A method and control unit for controlling a fuel injector, a computer program product, and a control device for a 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 a control device for controlling a fuel injector.

Background Art

[0002] In order to comply with current strict emission regulations, it is necessary to prevent the fuel injected into the cylinder of an internal combustion engine from reaching the cylinder wall. To achieve this goal, dividing the amount of fuel to be injected into a plurality of small injections is a promising approach. However, in order to accurately measure a small amount of fuel, the so-called ballistic operating range of the fuel injector must be accurately controlled. In this regard, a stable closing operation of the fuel injector is essential to avoid so-called valve bounce, which leads to an increase in emissions.

[0003] Patent Documents 1 and 2 relate to a fuel injector including 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 energization is applied to the coil, applying a magnetic force in the opposite direction to the moving direction of the movable iron core to reduce its speed and prevent valve bounce.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, precise timing of intermediate energization is crucial for ensuring stable closing of the fuel injector. If intermediate energization is performed too early, the direction of the valve body may change, leading to an undesirable increase in fuel injection volume.

[0006] On the other hand, if the intermediate energization is delayed too long, the speed of the movable core will not be sufficiently reduced, and as a result, the impact of the movable core may lift the valve body from its valve seat, potentially leading to undesirable additional fuel injection. In particular, Patent Document 1 discloses that it is preferable to stop energizing (applying voltage for holding current), then continuously stop energizing for a period longer than 3 / 4 of the time from stopping the holding current to the closing delay time Tb, and then apply voltage to start energizing in order to attract the movable core.

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

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

[0009] According to the subject matter described in the attached claims, a method, control unit, and 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] Injection control pulses may be provided by the 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 can determine / calculate injection control pulses based on the operating state of the engine, for example, in relation to the load, the mass of air in the cylinder, and / or the air-fuel ratio of the engine. The amount of fuel injected by the fuel injector may be controlled by the duration (width) of the injection control pulse. For example, under high load, 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 the engine operating cycle to divide the amount of fuel injected into multiple small injections.

[0011] The injection control pulse calculated by the ECU may be sent to a drive circuit that provides a corresponding drive current curve to energize the fuel injector coils 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 ECU are included in the proposed control device for controlling the fuel injector, which further includes a control unit (closed operation control unit) for controlling the closed operation of the fuel injector according to the proposed method described below. The closed operation control unit may be integrated within the ECU, within the drive circuit, or as a separate unit within the control device. The proposed method shall also be performed by a computer program product that can be stored in memory.

[0013] The fuel injector may preferably be a solenoid injector capable of directly injecting fuel into the 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 located at the upper end of the fuel injector, at least one fuel injection port and valve seat located at the lower end of the fuel injector, and a valve body located between the fuel supply unit and the valve seat. Furthermore, the fuel injector may include a movable iron core that can interact with the valve body to open and close the fuel injector.

[0014] The fuel injector may have fuel passages inside to allow fuel to flow from the fuel supply unit to the fuel injection port. The injector coil may be positioned between the fixed core and the housing of the fuel injector. The fixed core, injector coil, and housing can form an electromagnet.

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

[0016] When the injector coil is energized, the valve body can be displaced away from the valve seat in the opening direction (towards the upper end of the fuel injector). In particular, a magnetic attraction force can be applied between the movable core and the fixed core, which in turn moves the movable core toward the fixed core, allowing the valve body to be moved away from the valve seat and then brought into contact with it.

[0017] This allows the fuel passage to open, and fuel to be injected into the internal combustion engine through the fuel injection port. To stop fuel injection, the drive current / drive voltage may be switched, as a result allowing the valve body to return to the valve seat. In particular, when the magnetic attraction force is removed, the movable core and valve body can be returned to the closed position. After the required closing time, the valve body can abut against the valve seat, the movable core can be separated from the valve body, and the direction of motion of the movable core can be reversed. If the movable core is displaced too much in the reverse direction, it may collide with the valve body again and separate the valve body 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 after fuel injection has stopped (intermediate energizing) to reduce the speed at which the valve body and / or movable core move toward the valve seat. Preferably, the intermediate energizing is performed to reduce the speed of the movable core after it has separated from the valve body.

[0019] A detailed description of the components and functions of a fuel injector that can be controlled in accordance with the subject matter described herein can be found below in relation to Figure 2.

[0020] Here, the waveform of the injection control pulse is determined once when the injection procedure starts. However, the waveform of the injection control pulse may be updated during the injection procedure. Therefore, in the 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 an injection control pulse, the waveform of the injection control pulse can be evaluated by, for example, closed-process control. The end of the injection control pulse may also be detected by the ECU and transmitted from the ECU to the closed-operation control unit. A falling edge may be detected, for example, when the value of the injection control pulse falls below a predetermined threshold. Similarly, a rising edge indicating the start of the injection control pulse may be detected when its value exceeds a predetermined threshold. A first threshold may be used to detect the start of the injection control pulse, and a second threshold different from the first threshold may be used to detect the end of the injection control pulse.

[0023] Next, the valve closing timing is determined based on the detected end of the injection control pulse. The term "valve closing timing" is understood to mean the point at which the fuel injector is completely closed, i.e., the point at which the valve body is fully seated on the valve seat.

[0024] For 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 and the fuel injector is closed, a reverse drive voltage may be applied to the injector coil, interrupting the current supply to the injector coil. Due to the disappearance of the magnetic attraction force, the valve body may be pushed back to a closed position where it can be pressed against the valve seat by the load of at least one spring. At this time, the valve body abuts against the valve seat, and the slope of the drive voltage changes, potentially creating an inflection point. This inflection point can be analyzed, for example, by an ECU to determine the point at which the valve closing is completed (valve closing timing). For example, the inflection point can be precisely determined as a maximum or minimum value by forming the second derivative of the drive voltage curve.

[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 in order 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 can be stored in a map, for example, in a closed operation control unit. In this regard, the internal combustion engine may be operated on a test bench that allows the engine to be operated at any operating point in the entire 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 body moves toward 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] For example, the duration of the injection control pulse, fuel pressure, and fuel temperature may be considered 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 start and end points of the last output injection control pulse, and the fuel pressure and temperature may be measured by appropriate sensors attached to the internal combustion engine, respectively. 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 closing operation of the fuel injector begins.

[0028] In this regard, a long duration of the injection control pulse can lead to a delayed valve closing timing, as the long duration is associated with the full lift of the valve body, from which the valve body must return to its seat. With a short injection control pulse, the valve body may not reach its full lift (the ballistic operating range of the fuel injector), resulting in a shorter path back to the seat and potentially an earlier valve closing timing. Furthermore, high fuel pressure and temperature can increase the speed at which the valve body moves toward its seat, leading to 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, as well as fuel pressure and temperature. Other parameters affecting the valve body's closing behavior, such as fuel type and battery voltage, may also be considered in calculating this relationship.

[0029] For 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 instance, the ML model may be a neural network that can be trained on multiple training datasets containing 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 entire engine operation map. The map may be stored in the ECU, for example, and may be continuously updated.

[0030] For example, the ML model may be trained when the internal combustion engine is operating in learning mode. The learning mode may be activated, for example, by the ECU, under specific conditions during the operation of the combustion engine. For example, if the valve closing timing determined by the ML model at a particular engine operating point shows a standard deviation exceeding a predetermined value, the ECU can activate the learning mode whenever the engine is operating at this 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 and during vehicle operation. In this way, the map can be continuously improved even after the engine has already been installed in a vehicle. By determining the valve closing time using a detailed map, the calculation effort can be reduced without compromising 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. For 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 start when the valve body abuts against the valve seat. In this way, the movable core can be efficiently decelerated at the moment it separates from the valve body. To avoid the start of intermediate energization before the valve body reaches its valve seat due to variations in the determined valve closing timing, the predetermined time may also 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 direction of motion of the movable core after the valve body has seated. In other words, intermediate energization must start before the movable core changes direction and moves again in the valve opening direction. To calibrate the predetermined time before the direction of motion of the movable core reverses, its displacement can be measured on a test bench, for example, at different engine operating points and different valve closing timings.

[0032] As mentioned above, the duration of intermediate energization is also determined as a function of the valve closing timing. This is possible because the required duration of intermediate energization may depend primarily on the speed of the valve body and / or movable core at the valve closing timing. This speed may be higher when the valve closing time is slower and lower when the valve closing time is faster. In the first case, it can be assumed that the valve body has reached its full lift, and as a result, the valve body and movable core may be accelerated over the entire stroke returning to the valve seat during the closing operation, and thus can reach a high speed. In the second case, the valve body may return to the valve seat before reaching its full lift, and as a result, its speed and the speed of the movable core may be lower when it reaches the valve seat.

[0033] This allows the duration of intermediate energization to be longer when the valve closing timing is late and shorter when the valve closing timing is early. In particular, for example, a further relationship between the required duration of 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 intermediate energization and the valve closing timing, and this may be trained in the same way as the model for determining the valve closing timing. By determining the required duration of 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 body and / or movable core.

[0034] For example, the duration of intermediate energization may be further determined based on fuel pressure and fuel temperature. As mentioned above, higher fuel pressure and temperature can increase the speed at which the valve body moves toward its valve seat, resulting in an earlier closing timing. This means that an earlier closing timing does not necessarily mean that the fuel injector is in a ballistic motion where the valve body and / or movable core only reaches a low speed, but rather that the fuel injector may be fully open, provided with high fuel pressure and / or high fuel temperature, both of which can cause the valve body and / or movable core to accelerate. By considering fuel pressure and temperature in addition to closing timing to determine the duration of intermediate energization, the magnetic force that decelerates the valve body and / or movable core can be precisely adjusted.

[0035] In this regard, the relationship between the required duration of intermediate energization and the valve closing timing may be extended by further considering fuel pressure and fuel temperature when calculating the duration of intermediate energization. The extended 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 may be stored as a map in the valve closing control unit. Alternatively, an ML model may 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] For 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 until the valve body lifts off the valve seat. In particular, the opening delay time may be the time required for the movable core to reach the transmission surface of the valve body and move away from its valve seat after the start of energization to the injector coil. Setting the duration of the intermediate energization to a lower / shorter duration compared to the opening delay time ensures that the valve body is not lifted off its valve seat and that fuel is not injected into the engine.

[0037] An intermediate energization control pulse is calculated based on the determined start and duration of the intermediate energization. In particular, if the start and duration of the intermediate energization are determined based on the valve closing timing, the intermediate energization control pulse may be calculated by the closing operation control unit. As described above, the closing operation control unit is included in the control unit for controlling the fuel injector, which also includes the fuel injector's ECU and drive circuit.

[0038] To calculate the intermediate energization control pulse, the closed operation control unit can detect the end of the most recent injection control pulse and set the intermediate energization start point determined in relation 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 start point. A timer unit, which may be included in the closed operation control unit and / or ECU, may be used to set the start point of the intermediate energization control pulse in relation to the end of the most recent injection control pulse.

[0039] Next, the intermediate energization control pulse is output to the fuel injector. In particular, the intermediate control pulse may be output from the closed operation control unit to the drive circuit, which in response can provide a drive current / drive voltage to perform intermediate energization of the injector coil for a determined duration at a determined start time, and as a result can provide a magnetic force sufficient to appropriately decelerate the valve body and / or movable core. [Effects of the Invention]

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

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

[0042] [Figure 1] This is a schematic diagram showing an example of a fuel injection system for an internal combustion engine. [Figure 2] This is a cross-sectional view of an exemplary fuel injector connectable to a control device according to the subject matter disclosed herein. [Figure 3] (a) is a schematic diagram showing the injection control pulses for operating the fuel injector shown in Figure 2, (b) and (c) are schematic diagrams 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] Figures 1 and 2 are schematic diagrams illustrating the functional configuration of the control device shown herein, according to preferred examples of the subject matter disclosed herein. [Figure 5] This is a schematic diagram showing an example of the hardware configuration of the control device shown in Figures 1 and 2, taking into account the functional configuration shown in Figure 4. [Figure 6a] This flowchart shows a preferred example of a method relating to the subject matter disclosed herein. [Figure 6b] This flowchart explains the details of step S603a in the flowchart shown in Figure 6a. [Figure 7a] This flowchart explains the details of step S604a in the flowchart shown in Figure 6a. [Figure 7b] This flowchart explains the details of step S603b in the flowchart shown in Figure 7a. [Figure 8] (a) is a diagram illustrating the operation of the fuel injector shown in Figure 2 in a preferred example of the subject matter disclosed herein, with an intermediate energizing control pulse being two consecutive injection control pulses positioned between them, (b) and (c) are diagrams illustrating the corresponding drive voltage and drive current, and (d) is a diagram illustrating the resulting valve displacement curve, respectively. [Modes for carrying out the invention]

[0043] Figure 1 schematically shows 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, but may range from one to twelve, for example.

[0044] In the illustrated example, one fuel injector 101 is installed in each cylinder 108 of an internal combustion engine 1 (not described in detail) to directly inject fuel into the combustion chamber 107 of the cylinder 108. It may also be possible to install two or more injectors in each cylinder. The injected fuel is pressurized by a fuel pump 106 and sent to the fuel injector 101 via a fuel rail 105. The fuel pressure changes 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 be controlled by a control device 150 so that the pressure in the pipe of the fuel rail 105 is at a predetermined pressure based on information from a pressure sensor 102.

[0045] The fuel injection of each fuel injector 101 can be controlled by the width (pulse duration) of the injection control pulse sent from the engine control unit (ECU) 109 to the 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 may be part of the ECU 109 or a separate device. The drive circuit 127 and the ECU 109 may be included in the control device 150. The control device 150 may further include a closing operation control unit 600 (see Figures 4 and 5) for performing intermediate energization of the fuel injectors 101 between two consecutive fuel injections in order to control / stabilize its closing operation.

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

[0047] The illustrated fuel injector 101 includes a fuel supply unit 212 located at the upper end of the fuel injector 101, a fuel injection port 215 and a valve seat 202 located 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 located between the fuel supply unit 212 and the valve seat 202.

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

[0049] In the closed state, when the injector coil 208 is not energized, the valve body 201 is pressed into the valve seat 202 by the spring forces of the first spring 210 and the second spring 216, which bias the valve body 201 in the closing direction (towards the lower end of the fuel injector 101). The spring forces of the first spring 210 and the second spring 216 act against the spring force of the third spring 217, which biases the movable core 206 in the opening direction (towards the upper end of the fuel injector 101) and causes it to contact the intermediate member 214. Since the spring force of the second spring 216 is greater than the spring force of the third spring 217, a gap 250 is formed between the valve body 201 and the movable core 206.

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

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

[0052] When the injector coil 208 is energized, a magnetic driving force can be generated by the electromagnet, which includes the fixed core 207, the coil 208, and the housing 209. This magnetic driving force allows magnetic flux to circulate through the coil 208, the fixed core 207, the movable core 206, the housing 209, and the magnetic path through the movable core 206. As a result, a magnetic attractive force acts between the movable core 206 and the fixed core 207, causing the movable core 206 and the intermediate member 214 to be displaced toward the fixed core 207.

[0053] The movable core 206 can be displaced until the transmission surface 219 of the valve body 201 and the transmission surface 218 of the movable core 206 come into contact. During this time, the valve body 201 may still remain in contact with the valve seat 202. Only when the movable core 206 is displaced by the amount of the gap 250 created between the valve body 201 and the movable core 206, and the transmission surface 219 of the valve body 201 and the transmission surface 218 of the movable core 206 collide, can the kinetic energy of the movable core 206 separate the valve body 201 from the valve seat 202. This opens the fuel passage, allowing fuel to be injected into the internal combustion engine 1 through the fuel injection port 215.

[0054] When the movable core 206 comes into contact with the fixed core 207 during its displacement, the valve body 201 may be displaced in the valve-opening direction, and the movable core 206 may be displaced in the valve-closing direction. This means that when the fixed core 207 and the movable core 206 collide, the valve body 201 and the movable core 206 are separated, and the movable core 206 is displaced in the valve-closing direction, allowing it to come to rest in the target lift position (stable valve-open state).

[0055] Next, when the power supply to the injector coil 208 is turned off and the magnetic attraction force is removed, the movable core 206 can be pushed back to a closed position in which 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 movable core 206 via the transmission surface 219 of the valve body 201 and the transmission surface 218 of the movable core 206.

[0056] After the required closing time, the valve body 201 can abut against the valve seat 202, and the transmission surface 218 of the movable core 206 can be separated from the transmission surface 219 of the valve body 201.

[0057] When the fuel injector 101 is closed, the third spring 217 can switch from extension to compression, and when the valve body 201 strikes the valve seat 202, the transmission surface 218 of the movable core 206 separates from the transmission surface 219 of the valve body 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 relation to Figures 3(a) to 3(d).

[0058] Depending on the speed of the movable core 206 when the valve body 201 reaches the valve seat 202, the direction of motion of the movable core 206 may reverse, and as a result, the movable core 206 may move again in the valve opening direction. If the movable core is moving at a high speed at this time, the movable core may pass through the gap 250 again, causing further collision between the transmission surface 218 of the movable core 206 and the transmission surface 219 of the valve body 201, and thus causing the undesirable opening of the fuel injector 101.

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

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

[0061] Figures 3(a) to 3(c) show that when the injection control pulse ti is output to the drive circuit 127 at time ts, a high voltage 304 is applied to it, and power supply to the injector coil 208 begins. The high voltage may be a voltage with a value of 50V or more. As a result, the movable core 206 is displaced in the valve opening direction (see the solid displacement curve 335 in Figure 3(d)). After the movable core 206 passes through the gap 250 at the opening delay time t0, it comes into contact with the valve body 201. Subsequently, both elements, namely the movable core and the valve body, are displaced until the valve body 201 reaches full lift (see displacement curves 334 and 335 in Figure 3(d)).

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

[0063] Next, 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 Figure 3(b)). As a result, the current supply to the injector coil 208 is cut off (see Figure 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, having lost its magnetic attractive force, can be pushed back to a closed position where the valve body 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 Figure 3(d)).

[0064] time t EOI At the (valve closing timing), valves 201 and 202 are fully closed, and valve body 201 is fully seated on valve seat 202 again. When valve body 201 abuts against valve seat 202, the transmission surface 218 of the movable core 206 moves away from the transmission surface 219 of valve body 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 Figure 3(b)). This inflection point 330 occurs at the time when valves 201 and 202 are fully closed. EOI It can be used to determine...

[0065] In other words, when the fuel injector 101 is closed, the drive current flowing to the injector coil 208 is interrupted, and a back electromotive force is applied to the injector coil 208. After the drive current has completely disappeared, the back electromotive force gradually decreases, and when the valve body 201 strikes the valve seat 202, it changes the inductance, causing an inflection point 330 in the drive voltage (see Figures 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 the maximum or minimum value.

[0066] The displacement curve 335 of the movable core 206 shown in Figure 3(d) indicates that even after the valve body has seated, the movable core 206 continues to move for a considerable amount of time, thereby reversing its direction of motion. In the illustrated example, the movable core 206 moves at the valve closing timing t EOIAt point t, it passes its starting position and continues to move in the valve closing direction. After that, this movable core changes its direction of motion and returns to the starting position. However, at point t EOI Depending on the speed of the movable core 206, the movable core 206 may cross its starting position again and move further in the opening direction. If this movable core passes through the gap 250 again in that direction, the valve body is lifted from the valve seat 202, causing an undesirable valve bounce. As described above, in order to avoid such an undesirable phenomenon, intermediate energization of the injector coil 208 is performed to generate a magnetic attractive force that opposes the direction of motion of the movable core in the closing direction. An example of applying intermediate energization according to the subject matter described herein is shown in Figures 8(a) to 8(d).

[0067] Figure 4 is a schematic diagram illustrating the functional configuration of the control unit 150 shown in Figures 1 and 2, according to a preferred example of the subject matter disclosed herein. As already shown in Figures 1 and 2, the control unit 150 is connected to the fuel injector 101 and includes an ECU 109 and a drive circuit 127. Furthermore, the control unit 150 is connected to a power supply 401 and a plurality of sensors 420-425 (not shown in detail) attached to the engine 1. The plurality of sensors 420-425 include 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) of the engine 1, the fuel pressure sensor 102 mentioned 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 and determining 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 measurement signals received from multiple sensors 420 to 425.

[0068] In order to inject a determined amount of fuel into the engine 1 using the fuel injector 101, the injector control unit 404 of the ECU 109 calculates an injection control pulse ti. The illustrated injector control unit 404 includes an injection timing calculator 405, an injection duration calculator 407, an injector closing detector 409, a current profile calculation unit 408, and a closing operation control unit 600.

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

[0070] In particular, the injector closing detector 409 of the injector control unit 404 analyzes the drive current supplied to the injector 101 by the drive circuit 127 to determine the closing timing t of the valves 201 and 202 when the valve closing is completed. EOI To determine the time t, as explained above, when the valve body 201 abuts against the valve seat 202, the slope of the drive voltage changes, creating an inflection point 330 (see Figure 3(b)), and this inflection point is used to determine the time t. EOI This can be determined. For example, the injector closed detector 409 can derive the drive voltage curve applied to the fuel injector twice and determine the inflection point 330 from the resulting maximum or minimum value.

[0071] The computational effort involved in the double derivation of the drive voltage reduces the valve closing timing t. EOIis determined only by the injector closing detector 409 in the engine learning mode. This learning mode can be used to generate the relationship between the end te of the injection control pulse ti and the closing valve timing t EOI This relationship may depend on how the valve body 201 moves towards the valve seat 202 after the injection control pulse ti is switched off. In particular, depending on the duration ti_d of the injection control pulse ti, the fuel pressure p f , and the fuel temperature T f there may be a delay between the end te of the injection control pulse ti and the closing valve timing t EOI .

[0072] In this regard, a long duration of the injection control pulse is associated with the full lift of the valve body and thus may cause a slow closing valve timing t EOI . On the other hand, a high fuel pressure p f and a high fuel temperature T f increase the speed at which the valve body moves towards its valve seat, resulting in a faster closing valve timing t EOI .

[0073] To calculate the relationship between the end te of the injection control pulse ti and the closing valve timing t EOI in the learning mode considering the aforementioned dependencies, the closing operation control unit 600 receives the closing valve timing t EOI from the injector closing detector 409, 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 can receive the fuel pressure p f and the fuel temperature T f from each of the sensors 102, 423.

[0074] The engine learning mode may be executed on a test bench, and the engine is at each operating point of the entire engine map in different operating states (injection duration ti_d, fuel pressure p f , and fuel temperature T fThis relationship can be operated in a certain manner. This relationship can also be calculated during vehicle operation, for example, when the engine is operating at a steady-state operating point.

[0075] This allows the closing operation control unit 600 to create and store maps that provide the necessary relationships. Each map may also be stored in a different part of the control device 150. In particular, in learning mode, the termination te of the injection control pulse ti and the valve closing timing t EOI Machine learning models (ML models) can be used to calculate the relationship between different fuel pressures p. f and fuel temperature T f Multiple injection control pulses ti and associated valve closing timing t obtained EOI It may be a neural network that can be trained with multiple training data including the termination te of the injection control pulse ti and the valve closing timing t. EOI This allows for the generation of a detailed map that reflects the relationship with the entire engine operation map, thereby enabling the closed operation control unit 600 to obtain easily acquired sensor signals (te, ts, ti_d, p) without requiring calculations that require a great deal of computational effort. f , T f ) based solely on the valve closing timing t EOI It is possible to make a decision.

[0076] The closing operation control unit 600 controls the closing timing t of the fuel injector 101 based on the detected termination te of the injection control pulse ti using a map that includes the correspondence described above, in order to perform intermediate energization of the fuel injector 101 between two consecutive fuel injections. EOI To decide.

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

[0078] In connection with this, the closing operation control unit 600 sets the start end tb_s of the intermediate energization control pulse to the valve closing timing t EOI The predetermined time can be set thereafter. For example, the predetermined time may be set to zero, or intermediate energization may be started when the valve body 201 abuts against the valve seat 202. In this way, the movable core 206 can be efficiently decelerated at the moment it separates from the valve body 201. The closing operation control unit 600 may set the predetermined time to a value greater than zero, taking into account the reversal of the direction of motion of the movable core 206 after the valve body 201 has seated. In this case, intermediate energization must be started before the movable core 206 changes direction and moves again in the valve opening direction. To calibrate the predetermined time so that the start end tb_s of the intermediate energization control pulse is set before the direction of motion of the movable core 206 reverses, its displacement may be, for example, different engine operating points and different valve closing timings t EOI It can be measured on a test bench.

[0079] As described above, the closing operation control unit 600 also sets the duration of the intermediate energization tb_d to the valve closing timing t EOI This is determined as a function of t. This is because the required duration of intermediate energization is mainly determined by the valve closing timing t. EOI This is possible because it depends on the speed of the valve body 201 and / or the movable core 206. This speed depends on the closing time t. EOI When it is slow, the value is higher, and the valve closing time t EOIThe speed can be lower when it is earlier. In the first case, we can assume that the valve body 201 has reached its full lift, and as a result, the valve body 201 and the movable core 206 can be accelerated over the entire stroke returning to the valve seat 202 during the closing operation, and thus can reach a high speed. In the second case, the valve body 201 can return to the valve seat 202 before reaching its full lift, and as a result, its speed and the speed of the movable core 206 can be lower when it reaches the valve seat 202.

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

[0081] Figure 5 schematically shows an example of the hardware configuration of the control device 150 shown in Figures 1 and 2, taking into account the functional configuration shown in Figure 4.

[0082] In the illustrated example, the hardware configuration includes a CPU 501, a closed operation control unit 600, and a drive IC 502. For example, the CPU 501 and the closed 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 closed operation control unit 600 and the drive IC 502 via communication lines 222 and signal lines 223. The closed operation control unit 600 is positioned between the CPU 501 and the drive IC 502 and is connected to this drive IC via signal line 601.

[0083] Furthermore, the illustrated hardware configuration includes a boost circuit 514 for providing a high voltage VH in the high voltage source 516, which is generated by boosting the 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 a driver IC 502, and the boosted voltage VH output from the boost circuit 514 can be detected by the driver IC 502 or the CPU 501.

[0084] Furthermore, as shown in the illustrated example, a switching element 505 is positioned between the high-voltage source 516 of the boost circuit 514 and the high-voltage terminal 590 of the fuel injector 101. In addition, a switching element 507 is positioned between the low-voltage source 517 and the high-voltage terminal 590 of the fuel injector 101, and a further switching element 506 is positioned between the low-voltage terminal 591 of the fuel injector 101 and the ground potential 515. The 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 placed between the high-voltage terminal 590 of the injector coil 208 and the switching element 505, allowing current to flow from the high-voltage source 516 towards the injector coil 208 and the ground potential 515. Furthermore, a diode 511 is placed between the high-voltage terminal 590 of the coil 208 and the switching element 507, allowing current to flow from the low-voltage source 517 towards the injector coil 208 and the ground potential 515. The low-voltage source 517 may be a battery supplying a voltage VB that may be in the range of 12 to 14V, for example.

[0086] Furthermore, diodes 509 and 510 are provided in the illustrated hardware configuration to apply a reverse drive voltage to the injector coil 208. In addition, current sensing resistors 508, 512, and 513 are connected to the drive IC 502 to detect the current values ​​flowing from their respective sources to the fuel injector 101.

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

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

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

[0090] Figure 6a shows a flowchart illustrating a preferred example of the method according to the subject matter disclosed herein. When the process in step S600a begins, for example, the closed operation control unit 600 checks whether a rising edge of the injection control pulse 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. ​​Otherwise, the search for the rising edge of the injection control pulse is repeated until a positive result is obtained. Subsequently, it is checked whether a falling edge of the injection control pulse ti has occurred, and if so, the end te of the injection control pulse is determined by the closed operation control unit 600 in step S602a. Otherwise, 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. The closing operation control unit 600 may use a first threshold to detect the start of the injection control pulse, and a second threshold different from the first threshold to detect the end of the injection control pulse. Alternatively, the start end ts and end end 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 a flag for performing intermediate energization (IE control pulse flag) is set, the closing operation control unit 600, in step S603a, sets the valve closing timing t based on the end te of the injection control pulse ti. EOI Determine the intermediate energization (IE) control pulse tb. The IE control pulse flags are, for example, the termination te of the injection control pulse ti and the valve closing timing t. EOI If a valid relationship between the two is already stored in the control unit 150, for example as a map, it may be set by the ECU. 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 engine 1 is in learning mode. Engine 1 checks, for example, the termination te of the injection control pulse ti and the valve closing time t. EOI If the relationship is not valid, the system may be in learning mode. This may occur, for example, if the standard deviation of the determined valve closing time is too large.

[0093] If engine 1 is not in learning mode, the process is already complete. However, if this engine is in learning mode, in step S604a, the closed operation control unit 600 determines, for example, the duration ti_d of the injection control pulse ti, and the fuel pressure p f and fuel temperature T f Taking this into consideration, the termination te of the injection control pulse ti and the valve closing timing t EOI Determine the relationship.

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

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

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

[0097] Figure 7a shows the details of step S604a of the flowchart shown in Figure 6a, namely, the closing operation control unit 600 sets the closing timing t to the end of the injection control pulse ti. EOI A flowchart is shown to explain how the relationship is determined. The end of the injection control pulse ti and the valve closing timing t. EOI The relationship may also be determined by the ECU 109 or another unit of the control device 150.

[0098] After processing begins in step S700a, for example, the injector closing detector 409 measures the drive voltage signal of the fuel injector 101 in step S701a, and then filters the measured signal in step S702a. Next, the filtered drive voltage signal is analyzed to determine the valve closing timing t. EOI An inflection point 330 (see Figure 3b) indicating this is detected (S703a). In step S704a, the termination te and duration ti_d of the injection control pulse ti, and the valve closing time t are determined. EOI Fuel pressure p f and fuel temperature T f However, it is received from, for example, ECU109 (S704a).

[0099] In the subsequent step S705a, the termination te and duration ti_d of the injection control pulse ti, and the fuel pressure p are determined. f and fuel temperature T f The timing of valve closing from t EOIThe dependency is determined, for example, by using an ML model that can be trained on multiple training datasets including the aforementioned parameters. In other words, the dependency between the termination te of the injection control pulse ti and the valve closing timing t. EOI The relationship is as follows: in step S705a, the injection duration ti_d and the fuel pressure p f and fuel temperature T f The decision will be made taking into consideration the impact of the decision.

[0100] Next, in step S706a, for example, in the same manner as described in the previous step S705a, the time t of valve closing is set. EOI and fuel pressure p f and fuel temperature T f The dependency of the intermediate energization duration tb_d from is determined. The relationships determined in steps S705a and S706a are stored as a map in, for example, the closed operation control unit 600 or any other part of the control device 150, and the processing is completed in step S707a.

[0101] Figure 7b shows a flowchart illustrating the details of step S603b of the flowchart shown in Figure 6b, namely how the closed operation control unit 600 determines the start end tb_s and end end tb_e of the intermediate energization control pulse tb from the relationship / map determined in Figure 7a. The start end tb_s and 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 in step S700b, for example, the closing operation control unit 600 determines the termination time te and duration ti_d of the injection control pulse ti, as well as the valve closing time t. EOI Fuel pressure p f and fuel temperature T f This can be received, for example, from the ECU 109 (S701b). Based on the received parameters, the closing operation control unit 600 determines the valve closing timing t from the relationship / map determined and stored in step S705a of Figure 7a. EOI It is possible to read it (S702b).

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

[0104] In the subsequent 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 It is defined based on the intermediate energizing duration tb_d, and further, the valve closing timing t EOI Fuel pressure p f and fuel temperature T f The following are taken into consideration. In particular, the intermediate energization duration tb_d is determined using the relationship / map determined and stored in step S706a of Figure 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, the process is completed in step S706b.

[0105] Figures 8(a) to 8(d) schematically show how an intermediate energization control pulse is placed between two consecutive injection control pulses to operate the fuel injector shown in Figure 2. Furthermore, the drive voltage and drive current corresponding to the injection control pulse, as well as the resulting displacement curve, are shown.

[0106] Similar to Figures 3(a) to 3(d), at time ts, the first injection control pulse ti1 is output to the drive circuit 127, and a high voltage 1004 is applied, which starts the power supply to the injector coil 208, causing the movable core 206 to be displaced in the valve opening direction (see the solid displacement curve 1034 in Figure 8(d)). Similar to Figure 3(d), at the opening delay time t0, the movable core 206 passes through the gap 250 and comes into contact with the valve body 201, resulting in the displacement of both elements.

[0107] Next, both the movable core and the valve body elements are displaced until the valve body 201 reaches full lift (see displacement curves 1034 and 1035 in Figure 8(d)).

[0108] As shown in the current curve 1008, the current value rises sharply upon application of high voltage 1004, reaching a predetermined peak current value Ip and causing the fuel injector 101 to fully open. Subsequently, the application of high voltage 1004 decreases from value 1036 to pulse-width modulated low voltage 1005, resulting in a decrease in the current value to a first holding current value Ih1 according to the first current profile 1031. In the next step, by reducing the pulse width of the low voltage 1005, the current decreases to a second holding current value Ih2 according to the second current profile 1032 (see Figures 8(b) and (c)). By applying 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 Figure 8(b)). As a result, the current supply to the injector coil 208 is cut off (see Figure 8(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, having lost its magnetic attractive force, can be pushed back to a closed position where the valve body 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 Figure 8(d)).

[0110] Unlike the closing operation shown in Figures 3(a) to 3(d), at the point tb_s when the valve body 201 reaches the valve seat 202, an intermediate energizing 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 reaches only the second holding current value Ih2, which means that no displacement of the valve body 201 occurs (see displacement curve 1035 in Figure 8(d)). However, as can be seen from the displacement curve 1034 of the movable core in Figure 8(d), the magnetic force generated by the drive current 1010 causes deceleration of the movable core 206, and as a result, the movable core does not move beyond its starting position, nor does it 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 initiated by the injection control pulse ti2 at time ts2, which is done in the same way as the first fuel injection.

[0112] Comparing the displacement curves 335 and 1034 of the movable core shown in Figure 3(d) and Figure 8(d), the displacement of the movable core 206 is as follows: EOI It becomes clear that the system can be reliably stabilized by an intermediate current application having a duration of tb_d. [Explanation of Symbols]

[0113] 1. Internal combustion engine, engine 101 Fuel Injector 102 Pressure Sensor 105 Fuel rail, fuel pipe 106 Fuel pump 107 Combustion chamber 108 Cylinder 109 Engine Control Unit (ECU) 127 Drive Circuit 150 Control device 200a center axis 201 Valve body 202 valve seat 206 Movable Iron Core 207 Fixed iron core 208 Injector Coil 209 Housing 210 First spring 212 Fuel supply unit 214 Intermediate member 215 Fuel injection hole 216 Second spring 217 Third spring 218 Transmission surface 219 Transmission surface 222 communication lines 223 signal line 250 gap 304 Driving voltage (high voltage) 305 Driving voltage (low voltage) 308 Drive current 330 Inflection points 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 Spray Duration Calculator 408 Current Profile Calculation Unit 409 Injector Closed Detector 410 Current Profile Control Unit 420 Pulse Compensator 420 Speed ​​Sensor 421 Airflow 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 sensing resistor 509 diode 510 diode 511 diode 512 Current sensing resistor 513 Current sensing resistor 514 Boost Circuit 515 Ground potential 516 High Voltage Source 517 Low voltage source 530 coils 531 Transistors 532 diodes 533 Capacitor 535 diode 590 terminals 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. A method for controlling the closing operation of a fuel injector configured to perform injection into an internal combustion engine based on an injection control pulse, The relationship between the valve closing timing detected based on the drive voltage applied to the fuel injector in response to the injection control pulse and the end of the injection control pulse is calculated. The end of the injection control pulse is detected, Using the relationship between the detected valve closing timing and the end of the injection control pulse, the valve closing timing of the fuel injector is determined based on the detected end of the injection control pulse. Based on the determined valve closing timing, the start point for intermediate energization of the fuel injector is determined. Based on the start end where the intermediate energization is determined, an intermediate energization control pulse is calculated. The intermediate current control pulse is output to the fuel injector. A method for controlling a fuel injector, characterized by the features described above.

2. In the fuel injector control method according to claim 1, 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. A method for controlling a fuel injector, characterized by the features described above.

3. In the fuel injector control method according to claim 1, In addition to the starting end of the intermediate energization, the duration of the intermediate energization is determined. The intermediate energization control pulse is calculated based on the determined start end and duration of the intermediate energization. A method for controlling a fuel injector, characterized by the features described above.

4. In the fuel injector control method according to claim 3, The duration of the intermediate energization is determined based on the determined valve closing timing, fuel pressure, and fuel temperature. A method for controlling a fuel injector, characterized by the features described above.

5. In the fuel injector control method according to claim 1, The start of the intermediate energization is set to a predetermined time after the determined valve closing timing. A method for controlling a fuel injector, characterized by the features described above.

6. In the fuel injector control method according to claim 3, The duration of the intermediate energization is set to be shorter than the opening delay time of the fuel injector. A method for controlling a fuel injector, characterized by the features described above.

7. In the fuel injector control method according to claim 1, A machine learning model is used to calculate the relationship between the detected valve closing timing and the end of the injection control pulse. A method for controlling a fuel injector, characterized by the features described above.

8. In the fuel injector control method according to claim 7, The machine learning model is trained when the internal combustion engine operates in learning mode. A method for controlling a fuel injector, characterized by the features described above.

9. A fuel injector control unit configured to perform the fuel injector control method described in at least one of claims 1 to 8.

10. A control device for controlling a fuel injector configured to perform injection into an internal combustion engine, An engine control unit configured to control the internal combustion engine, A drive circuit configured to drive the fuel injector, The control unit for the fuel injector according to claim 9 and A control device for a fuel injector, characterized by comprising the following:

11. A computer program that is storeable in memory and, when executed by a computer, includes an instruction that causes the computer to execute the fuel injector control method described in at least one of claims 1 to 8.

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