Control method and control unit for fuel injector, computer program product, and control device for fuel injector

Abstract

To deal with a technical objective to improve accuracy of a small amount of fuel jetted to an internal combustion engine by optimizing timing of intermediate current applied to a coil of a fuel injector between two consecutive injections.SOLUTION: A closing operation control unit 600 receives from an ECU 109 a terminal te of an injection control pulse ti, a duration ti_d, and fuel pressure pf and fuel temperature Tf at a closing valve time tEOI, reads valve closing timing tEOI from a pre-stored relationship / a map on the basis of what has been received, defines a start time tb_s of intermediate current on the basis of the valve closing timing tEOI, and determines a duration tb_d of the intermediate current as a function of the valve closing timing tEOI on the one hand and the fuel pressure pf and the fuel temperature Tf on the other.SELECTED DRAWING: Figure 7b

Description

[Technical Field]

[0001] The present invention relates to a method, a control unit and a computer program product for controlling the closing operation of a fuel injector, and to a control device for controlling a fuel injector. [Background technology]

[0002] To comply with current stringent emission regulations, it is necessary to prevent fuel injected into an internal combustion engine's cylinder from reaching the cylinder wall. Splitting the injected fuel volume into multiple small injections is a promising approach to achieve this goal. However, to accurately meter small amounts of fuel, the so-called ballistic operating range of the fuel injector must be precisely controlled. In this regard, stable closing of the fuel injector is essential to avoid so-called valve bounce, which leads to increased emissions.

[0003] Patent documents 1 and 2 relate to a fuel injector that includes a coil, a movable iron core, and a valve body. In this injector, during the closing operation, after the valve body reaches its valve seat, intermediate current is applied to the coil, which applies a magnetic force in the direction opposite to the moving direction of the movable iron core, slowing down its speed and preventing the valve body from bouncing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 1990526 [Patent Document 2] U.S. Patent No. 10,662,886 Summary of the Invention [Problem to be solved by the invention]

[0005] However, accurate timing of the intermediate energization is important to ensure stable closing of the fuel injector. If the intermediate energization is performed too early, the valve disc may change direction, resulting in an undesirable increase in fuel injection volume.

[0006] On the other hand, if the intermediate energization is performed too late, the speed of the armature will not be sufficiently decelerated, and as a result, the impact of the armature will lift the valve element from its valve seat, which may result in undesired additional fuel injection.In particular, Patent Document 1 discloses that after energization (application of voltage for holding current) is stopped, it is preferable to continuously stop energization for a time longer than ¾ of the time from stopping the holding current to the closing delay time Tb, and then start energization by applying voltage to attract the armature.

[0007] However, Patent Document 1 does not provide details on how to determine the timing.

[0008] The subject matter described herein addresses the technical objective of improving the accuracy of small amounts of fuel injected into an internal combustion engine by optimizing the timing of intermediate energization applied to the fuel injector coil between two successive injections. This objective is achieved by the subject matter of the accompanying claims. [Means for solving the problem]

[0009] According to the subject matter of the appended claims, a method, a control unit and a computer program product are proposed for controlling the closing operation of a fuel injector configured to perform injection into an internal combustion engine based on injection control pulses.Furthermore, a control device for controlling the fuel injector is proposed.

[0010] The injection control pulse may be provided by an engine control unit (ECU) of an internal combustion engine (hereinafter also referred to as "engine" or "combustion engine"). In particular, internal combustion engines may be used to power vehicles such as automobiles, trucks, and buses. The ECU may determine / calculate the injection control pulse based on the engine's operating conditions, for example, in relation to the load, the air mass in the cylinder, and / or the engine's air-fuel ratio. The amount of fuel injected by the fuel injector may be controlled by the duration (width) of the injection control pulse. For example, at high loads, a long injection control pulse may be output by the ECU to cause the fuel injector to inject a large amount of fuel into the internal combustion engine. It is also possible for the ECU to output multiple injection control pulses during an engine operating cycle to divide the amount of fuel injected into multiple small injections.

[0011] The injection control pulses calculated by the ECU may be sent to a drive circuit that provides a corresponding drive current curve to energize the fuel injector coil so that the fuel injector performs injection. The drive circuit may be an integral part of the ECU or a separate device.

[0012] The drive circuit and the ECU are included in a proposed control device for controlling the fuel injector, which further includes a control unit (closing control unit) for controlling the closing operation of the fuel injector according to the proposed method described below. The closing control unit may be integrated in the ECU, in the drive circuit, or may be a separate unit in the control device. The proposed method is also intended to be implemented by a computer program product storable in a memory.

[0013] The fuel injector may preferably be a solenoid injector capable of directly injecting fuel into a combustion chamber of an internal combustion engine. The fuel injector may be electrically connected to a control device and may include a fuel supply unit disposed at an upper end of the fuel injector, at least one fuel injection hole and a valve seat disposed at a lower end of the fuel injector, and a valve body disposed between the fuel supply unit and the valve seat. Furthermore, the fuel injector may include a movable iron core capable of interacting with the valve body to open and close the fuel injector.

[0014] The fuel injector may include a fuel passage for allowing fuel to flow from a fuel supply unit to a fuel injection hole. The injector coil may be disposed between the fixed core and a housing of the fuel injector. The fixed core, the injector coil, and the housing may form an electromagnet.

[0015] In a closed state where the injector coil is not energized, the valve element may be pressed into the valve seat by the spring force of at least one spring that may bias the valve element in a valve closing direction (toward the lower end of the fuel injector). To energize the injector coil, an injection control pulse may be output from the control device, and this injection control pulse may apply a drive current / drive voltage to the injector coil.

[0016] When the injector coil is energized, the valve element moves away from the valve seat and displaces in the valve opening direction (toward the top of the fuel injector). In particular, a magnetic attraction force acts between the movable iron core and the fixed iron core, causing the movable iron core to move toward the fixed iron core and move the valve element away from the valve seat and then abut against it.

[0017] This opens the fuel passage, allowing fuel to be injected into the internal combustion engine through the fuel injection hole. To stop fuel injection, the drive current / drive voltage may be switched, allowing the valve element to return to the valve seat. In particular, when the magnetic attraction force is removed, the armature and valve element can be returned in the valve closing direction. After the required valve closing time, the valve element can hit the valve seat, causing the armature to separate from the valve element, and the direction of movement of the armature can be reversed. If the armature displaces too far in the opposite direction, it may collide with the valve element again, causing the valve element to separate from the valve seat.

[0018] To avoid such a situation and stabilize the closing operation of the fuel injector, the injector coil is energized again (intermediate energization) after fuel injection is stopped to slow down the speed at which the valve body and / or the movable core moves toward the valve seat. Preferably, the intermediate energization is performed so as to slow down the speed of the movable core after it separates from the valve body.

[0019] A detailed description of the parts and functions of a fuel injector that may be controlled in accordance with the subject matter described herein can be found below in connection with FIG.

[0020] Here, the waveform of the injection control pulse is determined once when starting the injection procedure. However, the waveform of the injection control pulse may be updated during the injection procedure. Therefore, in a first step of the proposed method, the end of the injection control pulse is detected, for example, based on its falling edge, and the valve closing timing is determined based on the detected end of the injection control pulse.

[0021] This step makes it possible to determine the valve closing timing even if an update occurs.

[0022] In other words, to detect the end of the injection control pulse, for example, the waveform of the injection control pulse can be evaluated by the closed process control. It may also be possible for the end of the injection control pulse to be detected by the ECU and transmitted from the ECU to the closed process control unit. The falling edge may be detected, for example, when the value of the injection control pulse falls below a predetermined threshold. Similarly, the rising edge indicating the beginning of the injection control pulse may be detected when its value exceeds a predetermined threshold. It may also be possible to use a first threshold to detect the beginning of the injection control pulse and a second threshold different from the first threshold to detect the end of the injection control pulse.

[0023] The valve closing timing is then determined based on the detected end of the injection control pulse, the term "valve closing timing" being understood as the point in time when the fuel injector is fully closed, i.e., when the valve disc is fully seated on the valve seat.

[0024] According to one example, the valve closing timing can be detected based on the drive voltage of the fuel injector. In particular, when the injection control pulse is turned off to close the fuel injector, a reverse drive voltage can be applied to the injector coil, and the current supply to the injector coil can be cut off. When the magnetic attraction force disappears, the valve disc can be pushed back to a closed position, where it can be pressed against the valve seat by the load of at least one spring. When this happens, the valve disc can strike the valve seat, causing a change in the slope of the drive voltage, resulting in an inflection point. This inflection point can be analyzed, for example, by an ECU, to determine the point at which the valve is completely closed (the valve closing timing). For example, by forming the second derivative of the drive voltage curve, the inflection point can be accurately determined as a maximum or minimum value.

[0025] By detecting the valve closing timing as described above, a relationship between the detected valve closing timing and the end of the injection control pulse can be calculated to determine the valve closing timing based on the detected end of the injection control pulse. In particular, this relationship can be calculated for multiple engine operating points and stored in a map, for example, in the closing control unit. In this regard, the internal combustion engine may be operated on a test bench that allows the engine to be operated at every operating point throughout the engine map. This relationship may also be calculated during vehicle operation, for example, when the engine is operating at a steady-state operating point.

[0026] The relationship between the end of the injection control pulse and the valve closing timing may depend on how the valve disc moves towards the valve seat after the injection control pulse is switched off. In particular, there may be a delay between the end of the injection control pulse and the valve closing timing.

[0027] According to one example, the duration of the injection control pulse, the fuel pressure, and the fuel temperature may be taken into account in the calculated relationship between the detected valve closing timing and the end of the injection control pulse. The duration of the injection control pulse may be determined based on the detected beginning and end of the last output injection control pulse, and the fuel pressure and temperature may each be measured by appropriate sensors attached to the internal combustion engine. In particular, the fuel pressure and temperature may be measured at the end of the injection control pulse in order to obtain these parameters at the correct time, i.e., when the fuel injector begins closing.

[0028] In this regard, a long injection control pulse duration can cause a late valve closing timing because the long duration is associated with the full lift of the valve disc, from which the valve disc must return to its seat. With a short injection control pulse, the valve disc may not have reached its full lift (the ballistic operating range of the fuel injector), resulting in a shorter path back to the seat and an earlier valve closing timing. Furthermore, high fuel pressure and temperature can increase the velocity at which the valve disc moves toward its seat, resulting in an earlier valve closing timing. Thus, the relationship between the end of the injection control pulse and the valve closing timing can be calculated as a function of the injection control pulse duration and fuel pressure and temperature. Other parameters that affect the valve disc's closing behavior, such as fuel type and battery voltage, may also be considered in calculating this relationship.

[0029] According to one example, a machine learning model (ML model) may be used to calculate the relationship between the detected valve closing timing and the end of the injection control pulse. For example, the ML model may be a neural network that may be trained with training data including multiple injection control pulses and associated valve closing timings acquired at different fuel pressures and temperatures. This allows for the generation of a detailed map that reflects the relationship between the end of the injection control pulse and the valve closing timing across the engine operating map. The map may be stored in, for example, an ECU and may be continuously updated.

[0030] According to one example, the ML model may be trained when the internal combustion engine operates in a learning mode. The learning mode may be activated, for example, by an ECU, under certain conditions during operation of the combustion engine. For example, if the valve closing timing determined by the ML model at a particular engine operating point exhibits a standard deviation greater than a predetermined value, the ECU may activate the learning mode whenever the engine operates at that operating point. During the learning mode, the valve closing timing is detected, for example, by the ECU based on the drive voltage, as described above. This can be done, for example, on a test bench as well as during vehicle operation. In this way, the map can be continuously improved, even after the engine is already installed in the vehicle. Determining the valve closing time using a detailed map reduces the calculation effort without sacrificing accuracy compared to detecting the valve closing time based on the drive voltage.

[0031] Based on the determined valve closing timing, the start time and duration of intermediate energization of the fuel injector are determined. According to one example, the start time of intermediate energization may be set to a predetermined time after the valve closing timing. In particular, the predetermined time may be set to zero, and intermediate energization may be initiated when the valve disc strikes the valve seat. In this way, the armature can be efficiently decelerated at the moment it separates from the valve disc. To avoid the intermediate energization from being initiated before the valve disc reaches its valve seat due to variations in the determined valve closing timing, the predetermined time may be set to a value greater than zero. Preferably, the predetermined time may be set to a value greater than the standard deviation of the determined valve closing timing. It may also be possible to determine the predetermined time in relation to the reversal of the moving direction of the armature after the valve disc seats. In other words, intermediate energization must be initiated before the armature changes direction and moves again in the valve opening direction. To calibrate the predetermined time before the moving direction of the armature is reversed, its displacement can be measured, for example, on a test bench at different engine operating points and different valve closing timings.

[0032] As mentioned above, the duration of the intermediate energization is also determined as a function of the valve closing timing. This is possible because the required duration of the intermediate energization depends primarily on the speed of the valve disc and / or armature at the valve closing timing. This speed may be higher when the valve closing time is late and lower when the valve closing time is early. In the first case, it can be assumed that the valve disc has reached its full lift, and as a result, the valve disc and armature may be accelerated throughout the entire return stroke to the valve seat during the closing operation and therefore reach a high speed. In the second case, the valve disc may return to the valve seat before reaching its full lift, and as a result, its speed and the speed of the armature may be low when the valve seat is reached.

[0033] As a result, the duration of the intermediate energization may be increased when the valve closing timing is late and decreased when the valve closing timing is early. In particular, for example, a further relationship between the required duration of the intermediate energization and the valve closing timing may be calculated and stored in the closing operation control unit as a further map. This relationship may be determined for multiple engine operating points on a test bench and / or during vehicle operation. Similar to the relationship for determining the valve closing timing, an ML model may be used to calculate the relationship between the required duration of the intermediate energization and the valve closing timing, which may be trained in the same manner as the model for determining the valve closing timing. By determining the required duration of the intermediate energization as a function of the valve closing timing based on the stored relationship, a sufficient magnetic force acting in the valve closing direction can be provided to decelerate the valve disc and / or the armature.

[0034] According to one example, the duration of the intermediate energization may be further determined based on fuel pressure and fuel temperature. As described above, high fuel pressure and temperature can increase the speed at which the valve disc moves toward its valve seat, resulting in an earlier valve closing timing. Thus, an earlier valve closing timing does not mean that the fuel injector is in ballistic motion, where the valve disc and / or armature only reach a low speed, but rather that the fuel injector is fully open and high fuel pressure and / or high fuel temperature are provided, both of which can cause the valve disc and / or armature to accelerate. By considering fuel pressure and temperature in addition to the valve closing timing to determine the duration of the intermediate energization, the magnetic force that decelerates the valve disc and / or armature can be precisely adjusted.

[0035] In this regard, the relationship between the required duration of intermediate energization and the valve closing timing may be expanded by further considering fuel pressure and fuel temperature when calculating the duration of intermediate energization. The expanded relationship for determining the duration of intermediate energization may be determined for multiple engine operating points on a test bench and / or during vehicle operation and stored as a map in the closing control unit. An ML model may also be used for this task, which may be trained as described above. By further considering fuel pressure and fuel temperature in the stored relationship to determine the required duration of intermediate energization, the magnetic force acting in the valve closing direction can be adjusted with greater precision.

[0036] According to one example, the duration of the intermediate energization may be set shorter than the opening delay time of the fuel injector. The opening delay time of the fuel injector may be the time from the start of the injection control pulse to the time when the valve disc lifts off the valve seat. In particular, the opening delay time may be the time it takes for the armature to reach the transmission surface of the valve disc and separate from its valve seat after the injector coil is energized. Setting the intermediate energization duration to a lower / shorter duration compared to the opening delay time ensures that the valve disc does not lift off its valve seat and fuel is not injected into the engine.

[0037] The intermediate energization control pulse is calculated based on the determined start and duration of the intermediate energization. In particular, when the start and duration of the intermediate energization are determined based on the valve closing timing, the intermediate energization control pulse can be calculated by the closing operation control unit. As described above, the closing operation control unit is included in a control device for controlling the fuel injector, and the control device also includes an ECU and a drive circuit of the fuel injector.

[0038] To calculate the intermediate energization control pulse, the closing control unit can detect the end of the most recent injection control pulse and set a determined starting edge of the intermediate energization control pulse relative to the detected end of the injection control pulse. The end point of the intermediate energization control pulse can then be determined by adding the intermediate energization duration to the set starting edge. A timer unit, which can be included in the closing control unit and / or the ECU, can be used to set the starting point of the intermediate energization control pulse corresponding to the end of the most recent injection control pulse.

[0039] Subsequently, an intermediate energization control pulse is output to the fuel injector. In particular, the intermediate control pulse may be output from the closing control unit to a drive circuit, and the drive circuit may responsively provide a drive current / drive voltage for intermediate energization of the injector coil at a determined start time and for a determined duration, thereby providing a magnetic force sufficient to appropriately decelerate the valve body and / or the armature. [Effects of the Invention]

[0040] According to the present invention, the technical objective of improving the accuracy of small amounts of fuel injected into an internal combustion engine can be addressed by optimizing the timing of intermediate energization applied to the coil of a fuel injector between two consecutive injections.

[0041] The claimed subject matter will be further described below on the basis of at least one preferred example with reference to the accompanying drawings. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a schematic diagram illustrating an example of a fuel injection system for an internal combustion engine. [Figure 2] 1 is a cross-sectional view of an exemplary fuel injector connectable to a control device in accordance with the subject matter disclosed herein; [Figure 3] 3A is a schematic diagram showing an injection control pulse for operating the fuel injector shown in FIG. 2, (b) and (c) are a schematic diagram showing the corresponding drive voltage and drive current supplied to the fuel injector, and (d) is a schematic diagram showing the resulting valve displacement curve. [Figure 4] 3 is a schematic diagram illustrating the functional configuration of the control device shown in FIGS. 1 and 2 according to a preferred example of the subject matter disclosed herein. [Figure 5] 5 is a schematic diagram showing an example of a hardware configuration of the control device shown in FIGS. 1 and 2, taking into consideration the functional configuration shown in FIG. 4. FIG. [Figure 6a] 1 is a flow chart illustrating a preferred example of a method according to the presently disclosed subject matter. [Figure 6b] 6B is a flowchart illustrating the details of step S603a in the flowchart shown in FIG. 6A. [Figure 7a] 6B is a flowchart illustrating the details of step S604a in the flowchart shown in FIG. 6A. [Figure 7b] 7B is a flowchart illustrating the details of step S603b in the flowchart shown in FIG. 7A. [Figure 8] 1A is a schematic diagram showing two successive injection control pulses with an intermediate energization control pulse disposed therebetween for operating the fuel injector shown in FIG. 2 in a preferred embodiment of the subject matter disclosed herein; (b) and (c) are corresponding drive voltages and drive currents; and (d) is a diagram showing the resulting valve displacement curve. DETAILED DESCRIPTION OF THE INVENTION

[0043] 1 is a diagram schematically illustrating an example of a fuel injection system for an internal combustion engine 1, which includes a fuel pump 106, a fuel rail 105 having a pressure sensor 102, four fuel injectors 101, and a control device 150. The number of fuel injectors is not limited to four, and may be in the range of 1 to 12, for example.

[0044] In the illustrated example, one fuel injector 101 is provided for each cylinder 108 of the internal combustion engine 1 (not described in detail), and injects fuel directly into the combustion chamber 107 of the cylinder 108. It may also be possible to provide two or more injectors for each cylinder. The fuel to be injected is pressurized by a fuel pump 106 and sent to the fuel injector 101 via a fuel rail 105. The fuel pressure varies depending on the balance between the flow rate of fuel discharged by the fuel pump 106 and the amount of fuel injected by the fuel injector 101 into the combustion chamber 107. However, the amount of fuel discharged from the fuel pump 106 may also be controlled by a control device 150 based on information from a pressure sensor 102 so that the pressure in the pipe of the fuel rail 105 becomes a predetermined pressure.

[0045] The fuel injection of each fuel injector 101 can be controlled by the width (pulse duration) of an injection control pulse sent from an engine control unit (ECU) 109 to a drive circuit 127. The drive circuit 127 can calculate a drive current curve based on the injection control pulse received from the ECU 109. The calculated drive current curve can then be supplied to each fuel injector 101. The drive circuit 127 can be part of the ECU 109 or a separate device. The drive circuit 127 and the ECU 109 can be included in the control device 150. The control device 150 can further include a closing operation control unit 600 (see FIGS. 4 and 5 ) for performing intermediate energization of the fuel injector 101 between two consecutive fuel injections to control / stabilize the closing operation thereof.

[0046] Figure 2 shows a cross-sectional view of an exemplary fuel injector connected to the control device 150 already shown in Figure 1, which includes the drive circuit 127 and the ECU 109. The control device 150 may further include a closing control unit 600 (see Figures 4 and 5).

[0047] The illustrated fuel injector 101 includes a fuel supply unit 212 disposed at the upper end of the fuel injector 101, a fuel injection hole 215 and a valve seat 202 disposed at the lower end of the fuel injector 101, and a valve body 201 having an intermediate member 214 and a movable iron core 206 disposed between the fuel supply unit 212 and the valve seat 202.

[0048] A fuel passage is provided inside fuel injector 101 so that fuel flows from fuel supply unit 212 to fuel injection hole 215 along central axis 200a of fuel injector 101. Injector coil 208 is disposed between fixed iron core (stator) 207 and housing 209 of fuel injector 101. Fixed iron core 207, injector coil 208, and housing 209 form an electromagnet.

[0049] In a valve-closed state in which injector coil 208 is not energized, valve element 201 is pressed against valve seat 202 by the spring forces of first spring 210 and second spring 216, which urge valve element 201 in a valve-closing direction (toward the lower end of fuel injector 101). The spring forces of first spring 210 and second spring 216 act against the spring force of third spring 217, which urges movable core 206 in a valve-opening direction (toward the upper end of fuel injector 101) to abut against intermediate member 214. Because the spring force of second spring 216 is greater than the spring force of third spring 217, a gap 250 is formed between valve element 201 and movable core 206.

[0050] The drive circuit 127 and the ECU 109 are connected to the fuel injector 101. The ECU 109 can receive a plurality of sensor signals indicating the operating state of the internal combustion engine 1 from various sensors, such as a pressure sensor 102 attached to a fuel rail pipe upstream of the fuel injector 101 (see FIG. 1 ), and can calculate the amount of fuel required depending on the operating state of the internal combustion engine, and based on this, can calculate the pulse duration and injection timing of the fuel injector 101. An injection control pulse output from the ECU 109 can be input to the drive circuit 127 via a signal line 223.

[0051] The drive circuit 127 may have a circuit that receives injection control pulses from the ECU 109 and supplies a drive current / drive voltage to the injector coil 208 of the fuel injector 101 to perform fuel injection. The ECU 109 communicates with the drive circuit 127 via a communication line 222 and can receive information from the drive circuit, and can switch the drive current generated by the drive circuit 127 depending on the fuel pressure and the operating state of the internal combustion engine.

[0052] When injector coil 208 is energized, a magnetic driving force can be generated by an electromagnet including stationary core 207, coil 208, and housing 209. This magnetic driving force can cause magnetic flux to circulate in a magnetic path passing through coil 208, stationary core 207, movable core 206, housing 209, and movable core 206. This causes a magnetic attraction force to act between movable core 206 and stationary core 207, displacing movable core 206 and intermediate member 214 toward stationary core 207.

[0053] The movable iron core 206 can be displaced until the transmission surface 219 of the valve element 201 and the transmission surface 218 of the movable iron core 206 come into contact with each other. During this time, the valve element 201 may remain in contact with the valve seat 202. Only when the movable iron core 206 is displaced by the gap 250 generated between the valve element 201 and the movable iron core 206 and the transmission surface 219 of the valve element 201 collides with the transmission surface 218 of the movable iron core 206 can the valve element 201 be separated from the valve seat 202 by the kinetic energy of the movable iron core 206. This opens the fuel passage, allowing fuel to be injected into the internal combustion engine 1 through the fuel injection hole 215.

[0054] When the movable core 206 comes into contact with the fixed core 207 during its displacement, the valve element 201 is displaced in the valve opening direction, and the movable core 206 is displaced in the valve closing direction. This means that when the fixed core 207 and the movable core 206 collide, the valve element 201 and the movable core 206 are separated from each other, and the movable core 206 is displaced in the valve closing direction and can come to rest at the target lift position (a stable valve open state).

[0055] Subsequently, when the power supply to the injector coil 208 is turned off and the magnetic attractive force is removed, the armature 206 can be pushed back to the closed position where the valve body 201 is pressed into the valve seat 202 by the spring force of the first spring 210 and the force due to the fuel pressure. The spring force of the first spring 210 acting on the valve body 201 can be transmitted to the armature 206 via the transmission surface 219 of the valve body 201 and the transmission surface 218 of the armature 206.

[0056] After the required closing time, the valve disc 201 can abut against the valve seat 202 and the transmission surface 218 of the armature 206 can move away from the transmission surface 219 of the valve disc 201 .

[0057] When the fuel injector 101 is closed, the third spring 217 can change from extension to compression, and when the valve disc 201 hits the valve seat 202, the transmission surface 218 of the movable iron core 206 moves away from the transmission surface 219 of the valve disc 201 and can continue to move independently in the valve closing direction, which causes a change in the inductance of the injector coil 208. This effect can be used to detect the closing point of the fuel injector, as will be described later in conjunction with Figures 3(a) to 3(d).

[0058] Depending on the speed of the armature 206 when the valve body 201 reaches the valve seat 202, the direction of movement of the armature 206 may be reversed, causing the armature 206 to move in the valve opening direction again. If the armature is moving at a high speed at this time, it may pass through the gap 250 again, causing a further collision between the transmission surface 218 of the armature 206 and the transmission surface 219 of the valve body 201, and thus causing the fuel injector 101 to undesirably open.

[0059] To avoid such undesirable valve bounce, during the closing operation of the fuel injector 101, preferably at a predetermined time before its direction of motion reverses and / or when the valve disc 201 hits the valve seat 202, intermediate energization of the injector coil 208 is performed to generate a magnetic attractive force as described above, thereby slowing down the speed of the armature 206. To calibrate / determine the predetermined time for applying intermediate energization before the armature's direction of motion reverses, its displacement can be measured, for example, on a test bench at different engine operating points and different valve closing timings. An example for applying intermediate energization according to the subject matter described herein is shown in Figures 8(a)-8(d).

[0060] 3, (a) is a diagram schematically illustrating the injection control pulse ti for operating the fuel injector 101 shown in FIG. 2, (b) and (c) are corresponding drive voltages 304, 305 and corresponding drive currents 308, 331, 332 supplied to the fuel injector 101, and (d) is a diagram schematically illustrating the resulting displacement curve of the valve body 201 (dotted displacement curve 334) and the displacement curve of the movable iron core 206 (solid displacement curve 335).

[0061] 3(a) to 3(c), it can be seen that when the injection control pulse ti is output to the drive circuit 127 at time ts, a high voltage 304 is applied thereto, and power supply to the injector coil 208 begins. The high voltage may have a value of 50 V or more. As a result, the armature 206 is displaced in the valve opening direction (see the solid displacement curve 335 in FIG. 3(d)). After the armature 206 passes through the gap 250 at the opening delay time t0, it abuts against the valve disc 201. Subsequently, both elements, i.e., the armature and the valve disc, are displaced until the valve disc 201 reaches its full lift (see the displacement curves 334 and 335 in FIG. 3(d)).

[0062] As shown in current curve 308, application of high voltage 304 causes a rapid increase in current value, reaching a predetermined peak current value Ip and fully opening fuel injector 101. After this, application of high voltage 304 is reduced from value 336 to pulse-width-modulated low voltage 305, resulting in a decrease in current value to a first holding current value Ih1 according to a first current profile 331. The low voltage may be a battery voltage having a value in the range of 12 V to 14 V. In a next step, by decreasing the pulse width of low voltage 305, the current decreases to a second holding current value Ih2 according to a second current profile 332 (see FIGS. 3(b) and 3(c)). By applying holding currents Ih1 and Ih2 to fuel injector 101, a stable valve-open state can be maintained.

[0063] Subsequently, when the injection control pulse ti is turned off at time te, the drive circuit 127 applies a reverse drive voltage to the injector coil 208 (see FIG. 3(b)). As a result, the current supply to the injector coil 208 is cut off (see FIG. 3(c)), the magnetic flux generated in the magnetic circuit is removed, and the magnetic attractive force is also removed. As a result, the movable iron core 206, which has lost its magnetic attractive force, is pushed back to the closed position where the valve element 201 can abut against the valve seat 202 by the load of the first spring 210 and the force due to the fuel pressure (see FIG. 3(d)).

[0064] Time t EOI At (valve closing timing), the valves 201, 202 are completely closed, and the valve element 201 is fully seated on the valve seat 202 again. When the valve element 201 hits the valve seat 202, the transmission surface 218 of the movable iron core 206 separates from the transmission surface 219 of the valve element 201 and continues to move in the valve closing direction. At this time, the slope of the drive voltage changes, and an inflection point 330 occurs (see FIG. 3(b)). This inflection point 330 occurs at the time t when the valves 201, 202 are completely closed. EOI can be used to determine

[0065] In other words, when the fuel injector 101 is closed, the drive current flowing through the injector coil 208 is cut off, and a counter electromotive force is applied to the injector coil 208. After the drive current completely disappears, the counter electromotive force gradually decreases, and when the valve disc 201 hits the valve seat 202, an inflection point 330 occurs in the drive voltage by changing the inductance (see FIGS. 3(b) to 3(d)). For example, by deriving the drive voltage curve applied to the fuel injector twice, the inflection point 330 can be accurately determined as a maximum or minimum value.

[0066] The displacement curve 335 of the armature 206 shown in Figure 3(d) shows that the armature 206 continues to move for a considerable period of time after the valve disc is seated, thereby reversing its direction of movement. In the example shown, the armature 206 moves at the valve closing timing t EOIAt time t, the armature passes through its starting position and continues to move in the valve closing direction. After that, the armature changes its direction of motion and returns to its starting position. However, at time t EOI Depending on the velocity of the armature 206 at the valve opening, the armature 206 may again cross its starting position and move further in the opening direction. If the armature passes through the gap 250 again in that direction, the valve disc may be lifted from the valve seat 202, causing undesirable valve bounce. As described above, to avoid this undesirable phenomenon, intermediate energization of the injector coil 208 is performed to generate a magnetic attractive force that opposes the direction of the armature's movement in the valve closing direction. An example for applying intermediate energization according to the subject matter described herein is shown in Figures 8(a)-8(d).

[0067] 4 is a diagram illustrating a schematic functional configuration of the control device 150 shown in FIGS. 1 and 2 according to a preferred embodiment of the subject matter disclosed herein. As already shown in FIGS. 1 and 2, the control device 150 is connected to the fuel injector 101 and includes the ECU 109 and the drive circuit 127. Furthermore, the control device 150 is connected to a power source 401 and a plurality of sensors 420-425 (not shown in detail) attached to the engine 1. The plurality of sensors 420-425 includes a speed sensor 420 for measuring the speed of the engine 1, an airflow meter 421 for measuring the amount of air introduced into each cylinder (not shown in detail) of the engine 1, the fuel pressure sensor 102 described above, a fuel temperature sensor 423 for measuring the temperature of the fuel in, for example, the fuel rail 105, a throttle position sensor 424 for measuring the opening of the throttle plate (not shown) of the engine 1, and a lambda sensor for measuring the oxygen in the exhaust gas flow of the engine 1 to determine its air-fuel ratio. The ECU 109 can determine the amount of fuel according to the operating state of the internal combustion engine 1 based on the measurement signals received from the plurality of sensors 420-425.

[0068] Injector control unit 404 of ECU 109 calculates injection control pulses ti to cause fuel injector 101 to inject the determined amount of fuel into engine 1. Injector control unit 404 shown in the figure includes an injection timing calculator 405, an injection duration calculator 407, an injector closure detector 409, a current profile calculator 408, and a closure operation control unit 600.

[0069] In particular, the injection timing (start time ts and end time te of injection) is determined by the injection timing calculator 405, and the injection duration ti_d is determined by the injection duration calculator 407 of the injector control unit 404, based on which an injection control pulse is generated. This injection control pulse is then sent from the injection timing calculator 405 and / or the injection duration calculator 407 to a current profile calculation unit 408 of the injector control unit 404 to calculate a drive current profile corresponding to the injection control pulse ti. This drive current profile is then sent to a current profile control unit 410 of the drive circuit 127, which generates the drive current required to open the fuel injector 101 at the determined start time for the determined injection duration.

[0070] In particular, the injector close detector 409 of the injector control unit 404 analyzes the drive current supplied to the injector 101 by the drive circuit 127, and detects the valve close timing t , at which the valves 201 and 202 are completely closed. EOI As described above, when the valve element 201 hits the valve seat 202, the slope of the drive voltage changes and an inflection point 330 (see FIG. 3(b)) occurs. This inflection point is used to determine the time t EOI For example, the injector closure detector 409 may derive the drive voltage curve applied to the fuel injector twice and determine the inflection point 330 from the resulting maximum or minimum.

[0071] Due to the computational effort associated with the double derivation of the drive voltage, the valve closing timing t EOIis determined solely by the injector closure detector 409 during the engine's learning mode. This learning mode is based on the end te of the injection control pulse ti and the valve closing timing t determined by the injector closure detector 409. EOI This relationship may depend on how the valve disc 201 moves towards the valve seat 202 after the injection control pulse ti is switched off. In particular, the duration ti_d of the injection control pulse ti, the fuel pressure p f , and fuel temperature T f Depending on the timing, the end te of the injection control pulse ti and the valve closing timing t EOI There may be a delay between

[0072] In this regard, the long duration of the injection control pulse is associated with a full lift of the valve disc and therefore a late valve closing timing t EOI On the other hand, high fuel pressure p f and high fuel temperature T f increases the speed at which the disc moves toward its seat, resulting in an earlier valve closing timing t EOI This can result in:

[0073] In the learning mode that takes into account the above-mentioned dependency, the end te of the injection control pulse ti and the valve closing timing t EOI In order to calculate the relationship between the valve closing timing t EOI receives the end te of the injection control pulse ti from the injection timing calculator 405, receives the injection duration ti_d from the injection duration calculator 407, and receives the fuel pressure p from each sensor 102, 423 f and fuel temperature T f can be received.

[0074] The learning mode of the engine may be performed on a test bench, where the engine is tested under different operating conditions (injection duration ti_d, fuel pressure p) at each operating point throughout the engine map. f , and fuel temperature T f) This relationship may also be calculated during vehicle operation, for example, when the engine is operating at a steady state operating point.

[0075] This allows the closing control unit 600 to create and store maps that provide the necessary relationships. It may also be possible for the respective maps to be stored in a separate part of the control device 150. In particular, in the learning mode, the end te of the injection control pulse ti and the valve closing timing t EOI A machine learning model (ML model) may be used to calculate the relationship between different fuel pressures p f and fuel temperature T f A plurality of injection control pulses ti and associated valve closing timings t EOI The neural network may be trained with a plurality of training data including the end te of the injection control pulse ti and the valve closing timing t EOI This allows the closing operation control unit 600 to generate a detailed map that reflects the relationship between the sensor signals (te, ts, ti_d, p f , T f ) based only on the valve closing timing t EOI can be determined.

[0076] The closing operation control unit 600 determines the valve closing timing t of the fuel injector 101 based on the detected end te of the injection control pulse ti using a map including the above-mentioned correspondence, in order to perform intermediate energization of the fuel injector 101 between two consecutive fuel injections. EOI Determine.

[0077] Determined valve closing timing t EOIBased on this, the closing operation control unit 600 determines the time tb_s and duration tb_d of the start of intermediate energization, calculates a corresponding intermediate energization control pulse tb, and then transfers it to the pulse compensator 420 included in the drive circuit 127. Upon receiving the intermediate energization control pulse tb from the closing operation control unit 600, the pulse compensator 420 can generate a drive current / drive voltage required to execute intermediate energization, and can send this drive voltage to the fuel injector 101.

[0078] In this regard, the closing operation control unit 600 sets the starting edge tb_s of the intermediate energization control pulse to the valve closing timing t EOI The predetermined time may be set to a predetermined time thereafter. For example, the predetermined time may be set to zero, and the intermediate energization may be started when the valve disc 201 hits the valve seat 202. In this way, the armature 206 can efficiently decelerate at the moment of separation from the valve disc 201. The closing operation control unit 600 may be able to set the predetermined time to a value greater than zero, taking into consideration the reversal of the movement direction of the armature 206 after the valve disc 201 is seated. In this case, it is necessary to start the intermediate energization before the armature 206 changes its direction and moves again in the valve opening direction. In order to calibrate the predetermined time so that the starting edge tb_s of the intermediate energization control pulse is set before the movement direction of the armature 206 is reversed, the displacement may be adjusted, for example, depending on different engine operating points and different valve closing timings t EOI It can be measured on a test bench at

[0079] As described above, the closing operation control unit 600 also adjusts the duration tb_d of the intermediate energization to the valve closing timing t EOI This means that the required duration of the intermediate energization is mainly determined by the valve closing timing t EOI This is possible because the speed of the valve element 201 and / or the armature 206 during the valve closing time t EOI is higher when the valve closing time t EOIIn the first case, it can be assumed that the valve disc 201 has reached its full lift, so that the valve disc 201 and the armature 206 can be accelerated throughout the entire stroke back to the valve seat 202 during the closing operation, and can therefore reach a high speed. In the second case, the valve disc 201 can return to the valve seat 202 before reaching its full lift, so that its speed and the speed of the armature 206 can be lower when the valve seat 202 is reached.

[0080] Furthermore, the closing operation control unit 600 determines the duration tb_d of the intermediate energization based on the fuel pressure p f and fuel temperature T f can be taken into consideration, because these parameters also affect the speed of the valve disc 201 and / or the armature core 206. In this way, a sufficient magnetic force acting in the valve closing direction can be provided to decelerate the valve disc 201 and / or the armature core 206, thereby preventing the valve disc 201 from bouncing.

[0081] FIG. 5 shows an example of a hardware configuration of the control device 150 shown in FIGS. 1 and 2, taking into consideration the functional configuration shown in FIG.

[0082] In the illustrated example, the hardware configuration includes a CPU 501, a closing operation control unit 600, and a drive IC 502. For example, the CPU 501 and the closing operation control unit 600 may be included in the ECU 109, and the drive IC 502 may be included in the drive circuit 127. The CPU 501 is connected to the closing operation control unit 600 and the drive IC 502 via a communication line 222 and a signal line 223. The closing operation control unit 600 is disposed between the CPU 501 and the drive IC 502, and is connected to the drive IC via a signal line 601.

[0083] The illustrated hardware configuration further includes a boost circuit 514 for providing a high voltage VH in a high voltage source 516. The high voltage VH is generated by boosting a battery voltage VB input to the boost circuit 514. The boost circuit 514 may be a DC / DC converter. In the illustrated example, the boost circuit 514 includes a coil 530, a transistor 531, a diode 532, and a capacitor 533. The transistor 531 is connected to the CPU 501 via the driving IC 502, and the boosted voltage VH output from the boost circuit 514 can be detected by the driving IC 502 or the CPU 501.

[0084] Furthermore, according to the illustrated example, a switching element 505 is disposed between a high voltage source 516 of the voltage boost circuit 514 and a high voltage side terminal 590 of the fuel injector 101. Additionally, a switching element 507 is disposed between a low voltage source 517 and the high voltage side terminal 590 of the fuel injector 101, and a further switching element 506 is disposed between a low voltage side terminal 591 of the fuel injector 101 and ground potential 515. Switching elements 505, 506, and 507 may be transistors, preferably field effect transistors (FETs), capable of switching the fuel injector 101 on and off.

[0085] In the illustrated example, a diode 535 is disposed between a high-voltage terminal 590 of injector coil 208 and switching element 505, allowing current to flow from high-voltage source 516 toward injector coil 208 and ground potential 515. Furthermore, a diode 511 is disposed between high-voltage terminal 590 of coil 208 and switching element 507, allowing current to flow from low-voltage source 517 toward injector coil 208 and ground potential 515. Low-voltage source 517 may be a battery that supplies a voltage VB that may be in the range of, for example, 12 to 14 V.

[0086] Further, diode 509 and diode 510 are provided in the illustrated hardware configuration to apply a back-drive voltage to injector coil 208. Additionally, current sense resistors 508, 512, and 513 are connected to driver IC 502 to sense the current flowing from their respective sources to fuel injector 101.

[0087] The CPU 501 can receive multiple sensor signals indicating the operating state of the internal combustion engine 1, for example, from multiple sensors 420 to 425 shown in Figure 4, and can calculate the amount of fuel required depending on the operating state of the internal combustion engine 1, and can calculate the injection control pulse ti based on that.

[0088] Subsequently, CPU 501 can output the calculated injection control pulse ti to driving IC 502 of fuel injector 101 via signal line 223. Based on the detected current value, driving IC 502 can switch switching elements 505, 506, and 507 to generate a desired driving current. In other words, switching elements 505, 506, and 507 can be switched between energized and de-energized by driving IC 502 to supply driving current to fuel injector 101.

[0089] To perform intermediate energization, the closing control unit 600 can also receive an injection control pulse ti via the signal line 223. The closing control unit 600 then detects the end te of the injection control pulse and calculates the valve closing timing t using the relationship described above. EOI The determined valve closing timing t EOI Based on this, the closing operation control unit 600 can set the start point tb_s and duration tb_d of the intermediate current and calculate the corresponding intermediate current control pulse tb. The calculated intermediate current control pulse tb can then be transferred to the driving IC 502 via the signal line 601, and the driving IC 502 can then switch the switching elements 505, 506, and 507 to generate a drive current for performing the intermediate current.

[0090] FIG. 6a shows a flowchart illustrating a preferred example of a method according to the subject matter disclosed herein. When step S600a begins, the closing control unit 600 checks, for example, whether a rising edge of the injection control pulse ti has occurred. The rising edge of the injection control pulse ti may be detected, for example, by analyzing whether its value exceeds a predetermined threshold. If so, the start ts of the injection control pulse is determined in step S601a. ​​If not, the search for the rising edge of the injection control pulse is repeated until a positive result is obtained. Subsequently, the closing control unit 600 checks whether a falling edge of the injection control pulse ti has occurred. If so, the closing control unit 600 determines the end te of the injection control pulse in step S602a. If not, the search for the falling edge of the injection control pulse is also repeated until a positive result is obtained. The falling edge of the injection control pulse ti may be detected by analyzing whether its value falls below a predetermined threshold. It may also be possible for a first threshold to be used to detect the start of an injection control pulse and a second threshold different from the first threshold to be used to detect the end of an injection control pulse by the closing operation control unit 600. Alternatively, the start edge ts and the end edge te of the injection control pulse may be determined by the ECU 109 in steps S601a and S602a and sent to the closing operation control unit 600.

[0091] If the flag for executing intermediate energization (IE control pulse flag) is set, the closing operation control unit 600 determines the valve closing timing t based on the end te of the injection control pulse ti in step S603a. EOI The IE control pulse flag is set to, for example, the end timing te of the injection control pulse ti and the valve closing timing t EOI may be set by the ECU if a valid relationship between is already stored in the control device 150, for example as a map. After generating the intermediate energization control pulse tb, the process is completed.

[0092] If the IE control pulse flag is not set, it is checked whether the engine 1 is in a learning mode. The engine 1 is in a learning mode, for example, between the end te of the injection control pulse ti and the valve closing time t EOI is not valid, this may be the case if the standard deviation of the determined valve closing times is too large, for example.

[0093] If the engine 1 is not in the learning mode, the process is already completed. However, if the engine is in the learning mode, the closing control unit 600 will, in step S604a, determine, for example, the duration ti_d of the injection control pulse ti, as well as the fuel pressure p f and fuel temperature T f Considering the end te of the injection control pulse ti and the valve closing timing t EOI Determine the relationship between

[0094] 6b shows a flowchart illustrating details of step S603a of the flowchart shown in FIG. 6a, i.e., how the closing operation control unit 600 generates the intermediate energization control pulse tb. The intermediate energization control pulse tb may be generated by the ECU 109 or another unit of the control device 150.

[0095] This process starts in step S600b at the end te of the injection control pulse ti. At this time, in steps S601b and S602b, a timer that may be included in the ECU is reset and started. Next, in step S603b, the closing operation control unit 600 calculates the end te of the injection control pulse ti and the valve closing timing t EOI In particular, the closing operation control unit 600 calculates the starting end tb_s and the ending end tb_e of the intermediate energization control pulse tb based on this relationship. EOI and the valve closing timing t EOI Based on this, the start point tb_s and the end point tb_e of the intermediate energization control are calculated.

[0096] The closing operation control unit 600 continuously checks whether the timer value is equal to or greater than the start time tb_s of the intermediate energization control pulse tb, and if so, starts outputting the intermediate energization control pulse tb to the drive circuit 127 in step S604b. Subsequently, the closing operation control unit 600 continuously checks whether the timer value is equal to or greater than the end time tb_e of the intermediate energization control pulse tb, and if so, stops outputting the intermediate energization control pulse tb to the drive circuit 127 in step S605b. Thereafter, the operation is completed in step 606b.

[0097] FIG. 7a shows the details of step S604a in the flowchart shown in FIG. 6a, that is, the closing operation control unit 600 determines the timing between the end te of the injection control pulse ti and the valve closing timing t EOI The flowchart below explains how to determine the relationship between the end te of the injection control pulse ti and the valve closing timing t EOI It may also be possible for the relationship between the ECU 109 and the control unit 150 to be determined by the ECU 109 or another unit of the control unit 150.

[0098] After starting the process in step S700a, for example, the injector closure detector 409 measures the drive voltage signal of the fuel injector 101 in step S701a, and then filters the measured signal in step S702a. The filtered drive voltage signal is then analyzed to determine the valve closing timing t EOI In step S704a, the end time te and duration ti_d of the injection control pulse ti, and the valve closing time t EOI Fuel pressure at p f and fuel temperature T f is received from, for example, ECU 109 (S704a).

[0099] In the following step S705a, the end time te and duration ti_d of the injection control pulse ti, and the fuel pressure p f and fuel temperature T f Valve closing timing t EOIThe dependency of the timing t is determined, for example, by using an ML model that can be trained with a plurality of training data including the aforementioned parameters. In other words, the timing t depends on the end te of the injection control pulse ti and the valve closing timing t. EOI The relationship between the injection duration ti_d and the fuel pressure p f and fuel temperature T f The decision is made taking into account the impact of

[0100] Next, in step S706a, the valve closing time t EOI and fuel pressure p f and fuel temperature T f The dependence of the intermediate energization duration tb_d on the relationship between the current supply duration tb_d and the current supply duration tb_d is determined. The relationships determined in steps S705a and S706a are stored as a map in the closing operation control unit 600 or any other part of the control device 150, for example, and the process is completed in step S707a.

[0101] 7b shows a flowchart illustrating the details of step S603b of the flowchart shown in FIG. 6b, i.e., how the closing operation control unit 600 determines the start end tb_s and the end end tb_e of the intermediate energization control pulse tb from the relationship / map determined in FIG. 7a. The start end tb_s and the end end tb_e of the intermediate energization control pulse tb may also be determined by the ECU 109 or another unit of the control device 150.

[0102] After starting the process of step S700b, for example, the closing operation control unit 600 determines the end time te and duration ti_d of the injection control pulse ti, and the valve closing time t EOI Fuel pressure at p f and fuel temperature T f may be received from, for example, the ECU 109 (S701b). Based on the received parameters, the closing control unit 600 determines the valve closing timing t from the relationship / map determined and stored in step S705a of FIG. 7a. EOI can be read out (S702b).

[0103] Next, in step S703b, the start time point tb_s of the intermediate energization is set to the determined valve closing timing t EOI In the next step S704b, the duration of the intermediate energization tb_d is determined based on the valve closing timing tb_d using the relationship / map determined and stored in step S706a of FIG. 7a. EOI and fuel pressure p f and fuel temperature T f is determined as a function of

[0104] In the following steps S703b and S704b, the start end tb_s and duration tb_d of the intermediate energization control pulse tb are set to the valve closing timing t EOI In the case of the intermediate energization duration tb_d, the valve closing timing t EOI Fuel pressure at p f and fuel temperature T f is taken into consideration. In particular, the intermediate energization duration tb_d is determined using the relationship / map determined and stored in step S706a of FIG. 7a. Finally, in step S705b, the end time tb_e of the intermediate energization control pulse tb is defined by adding the start time tb_s and duration tb_d of the intermediate energization. Then, in step S706b, the process is completed.

[0105] Figures 8(a)-8(d) show schematic diagrams illustrating the placement of an intermediate energization control pulse between two consecutive injection control pulses for operating the fuel injector shown in Figure 2. Additionally, the drive voltage and drive current corresponding to the injection control pulses and the resulting displacement curves are shown.

[0106] 3(a) to 3(d), at time ts, a first injection control pulse ti1 is output to the drive circuit 127, a high voltage 1004 is applied, and power supply to the injector coil 208 is initiated, causing displacement of the movable iron core 206 in the valve opening direction (see the solid displacement curve 1034 in FIG. 3(d)). As in FIG. 3(d), the movable iron core 206 passes through the gap 250 at the opening delay time t0 and comes into contact with the valve body 201, resulting in displacement of both elements.

[0107] Subsequently, both the movable iron core and the valve element are displaced until the valve element 201 reaches its full lift (see displacement curves 1034 and 1035 in FIG. 8(d)).

[0108] As shown in current curve 1008, application of high voltage 1004 causes a rapid increase in current until a predetermined peak current value Ip is reached, fully opening the fuel injector 101. Then, application of high voltage 1004 is reduced from value 1036 to pulse-width-modulated low voltage 1005, causing the current to decrease to a first holding current value Ih1 according to a first current profile 1031. In a next step, the pulse width of low voltage 1005 is reduced, causing the current to decrease to a second holding current value Ih2 according to a second current profile 1032 (see FIGS. 8(b) and 8(c)). By applying the holding currents Ih1 and Ih2 to the fuel injector 101, a stable valve-open state can be maintained.

[0109] When the injection control pulse ti1 is turned off at time te, the drive circuit 127 applies a reverse drive voltage to the injector coil 208 (see FIG. 8(b)). As a result, the current supply to the injector coil 208 is cut off (see FIG. 8(c)), the magnetic flux generated in the magnetic circuit is removed, and the magnetic attraction force is also removed. As a result, the movable iron core 206, which has lost its magnetic attraction force, is pushed back to the closed position where the valve element 201 can abut against the valve seat 202 by the load of the first spring 210 and the force due to the fuel pressure (see FIG. 8(d)).

[0110] Unlike the closing operation shown in Figures 3(a) to 3(d), at time tb_s when the valve disc 201 reaches the valve seat 202, an intermediate energization control pulse tb is output to the drive circuit 127, resulting in the application of a high drive voltage 1006 and the generation of a drive current 1010. Due to the short duration tb_d of the drive voltage 1006, the peak of the drive current 1010 only reaches the second holding current value Ih2, which means that no displacement of the valve disc 201 occurs (see displacement curve 1035 in Figure 8(d)). However, as can be seen from the armature displacement curve 1034 in Figure 8(d), the magnetic force generated by the drive current 1010 causes the armature 206 to decelerate, so that the armature does not move beyond its starting position, then does not change direction, but instead smoothly returns to its starting position.

[0111] The intermediate energization control pulse tb is switched off at time tb_e, and the next fuel injection is started at time ts2 by the injection control pulse ti2, which is carried out in the same manner as the first fuel injection.

[0112] Comparing the displacement curves 335 and 1034 of the armature shown in FIG. 3(d) and FIG. 8(d), the displacement of the armature 206 is EOI It becomes clear that the voltage can be reliably stabilized by intermediate energization with duration tb_d at [Explanation of symbols]

[0113] 1. Internal combustion engine 101 Fuel Injector 102 Pressure Sensor 105 Fuel rail, fuel pipe 106 Fuel pump 107 Combustion chamber 108 cylinders 109 Engine Control Unit (ECU) 127 Drive Circuit 150 control device 200a center axis 201 Valve body 202 Valve seat 206 moving core 207 Fixed core 208 injector coil 209 Housing 210 First Spring 212 Fuel Supply Unit 214 Intermediate parts 215 Fuel injection hole 216 Second Spring 217 Third Spring 218 Transmission Surface 219 Transmission Surface 222 communication line 223 Signal Line 250 gap 304 Drive voltage (high voltage) 305 Drive voltage (low voltage) 308 Drive Current 330 Inflection Point 331 Drive Current, First Current Profile 332 Drive Current, Second Current Profile 334 Displacement Curve 335 Displacement Curve 401 Power supply 404 Injector control unit 405 Injection timing calculator 407 Injection Duration Calculator 408 Current profile calculation unit 409 Injector Closed Detector 410 Current profile control section 420 Pulse Compensator 420 Speed ​​Sensor 421 Air flow meter 422 Sensors 423 Fuel Temperature Sensor 424 Throttle Position Sensor 425 Sensor 501 CPU 502 Driver IC 505 Switching element 506 Switching element 507 Switching element 508 Current Sense Resistor 509 Diode 510 Diode 511 Diode 512 Current detection resistor 513 Current detection resistor 514 Boost Circuit 515 Ground potential 516 High Voltage Source 517 Low Voltage Source 530 coil 531 Transistor 532 Diode 533 Capacitor 535 Diode 590 terminal 591 terminal 600 Closing operation control unit 601 Signal Line 1004 High Voltage 1005 Low Voltage 1006 Drive voltage, drive current 1008 Current curve 1010 Drive Current 1031 First Current Profile 1032 Second Current Profile 1034 Displacement Curve 1035 Displacement Curve

Claims

1. 1. A method for controlling closing of a fuel injector configured to perform injection into an internal combustion engine based on injection control pulses, comprising: Detecting the end of the injection control pulse; determining a valve closing timing of the fuel injector based on the detected end of the injection control pulse; determining a start point of intermediate energization of the fuel injector based on the determined valve closing timing; Calculating an intermediate energization control pulse based on the determined start end of the intermediate energization; The intermediate current control pulse is output to the fuel injector.

2. A method for controlling a fuel injector comprising:

2. 2. The method of controlling a fuel injector according to claim 1, the valve closing timing is detected based on a drive voltage of the fuel injector; A relationship between the detected valve closing timing and the end of the injection control pulse is calculated, and the valve closing timing is determined based on the detected end of the injection control pulse using the relationship.

2. A method for controlling a fuel injector comprising:

3. 3. The method for controlling a fuel injector according to claim 2, The relationship between the detected valve closing timing and the end of the injection control pulse is calculated taking into account the duration of the injection control pulse, fuel pressure, and fuel temperature.

2. A method for controlling a fuel injector comprising:

4. 2. The method of controlling a fuel injector according to claim 1, In addition to the start point of the intermediate current, a duration of the intermediate current is determined; The intermediate energization control pulse is calculated based on the determined start edge and duration of the intermediate energization.

2. A method for controlling a fuel injector comprising:

5. 5. The method for controlling a fuel injector according to claim 4, The duration of the intermediate energization is determined based on the determined valve closing timing, fuel pressure, and fuel temperature.

2. A method for controlling a fuel injector comprising:

6. 2. The method of controlling a fuel injector according to claim 1, The start point of the intermediate energization is set at a predetermined time after the valve closing timing.

2. A method for controlling a fuel injector comprising:

7. 5. The method for controlling a fuel injector according to claim 4, The duration of the intermediate energization is set to be shorter than the opening delay time of the fuel injector.

2. A method for controlling a fuel injector comprising:

8. 3. The method for controlling a fuel injector according to claim 2, A machine learning model is used to calculate the relationship between the detected valve closing timing and the end of the injection control pulse.

2. A method for controlling a fuel injector comprising:

9. 9. The method for controlling a fuel injector according to claim 8, The machine learning model is trained when the internal combustion engine operates in a learning mode.

2. A method for controlling a fuel injector comprising:

10. A control unit for a fuel injector configured to carry out the method for controlling a fuel injector according to at least one of claims 1 to 9.

11. 1. A control device for controlling a fuel injector configured to perform injection into an internal combustion engine, comprising: an engine control unit configured to control the internal combustion engine; a drive circuit configured to drive the fuel injector; A control unit for a fuel injector according to claim 10; A fuel injector control device comprising:

12. A computer program product storable in a memory and comprising instructions that, when executed by a computer, cause the computer to carry out the method for controlling a fuel injector according to at least one of claims 1 to 9.

Images