Control device for fuel injection system and method for controlling fuel injection system

Abstract

The present invention provides a fuel injection device control system capable of accurately estimating the valve closing completion time and valve opening start time, regardless of the drive command pulse width. [Solution] A control device comprising a movable element that causes a valve body to open and close, and a stator that attracts the movable element by supplying a drive current, wherein the control unit controls the energizing time of the drive current by the drive command pulse width, and the control unit comprises a sampling unit that collects the closing completion times of each when a plurality of drive command pulses of different pulse widths are generated, a closing delay time calculation unit that 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 closing completion time with respect to the pulse end time of each drive command pulse generated by the sampling unit, and a valve opening start time estimation unit 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 delay time and the valve opening start time that is held in advance and the delay time calculated by the valve closing delay time calculation unit.

Description

Technical Field

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

Background Art

[0002] As a technique related to a control device for a fuel injection device, there is a technique described in Patent Document 1 below. This Patent Document 1 describes, "A control device for a plurality of fuel injection devices including a valve body that opens a fuel passage by moving away from a valve seat, a mover that performs the opening and closing operation of the valve body, and a stator that attracts the mover 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 an opening start timing that has a correlation with the detected valve closing completion timing. Then, the pulse width of the drive command pulse is corrected based on the opening start timing." And it states that "the inflection point generated in the drive voltage becomes the valve closing completion timing of the fuel injection device."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[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. Therefore, it has been difficult to detect the valve closing completion timing and estimate the opening start timing that has a correlation 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 accurately estimate the valve closing completion time and the opening start time regardless of the pulse width of the drive command pulse. [Means for solving the problem]

[0006] To solve the above problems, for example, the configuration described in the claims may be adopted. The present invention includes multiple means for solving the above problems, but to give one example, a control device for a fuel injection device comprising a valve body that opens a fuel passage by moving away from a valve seat, a movable element that causes the valve body to open and close, and a stator that attracts the movable element when a drive current flows through a coil, wherein the control unit controls the energizing time of the drive current by the pulse width of a drive command pulse, and the control unit comprises a sampling unit that samples the closing completion time of each when a plurality of drive command pulses of different pulse widths are generated, a closing delay time calculation unit that 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 closing completion time with respect to the pulse end time of each drive command pulse generated by the sampling unit, and a valve opening start time estimation unit that estimates the valve opening 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 opening start time which is held in advance and the delay time calculated by the valve closing delay time calculation unit. [Effects of the Invention]

[0007] The present invention provides a control 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. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram showing a basic configuration example of an internal combustion engine equipped with a control device for a fuel injection system according to one embodiment of the present invention. [Figure 2] This 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. [Figure 3]This figure shows a detailed configuration example of the drive circuit and engine control unit (ECU) of a fuel injection device control device according to one embodiment of the present invention. [Figure 4] Figure 2 is a diagram illustrating the operation of the fuel injection system. [Figure 5] This is a functional block diagram of the control device for the fuel injection system of the embodiment. [Figure 6] This flowchart shows the control method for a fuel injection device according to an embodiment. [Figure 7] This figure shows the process for calculating the valve closing delay time when a drive command pulse with a very small pulse width is generated. [Figure 8] This figure shows the relationship between the valve closing delay time and the valve opening start time when a drive command pulse with an extremely small pulse width is generated for a fuel injection system of arbitrary specifications. [Figure 9] This figure shows the drive current and valve body displacement when the same drive command pulse is generated for two fuel injection valves. [Figure 10] This figure shows the relationship between the valve opening period and the injection amount in a fuel injection system. [Figure 11] This diagram illustrates the correction of the pulse width of the drive command pulse. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the fuel injection device control device and 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 the internal combustion engine equipped with the fuel injection device control device and the fuel injection device of the internal combustion engine will be described in this order first, and then the fuel injection device control device and fuel injection device control method will be described.

[0010] Internal combustion engine Figure 1 is an overall configuration diagram showing a basic configuration example 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 Figure 1 is a four-stroke engine that repeats four strokes: intake stroke, compression stroke, combustion (expansion) stroke, and exhaust stroke, and is, for example, a multi-cylinder engine equipped with four cylinders. The internal combustion engine 101 completes one combustion stroke (combustion cycle) for each cylinder through four strokes. Note that the number of cylinders in the internal combustion engine 101 is not limited to four, and may have, for example, three, six, or eight or more cylinders.

[0011] The internal combustion engine 101 is equipped with a piston 102, an intake valve 103, and an exhaust valve 104. The intake air to the internal combustion engine 101 passes through an air flow meter (AFM) 120 that detects the amount of incoming air, 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 the combustion chamber 121 of each cylinder via an intake pipe 110 and intake valve 103 provided for each cylinder.

[0012] Meanwhile, fuel is supplied from the fuel tank 123 to the high-pressure fuel pump 125 by the low-pressure fuel pump 124, and the high-pressure fuel pump 125 increases the pressure to the level required for fuel injection. Specifically, the high-pressure fuel pump 125 moves a plunger located inside it up and down using power transmitted from the exhaust camshaft (not shown) of the exhaust cam 128, thereby pressurizing (increasing) the fuel inside the high-pressure fuel pump 125.

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

[0014] As shown in FIG. 2 to be described later, the fuel injection control device 127 has a CPU (Central Processing Unit) 501, a RAM (Random Access Memory) 260 that executes a computer program, and a ROM (Read Only Memory) 261 that stores data. The ROM 261 may be a memory capable of erasing and rewriting its contents.

[0015] Based on a control command from the ECU 109, the CPU 501 of the fuel injection control device 127 calls a program from the RAM 260 and controls the solenoid based on the data stored in the ROM 261. Thereby, the on-off 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 the 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. This fuel injection device 200 operates a valve body by supplying (energizing) a drive current to a coil 208 (shown in FIG. 2 to be described later) to perform fuel injection.

[0017] In addition, the internal combustion engine 101 is provided with a fuel pressure sensor (fuel pressure sensor) 126 for measuring the fuel pressure in the high-pressure fuel pipe 129. The ECU 109 sends a control command to the fuel injection control device 127 to set the fuel pressure in the high-pressure fuel pipe 129 to a desired pressure based on the measurement result of the fuel pressure sensor 126. That is, the ECU 109 performs so-called feedback control to set the fuel pressure in the high-pressure fuel pipe 129 to a 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 in the combustion chamber 121 and ignites the air-fuel mixture in which the inhaled air and fuel are mixed in the combustion chamber 121 by means of discharge. The ignition coil 107 generates a high voltage for discharging 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 performs energization control of the ignition coil 107 and ignition control by the spark plug 106. The air-fuel mixture in which the inhaled air and fuel are mixed in the combustion chamber 121 burns due to the spark discharged from the spark plug 106, and the piston 102 is pushed down by this pressure.

[0020] The exhaust gas generated by combustion is discharged into the exhaust pipe 111 through the exhaust valve 104. The exhaust pipe 111 is provided with a three-way catalyst 112 and an oxygen sensor 113. 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. The ECU 109 performs feedback control so that the fuel injection amount supplied from the fuel injection device 200 becomes the target air-fuel ratio based on the detection result of the oxygen sensor 113.

[0021] Furthermore, the piston 102 is connected to the crankshaft 131 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. Based on the output of the crank angle sensor 116, the ECU 109 detects the rotational speed of the internal combustion engine 101.

[0022] The ECU 109 receives signals from the crank angle sensor 116, air flow meter 120, oxygen sensor 113, accelerator pedal position sensor 122, and fuel pressure sensor 126. The accelerator pedal position sensor 122 is a sensor that indicates the degree to which the accelerator pedal is opened by the driver.

[0023] The ECU 109 calculates the required torque for the internal combustion engine 101 based on the signal supplied from the accelerator pedal position sensor 122, and also determines whether or not the engine is idle. Furthermore, the ECU 109 calculates the amount of intake air required for the internal combustion engine 101 based on the required torque and outputs an opening signal corresponding to that amount to the throttle valve 119.

[0024] Furthermore, the ECU 109 has a rotational speed detection unit that calculates the rotational speed of the internal combustion engine 101 (hereinafter referred to as engine speed) based on a signal supplied from the crank angle sensor 116. In addition, the ECU 109 has a warm-up determination unit (not shown) that determines whether or not the three-way catalytic converter 112 is in a warmed-up state based on the temperature of the coolant obtained from the water temperature sensor 108 and the elapsed time since the start of the internal combustion engine 101.

[0025] The fuel injection control device 127 calculates the amount of fuel (target injection amount) according 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 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 a fuel injection hole 215 that serves as a fuel passage, and a movable element (movable iron core) 206 that drives the 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 used as an example for explanation.

[0027] In the diagram, the fuel injection device 200 has a fuel supply unit 212 positioned at the upper end, a fuel injection port 215 and a valve seat 202 positioned at the lower end, and a movable element (movable iron core) 206, a valve body 201, and a sleeve 214 positioned between the fuel supply unit 212 and the valve seat 202.

[0028] The sleeve 214 has a cylindrical shape and is fitted and connected to the outer circumferential surface of the upper side of the valve body 201, and moves together with the valve body 201. A flange 214a is formed at the upper end of the sleeve 214. The flange 214a is shaped to protrude around the upper side of the sleeve 214.

[0029] A first spring member 210 is positioned above the sleeve 214. A second spring member 216 and a movable element 206 are positioned around the sleeve 214 on the underside of the flange 214a, starting from the flange 214a side. The second spring member 216 biases the movable element 206 and the sleeve 214 in a direction that causes them to move apart. The flange 214a of the sleeve 214 transmits the force of the second spring member 216 to the valve body 201 and the movable element 206.

[0030] The fuel injector 200 has its end opposite to the fuel injection port 215 and valve seat 202 (towards the fuel supply unit 212) connected to a high-pressure fuel pipe 129 (see Figure 1), which is not shown. The end of the fuel injector 200 opposite to the fuel supply unit 212 (towards the fuel injection port 215) is inserted into a mounting hole (insertion hole) formed in a component (cylinder block, cylinder head, etc.) that forms the combustion chamber 121 (see Figure 1).

[0031] The fuel injector 200 receives fuel from the high-pressure fuel pipe 129 (see Figure 1) through the fuel supply unit 212 and injects the fuel into the combustion chamber 121 (see Figure 1) from the tip of the valve seat 202. Inside the fuel injector 200, the fuel passage is configured such that the fuel flows almost along the central axis 200a of the fuel injector 200, from the base end on the fuel supply unit 212 side to the tip end on the fuel injection hole 215 side.

[0032] The fuel injector 200 further comprises a coil 208, a stator (fixed iron core) 207, and a housing 209. The coil 208 is positioned between the stator 207 and the housing 209. The stator 207, coil 208, and housing 209 constitute an electromagnet. In the closed state, when the coil 208 is not energized, the valve body 201 is in contact with the valve seat 202 due to the biasing force of the first spring member 210, which biases the valve body 201 in the closing direction (towards the valve seat 202). This state is called the closed stable state (closed standby state). In the closed stable state, the movable element 206 is in contact with the stopper 217 and positioned in the closed position. The valve body 201 is driven via a sleeve 214 that transmits the load from the movable element 206.

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

[0034] In the valve-closed stable state, the sleeve 214 is biased downstream (towards the valve seat 202, in the valve-closing direction) by a force obtained by subtracting the biasing force of the second spring member 216 from the biasing force of the first spring member 210. In this state, the valve body 201 is stationary in contact with the valve seat 202. The movable element 206 is also biased in the valve-closing direction (towards 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 created between the lower end of the sleeve 214 fixed to the valve body 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 will act as a transmission surface and will contact the upper surface of the movable element 206.

[0036] The fuel injection device 200 is connected to a fuel injection control device 127 and an ECU (engine control unit) 109. The fuel injection control device 127 has a circuit that receives a drive command pulse (injection pulse) from the ECU 109 instructing fuel injection 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 a single component. The fuel injection control device 127 is a device that generates the drive voltage for the fuel injection device 200, and may be integrated with the ECU 109 or configured as a standalone unit.

[0038] The ECU 109 receives signals indicating the engine status from various sensors and calculates the appropriate pulse width and injection timing for the drive command pulse 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 the 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 the communication line 222. The ECU 109 switches the drive current generated by the fuel injection control device 127 depending on the fuel pressure and operating conditions supplied to the fuel injector 200. The fuel injection control device 127 can change control constants through communication with the ECU 109 and changes the current waveform according to the control constants.

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

[0041] The fuel injection control device 127 (see Figures 1 and 2), which is connected to the ECU 109, has a built-in CPU 501, as described above. The CPU 501 receives various signals indicating the engine status from the fuel pressure sensor 126, air flow meter 120, oxygen sensor 113, and crank angle sensor 116, etc., as explained using Figure 1. Based on these signals, the CPU 501 calculates the pulse width and injection timing of the drive command pulse to control the amount of fuel injected from the fuel injector 200 according to the operating conditions of the internal combustion engine.

[0042] Furthermore, the CPU 501 calculates the appropriate pulse width and injection timing of the drive command pulse according to the operating conditions of the internal combustion engine, and outputs the drive command pulse to the drive IC (Integrated Circuit) 502 of the fuel injection device 200 via the signal line 223. This CPU 501, which shows one specific example of the control unit according to the present invention, controls the energizing time of the drive current flowing through the coil 208 with the pulse width of the drive command pulse.

[0043] The amount of fuel injected by the fuel injector 200 (see Figures 1 and 2) is determined by the pulse width of the drive command pulse. Subsequently, the drive IC 502 supplies drive current to the fuel injector 200 by switching the switching elements 505, 506, and 507 between energized and de-energized.

[0044] The switching element 505 is connected between a high-voltage source, which is higher than the battery voltage VB input to the drive circuit of the fuel injection control device 127 (see Figure 2), and the high-voltage terminal of the solenoid 540 (corresponding to coil 208 in Figure 2) provided on the fuel injection device 200. The switching elements 505, 506, and 507 are composed of transistors such as FETs (Field effect transistors), and can switch between energizing and de-energizing the fuel injection device 200.

[0045] The boosted voltage VH, which is the initial voltage value of the high-voltage source, is, for example, 65V, and is generated by boosting the battery voltage VB using the boost circuit 514. The boost circuit 514 consists of, for example, a coil 530, a transistor 531, a diode 532, and a capacitor 533.

[0046] In the boost circuit 514, when transistor 531 is turned ON, the battery voltage VB flows to the ground potential 534 side. On the other hand, when transistor 531 is turned OFF, the high voltage generated in coil 530 is rectified through diode 532, and charge is accumulated in capacitor 533.

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

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

[0049] The drive IC 502 detects the current flowing through the fuel injector 200 using current-sensing resistors 508, 512, and 513, and switches the energization of switching elements 505, 506, and 507 between energization and de-energy based on the detected current value to generate the desired drive current. 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 injector 200 (see Figure 2) and the operating conditions. In addition, the ends of resistors 508, 512, and 513 are connected to the A / D conversion port of the drive IC 502, and the configuration allows the drive IC 502 to detect the voltage across the ends of resistors 508, 512, and 513.

[0051] [Fuel injection system operation] Figure 4 is a diagram illustrating the operation of the fuel injection system 200 shown in Figure 2, and is a graph showing the drive command pulse [Ps], drive voltage [E], drive current [I], and the displacement of the valve body [D] and the displacement of the movable part [Dm]. The graphs for the displacement of the valve body [D] and the displacement of the movable part [Dm] show the change in position along the central axis 200a of each fuel injection system 200. These graphs also show the drive voltages E1 to E4, drive currents I1 to I4, valve body displacements Dm1 to Dm4, and movable part displacements D1 to D4, corresponding to the input of four pulse widths, Ps1 to Ps4, as the drive command pulse [Ps]. Each pulse Ps1 to Ps4 has a pulse width W from the start time Ts to the respective end times Te1 to Te4. For example, pulse Ps4 has a pulse width W4 from the start time Ts to the respective end time Te4. The operation of the fuel injection device 200, controlled by the fuel injection control device 127 shown in Figure 2, will be explained below, based on Figure 4 and referring to Figures 2 and 3.

[0052] As shown in Figure 4, when any of the drive command pulses [Ps] (Ps1 to Ps4) having different pulse widths W are input, the corresponding drive voltage [E] is applied to the coil 208 (see Figure 2), and the supply of drive current [I] to the coil 208 begins. For example, when pulse Ps4 is input, the drive voltage E4 is applied to the coil 208, and the supply of 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, coil 208, and housing 209. This magnetomotive force causes a magnetic path (magnetic circuit) to be formed by the stator 207, housing 209, and movable element 206 to surround the coil 208, and magnetic flux flows around the formed magnetic path. At this time, a magnetic attractive force acts between the movable element 206 and the stator 207, causing the movable element 206 to be displaced toward the stator 207. Subsequently, the movable element 206 is displaced until its upper surface contacts the lower end of the sleeve 214. Until the movable element 206 contacts the sleeve 214, the valve body 201 continues to maintain contact with the valve seat 202.

[0054] When the displacement [D] of the movable element 206 reaches the size of the gap [d] between the valve body 201 (i.e., the lower end of the sleeve 214) and the movable element 206, the movable element 206 collides with the valve body 201 (sleeve 214). As a result, the valve body 201 is pulled upstream by the kinetic energy of the movable element 206 and moves away from the valve seat 202. This time corresponds to the valve opening start times To1 to To4. As a result, the valve body 201 is lifted away from the valve seat 202, the fuel passage opens, and fuel is injected from the fuel injection port 215. Then, the valve body 201 is rapidly displaced by the movable element 206, which has kinetic energy.

[0055] The fuel injection control device 127 applies a high voltage as the drive voltage [E] and flows a drive current [I] through the coil 208 from the start time Ts of the application of the drive command pulse [Ps] until the movable element 206 and the valve body 201 collide and the valve body 201 separates from the valve seat 202, or until sufficient kinetic energy is accumulated in the movable element 206 to separate. This generates a necessary and sufficient magnetic attractive force between the movable element 206 and the stator 207, allowing the movable element 206 to be quickly displaced. By quickly displacing the movable element 206, the valve body 201 can be driven by the movable element 206 even when the pressure of the supplied fuel is high.

[0056] Upon application of the drive voltage [E] (E1~E4) to the coil 208 from the start time Ts, the drive current [I] (I1~I4) flowing through the coil 208 rises sharply, and then reaches the respective peak current values ​​Pk1~Pk4.

[0057] Subsequently, when pulses Ps1 to Ps3 with relatively small pulse widths are applied, when the drive current [I] (I1 to I3) reaches the respective peak current values ​​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 Figure 3). As a result, the back electromotive force due to the inductance of the fuel injection device 200 energizes the diodes 509 and 510, and the current is fed back to the boost circuit 514. Consequently, the drive current [I] (I1 to I3) flowing through the coil 208 rapidly decreases and is interrupted.

[0058] On the other hand, when a pulse Ps4 with a pulse width of a certain size 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 drops to the hold current Ih, the drive voltage E4 is switched by the battery voltage VB, and the drive current I4 is maintained at the hold current Ih. Subsequently, when the movable element 206 collides with the stator 207, the valve body 201 moves away from the movable element 206 and is displaced upstream. The movable element 206 is also displaced downstream after colliding with the stator 207, but eventually comes to rest and stabilizes at the target position. This state is defined as the valve open stable state. Subsequently, when the pulse Ps4 turns OFF at the end time Te4, the fuel injection control device 127 applies a reverse drive voltage 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~I4) as described above, the magnetic flux generated in the magnetic circuit disappears and the magnetic attractive force is eliminated. As a result, the movable element 206, having lost its magnetic attractive force, is pushed back by the load of the first spring member 210 and the force due to the fuel pressure. This pushes the valve body 201, which is coupled to the sleeve 214, back to its original closed position where it contacts the valve seat 202. This time is the valve closing completion time Tc1~Tc4.

[0060] Furthermore, the biasing force of the first spring member 210 acting on the valve body 201 is transmitted to the movable element 206 via the lower end of the sleeve 214 connected to the valve body 201. After the valve body 201 contacts the valve seat 202, the movable element 206 detaches from the lower end of the sleeve 214 of the valve body 201 and continues to move downward (in the valve closing direction). After the valve closing completion time Tc1 to Tc4, the movable element 206 and the sleeve 214 of the valve body 201 become separated.

[0061] Thus, when the motion of the movable element 206 changes, the acceleration of the movable element 206 changes, and the inductance of the coil 208 changes. In other words, when the fuel injection device 200 is closed, the drive current flowing to 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 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 with a certain pulse width. By detecting these inflection points Pe2 to Pe4, the valve closing completion time Tc2 to Tc4 in the operation of the fuel injection device 200 can be detected.

[0062] Here, the flow rate injected from the fuel injector 200 depends on the time the valve body 201 is open, i.e., from the valve opening start time To to the valve closing completion time Tc. At this time, due to environmental factors, individual characteristic variations, and deterioration over time, deviations may occur in the valve opening start time To and the valve closing start time Tc even if the pulse width W of the drive command pulse [Ps] is the same. Reducing such deviations in injection amount is one of the important issues that must be addressed in order to reduce exhaust performance and fuel consumption from the engine.

[0063] For example, if the application of the drive command pulse [Ps] is terminated at termination times Te1, Te2, which are earlier than the valve opening start times To1, To2, such as pulses Ps1, Ts2, the motion of the movable element 206 will be interrupted by the termination of the timing attraction force during acceleration. As a result, the valve opening start times To1, To2 corresponding to pulses Ps1, Ts2 will be delayed compared to the valve opening start times To3, To4 of pulses Ps3, Ps4, which have a certain width.

[0064] To determine the optimal injection volume, it is important to detect the valve opening start time To and the valve closing completion time Tc, and to understand the effects of environmental factors, individual characteristic variations, and aging degradation. However, as mentioned above, the valve closing completion times Tc2 to Tc4 can be obtained by detecting the inflection points Pe2 to Pe4. On the other hand, obtaining the valve opening start time To can be difficult as 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 body 201 occur almost simultaneously, so an inflection point may not be detected in the drive voltage E1, and it may not be possible 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 of an Embodiment (Fuel Injection Control Device)≫ Figure 5 is a functional block diagram of the control device for the fuel injection device of the embodiment, and is a functional block diagram of the CPU 501 of the fuel injection control device 127 shown in Figures 2 and 3 for estimating the valve opening start time. 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 the valve closing completion time for each drive command pulse with multiple different pulse widths that are generated. Such a 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] Furthermore, the CPU 501 of the fuel injection control device 127 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 the valve closing delay time when a drive command pulse of 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. 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, as shown in Figure 4. The valve opening start time estimation unit 501j 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 that is stored in advance, and the valve closing delay time calculated by the valve closing delay time calculation unit 501i. Furthermore, the pulse width correction unit 501k corrects the pulse width of the drive command pulse based on the valve closing delay time calculated by the valve closing delay time calculation unit 501i and the valve opening start time estimated by the valve opening start time estimation unit 501j. Details of the functions performed by each of these functional units will be explained in the fuel injection method section below.

[0068] ≪Control method for a fuel injection device according to an embodiment≫ Next, a control method for the fuel injection system in an embodiment implemented by the fuel injection control device 127 described above will be explained.

[0069] <Estimation of valve closing completion time and valve opening start time> Figure 6 is a flowchart showing the control method of the fuel injection device according to the embodiment, illustrating the procedure for estimating the valve closing completion time and valve opening start time necessary to control the injection amount of the fuel injection device 200 (Figure 2) by controlling the fuel injection control device 127 shown in Figure 5. The procedure for estimating the valve closing completion time and valve opening start time in the fuel injection device control method will be explained below, following the flowchart in Figure 6 and referring to Figures 2 to 5. Note that the procedure shown in this flowchart is initiated, for example, when the engine (internal combustion engine) equipped with this fuel injection device 200 enters an idling state at a predetermined timing. The predetermined timing could be, for example, the timing when the fuel injection device of the internal combustion engine is replaced, or the timing when the external environment, such as temperature or humidity, changes significantly.

[0070] [Step S101] In step S101, the energization control unit 501c of the sampling unit 501b sets the pulse width of the drive command pulse for sampling when it receives an idling instruction from the target injection amount calculation unit 501a at the predetermined timing described above. At this time, the energization control unit 501c sets multiple (for example, five) different pulse widths within the range in which the inflection points Pe2 to Pe3 of the drive voltage [E], as explained using Figure 4, can be detected. Then, it selects one pulse width from the set multiple different pulse widths and sets it as the pulse width of the drive command pulse.

[0071] Here, multiple different pulse widths are predetermined by preliminary experiments such that the data for the valve closing delay time corresponding to the pulse width has a minimum value. The valve closing delay time is the delay between the valve closing completion time Tc and the end time Te, which is the pulse off time, and is defined as valve closing delay time [Tc-Te]. In this way, by setting multiple different pulse widths within a range where the data for 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 extremely small pulse widths, for which detection of the inflection point of the drive voltage [E] described later is impossible, is ensured.

[0072] As an example, if the fuel injection system 200 has a maximum pulse width of 5000 μsec, pulse widths of 260 μsec, 270 μsec, 280 μsec, 290 μsec, and 300 μsec are set, and the energization control unit 501c selects one of these pulse widths to be used as the pulse width for 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 with the single pulse width set in step S101 and performs power control processing to output it to the drive IC 502.

[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 the coil 208 is energized in conjunction with the generation of the drive command pulse in step S102. The voltage detection unit 501e is equipped with an A / D converter, and the drive voltage [E] detected as an analog value is converted to 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 and detects the inflection point of the waveform of the drive voltage [E] when the coil 208 is energized. This inflection point corresponds to one of the inflection points Pe2 to Pe4 explained using Figure 4, for example. At this time, the filter processing unit 501f may perform digital filtering after converting the drive voltage [E] detected by the voltage detection unit 501e in step S103 to a digital value, or it 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 body 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 it has completed generating all of the drive command pulses with multiple different pulse widths set in step S101. If the learning completion determination unit 501h determines that it has completed (YES), the process proceeds to step S107.

[0078] Furthermore, if the learning completion determination unit 501h determines that the learning is not complete (NO), the process returns to step S101. In the next step S101, the power supply control unit 501c of the sampling unit 501b selects one pulse width from among the set of different pulse widths and sets it as the pulse width for the drive command pulse. Then, steps S102 and beyond are carried out in the same manner.

[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 a desired minute pulse width is generated, based on all the valve closing completion times detected in step S105 and the corresponding pulse widths.

[0080] Here, a minute pulse width is defined as 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 setting range of multiple different pulse widths set in step S101. For example, if the fuel injection device 200 exemplified in step S101 has a maximum pulse width of 5000 μsec, then no inflection point appears in the drive voltage when a drive command pulse with a pulse width of 200 μsec is generated, so a pulse width of 200 μsec is a minute pulse width.

[0081] Figure 7 shows the calculation process for the valve closing delay time [Tc-Te] when a drive command pulse with a small pulse width is generated. As shown in Figure 7, the valve closing delay time calculation unit 501i creates an approximation curve using, for example, the least squares method, for multiple different pulse widths [W] and the valve closing delay time [Tc-Te] based on the valve closing completion time obtained by generating drive command pulses of those pulse widths [W]. The multiple 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 calculates the valve closing delay time Tc1-Te1 when a pulse Ps1 with a minute pulse width W1 is generated as the drive command pulse by extrapolating to the created approximation curve. It is known that the approximation curve has a local minimum when the range of pulse width of the drive command pulse is a wide range including minute pulse widths. Therefore, in the previous step S101, setting multiple different pulse widths so that an approximation curve with a local minimum is created is important for calculating a more accurate valve closing delay time Tc1-Te1 corresponding to minute pulse widths.

[0083] In step S107, the calculation of the valve closing delay time Tc1-Te1 is not limited to calculating the valve closing delay time Tc1-Te1 when a drive command pulse with the aforementioned minute pulse width is generated as the desired pulse width. In step S107, the valve closing delay time Tc-Te may also be calculated when a drive command pulse is generated with a pulse width outside the range of multiple 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 set as a constant in advance, and the valve opening start time [To]. Figure 8 shows the relationship between the valve closing delay time [Tc-Te] and the valve opening start time [To] when a drive command pulse with a minute pulse width is generated for a fuel injection device of arbitrary specifications. The relationship shown in Figure 8 is a value obtained by conducting a preliminary test in which multiple drive command pulses with minute pulse widths are generated, and the valve closing completion time Tc1 and the valve opening start time To1 for obtaining the valve closing delay time Tc1-Te1 are measured values ​​obtained using pressure sensors, acceleration sensors, and strain sensors, etc. The preliminary test is an example of testing a fuel injection device as a standalone unit. The relationship in Figure 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 applies the valve closing delay time Tc1-Te1 (see Figure 7) calculated in step S107 to the relationship shown in Figure 8, which was called up in step S108, and estimates the valve opening start time To1'. This valve opening start time To1' is the time estimated as the valve opening start time To1' when a drive command pulse with a small pulse width is generated. With this, the valve opening start time estimation process is completed.

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

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

[0089] Figure 9 shows the drive current and valve displacement when the same drive command pulse is generated for two fuel injectors, INJ_A and INJ_B. Although the two fuel injectors, INJ_A and INJ_B, are of the same specifications, they each have their own individual characteristics. As shown in Figure 9, even when drive command pulses Pa_A and Pa_B with the same pulse width are generated for fuel injectors of the same specifications, differences in valve displacement, i.e., valve opening start time To and valve closing completion time Tc, occur due to individual differences.

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

[0091] Figure 10 shows the relationship between the valve opening period [Td] and the injection amount [Q] in a fuel injection system. As shown in Figure 10, the fuel injection amount [Q] in a fuel injection system is proportional to the valve opening period [Td], and the longer the valve opening period [Td], the larger the fuel injection amount [Q]. The small pulse width, which is the desired pulse width explained earlier, is also the pulse width for which the valve opening period [Td] is 50 μm or less.

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

[0093] Therefore, the pulse width correction unit 501k (see Figure 5) provided in the CPU 501 of the fuel injection control device 127 corrects the variation in fuel injection amount caused by individual differences in each fuel injection device, as follows.

[0094] First, for the fuel injection system of the standard to be corrected, the relationship between the valve opening period [Td] and the fuel injection amount [Q] shown in Figure 10 is obtained. The relationship shown in Figure 10 is the relationship obtained through preliminary experiments for combustion injection systems of arbitrary standards, and the differences due to individual characteristics are negligibly small for fuel injection systems of the same standard. Therefore, the injection amount correction is performed using this relationship.

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

[0096] Figure 11 is a diagram illustrating the correction of the pulse width of the drive command pulse, and is a diagram illustrating the correction aimed at matching the fuel injection amount of fuel injector INJ_B shown in Figure 9 with the fuel injection amount of fuel injector INJ_A. The drive command pulses Pa_A and Pa_B shown in Figure 9 are, for example, the same drive command pulse Ps1.

[0097] In this case, as shown in Figure 11, the target valve closing completion time Tc(ob) for fuel injector INJ_B is calculated so that the valve opening period Td(B') of the corrected fuel injector INJ_B is the same as the valve opening period Td(A) of fuel injector INJ_A. This target valve closing time Tc(ob) is calculated from the valve opening start time To_Bb and the valve opening period Td(B') for the small pulse width drive command pulse Pa_B, which were estimated using the procedure shown in the flowchart above. Then, the pulse width of the drive command pulse [Ps] that results in this target valve closing completion time Tc(ob) is determined as the target pulse width W(ob) for fuel injector 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 determined by feedback of the difference between the measured 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] <<Effects of the Embodiment>> The fuel injection device control device (fuel injection control device 127) according to the embodiment described above controls a fuel injection device 200 which includes a valve body 201 that opens a fuel passage by moving away from a valve seat 202, a movable element 206 that causes the valve body 201 to open and close, and a stator 207 that attracts the movable element 206 when a drive current flows through a coil 208. This fuel injection control device 127 has a control unit (CPU 501) that controls the energization time of the drive current by the pulse width of the drive command pulse. This CPU 501 includes a sampling unit 501b that samples the completion time of each valve closing when multiple drive command pulses of different pulse widths are generated, a valve closing delay time calculation unit 501i that calculates the valve closing delay time when a drive command pulse of a desired pulse width is generated based on the relationship between multiple different pulse widths and the delay time (valve closing delay time) between the completion time of each valve closing and the pulse end time of each drive command pulse generated by the sampling unit, 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 that is held 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 when the pulse width of the drive command pulse is small enough that no inflection point corresponding to the valve closing completion time occurs in the drive voltage applied to the coil 208.

[0100] Furthermore, by correcting the pulse width of the drive command pulse based on the valve closing delay time and valve opening start time corresponding to the highly predicted valve closing completion time, it becomes possible to control the fuel injection amount with a drive command pulse of very small pulse width with high precision. As a result, even if the characteristics of the fuel injection device or the environmental factors of the fuel injection device change, the fuel injection amount in the fuel injection device can be stabilized.

[0101] It should be noted that the present invention is not limited to the embodiments and modifications described above, and includes a variety of further modifications. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0102] Furthermore, in this specification, processing steps describing chronological processing include not only processing 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]

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

Claims

1. A control device for a fuel injection system comprising: a valve body that opens a fuel passage by moving away from a valve seat; a movable element that causes the valve body to open and close; and a stator that attracts the movable element when a drive current flows through a coil, The control unit has a control unit that controls the energizing time of the drive current by the pulse width of the drive command pulse, The control unit, A sampling unit that samples the completion time of each valve closing when multiple drive command pulses with different pulse widths are generated, A valve closing delay time calculation unit 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 closing completion time relative to the pulse end time of each drive command pulse generated by the sampling unit. The system includes a relationship between the previously stored delay time and the valve opening start time, and a valve opening start time estimation unit that estimates the valve opening start time when a drive command pulse of the desired pulse width is generated, based on the delay time calculated by the valve closing delay time calculation unit. A control device for fuel injection systems.

2. The sampling unit generates a plurality of drive command pulses that fall within a predetermined pulse width range, which are the plurality of drive command pulses with different pulse widths. A control device for a fuel injection system according to claim 1.

3. The predetermined pulse width range includes the pulse width in which the delay time with respect to the pulse width of the drive command pulse is minimized. A control device for a fuel injection system according to claim 2.

4. The desired pulse width is a very short pulse width, shorter than the predetermined pulse width range. A control device for a fuel injection system according to claim 2.

5. The control unit, The system includes 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. A control device for a fuel injection system according to claim 1.

6. The pulse width correction unit is The pulse width of the drive command pulse is corrected so that the target injection amount of fuel injected from the fuel injector matches the valve closing completion time corresponding to the valve opening start time. A control device for a fuel injection system according to claim 5.

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

8. The desired pulse width is such that the drive voltage applied to the coil does not produce an inflection point corresponding to the valve closing completion time. A control device for a fuel injection system according to claim 1.

9. A control method for a fuel injection device comprising a valve body that opens a fuel passage by moving away from a valve seat, a movable element that causes the valve body to open and close, and a stator that attracts the movable element when a drive current flows through a coil, The control unit controls the energizing time of the drive current by the pulse width of the drive command pulse. The sampling unit of the control unit samples the closing completion time for each drive command pulse with multiple different pulse widths when it generates several drive command pulses. The valve closing delay time calculation unit of the control unit 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 between the pulse end time of each drive command pulse generated by the sampling unit and each valve closing completion time. The valve opening start time estimation unit of the control unit estimates the valve opening 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 opening start time, which is stored in advance, and the delay time calculated by the valve closing delay time calculation unit. A method for controlling a fuel injection system.

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