Internal combustion engine control device

Abstract

An internal combustion engine control device includes: a valve closing time calculation section; a valve closing delay time difference calculation section that normalizes a plurality of valve closing delay times with a fuel pressure to calculate a difference in the valve closing delay times; a content rate calculation section that calculates a synthetic fuel content rate of fuel contained in a fuel tank based on characteristic data that shows a relationship between the difference in the valve closing delay times and the synthetic fuel content rate of the synthetic fuel contained in the fuel; and a combustion control section that controls combustion of the internal combustion engine in such a manner that an exhaust gas temperature of exhaust gas discharged from a combustion chamber becomes a threshold temperature or more based on the synthetic fuel content rate.

Description

Technical Field

[0001] This invention relates to an internal combustion engine control device. Background Technology

[0002] Previously, techniques for burning gasoline mixed with ethanol fuel in internal combustion engines were known.

[0003] Patent Document 1 discloses a technology related to a fuel injection control device for injecting gasoline mixed with ethanol fuel. Patent Document 1 describes a method that "increases the fuel injection amount during the initial fuel injection period of a segmented fuel injection period as the ethanol concentration detected by the ethanol concentration sensor increases, and decreases the fuel injection amount during the later fuel injection period of a segmented period as the ethanol concentration detected by the ethanol concentration sensor increases, thereby controlling the injection amount of the mixed fuel injected by the fuel injection valve."

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-75023 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In recent years, new synthetic fuels have been developed to replace ethanol fuels through the synthesis of carbon dioxide from renewable energy sources. Therefore, a technology is needed to blend synthetic fuels with gasoline and burn them in an internal combustion engine.

[0009] However, the composition of synthetic fuels differs from that of gasoline. Therefore, in internal combustion engines that burn gasoline mixed with synthetic fuels, there are concerns about the generation of harmful components (such as formaldehyde) during the combustion of the synthetic fuels. Furthermore, the technology described in Patent Document 1 presents a technical problem: it is difficult to reduce the harmful components that may be generated when burning synthetic fuels. Therefore, if the internal combustion engine cannot properly control the combustion of synthetic fuels, it will produce its own unique harmful components (formaldehyde, acetaldehyde, etc.).

[0010] The present invention was made in view of the above-mentioned situation, and its object is to control the internal combustion engine in a way that suppresses the generation of harmful components that accompany the combustion of fuel containing synthetic fuel.

[0011] Means for solving technical problems

[0012] The internal combustion engine control device according to the present invention includes: a fuel temperature estimation unit that estimates the fuel temperature of the fuel supplied to the combustion chamber; a fuel pressure acquisition unit that acquires the fuel pressure of the fuel injected by the fuel injection device; a valve closing time calculation unit that detects the valve closing of the fuel injection device when the fuel temperature reaches a specified temperature and calculates the valve closing time of the fuel injection device; a valve closing delay time difference calculation unit that calculates the valve closing delay time spent by the fuel injection device in the open state from the start of valve closing to the completion of valve closing for each of the specified temperatures based on multiple valve closing times calculated at different specified temperatures, and calculates the difference of the valve closing delay time by normalizing the multiple valve closing delay times calculated for each of the specified temperatures with fuel pressure; a content rate calculation unit that calculates the content rate of synthetic fuel in the fuel contained in the fuel storage unit based on characteristic data showing the relationship between the difference of valve closing delay time and the content rate of synthetic fuel contained in the fuel; and a combustion control unit that controls the internal combustion engine such that the exhaust temperature of the exhaust gas discharged from the combustion chamber is above a threshold temperature based on the synthetic fuel content rate.

[0013] Invention Effects

[0014] According to the present invention, the internal combustion engine is controlled based on the synthetic fuel content to make the exhaust temperature above a threshold temperature, thereby suppressing the generation of harmful components during the combustion of fuel containing synthetic fuel.

[0015] Other issues, structures, and effects not mentioned above will be clarified through the following description of the implementation methods. Attached Figure Description

[0016] Figure 1 This is an overall configuration diagram of an internal combustion engine system equipped with the fuel injection control device according to the first embodiment of the present invention.

[0017] Figure 2 This is a cross-sectional view showing an example of the internal structure of a fuel injection device according to the first embodiment of the present invention.

[0018] Figure 3 This is a diagram illustrating a detailed configuration example of the drive circuit and ECU of the fuel injection control device according to the first embodiment of the present invention.

[0019] Figure 4 This is a diagram illustrating the drive command pulse, drive voltage, drive current, valve body displacement, and movable iron core displacement involved in the first embodiment of the present invention.

[0020] Figure 5 This is a block diagram illustrating a functional configuration example of the ECU and fuel injection control device according to the first embodiment of the present invention.

[0021] Figure 6 This is a flowchart illustrating an example of a control method for an internal combustion engine based on the synthetic fuel content according to the first embodiment of the present invention.

[0022] Figure 7 This is a flowchart illustrating an example of a method for estimating the synthetic fuel content according to the first embodiment of the present invention.

[0023] Figure 8 This is an example of characteristic data showing the relationship between the synthetic fuel content and the difference in valve closing delay time according to the first embodiment of the present invention.

[0024] Figure 9 This is a flowchart illustrating a method for estimating the content of ethanol fuel and synthetic fuel in gasoline according to the first embodiment of the present invention.

[0025] Figure 10 This is a graph showing the relationship between oxygen concentration and air-fuel ratio according to the first embodiment of the present invention.

[0026] Figure 11 It is shown Figure 9 The flowchart shows an example of the calculation process for the simultaneous equations shown in step S37.

[0027] Figure 12 This is a block diagram illustrating a functional configuration example of the ECU and fuel injection control device according to the second embodiment of the present invention.

[0028] Figure 13 This is a diagram illustrating an example of time-series data of the fuel level in the tank output by the fuel level sensor according to the second embodiment of the present invention.

[0029] Figure 14 This is a flowchart illustrating a method for estimating the content of ethanol fuel and synthetic fuel as the fuel level in the tank increases, according to the second embodiment of the present invention. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and the drawings, constituent elements that have substantially the same function or structure are given the same reference numerals, and repeated descriptions are omitted.

[0031] [First Implementation Method]

[0032] The fuel injection control device according to the first embodiment of the present invention will be described below. Furthermore, in each figure, common components are given the same reference numerals.

[0033] [Internal Combustion Engine System]

[0034] First, an example of the configuration of an internal combustion engine system equipped with the fuel injection control device according to this embodiment will be described.

[0035] Figure 1 This is an overall configuration diagram of an internal combustion engine system equipped with the fuel injection control device involved in this embodiment.

[0036] Figure 1 The internal combustion engine (engine) 101 shown is a four-stroke engine that repeats the four strokes of intake, compression, combustion (expansion) and exhaust. For example, it is a multi-cylinder engine with four cylinders (cylinder block). In addition, the number of cylinders in the internal combustion engine 101 is not limited to four, and may also have six or eight or more cylinders.

[0037] The internal combustion engine 101 includes a piston 102, an intake valve 103, and an exhaust valve 104. Intake air into the internal combustion engine 101 is fed by an air flow meter (AFM) 120, which detects the amount of incoming air, and the flow rate is adjusted by a throttle valve 119. Air passing through the throttle valve 119 is drawn in as a branch collector 115, and then supplied to the combustion chamber 121 of each cylinder via the intake pipe 110 and intake valve 103 provided for each cylinder (cylinder block).

[0038] On the other hand, fuel is supplied from the fuel tank 123 to the high-pressure fuel pump 125 via the low-pressure fuel pump 124, and the high-pressure fuel pump 125 increases the pressure to the level required for fuel injection. That is, the high-pressure fuel pump 125 uses power transmitted from the exhaust camshaft (not shown) of the exhaust cam 128 to move the plunger disposed within the high-pressure fuel pump 125 up and down, thereby pressurizing (boosting) the fuel within the high-pressure fuel pump 125.

[0039] A solenoid-driven on / off valve is provided at the suction inlet of the high-pressure fuel pump 125. The solenoid is connected to a control device (hereinafter referred to as "fuel injection control device 127") of the fuel injection device 200, which is an example of an engine control unit (ECU). The fuel injection device (fuel injection device 200) is a direct injection type fuel injection device that injects fuel directly into the combustion chamber (combustion chamber 121).

[0040] The fuel injection control device 127 controls the solenoid according to the control command from the ECU 109, so as to drive the opening and closing valve in such a way that the pressure of the fuel injected from the high-pressure fuel pump 125 (fuel pressure) becomes the desired pressure.

[0041] Fuel, pressurized by the high-pressure fuel pump 125, is delivered to the fuel injection device 200 via the high-pressure fuel piping 129. The fuel injection device 200 injects fuel directly into the combustion chamber 121 according to the instructions of the fuel injection control device 127. The coil 208, described later, is supplied with driving current, thereby actuating the valve body 201 to perform fuel injection.

[0042] Additionally, a fuel pressure sensor 126 is provided on the internal combustion engine 101 to measure the fuel pressure in the high-pressure fuel line 129. Based on the measurement result from the fuel pressure sensor 126, the ECU 109 sends a control command to the fuel injection control device 127 to bring the fuel pressure in the high-pressure fuel line 129 to the desired pressure. That is, the ECU 109 performs so-called feedback control to bring the fuel pressure in the high-pressure fuel line 129 to the desired pressure.

[0043] Furthermore, each combustion chamber 121 of the internal combustion engine 101 is equipped with a spark plug 106, an ignition coil 107, and a coolant temperature sensor 108. The spark plug 106 exposes its electrode portion into the combustion chamber 121, where it ignites the air-fuel mixture (combined with intake air) through discharge. The ignition coil 107 generates a high voltage for discharging through the spark plug 106. The coolant temperature sensor 108 measures the temperature of the coolant used to cool the cylinders of the internal combustion engine 101.

[0044] ECU 109 controls the energization of ignition coil 107 and ignition control based on spark plug 106. In combustion chamber 121, the air-fuel mixture is burned by a spark emitted from spark plug 106, and the pressure from this combustion pushes piston 102 down.

[0045] The exhaust gases produced by combustion are discharged into the exhaust pipe 111 via the exhaust valve 104. A three-way catalytic converter 112 and an oxygen sensor 113 are installed in the exhaust pipe 111. The three-way catalytic converter 112 purifies the exhaust gases of harmful substances such as nitrogen oxides (NOx). The oxygen sensor 113 detects the oxygen concentration in the exhaust gases 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 to ensure that the fuel injection quantity supplied from the fuel injection device 200 achieves a target air-fuel ratio.

[0046] Furthermore, the crankshaft 131 is connected to the piston 102 via connecting rod 132. The reciprocating motion of the piston 102 is converted into rotational motion by the crankshaft 131. A crankshaft angle sensor 116 is mounted on the crankshaft 131. The crankshaft angle sensor 116 detects the rotation and phase of the crankshaft 131 and outputs the detection result to the ECU 109. The ECU 109 can detect the rotational speed of the internal combustion engine 101 based on the output of the crankshaft angle sensor 116.

[0047] Signals supplied from the crankshaft angle sensor 116, air flow meter 120, oxygen sensor 113, accelerator opening sensor 122 indicating the opening of the accelerator operated by the driver, fuel pressure sensor 126, etc., are input to the ECU 109.

[0048] The ECU 109 calculates the required torque of the internal combustion engine 101 based on the signal supplied from the accelerator opening sensor 122, and determines whether it is in an idling state. In addition, the ECU 109 calculates the amount of air required for the internal combustion engine 101 based on the required torque, and outputs a matching opening signal to the throttle valve 119.

[0049] In addition, the ECU 109 has a speed detection unit (not shown) that calculates the rotational speed of the internal combustion engine 101 (hereinafter referred to as "engine speed") based on the signal supplied from the crankshaft angle sensor 116. Furthermore, the ECU 109 has a preheating determination unit (not shown) that determines whether the three-way catalyst 112 is in a preheated state based on the temperature of the coolant obtained from the water temperature sensor 108 and the elapsed time since the internal combustion engine 101 started.

[0050] A fuel level sensor 99 is installed inside the fuel tank 123. This fuel level sensor 99 is used to detect the remaining fuel in the fuel tank 123, for example, by using an electrical sensor. In this electrical fuel level sensor 99, a float (float) 99a disposed inside the fuel tank 123 is connected via a rod 99b.

[0051] Furthermore, as the float 99a moves up and down due to changes in the fuel level (fuel level) within the fuel tank 123, the rod 99b moves. This movement of the rod 99b is converted into a resistance value of a variable resistor, and an output signal corresponding to this resistance value is output to the ECU 109. The ECU 109 can detect the fuel level within the fuel tank 123 based on this output signal. Additionally, the configuration of the fuel level sensor 99 is not limited to... Figure 1 As shown in the diagram.

[0052] Fuel is supplied to fuel tank 123 from outside the vehicle by human or mechanical means. When fuel tank 123 is full of fuel, a fuel gauge (not shown) displays the fuel level in analog or digital form, allowing the driver to check the remaining fuel in fuel tank 123.

[0053] The fuel supplied to the fuel tank 123 is not necessarily only gasoline; for example, there may be gasoline containing ethanol. Alternatively, there may be a blended fuel composed of ethanol, synthetic fuels, and gasoline. Furthermore, the blending ratio of various fuels may not be the same and can vary depending on the country, region, gas station, etc. On the other hand, regarding methods for estimating the synthetic ratio of these fuels, although there are methods using dedicated sensors, these often negatively impact costs. Therefore, a method for accurately estimating the content of various fuels in gasoline is desired. Here, the fuel injection control device 127 according to this embodiment provides a method for estimating the synthetic fuel content α, which is used to accurately determine the content of synthetic fuel relative to the total fuel.

[0054] The fuel injection control device 127 calculates the fuel quantity (target injection quantity) corresponding to the intake air volume and outputs the corresponding fuel injection signal to the fuel injection device 200. Additionally, based on the oxygen concentration measured by the oxygen sensor 113, the target injection quantity is fed back to the fuel injection control device 127. Furthermore, the fuel injection control device 127 outputs an energizing signal to the ignition coil 107 and an ignition signal to the spark plug 106.

[0055] Next, use Figure 2 illustrate Figure 1 A detailed configuration example of the fuel injection device 200 shown.

[0056] Figure 2 This is a cross-sectional view showing an example of the internal configuration of the fuel injection device 200.

[0057] like Figure 2 As shown, the fuel injection device 200 includes: a fuel supply section 212 for supplying fuel, a valve seat 202 having a fuel injection port 215 that serves as a fuel passage, and a movable iron core (movable member) 206 for driving 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 described as an example.

[0058] In the fuel injection device 200, a fuel supply section 212 is formed at the upper end, and a fuel injection port 215 and a valve seat 202 are formed at the lower end. Furthermore, a movable iron core 206, a valve body 201, and an intermediate member 214 are arranged between the fuel supply section 212 and the valve seat 202.

[0059] The end of the fuel injection device 200 on the opposite side (fuel supply section 212 side) relative to the fuel injection port 215 and valve seat 202, and the high-pressure fuel pipe 129 (not shown) Figure 1 The end of the fuel injection device 200 on the opposite side (fuel injection orifice 215 side) relative to the fuel supply section 212 is inserted into the combustion chamber 121 (see reference). Figure 1 The mounting holes (insertion holes) formed on the components (cylinder block, cylinder head, etc.) of the cylinder.

[0060] The fuel injection device 200 receives fuel from the high-pressure fuel pipe 129 (see reference) via the fuel supply unit 212. Figure 1 ) receives fuel supply from the front end of valve seat 202 to combustion chamber 121 (refer to Figure 1 Fuel is injected internally. Inside the fuel injection device 200, the fuel passage is configured such that fuel flows approximately along the central axis 200a of the fuel injection device 200 from the base end on the fuel supply section 212 side to the front end on the fuel injection hole 215 side.

[0061] Coil 208 is positioned between fixed iron core (stator) 207 and housing 209. Fixed iron core 207, coil 208, and housing 209 constitute an electromagnet. In the closed valve state, where coil 208 is not energized, the valve body 201 abuts against valve seat 202 due to the force obtained by subtracting the force of the third spring member 217 from the forces exerted by the first spring member 210 and the second spring member 216 in the valve body 201 towards the closed valve direction. This state is designated as the valve-closed stable state (valve-closed standby state). In the valve-closed stable state, movable iron core 206 abuts against intermediate member 214 and is positioned in the closed valve position. Valve body 201 is driven via transmission surface 219, which transmits the load from movable iron core 206.

[0062] In the stable closed state, the intermediate component 214 is forced downstream (towards the valve seat 202, in the valve-closing direction) by the second spring component 216, and comes into contact with the valve body 201 and remains stationary. The movable iron core 206 is forced upstream (towards the fixed iron core 207, in the valve-opening direction) by the third spring component 217, and comes into contact with the intermediate component 214. Because the force of the second spring component 216 is greater than the force of the third spring component 217, a gap 250 is generated between the valve body 201 and the movable iron core 206.

[0063] Fuel injection control unit 127 and ECU 109 are connected to fuel injection unit 200. ECU 109 contains [details to be described later]. Figure 3 The CPU (Central Processing Unit) 501 shown is included. The fuel injection control device 127 has a circuit that receives drive command pulses from the ECU 109 and supplies drive current (drive voltage) to the fuel injection device 200. Alternatively, the ECU 109 and the fuel injection control device 127 can be configured as a single unit. At least the fuel injection control device 127 is a device that generates the drive voltage for the fuel injection device 200; it can be integrated with the ECU 109 or configured separately.

[0064] In ECU 109, signals indicating the status of internal combustion engine 101 are obtained from various sensors, and appropriate drive command pulse width and injection timing are calculated based on the operating conditions of internal combustion engine 101. The drive command pulse output from ECU 109 is input to fuel injection control device 127 through signal line 223.

[0065] The fuel injection control unit 127 controls the drive voltage applied to the coil 208, supplying drive current. The ECU 109 communicates with the fuel injection control unit 127 via communication line 222, and can switch the drive current generated by the fuel injection control unit 127 according to the pressure of the fuel supplied to the fuel injection device 200 and the operating conditions. The fuel injection control unit 127 can change the control constant through communication with the ECU 109, and the current waveform changes according to the control constant.

[0066] [Composition of the fuel injection control device]

[0067] Next, use Figure 3 The configuration of the fuel injection control device 127 will be described.

[0068] Figure 3 This is a diagram showing a detailed configuration example of the drive circuit of the fuel injection control device 127 and the ECU 109.

[0069] The CPU 501, built into the ECU 109, acquires various signals indicating the engine status from the fuel pressure sensor 126, air flow meter 120, oxygen sensor 113, crankshaft angle sensor 116, etc. Then, based on these signals and the operating conditions of the internal combustion engine 101, the CPU 501 performs calculations on the drive command pulse width and injection timing for controlling the amount of fuel injected from the fuel injection device 200.

[0070] Furthermore, the CPU 501 calculates the appropriate pulse width and injection timing of the drive command pulse based on the operating conditions of the internal combustion engine 101, and outputs the drive command pulse to the drive IC (Integrated Circuit) 502 (referred to as "IC" in the figure) of the fuel injection device 200 via signal line 223. The injection quantity is determined based on the pulse width of the drive command pulse. Then, the drive IC 502 switches the switching elements 505, 506, and 507 to be energized or de-energized, supplying drive current to the fuel injection device 200.

[0071] Switching element 505 is connected between a high-voltage source (higher than the voltage source VB input to the drive circuit of fuel injection control device 127) and the high-voltage side terminal of coil 208 of fuel injection device 200. Switching elements 505, 506, and 507 are, for example, FETs (Field Effect Transistors), transistors, etc., and are capable of switching the energization / de-energization of fuel injection device 200.

[0072] The initial voltage value of the high-voltage source, the boost voltage VH, is, for example, 65V, generated by boosting the battery voltage using the boost circuit 514. The boost circuit 514 is, for example, composed of a coil 530, a transistor 531, a diode 532, and a capacitor 533.

[0073] In the boost circuit 514, when transistor 531 is turned on, the battery voltage VB flows to the ground potential 534. Conversely, when transistor 531 is turned off, the high voltage generated in coil 530 is rectified by diode 532, and charge is stored in capacitor 533. Then, the transistor is repeatedly turned on and off, increasing the voltage in capacitor 533 until it reaches the boost voltage VH. Transistor 531 is connected to driver IC 502 or CPU 501, which detects the boost voltage VH output from the boost circuit 514. Alternatively, the boost circuit 514 can also be constructed using a DC / DC converter or the like.

[0074] Switching element 507 is connected between a low-voltage source and the high-voltage terminal of coil 208. The low-voltage source VB is, for example, battery voltage, with a voltage value of approximately 12-14V. Switching element 506 is connected between the low-voltage side terminal of fuel injection device 200 and ground potential 515.

[0075] The driver IC 502 detects the current flowing through the fuel injection device 200 using resistors 508, 512, and 513 for current sensing. Based on the detected current value, it switches the switching elements 505, 506, and 507 to either energize or de-energize, generating the desired drive current. Diodes 509 and 510 apply a reverse voltage to the coil 208 of the fuel injection device 200, rapidly reducing the current supplied to the coil 208.

[0076] CPU 501 communicates with driver IC 502 and communication line 222, and can switch the drive current generated by driver IC 502 according to the pressure of the fuel supplied to fuel injection device 200 and operating conditions. In addition, the two ends of resistors 508, 512, and 513 are connected to the A / D conversion port of driver IC 502, and driver IC 502 can detect the voltage applied across resistors 508, 512, and 513.

[0077] [Fuel injection system operation]

[0078] Next, use Figure 4 The operation of the fuel injection device 200 based on the fuel injection control device 127 will be explained.

[0079] Figure 4 It is a diagram showing the drive command pulse, drive voltage, drive current, valve body displacement, and displacement of the movable iron core.

[0080] like Figure 4 As shown, after the drive command pulse Ti is input at time Ts, a drive voltage 304 is applied from a high-voltage source that has been boosted to a voltage higher than the battery voltage VB, and the drive voltage 304 is applied to the coil 208 (reference). Figure 2 ) Supply current.

[0081] When coil 208 is energized, the electromagnet formed by the fixed iron core 207, coil 208, and housing 209 generates a magnetomotive force. Due to this magnetomotive force, magnetic flux flows through the magnetic circuit formed by the fixed iron core 207, housing 209, and movable iron core 206 surrounding coil 208. At this time, a magnetic attraction force acts between movable iron core 206 and fixed iron core 207, causing movable iron core 206 and intermediate member 214 to displace towards fixed iron core 207. Then, movable iron core 206 displaces until the transmission surface 219 of valve body 201 abuts against the transmission surface 218 of movable iron core 206. Meanwhile, valve body 201 continues to maintain contact with valve seat 202.

[0082] When the movable iron core 206 displaces by the amount of the gap 250 created between the valve body 201 and the movable iron core 206, and the transmission surface 219 of the valve body 201 collides with the transmission surface 218 of the movable iron core 206, the valve body 201 is lifted upstream due to the energy possessed by the movable iron core 206, and the valve body 201 moves away from the valve seat 202. This creates a gap in the valve seat, opens the fuel passage, and allows fuel to be injected from the fuel injection port 215. Due to the kinetic energy of the movable iron core 206, the valve body 201 displaces rapidly.

[0083] From time Ts until time T31 (valve opening start timing), when the movable iron core 206 collides with the valve body 201 and the valve body 201 leaves the valve seat 202, the fuel injection control device 127 applies a high drive voltage 304, causing a drive current 308 to flow through the coil 208. This generates sufficient magnetic attraction between the movable iron core 206 and the fixed iron core 207, enabling the movable iron core 206 to respond quickly. Furthermore, by enabling the movable iron core 206 to respond quickly, for example, even if there is a deviation in the gap 250 that constitutes the pre-stroke in each individual, the impact of this deviation on the injection quantity can be reduced.

[0084] In this embodiment, the fuel injection control device 127 sets the drive voltage 304 such that the drive current reaches its peak current value Ip at the valve opening start timing, and disconnects the voltage when the drive current reaches the peak current value Ip. Figure 4 The diagram shows the state where the voltage is disconnected when the peak current 308b reaches the peak current value Ip. In this way, the fuel injection control device 127 can disconnect the voltage at a time when excessive acceleration of the movable iron core 206 can be suppressed. Furthermore, the application time of the drive current until the peak current value Ip, as described in this embodiment, can be determined based on the valve opening start timing. For example, if the magnetic attraction generated until the valve opening start timing is weak, the fuel injection control device 127 can also ensure that the drive current reaches the peak current value Ip after the valve opening start timing. Additionally, the fuel injection control device 127 can also apply a reverse voltage when the drive current reaches the peak current value Ip.

[0085] After time T31, the driving voltage 304 decreases rapidly, resulting in a reduction in the driving current 317 (shown by the dashed line), and a decrease in the magnetic attraction between the movable core 206 and the fixed core 207. Due to this reduction in magnetic attraction, over-acceleration of the movable core 206 is suppressed, reducing the collision energy upon collision with the fixed core 207. In other words, the fuel injection control device 127 suppresses over-acceleration of the movable core 206 by applying a reverse voltage before the collision between the movable core 206 and the fixed core 207, thereby reducing the collision energy upon collision.

[0086] After the movable iron core 206 collides with the fixed iron core 207, the valve body 201 moves upstream, and the movable iron core 206 moves downward. When the fixed iron core 207 collides with the movable iron core 206, the valve body 201 separates from the movable iron core 206, and the movable iron core 206 moves downstream, soon coming to rest and stabilizing at the target lift position. This state is defined as the valve-opening stable state.

[0087] After applying a high drive voltage 304, when the drive current reaches a first current value Ih1 sufficient to maintain the valve open, the fuel injection control device 127 continuously applies a drive voltage 305 until time Te, which repeatedly applies the battery voltage VB and 0V. Then, the fuel injection control device 127 controls the flow of a first holding current 331 to maintain the first current value Ih1.

[0088] The fuel injection control device 127 maintains the first holding current 331 for a predetermined time, after which the current value is reduced. When a second current value Ih2 sufficient to maintain the valve open is reached, the fuel injection control device 127 controls the application of a drive voltage 305 to maintain the second current value Ih2, causing a second holding current 332 (drive current) to flow. This drive voltage 305 repeatedly applies the battery voltage VB and then applies 0V. The predetermined time is set based on factors such as the time until magnetic flux saturation. Furthermore, the first holding current 331 and the second holding current 332 are drive currents used to maintain the valve body 201 in the open state (open valve holding state).

[0089] Next, when the drive command pulse Ti changes to OFF at time Te, the fuel injection control device 127 applies a drive voltage in the opposite direction (i.e., applies a reverse voltage). This cuts off the current supply to the coil 208, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attraction disappears. As a result, the movable iron core 206, having lost its magnetic attraction, is pushed back to the closed position where the valve body 201 contacts the valve seat 202 due to the load of the first spring member 210 and the force generated by the fuel pressure.

[0090] The force acting on the first spring member 210 of the valve body 201 is transmitted to the movable iron core 206 via the transmission surface 219 on the valve body 201 side and the transmission surface 218 on the movable iron core 206 side. When the valve closing time, from the moment Te when the drive command pulse Ti becomes OFF until the moment Tb when valve closing is completed, has elapsed, the valve body 201 contacts the valve seat 202 at moment Tb. Thus, the time taken from the moment the drive current is cut off to the moment the valve body 201 actually contacts the valve seat 202 is called the "valve closing delay time". The valve closing delay time is expressed as the valve closing time obtained by subtracting time Te from time Tb, and is also recorded as the valve closing delay time (Tb-Te).

[0091] After the valve body 201 contacts the valve seat 202, the transmission surface 218 on the movable iron core 206 side disengages from the transmission surface 219 on the valve body 201 side and continues to move downwards (in the valve closing direction). After the valve closing is completed at time Tb, as... Figure 2 As shown, the movable iron core 206 is separated from the valve body 201. At this time, the drive voltage changes in a bend-like manner, as indicated by inflection point 330. The fuel injection control device 127 can detect the moment Tb when the valve is closed by this change.

[0092] When the fuel injection device 200 is closed, the third spring member 217 changes from extension to compression when the valve body 201 collides with the valve seat 202, and the direction of movement of the movable iron core 206 is reversed. This causes a change in the acceleration of the movable iron core 206 and a change in the inductance of the coil 208. In other words, when the fuel injection device 200 is closed, the drive current flowing in the coil 208 is cut off, and a back electromotive force is applied to the coil 208. Furthermore, since the back electromotive force gradually decreases as the drive current converges, the inductance changes as the back electromotive force decreases, thus creating an inflection point 330 in the drive voltage.

[0093] The aforementioned inflection point 330 represents the valve closing timing of the fuel injection device 200. When the second-order derivative of the time-series data of the drive voltage applied to the coil 208 is performed, the inflection point 330 exhibits an extreme value (maximum or minimum). Therefore, the fuel injection control device 127 can determine the inflection point 330 by detecting the extreme value of the time-series data of the drive voltage.

[0094] Next, use Figure 5 An example of the internal configuration of the ECU 109 and fuel injection control device 127 involved in this embodiment will be described.

[0095] Figure 5 This is a block diagram illustrating an example of the functional configuration of the ECU 109 and the fuel injection control device 127.

[0096] The fuel injection control device 127 determines whether the fuel (e.g., gasoline) stored in the fuel tank 123 contains ethanol fuel or synthetic fuel at the moment when the internal combustion engine 101 starts to drive after the fuel tank 123 is supplied with fuel.

[0097] In addition to the fuel injection control device 127, the ECU 109 also has a combustion control unit 610.

[0098] The combustion control unit (combustion control unit 610) controls the internal combustion engine (internal combustion engine 101) to ensure that the exhaust temperature of the exhaust gas discharged from the combustion chamber (combustion chamber 121) is above a threshold temperature, based on the synthetic fuel content α calculated by the fuel injection control device 127. At this time, the combustion control unit 610 outputs an ignition signal to the internal combustion engine 101 to control the combustion timing. The spark plug 106 of the internal combustion engine 101 (see reference...) Figure 1 The fuel is ignited according to the input ignition signal.

[0099] The various states of the internal combustion engine 101 are detected by the sensor group 105. The sensor group 105 is set in... Figure 1The term refers to the various sensors (fuel pressure sensor 126, water temperature sensor 108, crankshaft angle sensor 116, etc.) on the internal combustion engine 101 shown. The detection results of the sensor group 105 are input to the fuel injection control device 127 and the combustion control unit 610. Then, the fuel injection control device 127 and the combustion control unit 610 perform prescribed processing based on the detection results input from the sensor group 105.

[0100] The fuel injection control device 127 includes a fuel temperature estimation unit 601, a fuel pressure acquisition unit 602, a valve closing time calculation unit 603, a stoichiometric air-fuel ratio calculation unit 604, a valve closing delay time difference calculation unit 605, a fuel filler content calculation unit 606, and a storage unit 607. For detailed information on the operation of each part of the fuel injection control device 127, please refer to... Figure 6 This will be explained later.

[0101] The fuel temperature estimation unit (fuel temperature estimation unit 601) estimates the fuel temperature of the fuel supplied to the combustion chamber (combustion chamber 121). The fuel temperature is the temperature of the fuel injected by the fuel injection device 200. Furthermore, the fuel temperature estimation unit (fuel temperature estimation unit 601) estimates the fuel temperature based on the waveform of the drive current driving the fuel injection device (fuel injection device 200), whose coil (coil 208) resistance changes with the fuel temperature.

[0102] The fuel pressure acquisition unit (fuel pressure acquisition unit 602) acquires the fuel pressure injected by the fuel injection device (fuel injection device 200). For example, the fuel pressure acquisition unit 602 acquires the fuel pressure detected by the fuel pressure sensor 126.

[0103] The valve closing time calculation unit (valve closing time calculation unit 603) detects the valve closing of the fuel injection device (fuel injection device 200) when the fuel temperature reaches a specified temperature, and calculates the valve closing time of the fuel injection device (fuel injection device 200). In this embodiment, two specified temperatures are set.

[0104] The stoichiometric air-fuel ratio calculation unit (theoretical air-fuel ratio calculation unit 604) calculates the stoichiometric air-fuel ratio for combustion of fuel containing synthetic fuel based on the minimum oxygen concentration obtained from the oxygen concentration detection unit (oxygen sensor 113) that detects the oxygen concentration in the exhaust gas when the injection quantity (injection pulse width) of the fuel injected by the fuel injection device (fuel injection device 200) changes. Details of the stoichiometric air-fuel ratio calculation process will be described later. Figure 10 As shown.

[0105] The valve closing delay time difference calculation unit (valve closing delay time difference calculation unit 605) calculates the valve closing delay time spent by the fuel injection device (fuel injection device 200) in the open state from the start of valve closing to the completion of valve closing, based on multiple valve closing times calculated at different specified temperatures. Then, the valve closing delay time difference calculation unit (valve closing delay time difference calculation unit 605) normalizes the multiple valve closing delay times calculated for each of the multiple specified temperatures using fuel pressure to calculate the difference between the multiple valve closing delay times. For example, the valve closing delay time difference calculation unit 605 calculates the difference between the valve closing delay times (Tb-Te) obtained at the multiple temperatures as the valve closing delay time difference ΔTdelay.

[0106] The content calculation unit (content calculation unit 606) calculates the content of synthetic fuel in the fuel based on characteristic data showing the relationship between the difference in valve closing delay time and the synthetic fuel content α in the fuel (see below). Figure 8 The fuel content α of the fuel contained in the fuel storage section (fuel tank 123) is calculated. At this time, the content calculation unit 606 reads characteristic data from the storage section 607. This characteristic data represents the relationship between the valve closing delay time difference ΔTdelay and the mixed fuel temperature. In addition, the content calculation unit (content calculation unit 606) calculates the content of gasoline, ethanol and synthetic fuel in the fuel based on the difference between the stoichiometric air-fuel ratio and the valve closing delay time.

[0107] The storage unit 607 is composed, for example, of RAM (Random Access Memory) and ROM (Read Only Memory). The results calculated by each part of the fuel injection control device 127 are temporarily stored in the RAM and read out appropriately. Additionally, characteristic data is pre-stored in the ROM of the storage unit 607, and this characteristic data is read out by the rate calculation unit 606. The functions of each part of the fuel injection control device 127 are implemented by the CPU 501, which is configured in the ECU 109, loading the program code of the software read from the ROM into the RAM and executing it. Therefore, the ROM serves as an example of a computer-readable non-transitory storage medium storing a program executed by the CPU 501.

[0108] Here, refer to Figure 6 An example of the control method for the internal combustion engine 101 according to this embodiment will be described.

[0109] Figure 6 This is a flowchart illustrating an example of a control method for an internal combustion engine 101 determined based on the synthetic fuel content α. Figure 6 The process shown begins when the driver starts driving the vehicle, that is, when the internal combustion engine 101 starts driving.

[0110] When the synthetic fuel content α is greater than zero and the exhaust temperature is less than a threshold temperature, the combustion control unit (combustion control unit 610) advances the ignition timing of the fuel supplied to the combustion chamber (combustion chamber 121) to the knock limit. Specifically, the combustion control unit 610 determines whether the synthetic fuel content relative to the fuel loaded into the fuel tank 123 (hereinafter referred to as "synthetic fuel content α") exceeds 0% (S1). The process for calculating the synthetic fuel content α is described later. Figure 7 The flowchart shown is used to execute the procedure.

[0111] Synthetic fuel content α is preserved in Figure 5 In the RAM of the storage unit 607 shown. The synthetic fuel content α [%] is a value calculated by the following formula (1).

[0112] [Formula 1]

[0113]

[0114] If the combustion control unit 610 determines that the content α of synthetic fuel does not exceed 0% (S1's "No"), meaning that the fuel does not contain synthetic fuel, the process ends. Furthermore, since the fuel tank 123 contains only gasoline, the combustion control unit 610 performs combustion control of the internal combustion engine 101 that uses only gasoline as fuel.

[0115] On the other hand, if the content α of synthetic fuel exceeds 0% (S1's "Yes"), that is, if the fuel contains synthetic fuel other than gasoline, the combustion control unit 610 determines that... Figure 5 The sensor group 105 shown indicates whether the exhaust temperature is above the threshold temperature (S2). If the exhaust temperature is above the threshold temperature (S2 "Yes"), the combustion control unit 610 ends the process.

[0116] On the other hand, if the exhaust temperature is lower than the threshold temperature (S2 "No"), the combustion control unit 610 advances the ignition timing (S3). By advancing the ignition timing, the combustion temperature of the fuel increases.

[0117] Next, the combustion control unit 610 determines whether the knock limit is reached based on the detection value of the knock sensor obtained from the sensor group 105 (S4). If the knock limit is not reached ("No" in S4), the combustion control unit 610 returns to step S3, advances the ignition timing to the knock limit, and increases the exhaust temperature.

[0118] Even if the exhaust temperature is below the threshold, if it is at the knock limit (S4 "Yes"), the combustion control unit 610 changes the load of the internal combustion engine 101 (S5) to control the exhaust temperature to rise above the threshold. Therefore, the combustion control unit 610 performs the processing after step S2 again.

[0119] In this way, the combustion control unit 610 controls the internal combustion engine 101 in such a way that the exhaust temperature is above a desired threshold temperature when synthetic fuel is used. By controlling the exhaust temperature to be above the threshold temperature, the amount of harmful components such as formaldehyde that may be produced when using synthetic fuel can be reduced.

[0120] For Figure 6 The synthetic fuel content α determined in step S1 can be detected by the content calculation unit 606 of the ECU 109 based on the valve closing timing of the fuel injection device 200. As described above, Figure 4 The inflection point 330 shown is the valve closing timing. Furthermore, when the fuel in the fuel tank 123 changes (e.g., synthetic fuel is mixed into gasoline), the effect of the fuel change is immediately reflected in a change in the valve closing timing. Therefore, as described later... Figure 7 As explained in the document, by detecting the extreme value of the time series data of the driving voltage by the valve closing time calculation unit 603, the content calculation unit 606 can accurately estimate the ratio of synthetic fuel to fuel supplied to the fuel tank 123 (synthetic fuel content α).

[0121] In this embodiment, the relationship between the synthetic fuel content α relative to the fuel supplied to the fuel tank 123 and the valve closing timing, calculated by the content calculation unit 606, is recorded in the ROM of the storage unit 607. Furthermore, the content calculation unit 606 can read the relationship between the synthetic fuel content α and the valve closing timing from the ROM and calculate the synthetic fuel content α based on the valve closing timing.

[0122] Furthermore, since the fuel injection device 200 is provided for each cylinder of the internal combustion engine 101, the characteristics of the fuel injection device 200 (e.g., the relationship between valve closing timing and synthetic fuel content α) sometimes differ for each cylinder. Therefore, the characteristic values ​​of the fuel injection device 200 can also be recorded for each cylinder from the characteristic data stored in the storage unit 607. Alternatively, the fuel injection control device 127 can also... Figure 7 The following method is used to calculate the synthetic fuel content α.

[0123] <Calculation Method for Synthetic Fuel Content α>

[0124] Figure 7 It is shown in Figure 6The flowchart shows an example of the calculation method for the synthetic fuel content α determined in step S1. Figure 7 The process shown is performed simultaneously with the preheating of the internal combustion engine 101, causing the fuel temperature to rise. Therefore, Figure 6 and Figure 7 Each flowchart is executed individually.

[0125] First, the fuel temperature estimation unit 601 estimates the fuel temperature based on the change in current of the fuel injection device 200 (S11). The change in current of the fuel injection device 200 is used to estimate the temperature of the fuel injection device 200. For example, the fuel temperature estimation unit 601 monitors the drive current of the fuel injection device 200 for a predetermined time from the input of the drive command pulse. In the following description, the temperature of the fuel injection device 200 will be referred to as "fuel temperature".

[0126] As the internal combustion engine 101 preheats, the coil 208 of the fuel injection device 200 (refer to...) Figure 2 When it gets hot and the resistance increases, Figure 4 The slope of the driving current (the waveform of the peak current portion) changes from peak current 308a to peak current 308b. By using this principle, the fuel temperature estimation unit 601 can estimate the fuel temperature based on the peak current (S12).

[0127] Next, the fuel temperature estimation unit 601 determines whether the fuel temperature exceeds the specified temperature Tw1 (S13). Here, the specified temperature Tw1 used in step S13 is a lower value than the specified temperature Tw2 used in step S16.

[0128] As multiple specified temperatures, at least two points are specified: the temperature immediately after the internal combustion engine (internal combustion engine 101) is started, and the temperature after the internal combustion engine (internal combustion engine 101) has finished preheating. The reason for setting at least two specified temperatures is that the viscosity of fuel differs at low and high temperatures. Since the fuel temperature is lowest and the viscosity is highest immediately after the internal combustion engine 101 is started, the movement of the valve body 201 is hindered by fuel resistance, tending to have a longer valve closing delay time. On the other hand, since the viscosity of fuel is lowered when heated to about 80°C, the fuel resistance is reduced, and the movement of the valve body 201 is less likely to be hindered, tending to have a shorter valve closing delay time.

[0129] In this embodiment, two different temperatures between 20°C and 80°C are used as designated temperatures Tw1 and Tw2. For example, designated temperature Tw1 is set to 30°C and designated temperature Tw2 is set to 70°C. When the internal combustion engine 101 is first started, even if the fuel temperature is essentially the same as the outside air temperature, the fuel temperature rises due to preheating. Furthermore, by setting at least two different temperatures between 20°C and 80°C as designated temperatures, the fuel temperature will inevitably rise past the designated temperatures.

[0130] Regarding the case where the fuel temperature exceeds the specified temperature Tw1, for example according to Figure 4 The determination is made when the time T1 until the peak current reaches the current value Ip is above the threshold Th1. Furthermore, if the fuel temperature does not exceed the specified temperature Tw1 (No in S13), the fuel temperature estimation unit 601 terminates this process. After a specified time, the process of step S11 is performed again.

[0131] On the other hand, if the fuel temperature exceeds the specified temperature Tw1 (S13 "Yes"), the valve closing time calculation unit 603 detects the valve closing of the fuel injection device 200 at the specified temperature Tw1 (S14).

[0132] Then, the fuel pressure acquisition unit 602 stores the value obtained from the fuel pressure sensor 126 at a specified temperature Tw1 as fuel pressure Pf1 in the RAM of the storage unit 607. Additionally, the valve closing time calculation unit 603 calculates the valve closing time based on the time Te of the reverse voltage applied with the drive voltage and the valve closing time Tb. Figure 4 The value of the valve closing delay time (Tb-Te) shown is stored in the RAM of the storage unit 607 as the valve closing delay time Tc1 (S15).

[0133] After the fuel injection control device 127 obtains the valve closing delay time Tc1 at the specified temperature Tw1 in step S15, the combustion control unit 610 continues to preheat the internal combustion engine 101 until the fuel temperature reaches the specified temperature Tw2. During this period, the processes of steps S11, S12, and S16 are repeated.

[0134] The processes S11 and S12, performed during the preheating of the internal combustion engine 101 by the fuel temperature estimation unit 601, are as described above. After step S12, the fuel temperature estimation unit 601 determines whether the fuel temperature exceeds a specified temperature Tw2 (S16). The fuel temperature estimation unit 601 can determine whether the fuel temperature exceeds a specified temperature Tw2 during the preheating of the internal combustion engine 101 by the combustion control unit 610. Figure 4 The initial injection time T2, which is the time until the driving current reaches the specified current value, is determined as the moment when the fuel temperature exceeds the specified temperature Tw2.

[0135] If the fuel temperature does not exceed the specified temperature Tw2 (No in S16), the fuel temperature estimation unit 601 terminates this process. After a specified time, the process of step S11 is performed again.

[0136] On the other hand, if the fuel temperature exceeds the specified temperature Tw2 (S16 "Yes"), the valve closing time calculation unit 603 detects the valve closing of the fuel injection device 200 at the specified temperature Tw2 (S17).

[0137] Then, the fuel pressure acquisition unit 602 stores the value obtained from the fuel pressure sensor 126 at a specified temperature Tw2 as the fuel pressure Pf2 in the RAM of the storage unit 607. Additionally, the valve closing time calculation unit 603 calculates the valve closing time based on the time Te of the reverse voltage applied with the drive voltage and the valve closing time Tb. Figure 4 The value of the valve closing delay time (Tb-Te) shown is stored in the RAM of the storage unit 607 as the valve closing delay time Tc2 (S18).

[0138] After step S18, the valve closing delay time difference calculation unit 605 reads the valve closing delay time Tc1 and fuel pressure Pf1 at a specified temperature Tw1, and the valve closing delay time Tc2 and fuel pressure Pf2 at a specified temperature Tw2 from RAM (S19).

[0139] Then, the valve closing delay time difference calculation unit (valve closing delay time difference calculation unit 605) normalizes the multiple valve closing delay times calculated for each of the multiple specified temperatures using fuel pressure, and calculates the difference ΔTdelay of the multiple valve closing delay times (S20). For example, the valve closing delay time difference calculation unit 605 normalizes the valve closing delay times Tc1 and Tc2 at specified temperatures Tw1 and Tw2 using fuel pressures Pf1 and Pf2, calculates the difference ΔTdelay of the valve closing delay times (S20), and stores the difference ΔTdelay of the valve closing delay times in the RAM of the storage unit 607. Here, the process of normalizing the valve closing delay time using fuel pressure is, for example, a process of transforming the valve closing delay times Tc1 and Tc2 into the valve closing delay times when the fuel pressures Pf1 and Pf2 are the same. Even with the same fuel pressure, the valve closing delay time will be different if the properties of the fuel are different. Therefore, since the difference in valve closing delay time ΔTdelay varies for different fuel properties, the fuel properties can be determined based on the difference in valve closing delay time ΔTdelay.

[0140] After step S20, the content calculation unit 606 uses the difference ΔTdelay of the valve closing delay time read from RAM and the characteristic data (described later) stored in the storage unit 607. Figure 8(As shown in the relationship), the synthetic fuel content α(S21) is estimated, and the process ends.

[0141] Figure 8 This is an example of characteristic data showing the relationship between the synthetic fuel content α and the difference ΔTdelay in the valve closing delay time.

[0142] Figure 8 The horizontal axis represents the synthetic fuel content α, and the vertical axis represents the difference in valve closing delay time ΔTdelay. Furthermore, the multiple square points added to the graph represent the values ​​of the difference in valve closing delay time read from RAM.

[0143] like Figure 8 As shown, there is a linear relationship between the difference in valve closing delay time ΔTdelay and the synthetic fuel content α. That is, it can be seen that the larger the difference in valve closing delay time ΔTdelay, the greater the tendency for the synthetic fuel content α to increase. Therefore, in Figure 7 In step S21, the content calculation unit 606 reads the data from the storage unit 607 according to... Figure 8 The transformation formula derived from the characteristic data shown can be used to estimate the synthetic fuel content α based on the difference ΔT in the valve closing delay time.

[0144] Figure 9 This is a flowchart illustrating a method for estimating the content of ethanol fuel and synthetic fuel in gasoline.

[0145] Here, we will explain a method by which the fuel injection control device 127 estimates the content of ethanol fuel and the content of synthetic fuel in gasoline when the gasoline contains a mixture of synthetic fuel and ethanol fuel.

[0146] In this embodiment, even if the performance deviation of the fuel injection device 200 occurs in each cylinder, the content of ethanol fuel and synthetic fuel can be estimated without using specific values ​​recorded in the ROM for each cylinder.

[0147] First, the fuel temperature estimation unit 601 determines whether the preheating of the internal combustion engine 101 has been completed based on the temperature of the cooling water obtained from the water temperature sensor 108 (S31).

[0148] If the fuel temperature estimation unit 601 determines that the preheating of the internal combustion engine 101 is incomplete (S31 "No"), the fuel injection control device 127 performs a fuel property detection step using the fuel injection device 200 (S32). In this specification, the indicator used to identify gasoline, synthetic fuel, and ethanol fuel contained in the fuel is referred to as "fuel property". This fuel property detection step is performed in conjunction with the preheating of the internal combustion engine 101, for example, at fuel temperatures of 30°C and 70°C. Figure 7The process for estimating the synthetic fuel content α is performed in the same manner. Through this fuel property detection step, the synthetic fuel content α is calculated based on the fuel property of the fuel loaded into the fuel tank 123. The calculated synthetic fuel content α is stored in the RAM of the storage unit 607. After the fuel property is detected, the preheating completion determination in step S31 is performed again.

[0149] If, in step S31, the fuel temperature estimation unit 601 determines that preheating has been completed (S31 "Yes"), the stoichiometric air-fuel ratio calculation unit 604 performs the stoichiometric air-fuel ratio acquisition step (S33). This stoichiometric air-fuel ratio acquisition step is, for example, a process performed when the fuel temperature is 80°C. Here, refer to... Figure 10 The process of obtaining the theoretical air-fuel ratio by the theoretical air-fuel ratio calculation unit 604 is explained.

[0150] Figure 10 This is a graph showing the relationship between oxygen concentration and air-fuel ratio.

[0151] Figure 10 The horizontal axis represents the air-fuel ratio, and the vertical axis represents the oxygen concentration. The oxygen concentration relative to the air-fuel ratio can be represented, for example, by a downward-convex quadratic curve.

[0152] In the step of obtaining the stoichiometric air-fuel ratio in the stoichiometric air-fuel ratio calculation unit 604, the combustion control unit 610 changes the drive command pulse Ti of the fuel injection device 200, thereby changing the concentration of fuel injected into the combustion chamber (air-fuel ratio). Furthermore, the oxygen sensor 113 detects the oxygen concentration in the exhaust gas for each change in the drive command pulse Ti. Figure 10 The multiple square points added to the graph represent the oxygen concentration detected for each change in the drive command pulse Ti.

[0153] The stoichiometric air-fuel ratio calculation unit 604 explores the drive command pulse width at which the oxygen concentration is minimized by changing the drive command pulse width Ti obtained by the combustion control unit 610. This process of exploring the drive command pulse width is called learning. Then, after exploring the drive command pulse width at which the oxygen concentration is minimized, the stoichiometric air-fuel ratio calculation unit 604 obtains the ratio of fuel to air injected into the combustion chamber 121 at the drive command pulse width at which the oxygen concentration is minimized as the stoichiometric air-fuel ratio and saves it to the RAM of the storage unit 607.

[0154] Return again Figure 9 Let me continue explaining.

[0155] After steps S32 and S33, the content ratio calculation unit 606 determines whether the learning in the stoichiometric air-fuel ratio acquisition step has ended (S34). The content ratio calculation unit 606 determines that the learning has ended when the fuel temperature exceeds at least two specified temperatures Tw1 and Tw2, and exceeds the temperature at which the stoichiometric air-fuel ratio can be obtained (e.g., a set temperature above 80°C). If the content ratio calculation unit 606 determines that the learning has not ended ("No" in S34), the process ends. Then, after a predetermined time, the content ratio calculation unit 606 performs the processes S31 and S33 again.

[0156] On the other hand, when the content calculation unit 606 determines that the learning has ended ("Yes" in S34), it retrieves the synthetic fuel content α calculated in step S32 from the RAM of the storage unit 607, and reads the learned value of the stoichiometric air-fuel ratio obtained in step S33 from the RAM of the storage unit 607 (S35). Next, the content calculation unit 606 reads from the RAM and retrieves the difference ΔTdelay of the valve closing delay time detected in step S32 (S36).

[0157] Content calculation unit 606 calculates the content as described later. Figure 11 The simultaneous equations (S37) described in the text use the difference ΔTdelay of the valve closing delay time and the theoretical air-fuel ratio to determine the synthetic fuel content α, ethanol fuel content β, and gasoline content (1-α-β) as unknowns.

[0158] Figure 11 It is shown Figure 9 The flowchart shows an example of the calculation process for the simultaneous equations shown in step S37.

[0159] In this process, the input is... Figure 9 The learned value of the theoretical air-fuel ratio read in step S35, and the difference ΔTdelay of the valve closing delay time obtained in step S36. Figure 11 The data Y shown represents the input value, where the learned value of the stoichiometric air-fuel ratio and the difference ΔTdelay of the valve closing delay time are input. Figure 11 The data Y, representing the stoichiometric air-fuel ratio, is appended to the lower right of the data in the upper left corner, with "o2" indicating the stoichiometric air-fuel ratio. Additionally, "etha" indicates ethanol. Figure 11 The data Y, which represents the difference in valve closing delay time, is appended to the lower right of the data Y, which represents the difference in valve closing delay time. The data Y is appended to the upper right of the data Y, which represents ethanol, with "etha".

[0160] First, the content calculation unit 606 refers to the theoretical air-fuel ratio database stored in the ROM and obtains the theoretical air-fuel ratio data used in the calculation in step S43 for ethanol, synthetic fuel, and gasoline respectively (S41). In the figure, the lower right of data A is appended with "o2" indicating the theoretical air-fuel ratio, and the upper right of data A is appended with "etha" indicating ethanol, "syn" indicating synthetic fuel, and "gas" indicating gasoline, according to the type of data.

[0161] Next, the content calculation unit 606 refers to the database of valve closing delay times stored in the ROM and obtains the data of the valve closing delay time used in the calculation in step S43 (S42). In the figure, the lower right of data A is appended with "delay" indicating the valve closing delay time, and in the upper right of data A, "etha" is appended to indicate the type of data, "syn" is appended to indicate ethanol, and "gas" is appended to indicate synthetic fuel.

[0162] Next, the content calculation unit 606 calculates the content of ethanol and synthetic fuel using matrix calculation based on the following formula (2) (S43). Here, the data X on the left side of formula (2) represents the content of ethanol and synthetic fuel, which is the value calculated by the operation on the right side of formula (2). Furthermore, in the upper right corner of the data X, "etha" for ethanol and "syn" for synthetic fuel are appended as the type of each data. In addition, the data Y in formula (2) is the value input at the beginning of step S41 as described above.

[0163] [Equation 2]

[0164]

[0165] Next, the content calculation unit 606 substitutes the contents of ethanol and synthetic fuel obtained by the calculation in equation (2) into the following equation (3) to calculate the gasoline content in the fuel (S44). The gasoline content is represented by the data X with "gas" attached to the upper right. The data X contained on the right side of equation (3) corresponds to the gasoline content (1-α-β), ethanol fuel content β, and synthetic fuel content α mentioned above.

[0166] [Formula 3]

[0167] X gas =1-x etha -X syn …(3)

[0168] After processing in step S44, the content calculation unit 606 obtains the ethanol fuel content, synthetic fuel content, and gasoline content, and continues to... Figure 9 The processing of step S38.

[0169] If the content calculation unit 606 uses the simultaneous equations from step S37, it can calculate the ethanol fuel content, synthetic fuel content, and gasoline content. Then, based on the ethanol fuel content, synthetic fuel content, and gasoline content, the content calculation unit 606 estimates the amount of ethanol fuel and synthetic fuel contained in the fuel (S38) and ends the process.

[0170] After step S38, the combustion control unit 610 advances the ignition timing based on the estimated amounts of gasoline, ethanol fuel and synthetic fuel contained in the fuel, in a manner that is the optimal ignition timing that does not produce harmful components in the exhaust gas, thereby controlling the combustion of the internal combustion engine 101.

[0171] In the fuel injection control device 127 described above in the first embodiment, the difference in valve closing delay time is calculated based on the valve closing delay time and fuel pressure obtained for at least two different specified temperatures Tw1 and Tw2, and the synthetic fuel content α of the synthetic fuel contained in the gasoline is calculated. Therefore, the combustion control unit 610 can appropriately control the combustion of the internal combustion engine 101 based on the synthetic fuel content α accurately estimated by the fuel injection control device 127. In this way, by controlling combustion according to whether synthetic fuel is present, so that the exhaust temperature is above a specified value, the generation of harmful components such as formaldehyde can be suppressed, and exhaust gas can be purified.

[0172] Furthermore, at each specified temperature when the fuel temperature reaches two or more different points, the valve closing time is calculated for each specified temperature, and the valve closing delay time difference ΔTdelay is determined. Therefore, the influence of deviations in valve closing time caused by individual differences in the fuel injection device 200 can be eliminated.

[0173] Furthermore, when gasoline contains ethanol fuel and synthetic fuel, the synthetic fuel content α obtained after engine preheating, the learned value of the stoichiometric air-fuel ratio, and the difference in valve closing delay time can be substituted into the simultaneous equations of equation (2) to estimate the ethanol fuel and synthetic fuel. In this way, even if three fuels are mixed, the fuel injection control device 127 can determine the proportion of each fuel. Therefore, the combustion control unit 610 can appropriately control the combustion of the internal combustion engine 101 based on the accurate estimation of the content of the three fuels by the fuel injection control device 127.

[0174] [Second Implementation]

[0175] Next, refer to Figures 12-14 Hereinafter, configuration examples and operation examples of the fuel injection control device according to the second embodiment of the present invention will be described.

[0176] The frequency of vehicle driving varies depending on the driver. For example, some drivers drive daily, while others drive only weekly or monthly. However, fuel loaded into the fuel tank 123 is prone to oxidation and deterioration over time. Therefore, if the synthetic fuel content α of the fuel loaded into the fuel tank 123 at the time of vehicle operation (i.e., when the internal combustion engine 101 is driven) is used to estimate the content of ethanol fuel and gasoline, inaccurate values ​​may be obtained due to the effects of deterioration over time. Therefore, the fuel injection control device according to the second embodiment calculates the ethanol fuel content, synthetic fuel content, and gasoline content of the fuel during fuel supply.

[0177] Figure 12 This is a block diagram illustrating a functional configuration example of the ECU 109A according to the second embodiment.

[0178] ECU 109A except Figure 5 In addition to the fuel injection control device 127 and the combustion control unit 610 shown, the fuel increase determination unit 611 is also provided.

[0179] The fuel increase determination unit (fuel increase determination unit 611) determines the increase in fuel contained in the fuel storage section (fuel tank 123). For example, the fuel increase determination unit 611 determines the increase in fuel based on the fuel level sensor 99 (reference 123) due to fuel supply. Figure 1 The output signal is used to detect the supply of fuel to the fuel tank 123, that is, the increase of fuel in the fuel tank 123. When the fuel increase determination unit 611 detects the increase of fuel, it outputs information including the fuel increase detection and the amount of fuel increase to the fuel injection control device 127 (hereinafter referred to as "fuel increase determination result").

[0180] When a fuel increase determination result is input from the fuel increase determination unit 611, the fuel injection control device 127 begins the process described later. Figure 14 The process is as shown. Furthermore, when the fuel increase determination unit (fuel increase determination unit 611) determines that fuel has increased, the content of gasoline, ethanol and synthetic fuel contained in the fuel is calculated.

[0181] Figure 13 This is a diagram showing an example of time-series data of the fuel level in the tank output by the fuel level sensor 99. Figure 13 The horizontal axis represents time, and the vertical axis represents the fuel level in the tank.

[0182] At time T0, the fuel level in the tank is at its full capacity. Then, as time passes, the fuel level decreases. The main reasons for this decrease include vehicle movement and evaporation due to prolonged vehicle inactivity. When the fuel level drops to point F, where refueling is required, the driver supplies fuel to the fuel tank 123. Within a short period starting from the time the driver supplies fuel (Tf1), the fuel level rises from point F to Full. This means that an increase in the amount of fuel supplied to the fuel tank 123 has occurred.

[0183] Thus, if the slope of the straight line from point F of the fuel level in the tank at time Tf1 to the point where it becomes Full (the increase in fuel per unit time) is greater than a specified value, Figure 5 The fuel increase determination unit 611 shown determines that fuel has been supplied. Then, the fuel increase determination unit 611 outputs the fuel increase determination result to the fuel injection control device 127A. Upon receiving the fuel increase determination result, the fuel injection control device 127A begins... Figure 14 The treatment shown is for the estimated gasoline content.

[0184] Figure 14 This is a flowchart illustrating a method for estimating the content of ethanol fuel and synthetic fuel as the fuel level in the tank increases.

[0185] First, the fuel temperature estimation unit 601 determines whether the fuel level in the tank has increased (S30). If no fuel increase determination result is input from the fuel increase determination unit 611 to the fuel temperature estimation unit 601, the fuel level in the tank has not increased ("No" in S30), so the process of step S30 is repeated.

[0186] On the other hand, if a fuel increase determination result is input from the fuel increase determination unit 611 to the fuel temperature estimation unit 601, the fuel level in the tank increases (S30 indicates "Yes"), so the processing after step S31 is performed. The processing after step S31 is the same as that already referred to Figure 9 The flowcharts described are processed in the same way, so detailed explanations are omitted.

[0187] In this way, the estimated content of ethanol and synthetic fuels is calculated only when the fuel level in the tank increases, thus eliminating false detections of ethanol, synthetic fuel, and gasoline content in fuel that has deteriorated over time after being loaded into the fuel tank 123. Therefore, the ECU 109 can minimize the impact of fuel deterioration over time on the content calculation, controlling the internal combustion engine 101 to suppress the generation of harmful components.

[0188] Alternatively, the fuel increase determination unit 611 may be configured to be installed within the fuel injection control device 127.

[0189] [Variation Example]

[0190] In the above embodiments, full-lift control of valve body 201 was described as an example of fuel injection control. However, the fuel injection control according to the present invention can also be configured with half-lift control of valve body 201.

[0191] Furthermore, in the above embodiments, fuel properties are detected at two specified temperatures, but it is also possible to detect fuel properties at three or more specified temperatures. For example, when three specified temperatures are set, the difference ΔTdelay between the two valve closing delay times can be calculated. Therefore, the average value of the difference ΔTdelay between the two valve closing delay times can also be calculated and used as... Figure 11 The process is shown in step S37. Alternatively, the difference ΔTdelay between multiple valve closing delay times can be calculated, and a majority decision can be used to determine the difference ΔTdelay between valve closing delay times.

[0192] Furthermore, the ECU 109 and fuel injection control device 127 described in the above embodiments can be used not only in vehicles, but also for the control of internal combustion engines mounted on railways, construction machinery, generators, etc.

[0193] Furthermore, the fuel injection device 200 described in the above embodiments is a direct injection type fuel injection device that injects fuel directly into the combustion chamber 121, but it can also be a port type fuel injection device that injects fuel into the intake manifold 110. Additionally, the fuel injection control device 127 can be capable of calculating the synthetic fuel content of the fuel by detecting the valve-opening characteristics rather than the valve-closing characteristics of the fuel injection device 200.

[0194] Furthermore, the present invention is not limited to the above-described embodiments. As long as it does not depart from the spirit of the invention as described in the claims, various other application examples and modifications may also be adopted.

[0195] For example, the above embodiments are detailed and specific descriptions of the device configuration to illustrate the present invention in an easily understandable manner, and are not necessarily limited to embodiments having all the configurations described. Furthermore, other configurations may be added to, deleted from, or replaced in connection with a portion of the configuration of this embodiment.

[0196] Furthermore, while the designation of control lines and information lines is considered necessary for the description, not all control lines and information lines may necessarily be shown on the product. In reality, it can be assumed that almost all components are interconnected.

[0197] [Explanation of reference numerals in the attached figures]

[0198] 101: Internal combustion engine; 109: ECU; 123: Fuel tank; 127: Fuel injection control device; 200: Fuel injection device; 601: Fuel temperature estimation unit; 602: Fuel pressure acquisition unit; 603: Valve closing time calculation unit; 604: Theoretical air-fuel ratio calculation unit; 605: Time difference calculation unit; 606: Fuel content calculation unit; 607: Storage unit; 610: Combustion control unit; 611: Fuel increase judgment unit.

Claims

1. An internal combustion engine control device, characterized in that, have: The fuel temperature estimation unit estimates the fuel temperature of the fuel supplied to the combustion chamber. The fuel pressure acquisition unit acquires the fuel pressure of the fuel injected by the fuel injection device; The valve closing time calculation unit detects the valve closing of the fuel injection device at the moment when the fuel temperature reaches a specified temperature, and calculates the valve closing time of the fuel injection device. The valve closing delay time difference calculation unit calculates the valve closing delay time spent by the fuel injection device in the open state from the start of valve closing to the completion of valve closing based on multiple valve closing times calculated at different multiple specified temperatures. The difference of the valve closing delay time is calculated by normalizing the multiple valve closing delay times calculated for the multiple specified temperatures with the fuel pressure. The content calculation unit calculates the content of synthetic fuel in the fuel contained in the fuel containing unit based on characteristic data showing the relationship between the difference in the valve closing delay time and the content of synthetic fuel in the fuel. as well as The combustion control unit controls the internal combustion engine in such a way that the exhaust temperature of the exhaust gas discharged from the combustion chamber is above a threshold temperature, based on the synthetic fuel content.

2. The internal combustion engine control device according to claim 1, characterized in that, The fuel temperature estimation unit estimates the fuel temperature based on the waveform of the drive current driving the fuel injection device, and the resistance of the coil of the fuel injection device changes with the change of the fuel temperature.

3. The internal combustion engine control device according to claim 2, characterized in that, When the synthetic fuel content is greater than zero and the exhaust temperature is less than the threshold temperature, the combustion control unit advances the ignition timing of the fuel supplied to the combustion chamber to the knock limit.

4. The internal combustion engine control device according to claim 3, characterized in that, The fuel injection device is a direct injection type fuel injection device that injects the fuel directly into the combustion chamber. The internal combustion engine control device includes a stoichiometric air-fuel ratio calculation unit, which calculates the stoichiometric air-fuel ratio for combustion of fuel containing the synthetic fuel based on the minimum oxygen concentration obtained from an oxygen concentration detection unit that detects the oxygen concentration of the exhaust gas when the injection quantity of the fuel injected by the fuel injection device changes. The content calculation unit calculates the content of gasoline, ethanol and synthetic fuel in the fuel based on the difference between the theoretical air-fuel ratio and the valve closing delay time.

5. The internal combustion engine control device according to claim 3, characterized in that, It includes a fuel increase determination unit that determines an increase in the fuel contained in the fuel container. When the fuel increase determination unit determines that the fuel has increased, the content calculation unit calculates the content of gasoline, ethanol and synthetic fuel in the fuel.

6. The internal combustion engine control device according to claim 1, characterized in that, As different of the specified temperatures, at least two points are specified: the temperature at which the internal combustion engine is just started and the temperature at which the internal combustion engine is preheated.

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