Fuel injection control device and fuel injection control method

Abstract

To improve, even when characteristics and environmental factors of a fuel injector change, the robustness of fuel injection control in response to these changes.SOLUTION: A fuel injection control device performs control to apply an intermediate pulse to a fuel injection device 200, which comprises a valve body, a movable element that causes the valve body to open and close, a stator that applies magnetic attraction force to the movable element, and a stopper part that suppresses the motion of the movable element to a valve-seat side, the intermediate pulse being applied between a first drive command pulse and a subsequent second drive command pulse. The end time Tbp_e of the intermediate pulse is determined by the time at which the movable element collides with the stopper part in the first drive command pulse, and the start time Tbp_s of the intermediate pulse is determined on the basis of the fluctuation of the time at which the valve body driven by the second drive command pulse is seated on a valve seat or the fluctuation of the time at which the movable element driven by the second drive command pulse collides with the stopper part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fuel injection control device and a fuel injection control method for controlling the amount of fuel injected during multistage injection by a fuel injection device. [Background technology]

[0002] In recent years, downsized engines have become popular, which are compact and use a turbocharger to generate power. By reducing the displacement, downsized engines can reduce pumping losses, thereby improving fuel efficiency.

[0003] On the other hand, downsized engines tend to have smaller cylinder diameters, which means that injected fuel tends to adhere to the cylinder walls, which can lead to poor exhaust performance. Furthermore, if uneven fuel and air flow occurs in a downsized engine, unburned particulate matter is emitted, which can lead to poor exhaust performance.

[0004] Therefore, in downsized engines, the pressure of the fuel supplied into the engine cylinder is increased to atomize the injected fuel and form a uniform air-fuel mixture, thereby homogenizing the air and fuel inside the engine cylinder.

[0005] Additionally, in downsized engines, the amount of fuel needed for each combustion stroke is divided and injected (multi-stage injection) to form a uniform mixture, thereby homogenizing the air and fuel inside the engine cylinder. To achieve this, the fuel injection valve is required to shorten the injection interval during multi-stage injection. When the injection interval is shortened, there is a risk that the variation in the injection amount will increase due to the influence of the movement (bouncing) of the moving element that transmits force to the valve disc.

[0006] In response to this, for example, Patent Document 1 describes a fuel injection device that suppresses the occurrence of irregular injection, in which fuel is unintentionally injected temporarily during multi-stage injection, by adding an intermediate drive signal between the drive command pulses for pre-injection and post-injection. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-027348 Summary of the Invention [Problem to be solved by the invention]

[0008] In the fuel injection device described in Patent Document 1, an intermediate drive signal is added at a preset timing. With this method of adding an intermediate drive signal, for example, if the characteristics (individual characteristics) of the fuel injection valve change or if changes occur in environmental factors of the fuel injection valve (e.g., fuel pressure, fuel temperature, aging, etc.), it is not possible to add the intermediate drive signal at an appropriate timing in response to the change. This makes it difficult to provide the optimal drive command pulse to the fuel injection valve. Therefore, improving the robustness of fuel injection control in response to these changes has been an issue.

[0009] An object of the present invention is to provide a fuel injection control device and a fuel injection control method for solving the above problems. [Means for solving the problem]

[0010] In order to solve the above problem, one embodiment of the fuel injection control device of the present invention is a fuel injection control device that is applied to a fuel injection device that includes a valve body that moves toward and away from a valve seat to open and close a fuel passage, a moving element that performs the opening and closing operation of the valve body, a stator that has a coil that is excited when current is applied and that applies a magnetic attractive force to the moving element, and a stopper portion that suppresses movement of the moving element toward the valve seat. The fuel injection control device includes a control unit that controls the energization of the coil by a drive command pulse. When the drive command pulse is output multiple times per combustion stroke, the control unit applies an intermediate pulse between a first drive command pulse and a subsequent second drive command pulse. The end time of the intermediate pulse is determined by the time when the moving element collides with the stopper portion in the first drive command pulse, and the start time of the intermediate pulse is determined based on the fluctuation in the time when the valve element driven by the second drive command pulse seats on the valve seat, or the fluctuation in the time when the moving element driven by the second drive command pulse collides with the stopper portion. [Effects of the Invention]

[0011] According to at least one aspect of the present invention, even if the injection interval between the pre-injection and the post-injection is shortened, the intermediate pulse can be applied at an appropriate timing in accordance with fluctuations in the operation of the valve body or the moving element, thereby improving the robustness of the fuel injection control against changes in the characteristics of the fuel injection device or environmental factors of the fuel injection device. Problems, configurations, and effects other than those described above will become apparent from the following description of the preferred embodiments of the invention. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram showing an example of the basic configuration of an internal combustion engine equipped with a fuel injection control device according to an embodiment of the present invention; [Figure 2] 1 is a cross-sectional view showing an example of the internal configuration of a fuel injection device according to an embodiment of the present invention. [Figure 3] 2 is a diagram showing a detailed configuration example of a drive circuit and an ECU of the fuel injection control device according to the embodiment of the present invention; FIG. [Figure 4] 3 is a diagram showing an example of a conventional drive command pulse (injection pulse), drive voltage, detection filter, filtered signal, drive current, and displacement of a valve body and a movable iron core for the fuel injection device shown in FIG. 2. FIG. [Figure 5] 3 is a diagram showing the drive command pulse (injection pulse), drive voltage, detection filter, filtered signal, drive current, and displacement of the valve body and movable core when an intermediate pulse is added to the fuel injection device shown in FIG. 2. FIG. [Figure 6] FIG. 10 is a diagram illustrating a method for determining valve opening stability. [Figure 7]10 is a flowchart showing an example of a procedure for a process for calculating a valve opening stability index. FIG. 11 is a diagram showing a processing result for evaluating the valve opening stability. [Figure 8] 10 is a flowchart illustrating an example of a procedure for optimizing an intermediate pulse start time. [Figure 9] 10 is a flowchart illustrating an example of a procedure for an intermediate pulse control process. DETAILED DESCRIPTION OF THE INVENTION

[0013] A fuel injection control device and a fuel injection control method according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In this specification and the accompanying drawings, identical or similar components are given the same reference numerals, and redundant explanations may be omitted or only differences may be explained. The number of each component may be singular or plural unless otherwise specified.

[0014] [Internal combustion engine system] First, the configuration of an internal combustion engine system equipped with a fuel injection control device according to this embodiment will be described. FIG. 1 is a diagram showing the overall configuration of an internal combustion engine system equipped with a fuel injection control device according to this embodiment.

[0015] The internal combustion engine 101 shown in Fig. 1 is a four-stroke engine that repeats four strokes: an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke, and is, for example, a multi-cylinder engine having four cylinders. The internal combustion engine 101 completes one combustion stroke (combustion cycle) through four strokes for each cylinder. Note that the number of cylinders that the internal combustion engine 101 has is not limited to four, and may have, for example, three, six, eight or more cylinders.

[0016] The internal combustion engine 101 includes a piston 102, an intake valve 103, and an exhaust valve 104. The intake air into the internal combustion engine 101 passes through an air flow meter (AFM) 120 that detects the amount of air flowing in, and the flow rate is adjusted by a throttle valve 119. The air that has passed through the throttle valve 119 is drawn into a collector 115, which is a branching section, and is then supplied to a combustion chamber 121 of each cylinder via an intake pipe 110 and an intake valve 103 provided for each cylinder.

[0017] Meanwhile, fuel is supplied from a fuel tank 123 to a high-pressure fuel pump 125 by a low-pressure fuel pump 124, and the fuel is increased to a pressure required for fuel injection by the high-pressure fuel pump 125. That is, the high-pressure fuel pump 125 moves a plunger provided in the high-pressure fuel pump 125 up and down by power transmitted from an exhaust camshaft (not shown) of an exhaust cam 128, thereby pressurizing (increasing the pressure) the fuel in the high-pressure fuel pump 125.

[0018] A solenoid-driven open / close valve is provided at the intake port of high-pressure fuel pump 125. The solenoid is connected to a control device (hereinafter referred to as "fuel injection control device 127") that controls fuel injection device 200 provided in ECU (Engine Control Unit) 109, which is an example of an engine control device. Fuel injection device 200 is a direct injection type fuel injection device that directly injects fuel into combustion chamber 121.

[0019] 2, the fuel injection control device 127 has a CPU (Central Processing Unit) 501, a RAM (Random Access Memory) 261 that executes computer programs, and a ROM (Read Only Memory) 260 that stores data. The ROM 260 may be a memory whose contents can be erased and rewritten.

[0020] The CPU 501 of the fuel injection control device 127 calls up a program from the RAM 261 based on a control command from the ECU 109, and controls the solenoid based on the data stored in the ROM 260. As a result, the opening and closing valve is driven so that the pressure of the fuel discharged from the high-pressure fuel pump 125 (fuel pressure) becomes a desired pressure.

[0021] The fuel pressurized by the high-pressure fuel pump 125 is sent to the fuel injection device 200 via a high-pressure fuel pipe 129. The fuel injection device 200 directly injects fuel into the combustion chamber 121 based on a command from a fuel injection control device 127. When a drive current is supplied (energized) to a coil 208 (described later), the fuel injection device 200 operates a valve body to inject fuel.

[0022] The internal combustion engine 101 is also provided with a fuel pressure sensor (fuel pressure sensor) 126 that measures the fuel pressure in a high-pressure fuel pipe 129. Based on the measurement result by the fuel pressure sensor 126, the ECU 109 sends a control command to a fuel injection control device 127 to adjust the fuel pressure in the high-pressure fuel pipe 129 to a desired pressure. That is, the ECU 109 performs so-called feedback control to adjust the fuel pressure in the high-pressure fuel pipe 129 to the desired pressure.

[0023] Furthermore, each combustion chamber 121 of the internal combustion engine 101 is provided with an ignition plug 106, an ignition coil 107, and a water temperature sensor 108. The spark plug 106 exposes an electrode portion inside the combustion chamber 121 and ignites the mixture of intake air and fuel in the combustion chamber 121 by electrical discharge. The ignition coil 107 generates a high voltage for electrical discharge in the spark plug 106. The water temperature sensor 108 measures the temperature of the cooling water that cools the cylinders of the internal combustion engine 101.

[0024] The ECU 109 controls the energization of the ignition coil 107 and the ignition by the spark plug 106. A mixture of intake air and fuel in the combustion chamber 121 is combusted by a spark emitted from the spark plug 106, and the resulting pressure pushes the piston 102 down.

[0025] Exhaust gas generated by combustion is discharged into an exhaust pipe 111 via an exhaust valve 104. A three-way catalyst 112 and an oxygen sensor 113 are provided in the exhaust pipe 111. The three-way catalyst 112 purifies harmful substances contained in the exhaust gas, such as nitrogen oxides (NOx). The oxygen sensor 113 detects the oxygen concentration contained in the exhaust gas and outputs the detection result to the ECU 109. Based on the detection result of the oxygen sensor 113, the ECU 109 performs feedback control so that the amount of fuel injection supplied from the fuel injection device 200 becomes a target air-fuel ratio.

[0026] Furthermore, a crankshaft 131 is connected to the piston 102 via a connecting rod 132. The reciprocating motion of the piston 102 is converted into rotational motion by the crankshaft 131. A crank angle sensor 116 is attached to the crankshaft 131. The crank angle sensor 116 detects the rotation and phase of the crankshaft 131 and outputs the detection result to the ECU 109. The ECU 109 detects the rotation speed of the internal combustion engine 101 based on the output of the crank angle sensor 116.

[0027] Signals from a crank angle sensor 116, an air flow meter 120, an oxygen sensor 113, an accelerator opening sensor 122, a fuel pressure sensor 126, etc. are input to the ECU 109. The accelerator opening sensor 122 is a sensor that indicates the opening of the accelerator operated by the driver.

[0028] The ECU 109 calculates the torque required for the internal combustion engine 101 based on the signal supplied from the accelerator opening sensor 122, and determines whether the engine is in an idling state or not. The ECU 109 also calculates the amount of intake air required for the internal combustion engine 101 from the required torque and outputs an opening signal corresponding to the amount of intake air to the throttle valve 119.

[0029] The ECU 109 also has a rotation speed detection unit that calculates the rotation speed of the internal combustion engine 101 (hereinafter referred to as engine rotation speed) based on a signal supplied from the crank angle sensor 116. The ECU 109 also has a warm-up determination unit (not shown) that determines whether the three-way catalyst 112 is warmed up or not based on the temperature of the cooling water obtained from the water temperature sensor 108 and the elapsed time after the internal combustion engine 101 is started, etc.

[0030] The fuel injection control device 127 calculates the amount of fuel (target injection amount) corresponding to the intake air amount, and outputs a corresponding fuel injection signal to the fuel injection device 200. Furthermore, the fuel injection control device 127 outputs an energization signal to the ignition coil 107, and outputs an ignition signal to the ignition plug 106.

[0031] [Configuration of fuel injection system] Next, the configuration of the fuel injection device 200 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing an example of the internal configuration of the fuel injection device 200. As shown in FIG.

[0032] 2, fuel injection device 200 is made up of a fuel supply unit 212 that supplies fuel, a valve seat 202 having fuel injection holes 215 that serve as fuel passages, and a movable iron core (movable element) 206 that drives valve body 201. In this embodiment, an electromagnetic fuel injection device for an internal combustion engine that uses gasoline or mixed fuel as fuel will be described as an example.

[0033] In the fuel injection device 200, a fuel supply unit 212 is configured at the upper end side in the drawing, and a fuel injection hole 215 and a valve seat 202 are configured at the lower end side. Then, a movable iron core 206, a valve body 201, and a sleeve 214 are arranged between the fuel supply unit 212 and the valve seat 202.

[0034] Sleeve 214 has a cylindrical shape and is fitted and joined to the outer peripheral surface of the upper side of valve body 201. A flange is formed at the upper end of sleeve 214. The flange has a shape that protrudes outward from the upper side of sleeve 214.

[0035] A first spring member 210 is disposed above the sleeve 214. A second spring member 216 is disposed around the sleeve 214, between the lower surface (transmission surface 219) of the flange and the movable iron core 206. The second spring member 216 biases the movable iron core 206 and the sleeve 214 in directions that move them away from each other. The flange (transmission surface 219) of the sleeve 214 transmits the force of the second spring member 216 to the valve body 201 and the movable iron core 206.

[0036] The end of fuel injection device 200 on the opposite side (fuel supply unit 212 side) from fuel injection hole 215 and valve seat 202 is connected to high-pressure fuel pipe 129 (see FIG. 1), not shown. The end of fuel injection device 200 on the opposite side (fuel injection hole 215 side) from fuel supply unit 212 is inserted into a mounting hole (insertion hole) formed in a member (cylinder block, cylinder head, etc.) that forms combustion chamber 121 (see FIG. 1).

[0037] Fuel injection device 200 receives fuel from high-pressure fuel pipe 129 (see FIG. 1) through fuel supply unit 212, and injects the fuel into combustion chamber 121 (see FIG. 1) from the tip of valve seat 202. A fuel passage is formed inside fuel injection device 200 so that fuel flows substantially along central axis 200a of fuel injection device 200 from a base end on the fuel supply unit 212 side to a tip end on the fuel injection hole 215 side.

[0038] The coil 208 is disposed between the fixed iron core (stator) 207 and the housing 209. The fixed iron core 207, the coil 208, and the housing 209 constitute an electromagnet. In a closed valve state in which the coil 208 is not energized, the valve element 201 abuts against the valve seat 202 due to the biasing force of the first spring member 210 that biases the valve element 201 in the valve closing direction (toward the valve seat 202). This state is called a stable closed valve state (valve closed standby state). In the stable closed valve state, the movable iron core 206 abuts against the stopper 217 and is disposed in the closed valve position. The valve element 201 is driven via a transmission surface 219 of the sleeve 214 that transmits the load from the movable iron core 206.

[0039] Stopper 217 has a roughly cylindrical shape, and is fitted and coupled to the outer peripheral surface of valve element 201 downstream (on the valve seat 202 side) of movable iron core 206. Stopper 217 restricts movement of movable iron core 206 in the valve closing direction.

[0040] In the stable valve-closed state, the sleeve 214 is urged downstream (toward the valve seat 202, in the valve-closing direction) by the force obtained by subtracting the urging force of the second spring member 216 from the urging force of the first spring member 210, and the valve element 201 is in contact with the valve seat 202 and remains stationary. The movable iron core 206 is urged in the valve-closing direction (toward the valve seat 202) by the urging force of the second spring member 216, and is in contact with the stopper 217. A gap 250 is formed between the lower end 218 of the sleeve 214 of the valve element 201 and the upper surface (transmission surface) of the movable iron core 206.

[0041] A flange may be formed at the lower end of sleeve 214. In this case, the lower surface of the flange formed at the lower end of sleeve 214 serves as a transmission surface and comes into contact with the upper surface of movable core 206.

[0042] A fuel injection control device 127 and an ECU (engine control device) 109 are connected to the fuel injection device 200. The fuel injection control device 127 has a circuit that receives a drive command pulse (injection pulse) from the ECU 109 and supplies a drive current (drive voltage) to the fuel injection device 200.

[0043] The ECU 109 and the fuel injection control device 127 may be configured as an integrated component. The fuel injection control device 127 is a device that generates a drive voltage for the fuel injection device 200, and may be integrated with the ECU 109 or configured as a standalone device.

[0044] The ECU 109 receives signals indicating the state of the engine from various sensors and calculates an appropriate pulse width of a drive command pulse (injection pulse) and injection timing according to the operating conditions of the internal combustion engine. The pulse width of the drive command pulse output from the ECU 109 is input to the fuel injection control device 127 via a signal line 223.

[0045] The fuel injection control device 127 controls the drive voltage applied to the coil 208 and supplies a drive current to the coil 208. The ECU 109 communicates with the fuel injection control device 127 through a communication line 222. The ECU 109 switches the drive current generated by the fuel injection control device 127 depending on the pressure of the fuel supplied to the fuel injection device 200 and the operating conditions. The fuel injection control device 127 is able to change its control constants through communication with the ECU 109, and changes the current waveform according to the control constants.

[0046] [Configuration of fuel injection control device] Next, the configuration of the fuel injection control device 127 will be described with reference to FIG. FIG. 3 is a diagram showing a detailed configuration example of the drive circuit of the fuel injection control device 127 and the ECU 109.

[0047] As described above, the ECU 109 (see FIG. 2) incorporates the CPU 501. The CPU 501 receives various signals indicating the state of the engine from the fuel pressure sensor 126, the air flow meter 120, the oxygen sensor 113, the crank angle sensor 116, etc. Based on these signals, the CPU 501 calculates the pulse width and injection timing of a drive command pulse (injection pulse) for controlling the amount of fuel injected from the fuel injection device 200 in accordance with the operating conditions of the internal combustion engine.

[0048] Furthermore, CPU 501 calculates an appropriate pulse width and injection timing of a drive command pulse according to the operating conditions of the internal combustion engine, and outputs the drive command pulse to a drive IC (Integrated Circuit) 502 of fuel injection device 200 via signal line 223.

[0049] The CPU 501 is a specific example of a control unit according to this embodiment, and includes a current control unit 501a, a voltage detection unit 501b, a digital filter unit 501c, a valve closure detection unit 501d, and a fluctuation calculation unit 501e.

[0050] The energization control unit 501 a performs energization control processing to generate a drive command pulse and output it to the driving IC 502 . The voltage detection unit 501b performs a voltage detection process to detect the voltage value when the coil 208 is energized. The digital filter unit 501c, which is an example of a filter unit, performs digital filtering to detect an inflection point of the waveform of the voltage value when the coil 208 is energized. The valve closure detection unit 501d performs processing to detect the valve closure timing of the valve body 201 based on the inflection points of the waveform of the voltage value from a predetermined detection start timing (valve closure detection start time Tss in Figures 4 and 5) to a detection end timing (valve closure detection end time Tse in Figures 4 and 5). The fluctuation calculation unit 501e calculates the fluctuation of the voltage value obtained by digitally filtering the drive voltage in the digital filter unit 501c, and performs processing to determine the valve opening stability (described later) from the calculation results. The valve opening stability indicates the stability of the operation of the valve element 201 before the valve is closed, i.e., the stability of the operation of the valve element 201 in the open state.

[0051] The pulse width of the drive command pulse determines the amount of injection by the fuel injector 200. Thereafter, the drive IC 502 supplies a drive current to the fuel injector 200 by switching between energized and de-energized states of the switching elements 505, 506, and 507.

[0052] Switching element 505 is connected between a high voltage source higher than voltage source VB input to a drive circuit of fuel injection control device 127 (see FIG. 2) and a high-voltage side terminal of solenoid 540 (corresponding to coil 208 in FIG. 2) provided in fuel injection device 200. Switching elements 505, 506, 507 are configured by transistors such as FETs (Field Effect Transistors), for example, and can switch between energizing and de-energizing fuel injection device 200.

[0053] The boost voltage VH, which is the initial voltage value of the high voltage source, is, for example, 65 V, and is generated by boosting the battery voltage VB by a boost circuit 514. The boost circuit 514 is configured with, for example, a coil 530, a transistor 531, a diode 532, and a capacitor 533.

[0054] In the boost circuit 514, when the transistor 531 is turned on, the battery voltage VB flows to the ground potential 534. On the other hand, when the transistor 531 is turned off, the high voltage generated in the coil 530 is rectified through the diode 532, and an electric charge is accumulated in the capacitor 533. Then, this transistor is repeatedly turned on and off to increase the voltage of capacitor 533 until the voltage of capacitor 533 reaches boosted voltage VH. Transistor 531 is connected to driving IC 502 or CPU 501, and boosted voltage VH output from boost circuit 514 is configured to be detected by driving IC 502 or CPU 501. Note that boost circuit 514 may be configured by a DC / DC converter or the like.

[0055] Switching element 507 is connected between a low voltage source and a high voltage terminal of solenoid 540. Low voltage source VB is, for example, a battery voltage, and its voltage value is about 12 to 14 V. Switching element 506 is connected between a low voltage side terminal of fuel injection device 200 (see FIG. 2) and ground potential 515.

[0056] Drive IC 502 detects the value of the current flowing through fuel injector 200 using current detection resistors 508, 512, and 513, and switches between energized and de-energized states of switching elements 505, 506, and 507 based on the detected current value to generate the desired drive current. Diodes 509 and 510 apply a reverse voltage to solenoid 540 of fuel injector 200, rapidly reducing the current supplied to solenoid 540.

[0057] The CPU 501 communicates with the driving IC 502 through the communication line 222. The CPU 501 switches the driving current generated by the driving IC 502 depending on the pressure of the fuel supplied to the fuel injection device 200 (see FIG. 2) and the operating conditions. In addition, both ends of the resistors 508, 512, and 513 are connected to the A / D conversion port of the driving IC 502, and the driving IC 502 is configured to be able to detect the voltage applied across the resistors 508, 512, and 513.

[0058] [Operation of conventional fuel injection system] Next, the operation of the conventional fuel injection device 200 under the control of the fuel injection control device 127 will be described with reference to FIG. FIG. 4 is a diagram showing an example of a conventional drive command pulse (injection pulse), drive voltage, detection filter, filtered signal, drive current, and displacement of the valve body and movable core for the fuel injection device 200 shown in FIG.

[0059] As shown in FIG. 4, when a drive command pulse Ti is input at time Ts, a high voltage 304 is applied to the coil 208 (see FIG. 2) from a high voltage source that has been boosted to a voltage higher than the battery voltage VB, and current begins to be supplied to the coil 208.

[0060] After the coil 208 is energized, a magnetomotive force is generated by the electromagnet formed by the fixed core 207, the coil 208, and the housing 209. This magnetomotive force forms a magnetic path (magnetic circuit) that surrounds the coil 208 by the fixed core 207, the housing 209, and the movable core 206, and magnetic flux flows around the formed magnetic path. At this time, a magnetic attraction force acts between the movable core 206 and the fixed core 207, and the movable core 206 is displaced toward the fixed core 207. Thereafter, the movable core 206 is displaced until its upper surface abuts against the lower end 218 of the sleeve 214. Note that the valve element 201 continues to be in contact with the valve seat 202 until the movable core 206 abuts against the sleeve 214.

[0061] The movable iron core 206 is displaced by the gap 250 formed between the valve element 201 (i.e., the lower end 218 of the sleeve 214) and the movable iron core 206, and when the valve element 201 (transmission surface 219 of the sleeve 214) collides with the movable iron core 206, the valve element 201 is pulled up upstream by the kinetic energy of the movable iron core 206, and the valve element 201 moves away from the valve seat 202. As a result, a gap is formed between the valve element 201 and the valve seat 202, the fuel passage opens, and fuel is injected from the fuel injection hole 215. Then, the valve element 201 is suddenly displaced by the movable iron core 206 having kinetic energy.

[0062] The fuel injection control device 127 applies high voltage 304 and passes drive current 308 through coil 208 from time Ts until timing 334 when the movable iron core 206 and the valve disc 201 collide and the valve disc 201 separates from the valve seat 202, or until sufficient kinetic energy is accumulated in the movable iron core 206 to open the valve disc 201. As a result, a necessary and sufficient magnetic attraction force is generated between the movable iron core 206 and the fixed iron core 207, allowing the movable iron core 206 to respond quickly, as shown by displacement 335. By allowing the movable iron core 206 to respond quickly, the valve disc 201 can be driven by the movable iron core 206 even when the pressure of the supplied fuel is high.

[0063] The drive current flowing through the coil 208 rises sharply as indicated by drive current 308 (peak current) due to the application of high voltage 304. When drive current 308 reaches peak current value Ip, fuel injection control device 127 applies high voltage 304 in the reverse direction (applies reverse voltage). That is, fuel injection control device 127 turns off all of switching elements 505, 506, and 507 (see FIG. 3). As a result, diodes 509 and 510 are energized by the back electromotive force generated by the inductance of fuel injection device 200, and current is fed back to boost circuit 514. As a result, the drive current flowing through coil 208 drops sharply as indicated by current 317 and is then cut off. When current 317 reaches hold current 318, switching is performed at voltage 305 (battery voltage VB), and hold current 318 is maintained.

[0064] After the movable iron core 206 and the fixed iron core 207 collide, the valve element 201 is displaced upstream and the movable iron core 206 is displaced downstream. When the movable iron core 206 collides with the fixed iron core 207, the valve element 201 and the movable iron core 206 are separated and the movable iron core 206 is displaced downstream, but eventually the movable iron core 206 comes to rest at the target lift position and stabilizes. This state is called the stable open valve state.

[0065] The movable iron core 206 and the valve element 201 are configured to be capable of relative movement. Therefore, when the movable iron core 206 collides with the sleeve 214 of the valve element 201, the valve element 201 and the movable iron core 206 separate from each other, and the valve element 201 is displaced upstream.

[0066] Subsequently, when the drive command pulse Ti is turned OFF at time Te, the fuel injection control device 127 applies a drive voltage in the reverse direction to the coil 208 (applies a reverse voltage). This cuts off the current supply to the coil 208, and the magnetic flux generated in the magnetic circuit disappears, causing the magnetic attraction force to disappear. As a result, the movable iron core 206, which has lost its magnetic attraction force, is pushed back by the load of the first spring member 210 and the force due to the fuel pressure, and the valve element 201 reaches the closed position in which it contacts the valve seat 202.

[0067] The biasing force of the first spring member 210 acting on the valve element 201 is transmitted to the movable iron core 206 via the lower end 218 of the sleeve 214 coupled to the valve element 201. When the valve closing required time elapses from time Te when the drive command pulse Ti is turned OFF to time Tc1 when the valve closing is completed (at time Tc1), the valve element 201 comes into contact with the valve seat 202.

[0068] After the valve element 201 contacts the valve seat 202, the movable iron core 206 separates from the lower end 218 of the sleeve 214 of the valve element 201 and continues to move downward (in the valve closing direction). After time Tc1 when the valve is completely closed, the movable iron core 206 and the sleeve 214 of the valve element 201 are separated. At this time, a bend-like change appears in the drive voltage, as shown by inflection point 330 (an example of a first inflection point). This change makes it possible to detect the time Tc1 when the valve is completely closed.

[0069] When the fuel injection device 200 is closed, after the valve element 201 collides with the valve seat 202, only the biasing force of the second spring member 216 acts on the movable iron core 206, and the biasing force of the second spring member 216 and the inertial force of the movable iron core 206 cause the movable iron core 206 to collide with the stopper 217. At this time, a bend-like change appears in the drive voltage, as shown by inflection point 331 (an example of a second inflection point). This change makes it possible to detect the time Td1 at which the movable iron core 206 collides with the stopper 217.

[0070] In this way, when the motion of movable iron core 206 changes, the acceleration of movable iron core 206 changes, and the inductance of coil 208 changes. In other words, when fuel injection device 200 is closed, the drive current flowing through coil 208 is cut off and a back electromotive force is applied to coil 208. Then, as the drive current converges, the back electromotive force also gradually decreases, and the inductance changes as the back electromotive force decreases.

[0071] When the valve element 201 collides with the valve seat 202 (at time Tc1), a change in inductance causes an inflection point 330 in the drive voltage of the coil 208. Also, when the movable iron core 206 collides with the stopper 217 (at time Td1), a change in inductance causes an inflection point 331 in the drive voltage of the coil 208.

[0072] Inflection point 330 is the timing at which the valve of fuel injection device 200 is completely closed. For example, inflection point 330 appears as an extreme value (maximum or minimum value) when time-series data of the drive voltage applied to coil 208 is differentiated twice. Therefore, inflection point 330 can be identified by differentiating the time-series data of the drive voltage twice and detecting the extreme value. Inflection point 331 can also be found by differentiating the time-series data of the drive voltage twice.

[0073] The filtered signal is a signal obtained by performing digital filtering on the drive voltage, and has a waveform obtained by second-order differentiation of the drive voltage. Fig. 4 and Fig. 5, which will be described later, show schematic waveforms of the filtered signal (second-order differential value), and Fig. 6, which will be described later, shows an example of a detailed waveform of the filtered signal.

[0074] As described above, the waveform obtained by second-order differentiation of the drive voltage changes in accordance with the change in the slope of the drive voltage, and the value of the voltage after digital filtering changes. That is, when the valve element 201 closes, the acceleration of the movable iron core 206 changes, which appears as a change in the drive voltage. Therefore, by calculating the maximum value of the voltage after digital filtering, that is, the maximum value between the predetermined valve close detection start time Tss and the valve close detection end time Tse, it becomes possible to detect the time Tc1 when the valve element 201 closes and the time Td1 when the movable iron core 206 collides with the stopper 217.

[0075] As shown in FIG. 4, after the movable iron core 206 collides with the stopper 217, kinetic energy is consumed by the collision. Then, the movement of the movable iron core 206 gradually decreases due to the biasing force of the second spring member 216 in the valve closing direction, and the movable iron core 206 eventually transitions to a stable valve-closed state. Here, by shortening the time until the time Tst at which the stable valve-closed state is reached, it becomes possible to inject fuel stably even if the interval Tdw between the drive command pulse Ti1 for the pre-injection and the drive command pulse Ti2 for the subsequent injection is set to a small value. Hereinafter, when there is no need to distinguish between the drive command pulse Ti1 for the pre-injection and the drive command pulse Ti2 for the subsequent injection, they will be referred to as the "drive command pulse Ti."

[0076] However, when the interval Tdw between the drive command pulse Ti1 for the pre-injection and the drive command pulse Ti2 for the subsequent injection is extremely small, the drive command pulse Ti2 for the subsequent injection may be applied before the time Tst when the valve element 201 reaches the stable valve-closed state. In this case, the drive command pulse Ti2 for the subsequent injection is applied during the time period when the movable core 206 is bouncing, which may cause the movement of the movable core 206 and the valve element 201 to become unstable, resulting in the fuel injection amount injected from the fuel injection device 200 varying from the target injection amount. For this reason, it is desirable that the time from the time Tc1 when the valve element 201 collides with the valve seat 202 to the time Tst when the valve element 201 reaches the stable valve-closed state be short.

[0077] [Operation of the fuel injection device of this embodiment] Next, the operation of the fuel injection device 200 under the control of the fuel injection control device 127 according to this embodiment will be described with reference to Figures 5 to 9. In particular, a method for shortening the time from when the valve body 201 comes into contact with the valve seat 202 during the valve closing operation until the valve is in a stable closed state will be described. FIG. 5 is a diagram showing an example of the drive command pulse (injection pulse), drive voltage, detection filter, filtered signal, drive current, and displacement of the valve body and movable core when an intermediate pulse is added to the fuel injection device 200 shown in FIG.

[0078] As shown in FIG. 5 , when an intermediate pulse Tbp is applied between a drive command pulse Ti1 for the pre-injection and a drive command pulse Ti2 for the subsequent injection, a high voltage 306 is applied to the coil 208, and supply of current to the coil 208 begins. By energizing the coil 208, a magnetic attraction force can be generated in the valve-opening direction until the moving core 206 collides with the stopper 217. This reduces the speed at which the moving core 206 collides with the stopper 217, and shortens the time until the moving core 206 stabilizes at time Tst. As a result, the fuel injection device 200 quickly transitions to a stable valve-closed state, stabilizing the injection amount of fuel supplied from the fuel injection device 200 to the internal combustion engine 101. This homogenizes the air and fuel in the engine cylinder, improving exhaust performance.

[0079] As described above, the operation of the valve element 201 varies depending on the characteristics of the fuel injection device 200 and changes in environmental factors. The characteristics of the fuel injection device 200, in other words, individual characteristics, include, for example, the characteristics of the magnetic circuit and the spring. Furthermore, the environmental factors of the fuel injection device 200 include, for example, the fuel pressure and the fuel temperature. Furthermore, the characteristics of individual fuel injection devices and the environmental factors may change due to aging.

[0080] Variations in the operation of the valve element 201 affect fluctuations in the time Tc1 at which the valve is completely closed. Furthermore, variations in the operation of the valve element 201 also affect the bounding behavior of the movable iron core 206 after the movable iron core 206 collides with the stopper 217. Because the optimal intermediate pulse Tbp changes depending on the operations of the valve element 201 and the movable iron core 206, it is necessary to correct the intermediate pulse Tbp in accordance with these changes. Therefore, a method for achieving the optimal intermediate pulse Tbp will be described.

[0081] In order to suitably control the intermediate pulse Tbp, it is necessary to appropriately set the start time Tbp_s and end time Tbp_e of the intermediate pulse Tbp. A method for setting the intermediate pulse will be described below.

[0082] (End time of intermediate pulse) First, the process of determining the end time of the intermediate pulse Tbp will be described. When the movable core 206 collides with the stopper 217, the movable core 206 bounds. If the intermediate pulse Tbp is applied while the movable core 206 is bounding in the valve opening direction, a magnetic attractive force is generated in the valve opening direction, which accelerates the bounding of the movable core 206. Therefore, it is desirable to eliminate the magnetic attractive force generated by the intermediate pulse Tbp before the movable core 206 collides with the stopper 217.

[0083] That is, the time Td1 at which the movable core 206 collides with the stopper 217 is detected, and the end time Tbp_e of the intermediate pulse Tbp is determined taking into consideration the drive current and the time until the magnetic attractive force disappears. The end time Tbp_e of the intermediate pulse Tbp is earlier than the time at which the magnetic attractive force disappears. Based on this concept, it is possible to set an appropriate end time of the intermediate pulse Tbp.

[0084] As described above, in this embodiment, the end time of the intermediate pulse is determined by the time when the mover (movable iron core 206) collides with the stopper portion (stopper 217) in the first drive command pulse (pre-injection drive command pulse Ti1). This allows the application of the intermediate pulse to end at an appropriate timing according to fluctuations in the movement of the mover, even when the injection interval between the preceding and succeeding injections is shortened, thereby improving (suppressing) the effect of the mover's behavior (bouncing) on ​​the next injection.

[0085] More specifically, the end time of the intermediate pulse is determined based on the timing of the second inflection point (inflection point 331) after the first drive command pulse (drive command pulse Ti1 for pre-injection). By using the second inflection point in this way, it is possible to reliably detect the time when the mover (movable iron core 206) collides with the stopper portion (stopper 217).

[0086] The time from the end of the intermediate pulse Tbp until the magnetic attractive force disappears may be set to a fixed value. Alternatively, a model representing the magnetic attractive force, the drive current, and the characteristics of the magnetic attractive force may be prepared in advance within the ECU 109, and the time until the magnetic attractive force disappears may be calculated using this model. For example, a model that learns the time difference between the disappearance of the magnetic attractive force and the current value of the drive current may be used as the model. Instead of the model, map data that associates the current value of the drive current with the time difference may be used.

[0087] (Start time of intermediate pulse) Next, the process of determining the start time of the intermediate pulse Tbp will be described with reference to FIG. 6 is a diagram showing an example of a method for determining valve opening stability, showing an example of the voltage value after digital filtering (second-order differentiation) of the drive voltage, which is used by the fluctuation calculation unit 501e (see FIG. 3) to determine the valve opening stability. The vertical axis in the diagram represents the voltage value after digital filtering of the drive voltage ("-" means that there is no unit). The horizontal axis represents the time elapsed from the end time of the drive command pulse Ti.

[0088] As shown in FIG. 6, when the valve element 201 is stably open, the valve element 201 collides with the valve seat 202 after the drive command pulse Ti ends, and therefore the voltage value 601 after digital filtering becomes relatively large.

[0089] On the other hand, if the operation of the valve element 201 is unstable, the valve element 201 may collide with the valve seat 202 before the end of the drive command pulse Ti. This is the case when the magnetic attractive force of the coil 208 is not sufficient, and the valve element 201 is urged in the valve closing direction, preventing the valve from opening. In this case, the voltage value 602 after digital filtering is smaller than the voltage value 601 during stable operation, as shown in FIG.

[0090] Therefore, by comparing the voltage value after digital filtering with a preset threshold value Vth and using the comparison result, it is possible to determine whether the valve element 201 is stable or unstable before the valve is closed. The voltage value after digital filtering to be compared with the threshold value Vth is the voltage value between the preset valve close detection start time Tss and valve close detection end time Tse.

[0091] In the example of FIG. 6, when the operation of the valve element 201 is stable, the voltage value 601 after digital filtering is greater than the threshold value Vth, and therefore the difference (deviation from the stable valve opening condition) is a positive value. In this case, it can be determined that the valve is stably open. Conversely, when the operation of the valve element 201 is unstable, the voltage value 602 after digital filtering is smaller than the threshold value Vth, and therefore the difference (deviation from the unstable valve opening condition) is a negative value. In this case, it can be determined that the state is unstable.

[0092] In this embodiment, based on the concept of valve opening stability described above, for example, the start time of the intermediate pulse is determined based on the fluctuation in the time when the valve body driven by the second drive command pulse (drive command pulse Ti2 for subsequent injection) seats on the valve seat, or the fluctuation in the time when the movable element (movable iron core 206) driven by the second drive command pulse collides with the stopper portion (stopper 217). As a result, even if the injection interval between the pre-injection and the post-injection is shortened, the application of the intermediate pulse can be started at an appropriate timing in accordance with fluctuations in the operation of the valve body or the movable element.

[0093] More specifically, the start time of the intermediate pulse is determined, for example, by the fluctuation in the voltage value of the first inflection point (inflection point 330) or the second inflection point (inflection point 331) after the second drive command pulse (drive command pulse Ti2 for subsequent injection) calculated by the fluctuation calculation unit 501e. In this way, by using the fluctuation in the voltage value at the first inflection point or the second inflection point, the start time of the intermediate pulse can be determined, reflecting the fluctuation in the operation of the valve body or the movable element (movable iron core 206).

[0094] [Calculation of valve opening stability index] Next, the process of calculating the valve opening stability index in the fluctuation calculation section 501e (see FIG. 3) of the CPU 501 will be described with reference to FIG. 7 is a flowchart showing an example of the procedure for calculating the valve opening stability index. The valve opening stability index is an index used by the fluctuation calculation unit 501e when determining the stability of the valve opening. As an example, the standard deviation of the difference (deviation) between the voltage value after the digital filter processing and the threshold value Vth shown in FIG. 6 can be used as the valve opening stability index.

[0095] First, in step S701, the voltage detection unit 501b acquires the voltage value of the drive voltage applied to the coil 208 by the energization control unit 501a in time series.

[0096] Next, in step S702, the digital filter unit 501c performs digital filtering (second-order differentiation) on the voltage values ​​acquired in time series, and acquires the voltage value V_FL after the digital filtering.

[0097] Next, in step S703, the digital filter unit 501c acquires a first inflection point (corresponding to the inflection point 330) and a second inflection point (corresponding to the inflection point 331) based on the voltage value V_FL after digital filtering.

[0098] In this embodiment, the digital filter unit 501c performs digital filtering to detect the first inflection point and the second inflection point in advance from the waveform of the drive voltage. There are two main timings for detecting the first inflection point and the second inflection point. (1) Obtain an inflection point from the filtered signal of the drive voltage in the cycle immediately preceding the target combustion stroke cycle. (2) In the learning mode when the internal combustion engine system is idling, the inflection point is obtained from the filtered signal of the drive voltage. During idling, the actual injection amount may be small.

[0099] Next, in step S704, the fluctuation calculation unit 501e calculates the difference D_th (deviation in FIG. 6) between the voltage value of the first inflection point or the second inflection point of the filtered signal and a preset threshold value Vth.

[0100] Next, in step S705, the fluctuation calculation unit 501e calculates a standard deviation σ of the difference D_th between the voltage value of the first inflection point or the second inflection point of the filtered signal and the threshold Vth. toff (Example of valve opening stability index) is calculated. The digital filter unit 501c calculates the voltage value of the first inflection point or the second inflection point of the filtered signal in a plurality of combustion stroke cycles and stores the calculated voltage value in a memory. The fluctuation calculation unit 501e calculates the standard deviation σ of the difference D_th between the voltage value of the first inflection point or the second inflection point and the threshold Vth in a plurality of combustion stroke cycles. toff The standard deviation σ of the difference D_th between the voltage value at the first inflection point and the voltage value at the second inflection point and the threshold Vth is calculated. toff may be calculated.

[0101] As described above, in this embodiment, the fluctuation calculation unit 501e calculates the fluctuation of the voltage value when the coil 208 is energized by calculating the standard deviation σ of the difference D_th between the voltage value at the first inflection point or the second inflection point of the waveform of the voltage value and the threshold value Vth. toff (Example of valve opening stability index)

[0102] In this way, the standard deviation σ of the difference D_th between the voltage value of the first inflection point or the second inflection point and the threshold Vth is used as the valve opening stability index. toff Calculate the standard deviation σ toff The valve opening stability can be determined by comparing the standard deviation σ with a preset threshold. toff If is smaller than a predetermined threshold, it can be determined that the valve is stably open.

[0103] Alternatively, the valve opening stability of the valve element 201 can be determined based on whether the voltage value after digital filtering exceeds a threshold value Vth. For example, a threshold number of times used to determine the valve opening stability may be determined in advance, and the valve opening stability of the valve element 201 may be determined based on the result of comparing the number of times the threshold value Vth is exceeded among the determined number of injections with the threshold number of times. If the number of times the threshold value Vth is exceeded is greater than the threshold number of times, it can be determined that the valve is stably open.

[0104] As described above, by using the voltage value after digital filtering and the predetermined threshold value Vth, it is possible to determine the valve opening stability.

[0105] [Optimization of intermediate pulse start time] Using the fluctuation calculation unit 501e (see FIG. 3), it is possible to set the optimum start time Tbp_s of the intermediate pulse Tbp. Optimization of the start time of the intermediate pulse Tbp will be described below with reference to FIG. 8 is a flowchart showing an example of the procedure for optimizing the intermediate pulse start time in the fluctuation calculation section 501e. In this flowchart, the optimal start timing of the intermediate pulse Tbp is set.

[0106] First, in step S801, the fluctuation calculation unit 501e generates candidates for the time that will be the start time of the intermediate pulse Tbp. As an example, based on the first inflection point, a time near the timing when the valve disc 201 seats on the valve seat 202 (time Tc1 in FIG. 4) can be determined as a candidate for the intermediate pulse start time. A plurality of times near the seating timing can be set as candidates for the intermediate pulse start time.

[0107] Next, in step S802, the fluctuation calculation unit 501e calculates the valve opening stability index (standard deviation σ of the difference D_th) at the time of the drive command pulse Ti2 for the subsequent injection after the application of the intermediate pulse Tbp for a plurality of candidates for the start time of the intermediate pulse Tbp. toff ) is calculated and obtained.

[0108] Next, in step S803, the fluctuation calculation unit 501e calculates the valve opening stability index (standard deviation σ of the difference D_th) toff ) is minimized. The fluctuation calculation unit 501e determines the candidate start time of the intermediate pulse at this time as the start time Tbp_s of the intermediate pulse Tbp. After the process of step S803, the process proceeds to step S906 shown in FIG. 9.

[0109] In this way, the fluctuation calculation unit 501e calculates the standard deviation σ of the calculated difference D_th from among the preset candidates for the start time of the intermediate pulse. toff The time when is smallest is adopted as the start time Tbp_s of the intermediate pulse. By going through the above-described series of processing steps, the optimal start time Tbp_s of the intermediate pulse Tbp can be obtained. Then, the intermediate pulse Tbp can be determined based on the optimal start time Tbp_s and end time Tbp_e, taking into consideration individual variations in the operation of the valve disc 201. Information on the determined intermediate pulse Tbp is stored in the ROM 260.

[0110] [Intermediate pulse control processing] Next, the intermediate pulse control process by the CPU 501 (see FIG. 3) will be described with reference to FIG. FIG. 9 is a flowchart showing an example of the procedure of the intermediate pulse control process.

[0111] First, in step S901, the energization control unit 501a determines whether the number of injections in one combustion stroke is plural. If the number of injections is not plural (NO determination in step S901), the intermediate pulse control process ends.

[0112] On the other hand, if the number of injections during one combustion stroke is multiple (YES judgment in step S901), in step S902, the power supply control unit 501a acquires the second inflection point (inflection point 331 in Figure 4) that occurred in the drive voltage during the previous injection using the digital filter unit 501c.

[0113] Next, in step S903, the energization control unit 501a determines the end time Tbp_e of the intermediate pulse Tbp based on the time Td1 (see FIG. 4) when the second inflection point occurs.

[0114] Next, in step S904, the energization control unit 501a determines whether the start time of the intermediate pulse Tbp has been optimized. If the start time of the intermediate pulse Tbp has been optimized (YES determination in step S904), the process proceeds to step S906.

[0115] On the other hand, if the start time of the intermediate pulse Tbp has not been optimized (NO in step S904), the process proceeds to step S905. In step S905, the fluctuation calculation unit 501e optimizes the start time of the intermediate pulse Tbp. In step S905, the optimization process of the intermediate pulse start time is performed according to steps S801 to S803 shown in FIG. 8.

[0116] If the start time of the intermediate pulse Tbp has been optimized (YES in step S904 or after the process of step S905), the energization control unit 501a determines the start time Tbp_s of the intermediate pulse Tbp in step S906.

[0117] Next, in step S907, the energization control unit 501a generates an intermediate pulse Tbp from the start time Tbp_s and end time Tbp_e determined in steps S903 and S906. The voltage value of the high voltage 306 (see FIG. 5) of the intermediate pulse Tbp is set in advance. For example, the voltage value of the high voltage 306 may be the same as the voltage value of the high voltage 304. Alternatively, the voltage value of the high voltage 304 may be set according to the interval Tdw between the drive command pulse Ti1 for the pre-injection and the drive command pulse Ti2 for the subsequent injection.

[0118] The energization control unit 501a executes the intermediate pulse control process of steps S901 to S907 described above for each cycle of the combustion stroke. Then, the energization control unit 501a adds the generated intermediate pulse Tbp between the drive command pulse for the pre-injection and the drive command pulse for the subsequent injection. The driving IC 502 applies a driving voltage (high voltage 306) to the solenoid 540 in Fig. 3 (coil 208 in Fig. 2) in accordance with the intermediate pulse Tbp generated by the energization control unit 501a.

[0119] In this way, by using the intermediate pulse Tbp with the start time and end time appropriately set, it is possible to effectively suppress the bounding of the movable core 206 when the movable core 206 collides with the stopper 217. As a result, even if the injection interval between the pre-injection and the post-injection is shortened, the intermediate pulse can be applied at an appropriate timing in accordance with fluctuations in the operation of the valve body or the movable element. Therefore, even if the characteristics of the fuel injection device or environmental factors of the fuel injection device change, it is possible to improve the robustness of the fuel injection control against these changes.

[0120] For example, as shown by the voltage value 601 after digital filtering in Fig. 6, the operation of the valve element 201 is stabilized, and shot variation by the fuel injection device 200 is reduced, thereby stabilizing the amount of fuel injected. That is, fuel can be stably supplied to the engine from the fuel injection device 200. This makes it possible to improve the combustion stability of the engine using the fuel injection device 200, and ultimately improve the exhaust emitted from the engine. This makes it possible to improve the exhaust performance of the engine and reduce fuel consumption.

[0121] As described above, the present invention is not limited to the above-described embodiments, and various other modifications and applications are possible without departing from the spirit of the invention as set forth in the claims. For example, the above-described embodiments have been described in detail and specifically to clearly explain the present invention, and are not necessarily limited to those including all of the components described. Furthermore, it is also possible to add, replace, or delete other components from part of the configuration of the embodiments.

[0122] In addition, in this specification, processing steps describing chronological processing include not only processing that is performed chronologically in the order described, but also processing that is not necessarily performed chronologically but is performed in parallel or individually (for example, processing by objects). [Explanation of symbols]

[0123] 101...internal combustion engine, 109...ECU, 127...fuel injection control device, 200...fuel injection device, 201...valve body, 202...valve seat, 206...movable iron core (movable element), 207...stationary iron core (stator), 208...coil, 209...housing, 210...first spring member, 212...fuel supply unit, 214...sleeve, 215...fuel injection hole, 216...second spring member, 217...stopper, 218...lower end of sleeve, 219...transmission surface, 250...gap, 260...ROM, 261...RAM, 330...inflection point (first inflection point), 331...inflection point (second inflection point), 501...CPU (control unit), 501a...energization control unit, 501b...voltage detection unit, 501c...digital filter section (filter section), 501d...valve closure detection section, 501e...fluctuation calculation section, 540...solenoid (corresponding to coil 208), Ti1...pre-injection drive command pulse (first drive command pulse), Tc1...time when the valve disc collides with the valve seat (time when valve closure is completed), Td1...time when the movable iron core collides with the stopper, Ti2...subsequent injection drive command pulse (second drive command pulse), Tdw...interval, Tbp...intermediate pulse, Tbp_s...start time of intermediate pulse, Tbp_e...end time of intermediate pulse

Claims

1. a valve body that moves toward and away from a valve seat to open and close a fuel passage; a movable element that opens and closes the valve body; a stator having a coil that is excited when energized and that exerts a magnetic attraction force on the mover; a stopper portion that suppresses movement of the movable element toward the valve seat; A fuel injection control device applied to a fuel injection device comprising: a control unit that controls energization of the coil by a drive command pulse, the control unit, when outputting a plurality of drive command pulses per combustion stroke cycle, performs control to apply an intermediate pulse between a first drive command pulse and a subsequent second drive command pulse; an end time of the intermediate pulse is determined by a time at which the movable element collides with the stopper portion in the first drive command pulse; The start time of the intermediate pulse is determined based on a change in the time when the valve disc driven by the second drive command pulse sits on the valve seat or a change in the time when the movable element driven by the second drive command pulse collides with the stopper portion. Fuel injection control device.

2. The control unit an energization control unit that controls an energization time of the coil by a pulse width of a drive command pulse; a voltage detection unit that detects a voltage value when the coil is energized; a filter unit that detects an inflection point of the waveform of the voltage value; a valve closing detection unit that detects a valve closing timing of the valve body based on an inflection point of the waveform of the voltage value during a time period from a predetermined detection start timing to a predetermined detection end timing; a fluctuation calculation unit that compares a voltage value at a first inflection point corresponding to the time when the valve element sits on the valve seat and / or a voltage value at a second inflection point corresponding to the time when the movable element collides with the stopper portion with a preset threshold value, and calculates a fluctuation in the voltage value at the first inflection point or the second inflection point, an end time of the intermediate pulse is determined based on a timing of the second inflection point after the first drive command pulse; The start time of the intermediate pulse is determined by the fluctuation in the voltage value of the first inflection point or the second inflection point after the second drive command pulse, which is calculated by the fluctuation calculation unit.

2. The fuel injection control device according to claim 1.

3. The fluctuation calculation unit calculates a fluctuation in the voltage value when the coil is energized based on a standard deviation of a difference between the voltage value at the first inflection point or the second inflection point of the waveform of the voltage value and the threshold value.

3. The fuel injection control device according to claim 2.

4. The variation calculation unit adopts, as the start time of the intermediate pulse, the time at which the standard deviation of the calculated difference is smallest from among preset candidates for the start time of the intermediate pulse.

4. The fuel injection control device according to claim 3.

5. a valve body that moves toward and away from a valve seat to open and close a fuel passage; a movable element that opens and closes the valve body; a stator having a coil that is excited when energized and that exerts a magnetic attraction force on the mover; a stopper portion that suppresses movement of the movable element toward the valve seat; A fuel injection control method applied to a fuel injection device comprising: a control process for controlling energization of the coil by a drive command pulse; the control process performs control to apply an intermediate pulse between a first drive command pulse and a subsequent second drive command pulse when a drive command pulse is output multiple times per combustion stroke cycle; an end time of the intermediate pulse is determined by a time at which the movable element collides with the stopper portion in the first drive command pulse; The start time of the intermediate pulse is determined based on a change in the time when the valve disc driven by the second drive command pulse sits on the valve seat or a change in the time when the movable element driven by the second drive command pulse collides with the stopper portion. Fuel injection control method.

Images