. In the injection position, the control valve member 35 can prevent communication between the control chamber 42 and the high-pressure connecting passage 32 and can allow communication between the control chamber 42 and the low-pressure connecting passage 38, thereby reducing the pressure in the control chamber 42. The reduced pressure in the control chamber 42 allows the check valve member 45 to move and ultimately allows the fuel injector 12 to release fuel.

[0023] The check valve 40 may be a one-way valve including a check valve member 45. Figure 1 In the illustrated closed check position, communication between the check valve chamber 90 and the injection orifice 98 is prevented. When the check valve member is in the open position, communication between the check valve chamber 90 and the injection orifice 98 is permitted, thereby allowing fuel to be released. Spring 48 may bias the check valve member 45 toward the closed check position. Additionally, when the control chamber 42 is in communication with the high-pressure connecting passage 32 (e.g., when the control valve 30 is in the non-injection position, as described above), the check valve member 45 may remain in the closed check position. The needle valve member 45 may be configured to move from the closed check position to the open check position when the control valve 30 is in the actuated or injection position. For example, when the relief valve 20 is in the closed position and the control valve 30 is in the injection position, the control chamber 42 may be at a lower pressure than the pressure within the check valve chamber 90, thereby allowing pressurized fuel within the check valve chamber 90 to lift the check valve member 45 against the biasing force of spring 48 and release fuel through the orifice 98.

[0024] The ECM 80 can be configured to receive sensed inputs and generate commands or other signals to monitor or control the operation of the plurality of fuel injectors 12 of the fuel injection system 10. The ECM 80 can include a single microprocessor or multiple microprocessors that receive inputs and issue control signals, including the application of electrical energy to the solenoids 21 and 31. The ECM 80 can be configured to control the application of electrical energy (and therefore the current) to the solenoids 21 and 31. For example, the ECM 80 can issue commands to selectively energize the solenoids 21 and 31 with electrical power (e.g., increase the current applied to these solenoids), and can control circuits configured to de-energize the solenoids 21 and 31 (e.g., decrease the current applied to these solenoids) and / or control the decay rate of the electrical energy stored by the solenoids 21 and 31. The ECM 80 can include memory, secondary storage devices, a processor (such as a central processing unit), or any other component for performing tasks consistent with the present disclosure. The memory or secondary storage device associated with the ECM 80 may store data and software to enable the ECM 80 to perform its functions, including those described below with respect to method 700 ( Figure 7 ) described herein. Specifically, the data and software in the memory or secondary storage device may enable the ECM 80 to perform any of the valve return timing, signal analysis, and adaptive injector control functions described herein. Many commercially available microprocessors may be configured to perform the functions of the ECM 80. Various other well-known circuits may be associated with the ECM 80, including signal conditioning circuitry, communication circuitry, and other appropriate circuitry.

[0025] Figure 2A block diagram of an exemplary electronic control module (ECM) 80 is depicted. As mentioned above, the ECM 80 may include a processor 81, a memory 82, or any other components for performing tasks consistent with the present disclosure. The ECM 80 may be operable to generate and output commands for controlling the fuel injectors 12, such as a relief valve command 83 for controlling the electrical energy applied to the relief valve 20 (e.g., the relief valve solenoid 21) or a control valve command 84 for controlling the electrical energy applied to the control valve 30 (e.g., the control valve solenoid 31). The relief valve command 83 and the control valve command 84 may be generated or output by the ECM 80 in the form of signals or waveforms corresponding to instructions for applying or providing electrical energy to the relief valve 20 or the control valve 30, respectively. The ECM 80 may generate and output commands for controlling the fuel injectors 12 based on or in response to engine operating conditions 85. Engine operating conditions 85 may correspond to one or more signals indicative of engine parameters, such as engine speed generated or sensed by engine speed sensor 87, requested engine output reflected in engine request 88 generated by an operator or calculated by ECM 80, or any other input that ECM 80 may use to determine various factors associated with fuel injection. Engine operating conditions 85 may include one or more sensed operating conditions (e.g., engine speed from sensor 87) and one or more operating conditions calculated by ECM 80 or another control unit (e.g., a desired fuel injection amount reflected in engine request 88).

[0026] The ECM 80 may be operable to generate a relief valve command 83 or a control valve command 84 based, at least in part, on one or more pull-in duration maps 86. As mentioned above, it may be desirable to control or reduce the power drawn by the fuel injector 12 from one or more power supplies that provide electrical energy to one or more electronically controlled solenoids of the fuel injector 12. As described in further detail below, the ECM 80 may be operable to control the power drawn by the fuel injector 12 using one or more pull-in duration maps 86. The pull-in duration map 86 may represent a relationship between the amount of power drawn by the fuel injector 12 and an amount of time, which may be referred to as the pull-in duration. The pull-in duration may represent an amount of time that elapses after entering a pull-in current level or stage. This amount of time may be measured initially, for example, when electrical energy applied to a valve of the fuel injector 12 is first increased to actuate the valve of the fuel injector 12, or upon reaching a predetermined threshold electrical energy level (e.g., current level) associated with the pull-in current level. The pull-in current level may be the amount of electrical energy applied to a valve (e.g., relief valve 20) of fuel injector 12 to move the valve to an actuated position (e.g., a closed position). The pull-in duration may end at a second time when the electrical energy applied to the valve of fuel injector 12 begins to decrease to a lower intermediate level (the intermediate level may be referred to as a hold level) that holds the valve in the actuated position.

[0027] The amount of time that elapses between the first time (which may be referred to as the pull-in time) and the second time may be referred to as the pull-in duration. Generally, a longer pull-in duration results in more power being drawn by the fuel injector 12. Given a particular pull-in duration, the power drawn by the fuel injector 12 may be determined at least in part by one or more engine operating conditions 85, such as engine speed.

[0028] For example, Figure 3 An exemplary pull-in duration map 86 generated for a fuel injector 12 is depicted. In this example, through a series of tests (e.g., end-of-line (EOL) tests) performed on the fuel injector 12 (as described in more detail below), the relationship between different pull-in durations and the power drawn by the fuel injector 12 on one or more power supplies can be determined given a particular engine speed of an engine system (which includes the fuel injector 12). Figure 3 Four pull-in durations 302A to 302D are shown, but more than four durations or less than four durations may be tested. In this example, the lengths of the pull-in durations 302A to 302D decrease from left to right (e.g., 302A is the longest pull-in duration, and 302D is the shortest pull-in duration).

[0029] like Figure 3 As depicted, for any given engine speed, a shorter pull-in duration results in a lower amount of power drawn by the fuel injector 12. For example, at a first engine speed 306, the pull-in duration 302A, which may have the longest length, results in a first power draw; the pull-in duration 302B, which may have a shorter length, results in a second power draw that is less than the first power draw; the pull-in duration 302C, which may have a third length that is shorter than the first and second lengths, results in a third power draw that is less than the first and second power draws; and the pull-in duration 302D, which may have a fourth length, results in a fourth power draw that is less than each of the first, second, and third power draws. Figure 3 As depicted, one or more power sources providing electrical energy to the fuel injectors 12 may have a power limit 304 .

[0030] In some examples, one or more pull-in duration maps 86 may be generated by performing a series of tests (e.g., end-of-line (EOL) tests) on the fuel injector 12. EOL tests may be quantitative or qualitative control tasks performed at the end of a production line or at another time after manufacturing. For example, before the fuel injector 12 is used in the engine of a machine, the manufacturer of the fuel injector 12 may perform one or more EOL tests on the fuel injector 12 to ensure that the fuel injector 12 can withstand a certain amount (e.g., commercial grade) of heat, cold, or pressure. Any number of EOL tests may be performed on the fuel injector 12 to test any number of qualitative or quantitative metrics or factors of the fuel injector 12. However, in some examples, tests may be performed (e.g., by the ECM 80) on the fuel injector 12 during operation of the fuel injector 12 (e.g., during startup, shutdown, or steady-state operation of the engine system that includes the fuel injector 12) to generate the pull-in duration map 86 for the fuel injector 12. If desired, each fuel injector 12 may be tested individually so that the pull-in duration map 86 is specific to a single fuel injector 12.

[0031] Figure 4 A series of exemplary tests for generating the pull-in duration map 86 for the fuel injector 12 is depicted. Figure 4 Three tests 400A to 400C are depicted. For each of these three tests, the electrical energy 402 applied to the relief valve solenoid 21 of the fuel injector 12 was increased to simultaneously move the relief valve 20 of the fuel injector 12 to the closed position. However, in each test, the electrical energy 402 applied to the relief valve solenoid 21 of the fuel injector 12 was reduced to a holding level (as described above) to maintain the relief valve 20 of the fuel injector 12 in the closed position for a different period of time, thus each test having a different engagement duration (as described above). For example, the electrical energy 402 applied to the relief valve solenoid 21 of the fuel injector 12 in test 400A was reduced to a holding level earlier than in tests 400B and 400C; accordingly, test 400A had the shortest engagement duration. Similarly, test 400B begins reducing the electrical energy 402 applied to the spill valve solenoid 21 of fuel injector 12 to the holding level later than test 400A but earlier than test 400C, and thus has a longer pull-in duration than test 400A but shorter than test 400C. Test 400C begins reducing the electrical energy 402 applied to the spill valve solenoid 21 of fuel injector 12 to the holding level later than both tests 400A and 400B, and thus has the longest pull-in duration of the three tests. Accordingly, test 400C has the highest power draw on fuel injector 12, test 400A has the lowest, and test 400B falls between the two.

[0032] Thus, for each of the tests 400A-400C performed on the fuel injector 12, a different pull-in duration is tested, and the power draw of the fuel injector 12 is determined for the pull-in duration, thereby generating a power draw pull-in duration data point for the fuel injector 12. In this way, by performing a series of tests on the fuel injector 12, a pull-in duration map 86 can be generated that represents the expected power draw for any given pull-in duration. The pull-in duration map 86 generated for the fuel injector 12 can be provided to the ECM 80, which manages the operation of the fuel injector 12 in the engine system in which the fuel injector 12 is included. Then, given appropriate inputs, the ECM 80 can use the pull-in duration map 86 generated for the fuel injector 12 to determine the appropriate pull-in duration for the fuel injector 12 and generate and / or output a control command (e.g., a spill valve command 83 or a control valve command 84) based on the determined pull-in duration, as described in further detail below. After the pull-in duration map 86 is generated through a series of tests (e.g., EOL tests), the pull-in duration map 86 may be provided to the ECM 80 before or after the fuel injector 12 and / or after the ECM 80 is installed in a machine that employs the fuel injector 12. The pull-in duration map 86 may be provided to the ECM 80 in the form of one or more electronic or digital files or documents (e.g., adjustment files) that are readable by the ECM 80.

[0033] In some examples, the power drawn by the fuel injector 12 given a particular pull-in duration may be determined at least in part by one or more engine operating conditions 85, such as engine speed. In some such examples, the pull-in duration map 86 may be generated by testing individual pull-in durations across a range of engine speeds, such as Figure 3 Depicted. In some examples, valve arrival time (VAT) may be determined during one or more EOL tests. VAT may be the amount of time it takes for a valve of a fuel injector 12 to reach a fully actuated position, measured from the time the electrical energy applied to the valve solenoid of the fuel injector 12 is first increased to move the valve to the fully actuated position. In some examples, the pull-in duration determined for the fuel injector 12 is at least as long as the VAT determined for the fuel injector 12. The VAT may be measured directly or indirectly, such as by measuring a pressure-controlled start of injection (SOI) time. However, the VAT of the fuel injector 12 may be determined in any other suitable manner. For example, in some examples, the ECM 80 is capable of identifying, detecting, or determining the VAT of the valve of the fuel injector 12 in real time or near real time during operation of the fuel injector 12 within an engine system that includes the ECM 80.

[0034] Industrial Applicability

[0035] The fuel injection system 10 can be used in conjunction with any suitable machine, vehicle, or other device or system including an engine system (e.g., an internal combustion engine) having one or more fuel injectors 12 with electronically controlled valves. In particular, the fuel injection system 10 can be used in any internal combustion engine in which it is desirable to control the power drawn by the fuel injectors 12 included in the internal combustion engine. Generally, lower power draw reduces costs and improves the efficiency and safety of the engine system.

[0036] In some examples, to release a portion of fuel from fuel injector 12, relief valve 20 of fuel injector 12 is initially at rest in an open position, and control valve 30 of fuel injector 12 is initially at rest in a non-injection position. Electrical energy is then applied to relief valve solenoid 21 of relief valve 20 to move relief valve 20 to a closed position. When relief valve 20 is in the closed position, pressure within the fuel injector increases (as described above). Electrical energy is applied to control valve solenoid 31 to move control valve 30 to an injection position (as described above), thereby allowing the pressurized fuel within fuel injector 12 to be released from fuel injector 12 in a single portion of fuel. The electrical energy applied to both relief valve solenoid 21 and control valve solenoid 31 is then reduced (simultaneously or at different times) to move the respective valves or allow the respective valves to return to their respective resting positions. Each iteration of this cycle may be referred to as an injection event.

[0037] For both the relief valve 20 and the control valve 30, the electrical energy applied to the solenoid can be reduced to an intermediate holding level (as described above) between the time that electrical energy is increased to move the valve to its respective actuated position (which time may be referred to as the pull-in time) and the time that electrical energy is decreased to return the valve or allow the valve to return to its respective rest position. For both valves, the electrical energy applied to the solenoid can be reduced to an intermediate holding level (as described above) between 1) the time that electrical energy is increased to move the valve to its respective injection position (e.g., time t1, as described above). Figure 5 t2, as depicted and described in further detail below) and 2) the time at which the electrical energy applied to the valve is first reduced to a holding level (e.g., t2, as Figure 5 The amount of time that elapses between 1) the time when the electrical energy applied to the valve is first reduced to a holding level and 2) the time when the electrical energy applied to the valve begins to be further reduced to return the valve or allow the valve to return to its respective rest position can be referred to as the hold duration (e.g., the relief hold duration or the control hold duration, respectively). For both valves, the amount of time that elapses between 1) the time when the electrical energy applied to the valve is first reduced to a holding level and 2) the time when the electrical energy applied to the valve begins to be further reduced to return the valve or allow the valve to return to its respective rest position can be referred to as the hold duration (e.g., the relief hold duration or the control hold duration, respectively).

[0038] In some examples, the electrical energy supplied to the valve of fuel injector 12 during the pull-in duration or the hold duration is maintained within a specific range defined by the maximum and minimum electrical energy values ​​set for the pull-in duration or the hold duration. In such examples, the electrical energy supplied to the valve of fuel injector 12 can be allowed to alternately increase until it reaches a maximum value and decrease until it reaches a minimum value, such as by connecting and disconnecting fuel injector 12 from one or more power sources, respectively, in a process that can be referred to as chopping. Chopping can reduce the power draw of fuel injector 12 from the one or more power sources providing electrical energy to fuel injector 12 and / or can help prevent the coil of a solenoid or other electrical component from generating more heat than necessary.

[0039] Figure 5 Depicted are the spill valve command and the control valve command (both in waveform form) for releasing two portions of fuel from the fuel injector 12. Figure 5 In the depicted example, the electric energy applied to the relief valve solenoid 21 of the fuel injector 12 (upper waveform) and the electric energy applied to the control valve solenoid 31 of the fuel injector 12 (lower waveform) are respectively plotted with respect to the same time period.

[0040] The electrical energy applied to the spill valve solenoid 21 is shown for operating the fuel injector 12 using the power draw control method and system disclosed herein (upper solid line graph) and not using the power draw control method and system disclosed herein (upper dashed line graph). For example, for the first portion of fuel released from the fuel injector 12, as shown in FIG. Figure 5 As depicted, without using the power draw control methods and systems disclosed herein, at time t1, the electrical energy 502A applied to the spill valve solenoid 21 of the fuel injector 12 is increased to move the spill valve 20 of the fuel injector 12 to a closed position. The time during which the electrical energy applied to the spill valve solenoid 21 of the fuel injector 12 is increased to move the spill valve 20 of the fuel injector 12 to a closed position may be referred to as a spill pull-in time. The electrical energy 502A applied to the spill valve solenoid 21 of the fuel injector 12 may then be reduced, for example, at time t3 to a spill hold level that holds the spill valve 20 in the closed position (as described above). The amount of time that elapses between the spill pull-in time (e.g., time t1) and the time at which the electrical energy applied to the spill valve 20 is first reduced to the spill hold level (e.g., time t3) may be referred to as a spill pull-in duration (e.g., a spill pull-in duration 503A). When the relief valve 20 is in the closed position, the pressure within the fuel injector 12 increases.

[0041] like Figure 5As depicted, at time t4 a certain time after the overflow engage time (e.g., time t1), the electrical energy 504 applied to the control valve solenoid 31 of the fuel injector 12 is increased to move the control valve 30 of the fuel injector 12 to the open position or injection control position, thereby allowing the pressurized fuel within the fuel injector 12 to be released from the fuel injector 12 in the first portion of fuel. The time during which electrical energy is applied to the control valve solenoid 31 of the fuel injector 12 to move the control valve of the fuel injector 12 to the open position or injection control position may be referred to as the control engage time. If desired, the electrical energy 504 applied to the control valve solenoid 31 of the fuel injector 12 may then be reduced to a control hold level that maintains the control valve 30 in the open position or injection control position (as described above) at time t5. As Figure 5 As depicted, the same or similar spill valve command and control valve command may be used to release a second portion of fuel from the fuel injector 12 .

[0042] like Figure 5 As depicted, using the power draw control method and system disclosed herein, the electrical energy 502B applied to the spill valve solenoid 21 of the fuel injector 12 can be increased to move the spill valve 20 of the fuel injector 12 to the closed position at the same energizing time as the electrical energy 502A (e.g., time t1); however, the electrical energy 502B applied to the spill valve solenoid 21 of the fuel injector 12 can be reduced to the spill holding level at an earlier time (e.g., time t2) than the time when the electrical energy 502A is reduced (e.g., time t3), resulting in a spill energizing duration 503B that is shorter than the spill energizing duration 503A. Because the spill energizing duration 503B is shorter than the spill energizing duration 503A, the power drawn by the fuel injector 12 according to the waveform of the electrical energy 502B will be less than the power drawn by the fuel injector 12 according to the waveform of the electrical energy 502A.

[0043] To determine the length of the overflow pull-in duration 503B, one or more pull-in duration maps 86 may be used. For example, Figure 3 The depicted pull-in duration map 86 may correspond to a Figure 5 , the flooded pull-in duration map 86 is generated by the fuel injector 12 of the example, which is generated using a series of tests performed on the fuel injector 12 (as described above). In this example, the ECM 80 included in the engine system including the fuel injector 12 can retrieve the flooded pull-in duration map 86 and use the flooded pull-in duration map to determine the length of the flooded pull-in duration 503B for the waveform of the electrical energy 502B, such as by determining or receiving the engine operating conditions 85 including the engine speed of the engine system, and determining the appropriate length of the flooded pull-in duration 503B based on the engine speed. In some examples, such as Figure 5As depicted, when the ECM 80 uses a relatively short pull-in duration, the ECM 80 uses a relatively high level of electrical energy during the corresponding hold duration. This may be because more electrical energy may be required to hold the relief valve in a closed position if a shorter pull-in duration is used.

[0044] In some examples, the engine system may include multiple power sources capable of providing electrical energy to the fuel injectors 12 included in the engine system. In some such examples, the engine system may use different power sources or different combinations of power sources to provide electrical energy to the fuel injectors 12 at different times. For example, in some examples, the engine system may include a high-voltage energy source (e.g., an alternator, a generator, etc.) capable of providing electrical energy to one or more solenoids of the fuel injectors 12 and a low-voltage energy source (e.g., a battery) capable of providing electrical energy to the fuel injectors 12. In some such examples, the engine system (e.g., the ECM 80 included in the engine system) may use the high-voltage energy source to provide electrical energy to the fuel injectors 12 during the flood pull-in duration (e.g., the flood pull-in duration 503B) and use the low-voltage energy source to provide electrical energy to the fuel injectors 12 during the flood hold duration. For example, immediately after the flood pull-in duration 503B, (e.g., throughout the flood hold duration) the engine system may switch from using a high-voltage energy source to provide electrical energy 502B to the flood valve 20 of the fuel injector 12 to using a low-voltage energy source to provide electrical energy 502B to the flood valve 20 of the fuel injector 12. In this way, the engine system may further reduce the power drawn by the fuel injector 12 from one or more power supplies.

[0045] In some examples, when the engine system includes a high-voltage energy source and a low-voltage energy source and uses the low-voltage energy source to provide electrical energy to the spill valve 20 of the fuel injector 12 throughout the holding duration, the engine system (e.g., the ECM 80 included in the engine system) sets maximum and minimum values ​​for chopping electrical energy during the holding duration (as described above) based on one or more characteristics of the low-voltage energy source (such as the voltage and / or capacity of the low-voltage energy source). For example, Figure 6Depicted are the electrical energy applied to the valve of the fuel injector 12 with and without chopping. In this example, electrical energy is applied to the valve of the fuel injector 12 throughout the entire pull-in duration 603 and the hold duration 605. The electrical energy applied to the valve of the fuel injector 12 throughout the pull-in duration 603 is primarily provided by a high-voltage energy source, and the electrical energy applied to the valve of the fuel injector 12 throughout the hold duration 605 is primarily provided by a low-power energy source (e.g., a battery). In the first example, the engine system does not set a maximum value for the electrical energy 602A applied to the valve of the fuel injector 12 throughout the hold duration. In this example, when the engine system switches from the high-voltage energy source to the low-voltage energy source, the electrical energy (e.g., current) reaches a maximum current level (I1) proportional to the voltage of the low-voltage energy source and remains substantially constant. Therefore, throughout the hold duration 603, the electrical energy 602A applied to the valve of the fuel injector 12 is not chopped.

[0046] In a second example, the engine system sets a maximum current value (I2) less than current value I1 and a minimum current value (I3) less than current value I2 for electrical energy 602B applied to the valve of fuel injector 12. In this example, during hold time 605, when electrical energy 602B reaches current value I2, the engine system disconnects fuel injector 12 from the low-voltage energy source to reduce electrical energy 602B; and when electrical energy 502B drops to current value I3, the engine system reconnects fuel injector 12 to the low-voltage energy source to increase electrical energy 602B. Thus, throughout hold time 605, electrical energy 602B fluctuates between current value I2 and current value I3.

[0047] In some examples, the engine system (e.g., the ECM 80 included in the engine system) can adjust the pull-in time (e.g., the flooded pull-in time) to account for various factors. For example, in some examples, changing the pull-in time (as described above) or switching from a high-power energy source to a low-power energy source (as described above) can cause the valve of the fuel injector 12 to behave differently than expected, which can affect the operating efficiency of the engine system in which the fuel injector 12 is included. For example, in some examples, reducing the flooded pull-in time of the spill valve 20 of the fuel injector 12 can cause the spill valve 20 to move slower and, therefore, reach its fully actuated position at a later time (e.g., a later valve arrival time (VAT), as described above and below).

[0048] The amount of time that elapses between 1) the time when electrical energy applied to a valve (e.g., relief valve 20) of fuel injector 12 is first increased to move or permit the valve to its fully actuated position and 2) the time when the valve actually reaches its fully actuated position may be referred to as a valve arrival time (e.g., a relief valve arrival time). An engine system including fuel injector 12 may store or calculate an expected valve arrival time in ECM 80, and if one or more valve arrival times observed or measured during operation of fuel injector 12 differ from the expected valve arrival time, the engine system (e.g., ECM 80 included in the engine system) may calculate a difference between the one or more observed valve arrival times and the expected valve arrival time and adjust the pull-in time for fuel injector 12 based on the difference. For example, in some examples, the engine system may calculate an average of one or more relief valve arrival times of fuel injector 12 (this average may be referred to as an average relief valve arrival time) and compare the average relief valve arrival time to the expected relief valve arrival time of fuel injector 12. Then, for example, if the average spill valve arrival time is longer than the expected spill valve arrival time, the engine system may advance the spill valve engagement time for future spill valve commands 83 generated for fuel injector 12. Alternatively, for example, if the average spill valve arrival time is shorter than the expected spill valve arrival time, the engine system may delay the spill valve engagement time for future spill valve commands 83 generated for fuel injector 12. The spill valve engagement time may be advanced or delayed relative to any other timing involved in the operation of fuel injector 12, such as the time it takes for electrical energy applied to spill valve 20 of fuel injector 12 to decrease to a holding level, the time it takes for electrical energy applied to spill valve 20 of fuel injector 12 to decrease to return or allow spill valve 20 to return to a resting, open position, or the control engagement time. Thus, the timing of one valve (e.g., spill valve 20) may be adjusted while the timing of another valve (e.g., control valve 30) may remain constant between injections. These timings may be measured with respect to the engine's crank angle. In some examples, when the relief pull-in time is adjusted for the future relief valve command 83, the pull-in duration determined for the future relief valve command 83 is not affected by the adjustment of the relief pull-in time (e.g., uses the value from the pull-in duration map 86 without additional adjustment or correction). In other examples, when the relief pull-in time is adjusted for the future relief valve command 83, the pull-in duration determined for the future relief valve command 83 is adjusted according to the adjustment of the relief pull-in time.

[0049] Figure 7A flow chart depicts a method 700 for controlling a fuel injector of an engine system, which may include the fuel injection system 10. The method 700 may be repeatedly executed during operation of the engine system to adjust commands (e.g., the spill valve command 83) generated and / or output by a controller (e.g., the ECM 80) to compensate for varying engine operating conditions 85. It should be understood that while the steps of the method 700 are described herein as being applied to the spill valve solenoid 21 and the spill valve 20 of a fuel injector 12 that includes both the spill valve 20 and the control valve 30, the steps of the method 700 may similarly be applied to the control valve solenoid 31 and the control valve 30 of a fuel injector 12 that includes both the spill valve 20 and the control valve 30, or to any solenoid or valve of a fuel injector 12 that includes any number of valves, including an injector having only one electronically controlled valve.

[0050] like Figure 7 As depicted, the method 700 may begin at step 702 where a pull-in duration of the fuel injector 12 is determined based at least in part on at least one engine operating condition 85 of the engine system. For example, as described above, the ECM 80 may include or otherwise have access to one or more pull-in duration maps 86 generated for the fuel injector 12. As described above, the pull-in duration map 86 may represent a relationship between a pull-in duration and power draw of the fuel injector 12. As described above, the pull-in duration may be the time at which 1) the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 is increased to move the relief valve 20 of the fuel injector 12 to a closed position (e.g., a relief pull-in time, such as Figure 5 The amount of time that elapses between time t1) and time t2) when the electrical energy applied to the spill valve solenoid 21 is reduced to a maintained level. Generally, for a given set of engine operating conditions, a shorter pull-in duration results in a lower power draw of the fuel injector 12. As described above, the power draw of the fuel injector 12 may be determined, at least in part, by one or more engine operating conditions 85 of the engine system (such as engine speed), and the pull-in duration map 86 represents the relationship between the pull-in duration, power draw, and one or more engine operating conditions (e.g., engine speed detected by the speed sensor 87 and / or engine request 88). Thus, for example, given one or more engine operating conditions, the ECM 80 may retrieve the pull-in duration map 86 generated for the fuel injector 12 and determine or select a pull-in duration that minimizes the power draw of the fuel injector 12 or maximizes the power draw of the fuel injector 12 without exceeding the power limit while supplying the desired amount of fuel. If desired, the ECM 80 may use the pull-in duration map 86 to determine or select the pull-in duration of the fuel injector 12 based on other factors.

[0051] In some examples, the ECM 80 includes or otherwise has access to a plurality of pull-in duration maps 86 generated for a plurality of fuel injectors 12 included in the engine system, and the ECM 80 can select a pull-in duration map 86 generated for a fuel injector 12 from the plurality of pull-in duration maps 86 generated for the plurality of fuel injectors 12. In some examples, the pull-in duration map 86 is generated using a series of end-of-line (EOL) tests, as described above. In some examples, the series of EOL tests determines the spill valve arrival time (VAT) for the fuel injector 12, and the pull-in duration determined for the fuel injector 12 is at least the same as the spill VAT determined for the fuel injector 12.

[0052] like Figure 7 As depicted, after determining the pull-in duration of the fuel injector 12 based on at least one engine operating condition 85, method 700 may proceed to step 704, where the electrical energy applied to the solenoid valve 21 of the fuel injector 12 is increased during the pull-in time (as described above) to move the relief valve 20 of the fuel injector 12 to a closed position for the determined pull-in duration. For example, as described above, in some examples, fuel may not be released from the fuel injector 12 until sufficient electrical energy is applied to the relief valve solenoid 21 of the fuel injector 12 to move the relief valve 20 of the fuel injector 12 to the closed position. When the relief valve 20 is in the closed position, the pressure within the fuel injector 12 increases, such that when the control valve 30 of the fuel injector 12 is moved to the inject position, the pressurized fuel may be released from the fuel injector 12 in a single portion of fuel. In some examples, the pull-in duration begins immediately after the pull-in time. As described above, electrical energy may be applied from a power source (e.g., a high voltage energy source or a low voltage energy source) to the spill valve solenoid 21 of the fuel injector 12. The ECM 80 may apply electrical energy to the spill valve solenoid 21 of the fuel injector 12 (or cause the power source to apply electrical energy to the spill valve solenoid 21) by generating and / or outputting the appropriate spill valve command 83 as described above.

[0053] like Figure 7As depicted, after the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 is increased to move the relief valve 20 of the fuel injector 12 to the closed position for the determined pull-in duration, the method 700 may proceed to step 706, in which the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 is reduced to a holding level (as described above) after the determined pull-in duration. In some examples, the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 is reduced to the holding level immediately after the pull-in duration. In some examples, the engine system includes a high voltage energy source that at least partially provides the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 throughout the pull-in duration and a low voltage energy source (as described above) that at least partially provides the electrical energy applied to the relief valve solenoid 21 of the fuel injector 12 after the electrical energy is reduced to the holding level. The ECM 80 may reduce power to (or cause the power supply to reduce power to) the spill valve solenoid 21 of the fuel injector 12 by generating and / or outputting the appropriate spill valve command 83 as described above.

[0054] like Figure 7 As depicted, in some examples, method 700 includes optional step 708, in which a difference is calculated between one or more spill valve arrival times (e.g., one or more observed or measured spill valve arrival times) and an expected spill valve arrival time. As described above, the spill valve arrival time can be the amount of time that elapses between 1) the time when electrical energy applied to the spill valve solenoid 21 of the fuel injector 12 is first increased to move the spill valve 20 or allow the spill valve to move to the fully actuated position and 2) the time when the spill valve 20 of the fuel injector 12 actually reaches the fully actuated position. In some examples, the ECM 80 of the engine system includes or otherwise has an expected spill valve arrival time determined for the fuel injector 12 (the expected spill valve arrival time can be determined using one or more tests as described above) and can detect or otherwise measure the spill valve arrival time of the spill valve 20 of the fuel injector 12 during each of a plurality of injection events. The ECM 80 may then calculate an average of the relief valve arrival times and compare the resulting average relief valve arrival time to the expected relief valve arrival time.

[0055] like Figure 7As depicted, in some examples, after calculating the difference between one or more relief valve arrival times and an expected relief valve arrival time for the fuel injector 12, the method 700 proceeds to step 710, where the pull-in time of the fuel injector 12 is adjusted based on the difference between the one or more relief valve arrival times and the expected relief valve arrival time. For example, as described above, if the average relief valve arrival time calculated for the fuel injector 12 is longer than the expected relief valve arrival time for the fuel injector 12, the ECM 80 may accordingly delay the pull-in time for future injection events of the fuel injector 12. Alternatively, if the average relief valve arrival time calculated for the fuel injector 12 is shorter than the expected relief valve arrival time for the fuel injector 12, the ECM 80 may accordingly advance the relief pull-in time for future injection events of the fuel injector 12. As described above, the ECM 80 may delay or advance the relief pull-in time of the fuel injector 12 by generating and / or outputting an appropriate relief valve command 83.

[0056] Although the methods and systems disclosed herein are described with respect to a fuel injector 12 that includes multiple valves (e.g., a relief valve 20, a control valve 30, and a check valve), it should be understood that the methods and systems disclosed herein may also be applied to any type of valve included in a fuel injector and / or to a fuel injector that includes any number of valves. For example, a fuel injector may include only a single valve that performs the functions of a control valve as described herein, or a similar function, and a pull-in duration map 86 may be generated and applied to a single valve included in the fuel injector. Or, for example, a fuel injector may include only a single valve that performs both the functions of a relief valve and a control valve as described herein, or a similar function, and a pull-in duration map 86 may be generated and applied to a single valve included in the fuel injector. Or, for example, a fuel injector may include three or more valves, and three or more corresponding pull-in duration maps 86 may be generated and applied to the three or more valves.

[0057] Adjusting the pull-in duration of a fuel injector 12 may allow the ECM 80 to control or reduce the power drawn by the fuel injector 12. Controlling or reducing the power drawn by the fuel injector 12 may allow an engine system including the fuel injector 12 to operate with greater efficiency and less risk of wear or damage. Controlling or reducing the power drawn by the fuel injector 12 may also allow the engine system including the fuel injector 12 to operate more efficiently, such as by reducing the number of controllers or power supplies required to operate the engine. By generating and using the pull-in duration map 86 for multiple fuel injectors 12 included in the engine system, the engine system may improve its efficiency by controlling or reducing the power drawn by the fuel injectors 12 included in the engine system on an injector-by-injector basis.

[0058] It will be apparent to those skilled in the art that various modifications and variations may be made to the disclosed methods and systems without departing from the scope of the present disclosure. Other embodiments of the methods and systems will be apparent to those skilled in the art from consideration of the specification and practice of the devices and systems disclosed herein. The specification and examples are intended to be considered exemplary only, with the true scope of the present disclosure being indicated by the following claims and their equivalents.

Claims

1. A method for controlling a fuel injector of an engine system, the method comprising: determining, based on engine operating conditions of the engine system, an energized duration of the fuel injector during which current is applied to move a valve member away from a rest position; applying an electric current to a valve solenoid to move the valve member of the fuel injector to a closed position for a determined energized duration; as well as After the determined pull-in duration, the current applied to the valve solenoid is reduced to a holding level.

2. The method of claim 1 , wherein the pull-in duration begins immediately after a pull-in time at which the current is first applied to the valve solenoid to move the valve member to the closed position, and the current applied to the valve solenoid is reduced to the holding level immediately after the pull-in duration. 3 . The method of claim 1 , wherein determining the pull-in duration of the fuel injector comprises referencing the engine operating conditions using at least one pull-in duration map generated for the fuel injector. The method of claim 3 , wherein the engine operating conditions include an engine speed of the engine system. 5 . The method of claim 3 , wherein the engine system includes a plurality of fuel injectors including the fuel injector, and the method further comprises selecting the at least one pull-in duration map from a plurality of pull-in duration maps generated for the plurality of fuel injectors. The method of claim 3 , wherein the at least one pull-in duration map is generated using a series of tests performed on the fuel injector. 7 . The method of claim 6 , wherein the series of tests determines a valve arrival time of the fuel injector, and wherein the pull-in duration is at least as long as the valve arrival time.

8. A method according to any preceding claim, wherein the engine system further comprises a high voltage energy source for providing electrical energy to the valve solenoid and a low voltage energy source for providing electrical energy to the valve solenoid, wherein the current applied to the valve solenoid during the pull-in duration is at least partially provided by the high voltage energy source, and wherein the current applied to the valve solenoid is at least partially provided by the low voltage energy source after the current applied to the valve solenoid is reduced to the holding level.

9. The method of claim 8, wherein the current is provided at least in part by the low voltage energy source after reducing the current applied to the valve solenoid to the hold level for a hold duration. 10 . The method of claim 9 , further comprising setting a maximum holding current value and a minimum holding current value for the holding duration based on a voltage or a capacity of the low-voltage energy source.

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