Magnetic force-based control of an actuator

Abstract

Electromagnetic actuation system (10), comprising: an actuator comprising an electrical coil (24), a magnetic core and an armature (21); a controllable driver circuit (50, 320) for selectively driving a current through the electrical coil (24); and a control module (60) that provides an actuator command (52) to the driver circuit (50, 320) which causes a current to be driven through the electrical coil (24) to actuate the armature (21), wherein the control module (60) comprises a magnetic force control module (300) configured to adapt the actuator command (52) to allow a magnetic force (325) in the actuator to converge to a preferred force level, wherein the magnetic force control module (300) includes a feedback circuit for a current of the electric coil (24) which is designed to adapt the actuator command (52) to allow the current of the electric coil (24) to converge to a desired current of the electric coil (24).

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] This application claims priority over the preliminary US application number 61 / 968,007, filed on March 20, 2014, and the preliminary US application number 61 / 955,942, filed on March 20, 2014, and the US application number 14 / 643,893, filed on March 10, 2015, and published under number US 2015 / 0267666A1. TECHNICAL AREA

[0002] This revelation concerns solenoid-activated actuators. BACKGROUND

[0003] The statements in this section provide only background information relating to the present disclosure. Consequently, these statements are not intended to constitute an endorsement of the prior art.

[0004] Solenoid actuators can be used to control fluids (liquids and gases), or for positioning or control functions. A typical example of a solenoid actuator is the fuel injector. Fuel injectors are used to inject pressurized fuel into a manifold, intake port, or directly into the combustion chamber of an internal combustion engine. Common fuel injectors incorporate electromagnetically activated solenoid devices that overcome mechanical springs to open a valve located at the tip of the injector, allowing fuel to flow through it. Injector driver circuits control the flow of electrical current to the electromagnetically activated solenoid devices to open and close the injectors.Injector driver circuits can be operated in a peak-and-hold control configuration or in a switch saturation configuration.

[0005] Fuel injectors are calibrated, with calibration comprising an injector activation signal that includes an injector open time or injection duration and a corresponding metered or delivered injected fuel mass at a predetermined or known fuel pressure. Injector operation can be characterized by the fuel mass injected per fuel injection event in relation to the injection duration. Injector characterization includes metered fuel flow over a range between a high flow rate associated with high-speed, high-load engine operation and a low flow rate associated with engine idling conditions.

[0006] It is known that an engine control system can benefit from the rapid injection of several small fuel masses. Generally, if the residence time between successive injection events is less than a residence time threshold, the injected fuel masses from successive fuel injection events often result in a larger delivered quantity than desired, even when using the same injection durations. Consequently, such successive fuel injection events can become unstable, leading to unacceptable repeatability. This undesirable occurrence is due to the presence of residual magnetic flux in the fuel injector, generated by the preceding fuel injection event, which provides some assistance to the immediately following one.The residual magnetic flux is generated in response to persistent eddy currents and magnetic hysteresis in the fuel injector as a result of shifts in the injected fuel mass rates, which require different initial magnetic flux values. Generally, the fuel flow rate for each of the several closely spaced injection events is based on controlling an electrical current to the fuel injector, independent of any residual magnetic flux that may be present in the fuel injector.

[0007] German patent application DE 196 43 788 A1 discloses electrohydraulic pressure control devices comprising a force-controlled electromagnet with a coil and an armature, wherein the force of the electromagnet acting on the armature is controlled by a change in the magnetic field strength. A control variable for the excitation current of the electromagnet is generated by comparing an actual value of the instantaneous magnetic induction with a predetermined setpoint.

[0008] In the publication DE 10 2007 053 877 B3, a directional control slide for controlling working cylinders or servomotors is disclosed, which has a force-controlled magnet with a control unit that regulates the magnetic force depending on a position measuring device attached to the working cylinder.

[0009] The publication EP 0 074 420 A1 discloses an electrohydraulic proportional valve with a force-controlled magnet that acts on a valve body to influence a valve closing force and a stroke. SUMMARY

[0010] An electromagnetic actuation system comprises an actuator with an electrical coil, a magnetic core, and an armature. The system further includes a controllable driver circuit for selectively driving a current through the electrical coil. A control module provides an actuator command to the driver circuit, which causes a current to be driven through the electrical coil to actuate the armature. The control module includes a magnetic force control module configured to adjust the actuator command to allow a magnetic force within the actuator to converge to a preferred force level. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Now, one or more embodiments will be described using examples with reference to the accompanying drawings, in which: Fig. 1-1 illustrates a schematic sectional view of a fuel injector and an activation controller in accordance with the present disclosure; Fig. 1-2 a schematic sectional view of the activation controller Fig. 1-1 illustrated in accordance with the present revelation; Fig. 1-3 a schematic sectional view of an injector driver from Fig. 1-1 and 1-2 illustrated in accordance with the present revelation; Fig. 2 a non-restrictive exemplary first recording 1000 of a measured current and a measured fuel flow rate and a non-restrictive exemplary second recording 1010 of measured voltages at a main excitation coil and a search coil for two successive fuel injection events with identical current pulses separated by a residence time which does not indicate that they follow each other closely, illustrated in accordance with the present disclosure; Fig. 3 a non-restrictive exemplary first recording 1020 of a measured current and a measured fuel flow rate and a non-restrictive exemplary second recording 1030 of measured voltages at a main excitation coil and a search coil for two successive fuel injection events with identical current pulses separated by a residence time indicating that they follow each other closely, illustrated in accordance with the present disclosure; Fig. 4 an exemplary embodiment of a magnetic force control module using magnetic flux feedback and current feedback to control a current applied to an electrical coil of a fuel injector to control its activation, in accordance with the present disclosure; and Fig. 5 An exemplary embodiment of a magnetic force control module using magnetic flux feedback to control a current applied to an electrical coil of a fuel injector to control its activation, in accordance with the present disclosure, is illustrated. DETAILED DESCRIPTION

[0012] This disclosure describes the concepts of the currently claimed subject matter with reference to an exemplary application to linear-motion fuel injectors. However, the claimed subject matter can be more broadly applied to any linear or nonlinear electromagnetic actuators that use an electric coil to induce a magnetic field in a magnetic core, causing an attractive force to act on a movable armature. Typical examples include fluid control solenoids, gasoline, diesel, or CNG fuel injectors used in internal combustion engines, and nonfluidic solenoid actuators for positioning and control.

[0013] Now, with reference to the drawings, in which what is shown is intended only for the purpose of illustrating certain exemplary embodiments and not for the purpose of limiting them, it is illustrated Fig. Figure 1-1 schematically illustrates a non-limiting exemplary embodiment of an electromagnetically activated fuel injector 10 for direct injection. Although the illustrated embodiment depicts an electromagnetically activated fuel injector for direct injection, a fuel injector for port injection can be used equally well. The fuel injector 10 is configured to inject fuel directly into a combustion chamber 100 of an internal combustion engine. An activation controller 80 is electrically connected to the fuel injector 10 to control its activation. The activation controller 80 corresponds only to the fuel injector 10. In the illustrated embodiment, the activation controller 80 comprises a control module 60 and an injector driver 50.The control module 60 is electrically connected to the injector driver 50, which in turn is electrically connected to the fuel injector 10 to control its activation. Feedback signals 42 can be supplied from the fuel injector to the actuation controller 80. The fuel injector 10, the control module 60, and the injector driver 50 can be any suitable devices configured to operate as described herein. In illustrated embodiments, the control module 60 comprises a processing device. In one embodiment, one or more components of the actuation controller 80 are integrated into a connection assembly 36 of the fuel injector 36. In another embodiment, one or more components of the actuation controller 80 are integrated into a body 12 of the fuel injector 10.In yet another embodiment, one or more components of the activation controller 80 are located outside the fuel injection valve 10 – and in close proximity to it – and are electrically connected to the connection arrangement 36 via one or more cables and / or wires. The terms “cable” and “wire” are used interchangeably here to refer to the transmission of electrical power and / or electrical signals.

[0014] Control module, module, controller, controller unit, processor, and similar terms refer to any combination of one or more application-specific integrated circuits (ASICs), electronic circuits, central processing units (preferably microprocessors), and associated main memory and mass storage (read-only memory, programmable read-only memory, random access memory, hard disk drive, etc.) that execute one or more software or firmware programs or routines, combinational logic circuits, input / output circuits and devices, suitable signal conditioning and buffering circuits, and other components for providing the described functionality. Software, firmware, programs, instructions, routines, code, algorithms, and similar terms refer to any set of instructions with calibrations and lookup tables.The control module contains a set of control routines that are executed to provide the desired functions. These routines are executed, for example, by a central processing unit and can be used to monitor inputs from sensing devices and other network control modules, and to execute control and diagnostic routines for managing the operation of actuators. Routines can be executed at regular intervals, such as every 3, 125, 6, 25, 12.5, 25, and 100 milliseconds during continuous operation of the power unit and vehicle. Alternatively, routines can be executed in response to the occurrence of an event.

[0015] In general, an armature can be controlled either in an actuated position or in a static or rest position. The fuel injection valve 10 can be any suitable discrete fuel injection device that can be controlled either in an open (actuated) position or a closed (static or rest position). In one embodiment, the fuel injection valve 10 comprises a cylindrical hollow body 12 defining a longitudinal axis 101. A fuel inlet 15 is arranged at a first end 14 of the body 12, and a fuel nozzle 28 is arranged at a second end 16 of the body 12. The fuel inlet 15 is fluidically coupled to a high-pressure fuel distribution pipe 30, which is fluidly coupled to a high-pressure injection pump. A valve assembly 18 is included in the body 12 and comprises a needle valve 20, a spring-operated nozzle needle 22, and an armature section 21.The needle valve 20 engages in the fuel nozzle 28 to control the fuel flow through it. Although the illustrated embodiment shows a triangular needle valve 20, other embodiments may use a sphere. In one embodiment, the armature section 21 is rigidly coupled to the nozzle needle 22 and configured for linear displacement as a unit together with the nozzle needle 22 and the needle valve 20 in the first and second directions 81 and 82, respectively. In another embodiment, the armature section 21 may be slidably coupled to the nozzle needle 22. For example, the armature section 21 may be displaced in the first direction 81 until it is stopped by a nozzle needle stop that is rigidly attached to the nozzle needle 22.Similarly, the armature section 21 can be displaced in the second direction 82 independently of the nozzle needle 22 until it contacts a nozzle needle stop rigidly attached to the nozzle needle 22. Upon contact with the nozzle needle stop rigidly attached to the nozzle needle 22, the force of the armature section 21 causes the nozzle needle 22, together with the armature section 21, to be pushed in the second direction 82. The armature section 21 may include projections for engaging with various stops within the fuel injector 10.

[0016] An arrangement 24 with an annular electromagnet, comprising an electrical coil and a magnetic core, is configured for magnetic engagement with the armature section 21 of the valve assembly. For illustrative purposes, the arrangement 24 with the electrical coil and magnetic core is shown as being located outside the body of the fuel injector; however, embodiments presented here are directed such that the arrangement 24 with the electrical coil and magnetic core is either permanently installed in or integrated into the fuel injector 10. The electrical coil is wound on the magnetic core and includes terminals for receiving electrical current from the injector driver 50. Hereinafter, the “arrangement with the electrical coil and magnetic core” will simply be referred to as the “electrical coil 24”.When the electrical coil 24 is deactivated and not energized, the spring 26 pushes the valve assembly 18, including the needle valve 20, in the first direction 81 toward the fuel nozzle 28 to close the needle valve 20 and prevent fuel flow through it. When the electrical coil 24 is activated and energized, an electromagnetic force (hereinafter referred to as the "magnetic force") acts on the armature section 21 to overcome the spring force exerted by the spring 26 and pushes the valve assembly 18 in the second direction 82, thereby moving the needle valve 20 away from the fuel nozzle 28 and allowing pressurized fuel to flow within the valve assembly 18 through the fuel nozzle 28. A search coil 25 is mutually coupled to the electrical coil 24 and is preferably wound axially or radially adjacent to the coil 24. The search coil 25 is used as a detection coil.

[0017] The fuel injector 10 can include a holding device 29 that interacts with the valve assembly 18 to stop the valve assembly 18 from shifting when it is forced to open. In one embodiment, a pressure sensor 32 is configured to provide a fuel pressure 34 in the high-pressure fuel distribution pipe 30 near the fuel injector 10, preferably upstream of the fuel injector 10. In another embodiment, a pressure sensor 32' can be integrated into the inlet 15 of the fuel injector, instead of the pressure sensor 32 in the fuel distribution pipe 30, or in combination with the pressure sensor. In the Fig. In the embodiment illustrated in Figure 1-1, the fuel injector 10 is not limited to the spatial and geometric arrangement of the features described herein, and it may include additional features and / or other spatial and geometric arrangements known in the art to operate the fuel injector 10 between open and closed positions to control the supply of fuel to the engine 100.

[0018] The control module 60 generates an injector command signal (an actuator command) 52, which controls the injector driver 50, which activates the fuel injector 10 to the open position to effect a fuel injection event. In the illustrated embodiment, the control module 60 communicates with one or more external control modules, such as an engine control module (ECM) 5; however, in other embodiments, the control module 60 may be integrated with the ECM. The injector command signal 52 is correlated with a desired mass of fuel to be delivered by the fuel injector 10 during the fuel injection event. Similarly, the injector command signal 52 may be correlated with a desired fuel flow rate to be delivered by the fuel injector 10 during the fuel injection event.In the use herein, the term “desired injected fuel mass” means the desired mass of fuel to be supplied to the engine through the fuel injector 10. In the use herein, the term “desired fuel flow rate” means the rate at which fuel is to be supplied to the engine through the fuel injector 10 to achieve the desired fuel mass. The desired injected fuel mass may be based on one or more monitored input parameters 51, which are entered into the control module 60 or the ECM 5. The one or more monitored input parameters 51 may include, but are not limited to, an operator torque request, manifold absolute pressure (MAP), engine speed, engine temperature, fuel temperature, and ambient temperature, which may be obtained by known methods.The injector driver 50 generates an injector activation signal (an actuator activation signal) 75 in response to the injector command signal 52 to activate the fuel injector 10. The injector activation signal 75 controls a current flow to the electrical coil 24 to generate an electromagnetic force in response to the injector command signal 52. An electrical power source 40 provides a source of DC electrical power to the injector driver 50. In some embodiments, the electrical DC power source provides a low voltage, e.g., 12 V, and a boost converter can be used to output a high voltage, e.g., 24 V to 200 V, which is supplied to the injector driver 50.When the electrical coil 24 is activated using the injector activation signal 75, the electromagnetic force it generates pushes the armature section 21 in the second direction 82. Consequently, when the armature section 21 is pushed in the second direction 82, the valve assembly 18 is forced or moved into an open position in the second direction 82, allowing pressurized fuel to flow through it. The injector driver 50 controls the injector activation signal 75 for the electrical coil 24 by any suitable method, which may include, for example, a pulse-width modulated (PWM) flow of electrical power. The injector driver 50 is configured to control the activation of the fuel injector 10 by generating suitable injector activation signals 75.In embodiments that use multiple successive fuel injection events for a given engine cycle, an injector activation signal 75 can be generated that is defined for each of the fuel injection events within the engine cycle.

[0019] The injector activation signal 75 is characterized by an injection duration and a current waveform comprising an initial peak pull-in current and a secondary holding current. The initial peak pull-in current is characterized by a gradual ramp-up to achieve a peak current, which can be selected as described herein. The initial peak pull-in current generates an electromagnetic force acting on the armature section 21 of the valve assembly 18 to overcome the spring force and push the valve assembly 18 in the second direction 82 into the open position, thereby initiating the flow of pressurized fuel through the fuel nozzle 28. When the initial peak pull-in current is reached, the injector driver 50 reduces the current in the electrical coil 24 to the secondary holding current.The secondary holding current is characterized by an approximately steady-state current that is lower than the initial peak pull-in current. The secondary holding current is a current level controlled by the injector driver 50 to keep the valve assembly 18 in the open position to allow pressurized fuel to continue flowing through the fuel nozzle 28. The secondary holding current is preferably indicated by a minimum current level. The injector driver 50 is configured as a bidirectional current driver capable of providing a negative current flow to draw current from the electrical coil 24. As used herein, the term "negative current flow" means that the direction of current flow to excite the electrical coil is reversed. Consequently, the terms "negative current flow" and "reversed current flow" are used interchangeably here.

[0020] Embodiments described herein are directed towards controlling the fuel injector for multiple fuel injection events that occur in close succession during a power engine cycle. In the context of this text, the term "close succession" means a residence time between each successive fuel injection event that is less than a predetermined residence time threshold. In the context of this text, the term "residence time" means the time interval between the end of injection of the first fuel injection event (actuator event) and the start of injection for a corresponding second fuel injection event (actuator event) of each successive pair of fuel injection events.The residence time threshold can be chosen to define a time interval such that residence times shorter than the threshold indicate the generation of instability and / or variations in the amount of fuel injected during each fuel injection event. This instability and / or variation in the amount of fuel injected may be a response to secondary magnetic effects. These secondary magnetic effects include persistent eddy currents and magnetic hysteresis within the fuel injector, and a resulting residual flow. The persistent eddy currents and magnetic hysteresis arise from transitions in initial flow rates between closely spaced fuel injection events.Consequently, the residence time threshold is not defined as an arbitrarily fixed value, and its selection may be based on, but is not limited to, a fuel temperature, a fuel injector temperature, a fuel injector type, a fuel pressure, and fuel properties such as fuel types and fuel blends. As used herein, the term "flux" denotes a magnetic flux representing the total magnetic field generated by the electrical coil 24 and passing through the armature section. Since the windings of the electrical coil 24 couple the magnetic flux into the magnetic core, this flux may therefore be equated to the flux coupling. The flux coupling is also based on the flux density passing through the armature section, on the surface of the armature section adjacent to the air gap, and on the number of windings of the coil 24.Consequently, the terms "flux", "magnetic flux" and "flux coupling" are used interchangeably here unless otherwise specified.

[0021] For fuel injection events that are not closely spaced, a fixed current waveform can be used for each fuel injection event, regardless of the residence time, because the first fuel injection event of a successive pair has little influence on the injected fuel mass of the second fuel injection event of the successive pair. However, if the first and second fuel injection events are closely spaced and a fixed current waveform is used, the first fuel injection event may tend to influence the injected fuel mass of the second fuel injection event and / or subsequent fuel injection events.Each time a fuel injection event is influenced by one or more preceding fuel injection events of a power engine cycle, the respective injected fuel mass of the corresponding fuel injection event can lead to unacceptable repeatability over the course of several power engine cycles, and the successive fuel injection events are considered closely consecutive. More generally, any successive actuator events where a residual flow from the preceding actuator event influences the behavior of the subsequent actuator event relative to a standard, for example, relative to behavior in the absence of the residual flow, are considered closely consecutive.

[0022] Fig. Figure 1-2 illustrates the Activation Controller 80 from Fig. 1-1 in accordance with the present disclosure. A signal flow path 362 provides communication between the control module 60 and the injector driver 50. For example, the signal flow path 362 provides the injector command signal (e.g., the command signal 52 from Fig. 1-1) ready, which controls the injector driver 50. The control module 60 also communicates with the external ECM 5 via a signal flow path 364 within the activation controller 380, which is in electrical communication with a power transmission cable. For example, the signal flow path 364 can transmit monitored input parameters (e.g., the monitored input parameters 51 of Fig. 1-1) from the ECM 5 to the control module 60 to generate the injector command signal 52. In some embodiments, the signal flow path 364 can provide fuel injector feedback parameters (e.g., the feedback signals 42 from Fig. 1-1) to the ECM 5.

[0023] The injector driver 50 receives electrical DC power from the power source 40. Fig. 1-1 via a power supply flow path 366. By using a small modulation signal added to the power supply flow path 366, the signal flow path 364 can be eliminated. Using the received electrical DC power, the fuel injector driver 50 can generate injector activation signals (e.g., the injector activation signals 75 from Fig. 1-1) based on the injector command signal from the control module 60.

[0024] The injector driver 50 is designed to control the activation of the fuel injector 10 by generating suitable injector activation signals 75. The injector driver 50 is a bidirectional current driver that provides a positive current flow via a first current flow path 352 and a negative current flow via a second current flow path 354 to the electrical coil 24 in response to respective injector activation signals 75. The positive current via the first current flow path 352 is provided to energize an electrical coil 24, and the negative current via the second current flow path 354 reverses the current flow to draw current from the electrical coil 24. The current flow paths 352 and 354 form a closed circuit; that is, a positive current into 352 results in an equal and opposite (negative) current in flow path 354, and vice versa.A signal flow path 371 can supply a voltage from the first current flow path 352 to the control module 60, and a signal flow path 373 can supply a voltage from the second current flow path 354 to the control module 60. The voltage and current applied to the electrical coil 24 are based on a difference between the voltages at the signal flow paths 371 and 373. In one embodiment, the injector driver 50 uses open-loop operation to control the activation of the fuel injector 10, wherein the injector activation signals are characterized by precise predetermined current waveforms.In another embodiment, the injector driver 50 uses closed-loop operation to control the activation of the fuel injector 10, wherein the injector activation signals are based on fuel injector parameters that are provided as feedback to the control module via signal flow paths 371 and 373. A measured current flow to the coil 24 can be supplied to the control module 60 via a signal flow path 356. In the illustrated embodiment, the current flow is measured by a current sensor on the second current flow path 354.The fuel injector parameters can include values ​​for the flow coupling, voltage and current within the fuel injector 10, or the fuel injector parameters can include proxies used by the control module 60 to estimate the flow coupling, voltage and current within the fuel injector 10.

[0025] In some embodiments, the injector driver 50 is designed for full four-quadrant operation. Fig. Figure 1-3 illustrates an exemplary embodiment of the injection valve driver 50. Fig. 1-2, which uses two sets of switches 370 and 372 to control the current flow provided between the injector driver 50 and the electrical coil 24. In the illustrated embodiment, the first set of switches 370 comprises switch devices 370-1 and 370-2, and the second set of switches 372 comprises switch devices 372-1 and 372-2. The switch devices 370-1, 370-2, 372-1, and 372-2 can be semiconductor switches and can include silicon semiconductor switches (Si semiconductor switches) or wide bandgap semiconductor switches (WBG semiconductor switches), which enable high-speed switching at high temperatures. The four-quadrant operation of the injector driver 50 controls the direction of current flow into and out of the electrical coil 24 based on a corresponding switching state determined by the control module 60.The control module 60 can determine a positive switching state, a negative switching state, and a zero switching state, and command the first and second switch sets 370 and 372 between open and closed positions based on the determined switching state. In the positive switching state, the switching devices 370-1 and 370-2 of the first switch set 370 are commanded to the closed position, and the switching devices 372-1 and 372-2 of the second switch set 372 are commanded to the open position to control a positive current into the first current flow path 352 and out of the second current flow path 354. These switching devices can further be modulated using pulse width modulation to control the amplitude of the current.In the negative switching state, the switching devices 370-1 and 370-2 of the first switching set 370 are commanded to the open position, and the switching devices 372-1 and 372-2 of the second switching set 372 are commanded to the closed position, in order to control the negative current into the second current flow path 354 and out of the first current flow path 352. These switching devices can further be modulated using pulse width modulation to control the amplitude of the current. In the zero switching state, all switching devices 370-1, 370-2, 372-1, and 372-2 are commanded to the open position to prevent any current from flowing into or out of the electromagnetic arrangement. Consequently, bidirectional control of the current through the coil 24 can be achieved.

[0026] In some embodiments, the negative current for drawing current from the electrical coil 24 is applied for a duration sufficient to reduce any residual flow within the fuel injector 10 after a secondary holding current has been reduced. In other embodiments, however, the negative current is only applied after the secondary holding current has been reduced, and only after the fuel injector has closed or the actuator has returned to its static or rest position. Furthermore, additional embodiments may include the switching of the switch sets 370 and 372 alternately between open and closed positions to change the direction of current flow to the coil 24, which incorporates pulse-width modulation control to create current flow profiles.The use of the two sets of switches 370 and 372 enables precise control of the direction and amplitude of the current flow applied to the current flow paths 352 and 354 of the electrical coil 24 for several successive fuel injection events during a power engine event by reducing the presence of eddy currents and magnetic hysteresis within the electrical coil 24.

[0027] Fig. Figure 2 illustrates a non-restrictive exemplary first recording 1000 of a measured current and fuel flow rate, and a non-restrictive exemplary second recording 1010 of measured voltages at a main excitation coil and a search coil for two successive fuel injection events with identical current pulses separated by a dwell time that does not indicate close succession. A dashed vertical line 1001 extending through each of the recordings 1000 and 1010 represents a first time point at which an injection end occurs for the first fuel injection event, and a dashed vertical line 1002 represents a second time point at which an injection start occurs for the second fuel injection event.The residence time 1003 represents a time interval between the dashed vertical lines 1001 and 1002, which separates the first and second fuel injection events. In the illustrated embodiment, the residence time exceeds a residence time threshold. Consequently, the first and second fuel injection events do not indicate that they occur in close succession.

[0028] With reference to the first recording 1000, profiles 1011 and 1012 of the measured current and flow rate for the two fuel injection events are illustrated. The vertical y-axis along the left side of recording 1000 shows the electrical current in amperes (A), and the vertical y-axis along the right side of recording 1000 shows the fuel flow rate in milligrams (mg) per millisecond (ms). Profile 1011 of the measured current is essentially identical for each of the fuel injection events. Similarly, profile 1012 of the measured fuel flow rate is essentially identical for each of the fuel injection events because the fuel injection events do not indicate that they occur in close succession.

[0029] With reference to the second recording 1010, profiles 1013 and 1014 of the measured voltage of a main excitation coil and a search coil for the two fuel injection events are illustrated. The measured voltage of the main coil can be a measured voltage of the electrical coil 24 of Fig. 1-1 represent and the measured voltage of the search coil can represent a measured voltage of a search coil connected to the electrical coil 24 of Fig. The main excitation coil and search coil are mutually magnetically coupled. The vertical y-axis of record 1010 indicates the voltage (V). Consequently, when the main excitation coil is energized, a magnetic flux generated by the main excitation coil can be coupled into the search coil due to mutual magnetic coupling. Profile 1014 of the measured search coil voltage shows the voltage induced in the search coil, which is proportional to the rate of change of the mutual flux coupling. Profiles 1013 and 1014 of the measured main excitation coil and search coil voltages are essentially identical for both the first and second fuel injection events, which do not indicate that they occur in close succession.

[0030] Fig. Figure 3 illustrates a non-restrictive exemplary first recording 1020 of a measured current and fuel flow rate, and a non-restrictive exemplary second recording 1030 of measured main excitation coil and search coil voltages for two successive fuel injection events with identical current pulses separated by a dwell time indicating that they occur close together. The horizontal x-axis in each of the recordings 1020 and 1030 shows the time in seconds (s). A dashed vertical line 1004 extending through each of the recordings 1020 and 1030 represents a first injection end time for the first fuel injection event, and a dashed vertical line 1005 represents a second injection start time for the second fuel injection event.The residence time 1006 represents a time interval between the dashed vertical lines 1004 and 1005, which separates the first and second fuel injection events. In the illustrated embodiment, the residence time is less than a residence time threshold value. Consequently, the first and second fuel injection events indicate that they occur in close succession.

[0031] With reference to the first recording 1020, profiles 1021 and 1022 of the measured current and flow rate for the two fuel injection events are illustrated. The vertical y-axis along the left side of recording 1020 shows the electrical current in amperes (A), and the vertical y-axis along the right side of recording 1020 shows the fuel flow rate in milligrams (mg) per second (s). Profile 1021 of the measured current is essentially identical for each of the fuel injection events. However, profile 1022 of the measured fuel flow rate illustrates a variation in the measured fuel flow rate between each of the first and second fuel injection events, even though the measured current profiles are essentially identical.This variance in the measured fuel flow rate is inherent in closely spaced fuel injection events and leads, in an undesirable way, to a supplied injected fuel mass at the second fuel injection event that differs from the injected supplied fuel mass at the first fuel injection event.

[0032] With reference to the second recording 1030, profiles 1023 and 1024 of the measured voltage of the main excitation coil and the search coil for the two fuel injection events are illustrated. The measured voltage of the main coil can be a measured voltage of the electrical coil 24 of Fig. 1-1 represent and the measured voltage of the search coil can represent a measured voltage of a search coil connected to the electrical coil 24 of Fig. 1-1 is mutually magnetically coupled. The vertical y-axis of record 1030 indicates the voltage (V). Therefore, when the main excitation coil is energized, a magnetic flux generated by the main excitation coil can be coupled to the search coil due to mutual magnetic coupling. Profile 1024 of the measured search coil voltage shows the voltage induced in the search coil, which is proportional to the rate of change of the mutual flux coupling. Profiles 1023 and 1024 of the measured main excitation coil and search coil voltages in record 1030 differ during the second injection event compared to the first fuel injection event. This difference indicates the presence of residual flux or magnetic flux when the injection events occur in close succession. Referring to record 1010 of Fig. 2. Profiles 1013 and 1014 of the measured voltage of the main excitation coil and the search coil during the second injection event do not differ from the first fuel injection event if the first and second fuel injection events do not follow each other closely.

[0033] Again with reference to Fig. Figures 1-1 are exemplary embodiments further directed towards providing feedback signals 42 from the fuel injector 10 back to the control module 60 and / or to the injector driver 50. As discussed in greater detail below, sensor devices can be integrated into the fuel injector 10 to measure various fuel injector parameters, namely the flux coupling of the electrical coil 24, the voltage of the electrical coil 24, and the current supplied to the electrical coil 24. A current sensor can be provided on a current flow path between the activation controller 80 and the fuel injector to measure the current supplied to the electrical coil, or the current sensor can be integrated into the fuel injector 10 on the current flow path.The fuel injector parameters provided via the feedback signals 42 can include the flux coupling, voltage, and current, which are measured directly by corresponding sensor devices integrated into the fuel injector 10. Additionally or alternatively, the fuel injector parameters can include proxy values ​​provided via the feedback signals 42 to the control module 60, which is used to estimate the flux coupling, magnetic flux, voltage, and current within the fuel injector 10. If the control module 60 has feedback on the flux coupling of the electrical coil 24, the voltage of the electrical coil 24, and the current supplied to the electrical coil 24, it can advantageously modify the activation signal 75 for the fuel injector 10 for several successive injection events.It is understood that conventional fuel injectors are controlled by an open-loop system based solely on a desired current waveform obtained from reference tables, without any information relating to the force-generating component of the flux coupling (e.g., the magnetic flux) that causes movement of the armature section 21. Consequently, conventional pilot-operated fuel injectors, which only consider the current flow to control the fuel injector, are prone to instability during successive, closely spaced fuel injection events.

[0034] Embodiments here are directed towards controlling the active magnetic flux in the fuel injector to directly control the electromagnetic force that pushes the armature section 21 in the second direction 82. Directly controlling the electromagnetic force by controlling the active magnetic flux can be used to overcome unwanted delays and instabilities caused by secondary magnetic effects, such as eddy currents and magnetic hysteresis in the fuel injector. As mentioned above, the electromagnetic force is generated when the electrical coil 24 is energized. This electromagnetic force is generated by the active magnetic flux passing through the armature section 21 in the fuel injector 10.It is understood that the active magnetic flux is equivalent to the flux coupling divided by the number of windings of the coil 24 in the embodiments described here, since the electrical coil 24 is excited by a typical induction. Consequently, implementing active magnetic flux control to directly control the magnetic force requires that the flux coupling of the electrical coil 24 be obtained.

[0035] The embodiments described here do not concern themselves with any technique for obtaining the active magnetic flux or equivalent flux coupling. In some embodiments, a search coil can be used around the electrical coil, with the magnetic flux generated by the electrical coil being coupled into the search coil due to mutual magnetic coupling. A voltage induced in the search coil is proportional to the rate of change of the mutual flux coupling. Consequently, the voltage of the search coil can be supplied to the control module 60 via the feedback signals 42 to estimate the flux coupling. Therefore, the search coil indicates sensing devices that are built into the fuel injector 10 to obtain the flux coupling.In other embodiments, a magnetic field sensor, such as a Hall sensor, can be positioned within a magnetic flux path in the fuel injector to measure the active magnetic flux. Similarly, other magnetic field sensors, such as analog Hall sensors and magnetoresistive (MR) sensors, can be used to measure the active magnetic flux, but are not limited to these. The active magnetic flux measured by such magnetic field sensors can be supplied to the control module 60 via the feedback signals 42. It is understood that these magnetic field sensors indicate sensing devices integrated into the fuel injector to obtain the active magnetic flux.

[0036] Fig. Figure 4 illustrates an exemplary embodiment of a magnetic force control module using magnetic flux feedback and current feedback to control a current applied to an electrical coil of a fuel injector to control its activation. The magnetic force control module 300 can be integrated within the control module 60 of the activation controller 80. Fig. 1-1 be implemented - and be executed by a processing device of the same. Consequently, the magnetic force control module 300 is implemented with reference to Fig. 1-1 described.

[0037] The magnetic force control module 300 comprises a force command generation module (FCG module) 310, a first differential unit 312, a proportional-integral force control module (PL force control module) 314, a second differential unit 316, a PI current control module 318, an injector driver 320, a current sensor 322, and a force mapping module 324. The control module 60 of the activation controller 80 of Fig. 1-1 can include the FCG module 310, the first and second differential units 312 and 316 respectively, the PI force control module 314, and the force assignment module 324. The injector driver 50 of the force activation controller 80 of Fig. 1-1 can include the PI current control module 318 and the injector driver 320. However, the control module 60 and the injector driver 50 can include different combinations of these features listed above.

[0038] In the illustrated embodiment, a desired fuel flow rate 309 is input into the FCG module 310. The desired fuel flow rate 309 can be supplied by an external module, e.g., the ECM 5, based on the aforementioned input parameters 51, to achieve a desired injected fuel mass, as described above with reference to Fig. As described in Figure 1-1, the FCG module 310 issues a magnetic force command 311 based on the desired fuel flow rate 309. The magnetic force command 311 indicates a command to generate a magnetic force required to move the armature section 21 in the second direction 82 to activate the fuel injector 10 in the open position to deliver the desired fuel flow rate 309 to the combustion chamber 100. However, it should be noted that the magnetic force command 311 does not account for the presence of residual flux, such as magnetic flux, which may be present in the fuel injector due to hysteresis and eddy current effects. The presence of residual flux can cause instability within the fuel injector, which can affect fuel flow rates and the amount of fuel injected and delivered to the combustion chamber.Consequently, moving the armature section 21 based solely on the magnetic force command can result in a fuel flow rate actually delivered to the combustion chamber that differs from the desired fuel flow rate 309, thus resulting in an inaccurate or incorrect injected fuel mass being delivered to the fuel injector 10.

[0039] The magnetic force command 311 is input into the first differential unit 312. The first differential unit 312 compares a magnetic force feedback 325 in the fuel injector 10 with the magnetic force command 311. The magnetic force feedback 325 is output by the force mapping module 324 based on a magnetic flux feedback 323 provided by the fuel injector 10. The magnetic flux feedback 323 indicates the active magnetic flux present in the fuel injector 10. The active magnetic flux or equivalent flux coupling present in the fuel injector 10 can be determined by any of the above with reference to the illustrated embodiment of Fig. The method described in 1-1 is obtained using one or more sensing devices integrated into the fuel injector 10. Therefore, the feedback 323 of the active magnetic flux from the fuel injector 10 can be obtained via the feedback signals 42, as described above with reference to the illustrated embodiment of Fig. As described in 1-1, the force mapping module 324 can be transferred. Based on known relationships, it can use lookup tables or analytical functions to output the magnetic force in the fuel injector 10 (the magnetic force feedback 325). Consequently, the magnetic force feedback 325 indicates the magnetic force of the armature section 21, which includes a force attributable to the residual flow when the active magnetic flux is present in the fuel injector 10.

[0040] Based on the comparison between the magnetic force feedback 325 and the magnetic force command 311, the first differential unit 312 outputs an adjusted magnetic force command 313, which takes into account the presence of a magnetic flux 323 in the fuel injector 10. The adjusted magnetic force command 313 is input into the PL force control module 314, thereby generating a current command 315. The current command 315 specifies a commanded pull-in current and holding current over a period of time to activate the fuel injector 10 to deliver the desired fuel flow rate 309. While the current command 315 takes into account the magnetic force feedback 325 in the fuel injector, it does not consider any current present in the fuel injector, such as that flowing through the electrical coil 24.

[0041] Consequently, a current feedback signal 327 indicates a current measured by the current sensor 322, which is located at a current flow path between the fuel injector 10 and the injector driver 320. The second differential unit 316 outputs an adjusted current command 317 based on a comparison between the current command 315 and the current feedback signal 327 measured by the current sensor 322. The adjusted current command 317, which takes into account the magnetic flux and the current feedback from the fuel injector 10, is input to the PI current control module 318, thereby generating a PWM signal 319 of the commanded electrical power flow, which is then input to the injector driver 320.Based on the PWM signal 319 of the commanded electrical power flow, which takes into account the current feedback 327 and the magnetic force feedback 325 in the fuel injector 10, the injector driver 320 can provide a current in a first direction 321 to excite the electrical coil 24 in order to activate the fuel injector 10 to deliver the desired injected fuel mass to the combustion chamber 100 of the engine. It is understood that the injector driver 320 can include a bidirectional current driver capable of providing a positive current (e.g., in the first direction 321) to excite the electrical coil and a negative or reverse current to draw current from the electrical coil for purposes such as reducing the residual flow.Therefore, the magnetic force control module 300 enables the desired fuel flow rate 309 to be achieved for each of several fuel injection events in rapid succession using closed-loop operation based on the magnetic force feedback 325 and the current feedback 327 in the fuel injector 10.

[0042] Fig. Figure 5 illustrates an exemplary embodiment of a magnetic force control module using magnetic flux feedback to control a current applied to an electrical coil of a fuel injector to control its activation. The magnetic force control module 400 can be integrated within the control module 60 of the activation controller 80. Fig. 1-1 must be implemented - and executed by a processing device of the same.

[0043] Therefore, the magnetic force control module 400 is used with reference to Fig. 1-1 described. The magnetic force control module 400 comprises a force command generation module (FCG module) 410, a first differential unit 412, a proportional-integral force control module (PL force control module) 414, an injector driver 420, and a force assignment module 424. The control module 60 of the activation controller 80 of Fig. 1-1 can include the FCG module 410, the differential unit 412, the PI force control module 414, and the force assignment module 424. The injector driver 50 of the force activation controller 80 of Fig. 1-1 can include the injector driver 320. However, the control module 60 and the injector driver 50 can include other combinations of these features listed above.

[0044] In the illustrated embodiment, a desired fuel flow rate 409 is input into the FCG module 410. The desired fuel flow rate 409 can be supplied by an external module, e.g., the ECM 5, based on the aforementioned input parameters 51, to achieve a desired injected fuel mass, as described above with reference to Fig. As described in Figure 1-1, the FCG module 410 issues a magnetic force command 411 based on the desired fuel flow rate 409. The magnetic force command 411 indicates a command to generate a magnetic force required to move the armature section 21 in the second direction 82 to activate the fuel injector 10 in the open position to deliver the desired fuel flow rate 409 to the combustion chamber 100. However, it should be noted that the magnetic force command 411 does not account for the presence of residual flux, such as magnetic flux, which may be present in the fuel injector due to hysteresis and eddy current effects. The presence of residual flux can cause instability in the fuel injector, which can affect fuel flow rates and injected fuel masses delivered to the combustion chamber.Consequently, moving the armature section 21 based solely on the magnetic force command can result in a fuel flow rate actually delivered to the combustion chamber that differs from the desired fuel flow rate 409, thus resulting in an inaccurate or incorrect injected fuel mass being delivered to the fuel injector 10.

[0045] The magnetic force command 411 is input into the differential unit 412. The first differential unit 412 compares a magnetic force feedback 425 in the fuel injector 10 with the magnetic force command 411. The magnetic force feedback 425 is output by the force mapping module 424 based on a magnetic flux feedback 423 provided by the fuel injector 10. The magnetic flux feedback 423 indicates the active magnetic flux present in the fuel injector 10. The active magnetic flux or equivalent flux coupling present in the fuel injector 10 can be obtained using one or more sensing devices integrated into the fuel injector 10 by any of the methods described above with reference to the illustrated embodiment of Fig. 1-1. Therefore, the active magnetic flux feedback 423 from the fuel injector 10 can be transmitted via the feedback signals 42, which are described above with reference to the illustrated embodiment of Fig. As described in Figures 1-1. Based on known relationships, the force mapping module 424 can use lookup tables or analytical functions to output the magnetic force in the fuel injector 10 (the magnetic force feedback 425). Consequently, the magnetic force feedback 425 indicates the magnetic force of the armature section 21, which includes a force attributable to the residual flux when the active magnetic flux is present in the fuel injector 10.

[0046] Based on the comparison between the magnetic force feedback 425 and the magnetic force command 411, the differential unit 412 outputs an adjusted magnetic force command 413, which takes into account the presence of a magnetic flux 423 in the fuel injector 10. The adjusted magnetic force command 413 is input to the magnetic force control module 414, which generates a PWM signal 429 of the electrical power flow and inputs it to the injector driver 420. Consequently, the PWM signal 429 of the commanded electrical power flow takes into account the magnetic force feedback 425 in the fuel injector, while the PWM signal 419 of the commanded electrical power flow from the magnetic force control module 300 Fig.4, however, takes into account both the magnetic force feedback 325 and the current feedback 327. Therefore, the magnetic force control module 400 enables a desired fuel flow rate 409 to be achieved for each of several fuel injection events in rapid succession using closed-loop operation based on the magnetic force feedback 425 in the fuel injector 10.

[0047] The disclosure has described certain preferred embodiments and modifications thereof. Upon reading and understanding the description, others may encounter further modifications and alterations. It is therefore intended that the disclosure is not limited to the specific disclosed embodiments considered to be the best way to implement this disclosure, but rather that the disclosure will encompass all embodiments that fall within the scope of the appended claims.

Claims

[1] Electromagnetic actuation system (10), comprising: an actuator comprising an electrical coil (24), a magnetic core and an armature (21); a controllable driver circuit (50, 320) for selectively driving a current through the electrical coil (24); and a control module (60) that provides an actuator command (52) to the driver circuit (50, 320) which causes a current to be driven through the electrical coil (24) to actuate the armature (21), wherein the control module (60) comprises a magnetic force control module (300) configured to adapt the actuator command (52) to allow a magnetic force (325) in the actuator to converge to a preferred force level, wherein the magnetic force control module (300) includes a feedback circuit for a current of the electric coil (24) which is designed to adapt the actuator command (52) to allow the current of the electric coil (24) to converge to a desired current of the electric coil (24). [2] Electromagnetic actuation system (10) according to claim 1, wherein the electromagnetic actuation system (10) comprises a fuel injection valve and the preferred force level corresponds to a desired fuel flow rate (309). [3] Electromagnetic actuation system (10) according to claim 1, wherein the controllable driver circuit (50, 320) comprises a bidirectional driver circuit. [4] Electromagnetic actuation system (10) according to claim 1, wherein the magnetic force control module (300) comprises a search coil (25) which is magnetically coupled to the electrical coil (24) and is configured to detect a time rate of change of the magnetic flux (323) in the actuator, and a force assignment module (324) to provide a magnetic force output (325) based on the time rate of change of the magnetic flux (323). [5] Electromagnetic actuation system (10) according to claim 1, wherein the magnetic force control module (300) comprises a magnetoresistive sensor configured to detect flux in the actuator and a force mapping module (324) to provide a magnetic force output based on the flux in the actuator. [6] Electromagnetic actuation system (10) according to claim 1, wherein the magnetic force control module (300) comprises a Hall effect sensor configured to detect flux in the actuator and a force mapping module (324) to provide a magnetic force output based on the flux in the actuator. [7] Method for controlling an electromagnetic actuator, the method comprising: a current is driven through an electrical coil (24) of the actuator when actuation is desired; the current through the electrical coil (24) is adjusted on the basis of magnetic force feedback (325) to allow a magnetic force in the actuator to converge to a preferred force level (309); and the current through the electrical coil (24) is adjusted on the basis of feedback (327) of the current of the electrical coil (24) in order to allow the current of the electrical coil (24) to converge to a desired current of the electrical coil (24).

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