Control device for fuel injection device and control method for fuel injection device

Abstract

This control device for a fuel injection device comprises a valve element that opens a fuel passage by moving away from a valve seat, a movable element for performing an opening / closing operation on the valve element, and a stator that attracts the movable element when a drive current flows through a coil. The control device includes a control unit for controlling an energization time of the drive current with the pulse width of drive command pulse. The control unit comprises: a sampling unit for sampling valve closing completion times of instances where drive command pulses of a plurality of different pulse widths are generated; a valve closing delay time calculation unit for calculating the delay time of an instance where drive command pulses of a desired pulse width were generated, from a relationship between the plurality of different pulse widths and delay times of each of the valve closing completion times with respect to a pulse end time of each of the drive command pulses generated at the sampling unit; and a valve opening start time estimation unit for estimating a valve opening start time of the instance where the drive command pulses of the desired pulse width were generated on the basis of a pre-retained relationship between the delay time and the valve opening start time, and the delay time calculated at the valve closing delay time calculation unit.

Description

Fuel injection device control device and fuel injection device control method

[0001] The present invention relates to a control device for a fuel injection device and a control method for a fuel injection device.

[0002] Patent Document 1 below describes a technology related to a control device for a fuel injection device. This document states, "A control device for a plurality of fuel injection devices, each including a valve element that opens a fuel passage by separating from a valve seat, a moving element that performs opening and closing operations of the valve element, and a stator that attracts the moving element when a drive current flows through a coil. This control device has a control unit that controls the energization time of the drive current by the pulse width of a drive command pulse. The control unit estimates a valve-opening start timing that is correlated with the detected valve-closing completion timing. The control unit then corrects the pulse width of the drive command pulse based on the valve-opening start timing," and further states, "An inflection point that occurs in the drive voltage is the valve-closing completion timing of the fuel injection device."

[0003] Japanese Patent Application Laid-Open No. 2020-159205

[0004] However, in a region where the pulse width of the drive command pulse is narrow, it is difficult for an inflection point to occur in the drive voltage, making it difficult to detect the valve closing completion timing and to estimate the valve opening start timing, which is correlated with the valve closing completion timing.

[0005] Therefore, an object of the present invention is to provide a control device for a fuel injection device and a control method for a fuel injection device that can estimate the valve closing completion time and valve opening start time with high accuracy regardless of the pulse width of the drive command pulse.

[0006] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above-described problems. One example of such a control device for a fuel injection device includes: a valve element that opens a fuel passage by separating from a valve seat; a movable element that opens and closes the valve element; and a stator that attracts the movable element when a drive current flows through a coil, the control device having a control unit that controls a duration of the drive current using a pulse width of a drive command pulse, the control unit including: a sampling unit that samples each of the valve close completion times when drive command pulses of a plurality of different pulse widths are generated; a valve close delay time calculation unit that calculates the delay time when a drive command pulse of a desired pulse width is generated, based on the relationship between the plurality of different pulse widths and the delay time of each valve close completion time relative to the pulse end time of each of the drive command pulses generated by the sampling unit; and a valve open start time estimation unit that estimates the valve open start time when a drive command pulse of the desired pulse width is generated, based on a relationship between the delay time and a valve open start time that is stored in advance, and the delay time calculated by the valve close delay time calculation unit.

[0007] The present invention can provide a control device for a fuel injection device and a control method for a fuel injection device that can estimate the valve closing completion time and the valve opening start time with high accuracy, regardless of the pulse width of the drive command pulse.

[0008] 1 is an overall configuration diagram showing an example of the basic configuration of an internal combustion engine equipped with a control device for a fuel injection device according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of the internal configuration of a fuel injection device according to one embodiment of the present invention. FIG. 3 is a diagram showing an example of detailed configurations of a drive circuit and an engine control unit (ECU) of the control device for a fuel injection device according to one embodiment of the present invention. FIG. 4 is a diagram explaining the operation of the fuel injection device shown in FIG. 2. FIG. 5 is a functional block diagram of the control device for the fuel injection device according to an embodiment. FIG. 6 is a flowchart showing a control method for the fuel injection device according to an embodiment. FIG. 7 is a diagram showing a calculation process for a valve closing delay time when a drive command pulse with a minute pulse width is generated. FIG. 8 is a diagram showing the relationship between the valve closing delay time and the valve opening start time when a drive command pulse with an extremely minute pulse width is generated for a fuel injection device of an arbitrary standard. FIG. 9 is a diagram showing the drive current and the displacement of the valve disc when the same drive command pulse is generated for two fuel injection valves. FIG. 10 is a diagram showing the relationship between the valve opening period and the injection amount in a fuel injection device. FIG. 11 is a diagram for explaining correction of the pulse width of the drive command pulse.

[0009] Hereinafter, embodiments of a fuel injection device control device and a fuel injection device control method of the present invention will be described in detail with reference to the drawings. In the following embodiments, the configuration of an internal combustion engine equipped with a fuel injection device control device and a fuel injection device of the internal combustion engine will be described in that order, and then the fuel injection device control device and the fuel injection device control method will be described.

[0010] <Internal Combustion Engine> Fig. 1 is an overall configuration diagram showing an example of the basic configuration of an internal combustion engine 101 equipped with a fuel injection device control device according to one embodiment of the present invention. 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 with 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 included in the internal combustion engine 101 is not limited to four, and may include, for example, three, six, eight, or more cylinders.

[0011] 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 passes through the throttle valve 119 is drawn into a collector 115, which is a branching portion, 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.

[0012] 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.

[0013] An opening / closing valve driven by a solenoid is provided at the intake port of the high-pressure fuel pump 125. The solenoid is connected to a control device for the fuel injection device (hereinafter referred to as a fuel injection control device 127). The fuel injection control device 127 is a control device connected to an ECU (Electric Control Unit) 109, which is an example of an engine control device. The fuel injection control device 127 controls a fuel injection device 200, which is a direct injection type fuel injection device that directly injects fuel into the combustion chamber 121.

[0014] 2, the fuel injection control device 127 has a CPU (Central Processing Unit) 501, a RAM (Random Access Memory) 260 that executes computer programs, and a ROM (Read Only Memory) 261 that stores data. The ROM 261 may be a memory whose contents can be erased and rewritten.

[0015] The CPU 501 of the fuel injection control device 127 calls up a program from the RAM 260 based on a control command from the ECU 109, and controls the solenoid based on data stored in the ROM 261. 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 shown in FIG. 1 (fuel pressure) becomes a desired pressure.

[0016] 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 the fuel injection control device 127. The fuel injection device 200 operates a valve body to inject fuel when a drive current is supplied (energized) to a coil 208 (shown in FIG. 2 ) described later.

[0017] The internal combustion engine 101 is also provided with a fuel pressure sensor 126 that measures the fuel pressure in a high-pressure fuel pipe 129. The ECU 109 sends a control command to the fuel injection control device 127 to adjust the fuel pressure in the high-pressure fuel pipe 129 to a desired pressure based on the measurement result from the fuel pressure sensor 126. In other words, the ECU 109 performs so-called feedback control to adjust the fuel pressure in the high-pressure fuel pipe 129 to the desired pressure.

[0018] Furthermore, each combustion chamber 121 of the internal combustion engine 101 is provided with a spark 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.

[0019] 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.

[0020] 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 injected from the fuel injection device 200 matches the target air-fuel ratio.

[0021] 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 results 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.

[0022] The ECU 109 receives 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. The accelerator opening sensor 122 is a sensor that indicates the opening of the accelerator operated by the driver.

[0023] The ECU 109 calculates the torque required for the internal combustion engine 101 based on the signal supplied from the accelerator position 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.

[0024] 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 coolant temperature obtained from the water temperature sensor 108 and the elapsed time since the internal combustion engine 101 was started, etc.

[0025] 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 spark plug 106.

[0026] <Fuel Injection Device> Figure 2 is a cross-sectional view showing an example of the internal configuration of a fuel injection device 200 according to one embodiment of the present invention, and is a diagram showing the configuration of the fuel injection device 200 shown in Figure 1. As shown in Figure 2, the fuel injection device 200 has a fuel supply unit 212 that supplies fuel, a valve seat 202 having fuel injection holes 215 that serve as fuel passages, and a mover (movable iron core) 206 that drives a valve body 201. In this embodiment, an electromagnetic fuel injection device for an internal combustion engine that uses gasoline or a mixed fuel as fuel will be described as an example.

[0027] In the fuel injection device 200, a fuel supply section 212 is arranged at the upper end side in the drawing, a fuel injection hole 215 and a valve seat 202 are arranged at the lower end side, and a movable element (movable iron core) 206, a valve body 201, and a sleeve 214 are arranged between the fuel supply section 212 and the valve seat 202.

[0028] The sleeve 214 has a cylindrical shape, is fitted onto and connected to the outer peripheral surface of the upper side of the valve body 201, and moves together with the valve body 201. A flange 214a is formed on the upper end of the sleeve 214. The flange 214a has a shape that protrudes outward from the upper side of the sleeve 214.

[0029] A first spring member 210 is disposed above the sleeve 214. Additionally, a second spring member 216 and armature 206 are disposed around the sleeve 214 on the underside of the flange 214a, in this order from the flange 214a side. The second spring member 216 biases the armature 206 and the sleeve 214 in directions that move them away from each other. The flange 214a of the sleeve 214 transmits the force of the second spring member 216 to the valve body 201 and the armature 206.

[0030] 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 ).

[0031] 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 configured 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.

[0032] The fuel injection device 200 further includes a coil 208, a stator (stationary core) 207, and a housing 209. The coil 208 is disposed between the stator 207 and the housing 209. The stator 207, the coil 208, and the housing 209 constitute an electromagnet. In a valve-closed 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 a first spring member 210 that biases the valve element 201 in the valve-closing direction (toward the valve seat 202). This state is referred to as a stable valve-closed state (valve-closed standby state). In the stable valve-closed state, the armature 206 abuts against a stopper 217 and is positioned in the valve-closed position. The valve element 201 is driven via a sleeve 214 that transmits the load from the armature 206.

[0033] The stopper 217 has a roughly cylindrical shape, and is fitted and coupled to the outer peripheral surface of the valve body 201 downstream (toward the valve seat 202) of the moving element 206. The stopper 217 restricts the movement of the moving element 206 in the valve closing direction.

[0034] In the stable valve-closed state, the sleeve 214 is biased downstream (toward the valve seat 202, in the valve closing direction) by the biasing force of the first spring member 210 minus the biasing force of the second spring member 216. In this state, the valve element 201 is in contact with the valve seat 202 and is stationary. Furthermore, the movable element 206 is biased in the valve closing direction (toward the valve seat 202) by the biasing force of the second spring member 216, and is in contact with the stopper 217. Furthermore, a gap [d] is generated between the lower end of the sleeve 214, which is fixed to the valve element 201, and the upper surface of the movable element 206.

[0035] A flange may be formed at the lower end of the sleeve 214. In this case, the lower surface of the flange formed at the lower end of the sleeve 214 serves as a transmission surface and comes into contact with the upper surface of the mover 206.

[0036] 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 that instructs the injection of fuel and supplies a drive current (drive voltage) to the fuel injection device 200.

[0037] 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 component.

[0038] The ECU 109 receives signals indicating the engine state from various sensors and calculates an appropriate pulse width of the drive command 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.

[0039] 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 in accordance with the control constants.

[0040] [Configuration of the fuel injection device control device (fuel injection control device 127)] Next, the configuration of the fuel injection control device 127 will be described with reference to Fig. 3. Fig. 3 is a diagram showing a detailed configuration example of a drive circuit of the fuel injection device control device (fuel injection control device 127) and the engine control device (ECU 109: see Figs. 1 and 2) according to one embodiment of the present invention.

[0041] As described above, the fuel injection control device 127 (see FIGS. 1 and 2) connected to the ECU 109 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, and the like, which are described with reference to FIG. 1. Based on these signals, the CPU 501 calculates the pulse width and injection timing of a drive command 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.

[0042] Furthermore, CPU 501 calculates an appropriate pulse width of a drive command pulse and injection timing in accordance with 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 through signal line 223. This CPU 501 represents one specific example of a control unit according to the present invention, and controls the energization time of the drive current flowing through coil 208 by the pulse width of the drive command pulse.

[0043] The amount of injection by fuel injection device 200 (see FIGS. 1 and 2) is determined by the pulse width of the drive command pulse. After that, drive IC 502 switches between energized and de-energized states of switching elements 505, 506, and 507 to supply drive current to fuel injection device 200.

[0044] Switching element 505 is connected between a high-voltage source higher than battery voltage 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.

[0045] 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.

[0046] 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 a charge is accumulated in the capacitor 533.

[0047] This transistor is repeatedly turned on and off until the voltage of capacitor 533 reaches boosted voltage VH, thereby increasing the voltage of capacitor 533. Transistor 531 is connected to drive IC 502 or CPU 501, and boosted voltage VH output from boost circuit 514 is configured to be detected by drive IC 502 or CPU 501. Note that boost circuit 514 may be configured by a DC / DC converter or the like.

[0048] Switching element 507 is connected between a low-voltage power source and a high-voltage terminal of solenoid 540. The low-voltage power source is, for example, battery voltage VB, and its voltage value is approximately 12 to 14 V. Switching element 506 is connected between a low-voltage terminal of fuel injection device 200 (see FIG. 2) and ground potential 515.

[0049] The driver IC 502 detects the value of the current flowing through the fuel injector 200 using current detection resistors 508, 512, and 513, and switches between energized and de-energized states of the switching elements 505, 506, and 507 based on the detected current value to generate the desired drive current. The diodes 509 and 510 apply a reverse voltage to the solenoid 540 of the fuel injector 200, rapidly reducing the current supplied to the solenoid 540.

[0050] The CPU 501 communicates with the drive IC 502 through communication lines 152 and 153. The CPU 501 switches the drive current generated by the drive IC 502 depending on the pressure of the fuel supplied to the fuel injection device 200 (see FIG. 2) and the operating conditions. Both ends of the resistors 508, 512, and 513 are connected to the A / D conversion port of the drive IC 502, and the drive IC 502 is configured to detect the voltage applied across the resistors 508, 512, and 513.

[0051] [Operation of Fuel Injection Device] FIG. 4 is a diagram illustrating the operation of the fuel injection device 200 shown in FIG. 2, and is a graph showing the drive command pulse [Ps], drive voltage [E], drive current [I], and valve disc displacement [D] and armature displacement [Dm]. The graphs of valve disc displacement [D] and armature displacement [Dm] show changes in position along the central axis 200a of each fuel injection device 200. These graphs also show the drive voltages E1 to E4, drive currents I1 to I4, valve disc displacements Dm1 to Dm4, and armature displacements D1 to D4 corresponding to input of pulses Ps1 to Ps4 with four pulse widths as the drive command pulse [Ps]. Each pulse Ps1 to Ps4 has a pulse width W from start time Ts to end time Te1 to Te4. As an example, pulse Ps4 has a pulse width W4 from start time Ts to end time Te4. The operation of the fuel injection device 200 under the control of the fuel injection control device 127 shown in FIG. 2 will be described below based on FIG. 4 with reference to FIGS. 2 and 3.

[0052] 4, when one of the drive command pulses [Ps] (Ps1 to Ps4) having a pulse width W is input, a corresponding drive voltage [E] is applied to the coil 208 (see FIG. 2), and supply of a drive current [I] to the coil 208 begins. For example, when the pulse Ps4 is input, a drive voltage E4 is applied to the coil 208, and supply of a drive current I4 to the coil 208 begins.

[0053] After the coil 208 is energized, a magnetomotive force is generated by the electromagnet formed by the stator 207, the coil 208, and the housing 209. This magnetomotive force causes the stator 207, the housing 209, and the mover 206 to form a magnetic path (magnetic circuit) surrounding the coil 208, and magnetic flux flows around the formed magnetic path. At this time, a magnetic attraction force acts between the mover 206 and the stator 207, displacing the mover 206 toward the stator 207. The mover 206 then displaces to a position where its upper surface abuts against the lower end of the sleeve 214. Note that the valve element 201 continues to be in contact with the valve seat 202 until the mover 206 abuts against the sleeve 214.

[0054] When the displacement [D] of the armature 206 reaches the size of the gap [d] between the valve element 201 (i.e., the lower end of the sleeve 214) and the armature 206, the armature 206 collides with the valve element 201 (sleeve 214). As a result, the kinetic energy of the armature 206 pulls the valve element 201 upstream and separates it from the valve seat 202. This time corresponds to the valve opening start times To1 to To4. As a result, the valve element 201 is lifted from the valve seat 202, opening the fuel passage and injecting fuel from the fuel injection hole 215. Then, the armature 206, which has kinetic energy, causes a steep displacement of the valve element 201.

[0055] The fuel injection control device 127 applies a high voltage as the drive voltage [E] and causes a drive current [I] to flow through the coil 208 from the start time Ts of application of the drive command pulse [Ps] until the armature 206 and the valve disc 201 collide and separate the valve disc 201 from the valve seat 202, or until sufficient kinetic energy for separation is accumulated in the armature 206. As a result, a necessary and sufficient magnetic attraction force is generated between the armature 206 and the stator 207, allowing the armature 206 to be quickly displaced. By quickly displacing the armature 206, the armature 206 can drive the valve disc 201 even when the pressure of the supplied fuel is high.

[0056] When the drive voltage [E] (E1 to E4) is applied to the coil 208 from the start time Ts, the drive current [I] (I1 to I4) flowing through the coil 208 rises sharply and then reaches each peak current value Pk1 to Pk4.

[0057] Thereafter, when pulses Ps1 to Ps3 with relatively small pulse widths are applied, when the drive current [I] (I1 to I3) reaches each peak current value Pk1 to Pk3, the fuel injection control device 127 applies the drive voltage [E] (E1 to E3) in the reverse direction (applies a reverse voltage). That is, the fuel injection control device 127 turns off all of the switching elements 505, 506, and 507 (see FIG. 3). As a result, the back electromotive force due to the inductance of the fuel injection device 200 causes the diodes 509 and 510 to conduct, and the current is fed back to the boost circuit 514. As a result, the drive current [I] (I1 to I3) flowing through the coil 208 rapidly decreases and is cut off.

[0058] On the other hand, when a pulse Ps4 having a certain pulse width is applied, the fuel injection control device 127 reduces the drive voltage [E] when the drive current I4 reaches the peak current value Pk4. As a result, when the drive current I4 decreases to the hold current Ih, the drive voltage E4 is switched at the battery voltage VB, and the drive current I4 is maintained at the hold current Ih. When the armature 206 subsequently collides with the stator 207, the valve element 201 separates from the armature 206 and displaces upstream. After colliding with the stator 207, the armature 206 also displaces downstream, but eventually stops at the target position and stabilizes. This state is referred to as a stable valve-open state. Subsequently, when the pulse Ps4 is turned OFF at end time Te4, the fuel injection control device 127 applies a drive voltage in the reverse direction to the coil 208 (applies a reverse voltage). As a result, the drive current I4 to the coil 208 decreases and is shut off.

[0059] Then, by interrupting the drive current [I] (I1 to I4) as described above, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attractive force disappears. As a result, the moving element 206, which has lost its magnetic attractive force, is pushed back by the load of the first spring member 210 and the force of the fuel pressure. As a result, the valve element 201 connected to the sleeve 214 is pushed back to its original closed position in contact with the valve seat 202. This time corresponds to the valve closing completion times Tc1 to Tc4.

[0060] Furthermore, the biasing force of the first spring member 210 acting on the valve element 201 is transmitted to the armature 206 via the lower end of the sleeve 214 coupled to the valve element 201. After the valve element 201 comes into contact with the valve seat 202, the armature 206 separates from the lower end of the sleeve 214 of the valve element 201 and continues to move downward (in the valve closing direction). After the valve closing completion times Tc1 to Tc4, the armature 206 and the sleeve 214 of the valve element 201 are separated from each other.

[0061] In this way, when the motion of the mover 206 changes, the acceleration of the mover 206 changes, and the inductance of the coil 208 changes. In other words, when the fuel injection device 200 is to close, the drive current flowing through the coil 208 is interrupted, and a back electromotive force is applied to the coil 208. Then, as the drive current [I] converges, the back electromotive force also gradually decreases, and the inductance changes as the back electromotive force decreases. Due to this change in inductance, inflection points Pe2 to Pe4 appear in the drive voltages E2 to E4 corresponding to pulses Ps2 to Ps4, each having a certain pulse width. By detecting these inflection points Pe2 to Pe4, the valve closing completion times Tc2 to Tc4 in the operation of the fuel injection device 200 can be detected.

[0062] The flow rate injected from fuel injection device 200 depends on the time when valve element 201 is open, i.e., the valve opening start time To to the valve closing completion time Tc. Even if the pulse width W of the drive command pulse [Ps] is the same, deviations may occur in the valve opening start time To and the valve closing start time Tc due to environmental factors, individual characteristic variations, aging, and other influences. Reducing such deviations in the injection amount is one of the important issues to be resolved in order to improve engine exhaust performance and reduce fuel consumption.

[0063] For example, when the application of the drive command pulse [Ps] is terminated at the end times Te1 and Te2 before the valve-opening start times To1 and To2, as in the case of pulses Ps1 and Ts2, the timing attraction force is terminated midway through the acceleration of the movement of the mover 206. Therefore, the valve-opening start times To1 and To2 corresponding to the pulses Ps1 and Ts2 are delayed from the valve-opening start times To3 and To4 of the pulses Ps3 and Ps4, which have a certain width.

[0064] To measure an optimal injection amount, it is important to detect the valve opening start time To and the valve closing completion time Tc and to understand the influence of environmental factors, individual characteristic variations, aging, and the like. However, the valve closing completion times Tc2 to Tc4 can be obtained by detecting the inflection points Pe2 to Pe4 as described above. However, the valve opening start time To can be difficult to obtain because it is not easily reflected in changes in voltage or current. Furthermore, in the case of a pulse Ps1 with an extremely narrow pulse width, the valve opening and closing operations of the valve element 201 occur almost simultaneously, so an inflection point cannot be detected in the drive voltage E1, and it may be impossible to obtain the valve closing completion time Tc1 based on the drive voltage E1.

[0065] Therefore, when the pulse width of the drive command pulse [Ps] is small and a very small amount of fuel injection is to be controlled, the fuel injection control device and fuel injection control method shown in the following embodiment are applied.

[0066] <<Fuel Injection Device Control Device (Fuel Injection Control Device) of the Embodiment>> Figure 5 is a functional block diagram of the fuel injection device control device of the embodiment, and is a functional block diagram for estimating the valve opening start time, which is provided in the CPU 501 of the fuel injection control device 127 shown in Figures 2 and 3. As shown in Figure 5, the CPU 501 of the fuel injection control device 127 includes a target injection amount calculation unit 501a and a sampling unit 501b. The sampling unit 501b samples each valve closing completion time when drive command pulses with multiple different pulse widths are generated. The sampling unit 501b includes an energization control unit 501c, an injector drive communication unit 501d, a voltage detection unit 501e, a filter processing unit 501f, a valve closing completion time detection unit 501g, and a learning completion determination unit 501h.

[0067] The CPU 501 of the fuel injection control device 127 also includes a valve closing delay time calculation unit 501i, a valve opening start time estimation unit 501j, and a pulse width correction unit 501k. The valve closing delay time calculation unit 501i calculates a valve closing delay time when a drive command pulse with a desired pulse width is generated, based on the relationship between the pulse width of each drive command pulse obtained by sampling in the sampling unit 501b and the valve closing delay time. Referring to FIG. 4, the valve closing delay time is the delay time from the valve closing completion time Tc relative to the end time Te, which is the pulse off time. The valve opening start time estimation unit 501j estimates the valve opening start time when a drive command pulse with a desired pulse width is generated, based on the relationship between the valve closing delay time and the valve opening start time stored in advance, and the valve closing delay time calculated by the valve closing delay time calculation unit 501i. Furthermore, a pulse width corrector 501k corrects the pulse width of the drive command pulse based on the valve closing delay time calculated by the valve closing delay time calculator 501i and the valve opening start time estimated by the valve opening start time estimator 501j. Details of the functions executed by these functional units will be described later in the fuel injection method.

[0068] <<Control Method of Fuel Injection Device According to Embodiment>> Next, a control method of the fuel injection device according to the embodiment, which is carried out by the above-described fuel injection control device 127, will be described.

[0069] <Estimation of Valve Closing Completion Time and Valve Opening Start Time> FIG. 6 is a flowchart showing a control method for a fuel injection device according to an embodiment, illustrating a procedure for estimating the valve closing completion time and valve opening start time required to control the injection amount of fuel injection device 200 ( FIG. 2 ) by the control of fuel injection control device 127 shown in FIG. 5 . Hereinafter, the procedure for estimating the valve closing completion time and valve opening start time in the control method for a fuel injection device will be described along with the flowchart of FIG. 6 and with reference to FIGS. 2 to 5 . Note that the procedure shown in this flowchart is initiated, for example, when an engine (internal combustion engine) equipped with this fuel injection device 200 enters an idling state at a predetermined timing. The predetermined timing may be, for example, when the fuel injection device of the internal combustion engine is replaced, or when an external environment such as temperature or humidity changes significantly.

[0070] [Step S101] In step S101, when the current supply control unit 501c of the sampling unit 501b receives an idling instruction from the target injection amount calculation unit 501a at the predetermined timing described above, it sets the pulse width of the drive command pulse for sampling. At this time, the current supply control unit 501c sets multiple (e.g., five) different pulse widths within a range in which the inflection points Pe2 to Pe3 of the drive voltage [E] described with reference to FIG. 4 can be detected. Then, one pulse width is selected from the multiple different pulse widths that have been set, and set as the pulse width of the drive command pulse.

[0071] Here, the plurality of different pulse widths are set in advance through preliminary experiments so that the data on the valve closing delay time corresponding to the pulse width has a minimum value. The valve closing delay time is the delay time between the valve closing completion time Tc and the end time Te, which is the pulse-off time, and is the valve closing delay time [Tc - Te]. In this way, by setting the plurality of different pulse widths within a range in which the data on the valve closing delay time corresponding to the pulse width has a minimum value, the detection accuracy of the valve closing completion time corresponding to the extremely small pulse width, which makes it impossible to detect an inflection point of the drive voltage [E] described below, is ensured.

[0072] As an example of the above, if the fuel injection device 200 has a maximum pulse width of 5000 μsec, the pulse widths are set to 260 μsec, 270 μsec, 280 μsec, 290 μsec, and 300 μsec, and the current control unit 501c selects one of these pulse widths as the pulse width of the drive command pulse.

[0073] [Step S102] In step S102, the injector drive communication unit 501d of the sampling unit 501b generates a drive command pulse having one pulse width set in step S101, and outputs the pulse to the drive IC 502, thereby performing a current supply control process.

[0074] [Step S103] In step S103, the voltage detection unit 501e of the sampling unit 501b performs a voltage detection process to detect the drive voltage [E] when current is applied to the coil 208 in response to the generation of the drive command pulse in step S102. The voltage detection unit 501e includes an A / D converter, and the drive voltage [E] detected as an analog value is converted into a digital value by the A / D converter and used as a signal by the CPU 501.

[0075] [Step S104] In step S104, the filter processing unit 501f of the sampling unit 501b performs filtering on the drive voltage [E] detected in step S103 to detect an inflection point in the waveform of the drive voltage [E] when current is applied to the coil 208. This inflection point corresponds to, for example, any of the inflection points Pe2 to Pe4 described with reference to FIG. 4. In this case, the filter processing unit 501f may convert the drive voltage [E] detected by the voltage detection unit 501e in step S103 into a digital value and then perform digital filtering, or may perform analog filtering using an analog value.

[0076] [Step S105] In step S105, the valve closing completion time detection unit 501g of the sampling unit 501b detects the valve closing completion time of the valve element 201 based on the inflection point detected by the filter processing unit 501f in step S104. This valve closing completion time is based on the pulse-on time of the drive command pulse [Ps] generated in step S102.

[0077] [Step S106] In step S106, the learning completion determination unit 501h of the sampling unit 501b determines whether or not generation of all drive command pulses with the multiple different pulse widths set in step S101 has been completed. If the learning completion determination unit 501h determines that the learning has been completed (YES), the process proceeds to step S107.

[0078] If the learning completion determination unit 501h determines that the learning is not completed (NO), the process returns to step S101. As a result, in the next step S101, the energization control unit 501c of the sampling unit 501b selects the next pulse width from the multiple different pulse widths that have been set, and sets the pulse width of the drive command pulse. Then, step S102 and subsequent steps are similarly performed.

[0079] [Step S107] In step S107, the valve closing delay time calculation unit 501i calculates the valve closing delay time [Tc-Te] when a drive command pulse of the desired minute pulse width is generated, based on all of the valve closing completion times detected in step S105 and the corresponding pulse widths.

[0080] Here, the minute pulse width refers to a pulse width in which no inflection point appears in the drive voltage [E] when a drive command pulse is generated. This minute pulse width is shorter than the range of different pulse widths set in step S101. For example, if the fuel injection device 200 illustrated in step S101 has a maximum pulse width of 5000 μsec, no inflection point appears in the drive voltage when a drive command pulse with a pulse width of 200 μsec is generated, and therefore the pulse width of 200 μsec is the minute pulse width.

[0081] 7 is a diagram showing the calculation process for the valve closing delay time [Tc - Te] when a drive command pulse with a minute pulse width is generated. As shown in FIG. 7, the valve closing delay time calculation unit 501i creates an approximation curve, using, for example, the least squares method, for the valve closing delay time [Tc - Te] based on a plurality of different pulse widths [W] and the valve closing completion times obtained by generating drive command pulses with those pulse widths [W]. The plurality of different pulse widths [W] are the pulse widths set in step S101, and the valve closing completion times are the values ​​detected in step S105.

[0082] The valve closing delay time calculation unit 501i extrapolates the created approximate curve to calculate the valve closing delay time Tc1-Te1 when a pulse Ps1 with a minute pulse width W1 is generated as a drive command pulse. It is known that the approximate curve will have a minimum value when the pulse width of the drive command pulse is set to a wide range that includes the minute pulse width. Therefore, in the previous step S101, it is important to set a plurality of different pulse widths so that an approximate curve with a minimum value is created in order to calculate a more accurate valve closing delay time Tc1-Te1 corresponding to the minute pulse width.

[0083] Note that step S107 is not limited to calculating the valve-closing delay time Tc1-Te1 when a drive command pulse having the above-described minute pulse width is generated as the desired pulse width. Step S107 may also calculate the valve-closing delay time Tc-Te when a drive command pulse is generated with a pulse width outside the range of the different pulse widths set in step S101 as the desired pulse width.

[0084] Furthermore, the valve closing completion time is calculated from the calculated valve closing delay time and the pulse width of the minute pulse (desired pulse width).

[0085] [Step S108] In step S108, the valve-opening start time estimation unit 501j retrieves the relationship between the valve-closing delay time [Tc-Te], which is preset as a constant, and the valve-opening start time [To]. FIG. 8 is a diagram showing the relationship between the valve-closing delay time [Tc-Te] and the valve-opening start time [To] when a drive command pulse with a small pulse width is generated for a fuel injection device conforming to a given standard. The relationship shown in FIG. 8 is a value obtained by conducting a preliminary test in which multiple drive command pulses with small pulse widths are generated. The valve-closing completion time Tc1 and the valve-opening start time To1 used to obtain the valve-closing delay time Tc1-Te1 are actual measurements obtained using a pressure sensor, an acceleration sensor, a strain sensor, and the like. The preliminary test corresponds to a test of a stand-alone fuel injection device. The relationship shown in FIG. 8 is stored in the ROM 261 of the fuel injection control device 127.

[0086] [Step S109] In step S109, the valve-opening start time estimation unit 501j estimates the valve-opening start time To1' by applying the valve-closing delay time Tc1-Te1 (see FIG. 7) calculated in step S107 to the relationship shown in FIG. 8 called up in step S108. This valve-opening start time To1' is the time estimated as the valve-opening start time To1' when a drive command pulse with a minute pulse width is generated. This completes the valve-opening start time estimation process.

[0087] The above-described process for estimating the valve-opening start time is performed during idling. Therefore, when idling, the sampling unit 501b receives the drive pulse width for estimating the valve-opening start time To, the fuel pressure acquired by the fuel pressure sensor, the temperature, and other results, and determines the next required drive command pulse width Ti required for idling.

[0088] <Control of Injection Amount> Next, a method of controlling the fuel injection amount based on the valve opening start time To1' when the drive command pulse with the minute pulse width obtained as described above is generated will be described.

[0089] 9 is a diagram showing the drive current and valve disc displacement when the same drive command pulse is generated for the two fuel injection devices INJ_A and INJ_B. The two fuel injection devices INJ_A and INJ_B are devices of the same specification, but each has its own individual characteristics. As shown in FIG. 9, even when drive command pulses Pa_A and Pa_B of the same pulse width are generated for the fuel injection devices INJ_A and INJ_B of the same specification, differences in the valve disc displacement, i.e., the valve opening start time To and the valve closing completion time Tc, occur due to individual differences.

[0090] Furthermore, the fuel injection amount of each fuel injection device depends on the valve opening period Td (=Tc-To) from the valve opening start time To to the valve closing completion time Tc. For example, the fuel injection amount of fuel injection device INJ_A depends on the valve opening period Td(A) (=Tc_A-To_A), and the fuel injection amount of fuel injection device INJ_B depends on the valve opening period Td(B) (=Tc_B-To_B).

[0091] 10 is a diagram showing the relationship between the valve-opening period [Td] and the injection amount [Q] in a fuel injection device. As shown in FIG. 10, the fuel injection amount [Q] in a fuel injection device is proportional to the valve-opening period [Td], and the longer the valve-opening period [Td], the larger the fuel injection amount [Q]. Note that the minute pulse width as the desired pulse width described above is also a pulse width in which the valve-opening period [Td] is 50 μm or less.

[0092] Therefore, the fuel injection amount of the fuel injection device INJ_B shown in Figure 9 is smaller than the fuel injection amount of the fuel injection device INJ_A, and the difference between the valve opening start time To and the valve closing completion time Tc becomes a factor that causes variations in the fuel injection amount in the fuel injection device.

[0093] Therefore, the pulse width correction section 501k (see FIG. 5) provided in the CPU 501 of the fuel injection control device 127 corrects the variations in the fuel injection amount due to the individual differences between the fuel injection devices as follows.

[0094] First, the relationship between the valve opening period [Td] and the fuel injection amount [Q] shown in Figure 10 is obtained for a fuel injection device of a specified standard. The relationship shown in Figure 10 is a relationship obtained through preliminary experiments for a fuel injection device of a specified standard, and differences in individual characteristics among fuel injection devices of the same standard are so small that they can be ignored. Therefore, the injection amount is corrected using this relationship.

[0095] Then, for the fuel injection device of the standard to be corrected, the valve opening period [Td] corresponding to the target fuel injection amount Q(ob) is detected as the target valve opening period Td(ob) based on the relationship shown in Figure 10. Next, the difference between the target valve opening period Td(ob) obtained here and the valve opening start time To1' estimated according to the flowchart of Figure 6 is calculated, and this value becomes the target valve closing completion time Tc(ob).

[0096] 11 is a diagram for explaining correction of the pulse width of the drive command pulse, and is a diagram for explaining correction for the purpose of making the fuel injection amount of the fuel injection device INJ_B shown in FIG. 9 equal to the fuel injection amount of the fuel injection device INJ_A. The drive command pulse Pa_A and the drive command pulse Pa_B shown in FIG. 9 are, for example, the same drive command pulse Ps1.

[0097] In this case, as shown in FIG. 11 , a target valve-closing completion time Tc(ob) for the fuel injection device INJ_B is calculated so that the corrected valve-opening duration Td(B') of the fuel injection device INJ_B is the same as the valve-opening duration Td(A) of the fuel injection device INJ_A. This target valve-closing time Tc(ob) is calculated from the valve-opening start time To_Bb for the drive command pulse Pa_B with a small pulse width, estimated using the procedure shown in the flowchart above, and the valve-opening duration Td(B'). Then, the pulse width of the drive command pulse [Ps] that results in this target valve-closing completion time Tc(ob) is determined as a target pulse width W(ob) for the fuel injection device INJ_B, and the pulse width of the drive command pulse Pa_B is corrected to the target pulse width W(ob). Such a target pulse width W(ob) may be obtained by feedback of the difference between the actual measurement value and the target value, or by learning the relationship between the valve closing completion time Tc and the pulse width [W] of the drive command pulse.

[0098] Effect of the Embodiment The control device for the fuel injection device according to the present embodiment (fuel injection control device 127) described above controls fuel injection device 200, which includes valve element 201 that opens a fuel passage by separating from valve seat 202, movable element 206 that opens and closes valve element 201, and stator 207 that attracts movable element 206 by a drive current flowing through coil 208. This fuel injection control device 127 has a control unit (CPU 501) that controls the energization time of the drive current using the pulse width of a drive command pulse. The CPU 501 includes a sampling unit 501b that samples each valve-closing completion time when drive command pulses of a plurality of different pulse widths are generated; a valve-closing delay time calculation unit 501i that calculates a valve-closing delay time when a drive command pulse of a desired pulse width is generated, based on the relationship between the plurality of different pulse widths and the delay time (valve-closing delay time) between the pulse end time of each drive command pulse generated by the sampling unit and each valve-closing completion time; and a valve-opening start time estimation unit 501j that estimates the valve-opening start time when a drive command pulse of a desired pulse width is generated, based on the relationship between the valve-closing delay time and the valve-opening start time stored in advance and the valve-closing delay time calculated by the valve-closing delay time calculation unit 501i.

[0099] This makes it possible to predict with high accuracy the valve closing delay time and valve opening start time corresponding to the valve closing completion time, even if the pulse width of the drive command pulse is small enough that an inflection point corresponding to the valve closing completion time does not occur in the drive voltage applied to coil 208.

[0100] The pulse width of the drive command pulse is then corrected based on the valve closing delay time and valve opening start time corresponding to the highly accurately predicted valve closing completion time, thereby enabling highly accurate control of the fuel injection amount using a drive command pulse with a small pulse width. As a result, the fuel injection amount of the fuel injection device can be stabilized even if the characteristics of the fuel injection device or environmental factors of the fuel injection device change.

[0101] The present invention is not limited to the above-described embodiments and modifications, and includes various other modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0102] Furthermore, in this specification, the 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 (e.g., processing by objects).

[0103] 127... Fuel injection control device (control device for fuel injection device) 201... Valve body 202... Valve seat 206... Movable element 207... Stator 208... Coil 501... CPU (control unit) 501b... Sampling unit 501i... Valve closing delay time calculation unit 501j... Valve opening start time estimation unit 501k... Pulse width correction unit

Claims

1. A control device for a fuel injection device comprising: a valve disc that opens a fuel passage by separating from a valve seat, a movable element that opens and closes the valve disc, and a stator that attracts the movable element when a drive current flows through a coil, the control device having a control unit that controls the energization time of the drive current using the pulse width of a drive command pulse, the control unit having: a sampling unit that samples each valve close completion time when drive command pulses of a plurality of different pulse widths are generated; a valve close delay time calculation unit that calculates the delay time when a drive command pulse of a desired pulse width is generated, based on the relationship between the plurality of different pulse widths and the delay time of each valve close completion time relative to the pulse end time of each of the drive command pulses generated by the sampling unit; and a valve open start time estimation unit that estimates the valve open start time when a drive command pulse of the desired pulse width is generated, based on the relationship between the delay time and the valve open start time stored in advance and the delay time calculated by the valve close delay time calculation unit.

2. The control device for a fuel injection device according to claim 1, wherein the sampling section generates a plurality of drive command pulses within a predetermined pulse width range as the plurality of drive command pulses with different pulse widths.

3. The control device for a fuel injection device according to claim 2, wherein the predetermined range of pulse widths includes a pulse width at which the delay time relative to the pulse width of the drive command pulse becomes a minimum value.

4. The fuel injection control device according to claim 2, wherein the desired pulse width is a minute pulse width that is shorter than the range of the predetermined pulse width.

5. A control device for a fuel injection device as described in claim 1, wherein the control unit has a pulse width correction unit that corrects the pulse width of the drive command pulse based on the delay time calculated by the valve closing delay time calculation unit and the valve opening start time estimated by the valve opening start time estimation unit.

6. A control device for a fuel injection device as described in claim 5, wherein the pulse width correction unit corrects the pulse width of the drive command pulse so that the valve closing completion time corresponds to a target injection amount of fuel injected from the fuel injection device and the valve opening start time.

7. A control device for a fuel injection device according to claim 1, wherein the desired pulse width is a pulse width that makes the valve open period from the valve opening start time to the valve closing completion time 50 μm or less.

8. A control device for a fuel injection device according to claim 1, wherein the desired pulse width is small enough that an inflection point corresponding to the valve closing completion time does not occur in the drive voltage applied to the coil.

9. A control method for a fuel injection device comprising a valve disc that opens a fuel passage by separating from a valve seat, a movable element that opens and closes the valve disc, and a stator that attracts the movable element by a drive current flowing through a coil, wherein a control unit controls the energization time of the drive current using the pulse width of a drive command pulse, a sampling unit of the control unit samples each valve close completion time when drive command pulses of a plurality of different pulse widths are generated, a valve close delay time calculation unit of the control unit calculates the delay time when a drive command pulse of a desired pulse width is generated from the relationship between the plurality of different pulse widths and the delay time of each valve close completion time relative to the pulse end time of each of the drive command pulses generated by the sampling unit, and a valve open start time estimation unit of the control unit estimates the valve open start time when a drive command pulse of the desired pulse width is generated, based on the relationship between the delay time and the valve open start time stored in advance and the delay time calculated by the valve close delay time calculation unit.

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