Control device for fuel injection device

Abstract

The purpose of the present invention is to ensure both the combustion stability of an internal combustion engine and the suppression of PN during operation in a catalyst warm-up mode accompanying ignition delay. A control device (150) is a control device for a fuel injection device (101) that directly injects fuel into a cylinder (615) of an internal combustion engine (10) that operates in a catalyst warm-up mode in which a catalyst is warmed up by an ignition delay that delays an ignition timing to an expansion stroke. During operation in the catalyst warm-up mode, the control device (150) controls the fuel injection device (101) such that the fuel injection immediately before the ignition timing is performed during the expansion stroke among a plurality of fuel injections performed in one combustion cycle, and such that the injection amount of the fuel injection immediately before the ignition timing is reduced as the ignition timing is delayed.

Description

Technical Field

[0001] The present invention relates to a control device for controlling a fuel injection device of an internal combustion engine. Background Art

[0002] In recent years, with the tightening of exhaust gas regulations, internal combustion engines are required to reduce the total amount of unburned particulate matter (PM) and the number of unburned particulates (PN), hydrocarbons (HC), and NOx (nitrogen oxides) emitted during driving modes determined by fuel efficiency standards such as WLTC. PN and HC are generated when fuel injected from the fuel injection device adheres to the piston and wall surfaces within the cylinder. Reducing fuel adhesion is effective in suppressing PN and HC. PN tends to increase in the area immediately before ignition where the equivalence ratio of air to fuel is high, that is, in the cylinder where a fuel-rich mixture exists. HC is emitted in large quantities during engine startup when the catalyst is not activated. Ignition delay technology is known as a technique for achieving early catalyst activation. This ignition delay technology delays the ignition timing compared to idling after catalyst warm-up, increasing exhaust losses and raising exhaust temperature, thereby heating the catalyst early. The operating mode of an internal combustion engine that warms up the catalyst by delaying ignition is also called a "catalyst warm-up mode."

[0003] Ignition delay is the process of delaying the ignition timing from the optimal ignition timing for optimal fuel efficiency. Specifically, ignition delay is applied to the expansion stroke, which is the piston's transition from top dead center to bottom dead center at the end of the compression stroke. However, ignition delay can easily lead to combustion instability. To ensure ignition and improve combustion stability, a rich mixture must be created around the spark plug for ignition.

[0004] As a technique for enriching the fuel mixture around the spark plug at the time of ignition, an effective method is to form a cavity on the top surface of the piston, inject fuel during the compression stroke, and then swirl up the fuel mixture that enters the cavity, thereby collecting the fuel mixture around the spark plug. Another effective method for enriching the fuel mixture around the spark plug at the time of ignition is to place the fuel injection device near the spark plug (hereinafter also referred to as "center injection") and inject fuel just before the time of ignition.

[0005] Patent Document 1 discloses a technique in which, in order to ensure combustion stability, the more retarded the ignition timing of the expansion stroke is, the shorter the period from the end of fuel injection in the expansion stroke to the ignition timing is. Prior art literature Patent Literature

[0006] Patent Document 1: International Publication No. 2016 / 194184 Summary of the Invention Problems to be solved by the invention

[0007] The penetration (reaching distance) of the fuel spray injected from the fuel injection device is easily changed due to changes in the pressure in the cylinder. The later the ignition timing of the expansion stroke is delayed, the lower the pressure in the cylinder, and therefore the more likely the penetration of the spray is to become longer. When the penetration of the spray becomes longer, the spray easily diffuses into the cylinder, making it difficult to maintain the mixture around the spark plug at the time of ignition. In particular, in the case of a center injection type in which the fuel injection device is arranged near the spark plug, since the spark plug and the fuel injection position are close, in order to maintain the mixture around the spark plug at the time of ignition, it is necessary to inject fuel just before the ignition moment.

[0008] The further the ignition timing during the expansion stroke is delayed, the shorter the period from the end of fuel injection during the expansion stroke to the ignition timing. This results in the end of fuel injection being closer to the ignition timing. This shortens the time the spray can vaporize, making it more likely that the fuel will adhere to the piston and cylinder wall at the time of ignition, increasing PN. The technology disclosed in Patent Document 1 does not address this issue, leaving room for improvement.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to achieve both ensuring combustion stability and suppressing PN in an internal combustion engine during operation in a catalyst warm-up mode with ignition delay. Technical means to solve the problem

[0010] In order to solve the above-mentioned problem, the control device of the fuel injection device of the present invention is a control device of the fuel injection device that directly injects fuel into the cylinder of an internal combustion engine operating in a catalyst preheating mode. The catalyst preheating mode preheats the catalyst by delaying the ignition timing to the ignition delay of the expansion stroke. The control device of the fuel injection device is characterized in that, when operating in the catalyst preheating mode, the fuel injection device is controlled in the following manner: the fuel injection just before the ignition timing among the multiple fuel injections performed in one combustion cycle is performed in the expansion stroke, and the more delayed the ignition timing is, the smaller the injection amount of the fuel injection just before the ignition timing is. Effects of the Invention

[0011] According to the present invention, it is possible to achieve both ensuring combustion stability and suppressing PN in an internal combustion engine during operation in a catalyst warm-up mode with ignition delay. Other problems, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1This is a diagram showing a schematic configuration of an internal combustion engine including a fuel injection device. Figure 2 Yes means including Figure 1 A diagram showing a schematic configuration of an internal combustion engine system of an internal combustion engine shown. Figure 3 Yes Figure 1 The diagram shows a longitudinal sectional view of a fuel injection device and a schematic configuration diagram of a control device. Figure 4 yes Figure 3 An enlarged view of the movable parts and the area around the valve core. Figure 5 This diagram shows the relationship among the injection pulse output from the ECU, the drive voltage applied to the solenoid of the fuel injection device, the drive current supplied to the solenoid, and the displacement of the valve element and the movable element. Figure 6 This is a diagram explaining fuel injection control performed during operation in the catalyst warm-up mode. Figure 7 This is a projection diagram of the spray injected from the fuel injection device. Figure 8 This is a diagram showing the relationship between the penetration force of the spray injected from the fuel injection device and the pressure in the cylinder. Figure 9 This is a diagram illustrating a first embodiment of the fuel injection control immediately before the ignition timing during operation in the catalyst warm-up mode. Figure 10 This is a diagram illustrating a second embodiment of the fuel injection control immediately before the ignition timing during operation in the catalyst warm-up mode. Figure 11 This is a diagram showing the relationship among the injection pulse output from the ECU, the drive voltage applied to the solenoid of the fuel injection device, the drive current supplied to the solenoid, and the displacement of the valve body in the second embodiment. Figure 12 This is a diagram showing the relationship between the injection pulse width and the injection amount of the fuel injection device. Figure 13 This is a diagram showing the relationship between the ignition retard amount, fuel pressure, injection amount, engine speed, and the elapsed time from the start of the internal combustion engine. Figure 14 This is a diagram illustrating a third embodiment of the fuel injection control immediately before the ignition timing during operation in the catalyst warm-up mode. DETAILED DESCRIPTION

[0013] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. In addition, unless otherwise specified, configurations or functions denoted by the same reference numerals in each embodiment have the same configurations or functions in each embodiment, and their description will be omitted.

[0014] [Implementation Method 1] use Figures 1 to 9 The control device 150 of the fuel injection device 101 according to the first embodiment will be described. Figure 1 1 is a diagram showing a schematic configuration of an internal combustion engine 10 including a fuel injection device 101 .

[0015] The internal combustion engine 10 is a direct injection internal combustion engine that injects fuel directly into a cylinder 615. The internal combustion engine 10 includes a fuel injection device 101, an ignition plug 604, an intake port 607, an exhaust port 608, a cylinder 614, a piston 609, an intake valve 605, and an exhaust valve 610.

[0016] Spark plug 604 is positioned in the upper center of cylinder 614. Negative electrode 612 and positive electrode 613 of spark plug 604 are exposed in cylinder 615. Fuel injection device 101 is a center-injection fuel injection device positioned near spark plug 604 and injects fuel into cylinder 615. Alternatively, fuel injection device 101 may be a port-injection fuel injection device positioned above intake port 607 and injecting fuel into intake port 607.

[0017] The top surface 606 of the piston 609 on the spark plug 604 side has a flat surface. A partition wall 602 is installed on the intake port 607 to block the flow between the upper part 620 and the lower part 611 of the intake port 607. A valve 601 is provided upstream of the partition wall 602. The valve 601 can be controlled to open and close by the control device 150. Figure 1 , the valve 601 is shown to be closed.

[0018] In addition, Figure 1 In FIG, for the sake of convenience, the intake valve 605 and the exhaust valve 610 are shown. However, in a general direct injection internal combustion engine 10 equipped with two intake valves 605 and two exhaust valves 610, the intake valve 605 and the exhaust valve 610 are not shown in the cross-sectional view passing through the center axis of the cylinder 614. Figure 1 , the state of the spray in the cylinder 615 immediately after the fuel is injected from the fuel injection device 101 is shown ( D1 to D8 ).

[0019] Figure 2 Yes means including Figure 1 FIG. 2 is a diagram showing a schematic configuration of an internal combustion engine system 1 of an internal combustion engine 10 .

[0020] Air flowing into the cylinder 615 of the internal combustion engine 10 passes through an air filter 701, a supercharger chamber 704 of a turbine 702 equipped with a supercharger, an intercooler 705, a throttle valve 706, and an intake port 607. The air filter 701 has the function of removing dust from the air and preventing dust from being drawn into the cylinder 615, thereby suppressing wear of the cylinder 614 and the piston 609.

[0021] Turbines 702 are installed on the intake and exhaust sides of supercharger 704, connected by shaft 707. Turbines 702 rotate according to the exhaust gas flow rate, increasing the amount of air flowing into cylinders 615 to improve output. The air passing through supercharger 704 heats up due to the supercharging of turbine 702 and is then cooled by intercooler 705. The cooled air then flows into cylinders 615 through throttle valve 706, which adjusts the air flow, and air intake 607.

[0022] The air flowing into cylinder 615 mixes with the fuel injected from fuel injection device 101 to form a mixture, which is ignited and combusted by spark plug 604. This combustion pushes piston 609 downward, and the driving force of piston 609 is transmitted to crankshaft 710, causing exhaust valve 610 to open. Exhaust gas in cylinder 615 passes through exhaust port 608, rotates turbine 702 at the flow rate of the exhaust gas, and passes through catalyst device 703.

[0023] Exhaust gas passes through the catalytic device 703, where HC, NOx, and CO are reduced and then discharged to the exterior of the vehicle. The catalytic device 703 is comprised of, for example, a three-way catalyst. Using a catalyst such as palladium, rhodium, and platinum, the catalytic device 703 removes HC, NOx, and CO contained in the exhaust gas through reduction and oxidation reactions. However, the catalytic device 703 has a low reduction capability at low catalyst temperatures. In particular, under low-temperature conditions, such as during startup of the internal combustion engine 10, combustion is required to quickly warm up the catalyst.

[0024] Figure 3 Yes Figure 1 The fuel injection device 101 is shown in a longitudinal sectional view and a schematic configuration diagram of the control device 150. Figure 4 yes Figure 3 An enlarged view of the movable member 202 and the valve core 214.

[0025] The fuel injection of the fuel injection device 101 is controlled by the injection pulse output from the engine control unit (ECU) 104. The ECU 104 is provided with an A / D converter and an I / O port for acquiring signals from various sensors. In the ECU 104, signals representing the state of the internal combustion engine 10 are acquired from various sensors, and the pulse width (injection pulse width) of the injection pulse for controlling the injection amount of fuel injection, as well as the start and end times of the fuel injection are calculated according to the operating conditions or operating mode of the internal combustion engine 10. The injection pulse output from the ECU 104 is input to the drive circuit 103 via the signal line 110. The drive circuit 103 determines the drive current waveform supplied to the solenoid 205 of the fuel injection device 101 based on the instruction from the ECU 104, and supplies the drive current waveform to the solenoid 205 of the fuel injection device 101 according to the timing based on the injection pulse.

[0026] ECU 104 also communicates with drive circuit 103 via communication line 111. ECU 104 can switch the drive current waveform determined by drive circuit 103 or change the current and time settings based on the fuel pressure supplied to fuel injection device 101 and the operating conditions or mode of internal combustion engine 10. Drive circuit 103 can also be mounted as a component or substrate integral with ECU 104. In this embodiment, drive circuit 103 and ECU 104 are collectively referred to as "control device 150."

[0027] The fuel injection device 101 is a normally closed electromagnetic valve (electromagnetic fuel injection device). Figure 3 As shown, the fuel injection device 101 has a valve core 214 for closing or opening a fuel injection hole 219 for injecting fuel. When the solenoid 205 is not energized, the valve core 214 is moved in the valve closing direction ( Figure 3 In the closed valve state, the return spring 212 as the second spring applies force in the valve opening direction ( Figure 3 At this time, since the force of the spring 210 acting on the valve core 214 is greater than the force of the return spring 212, Figure 4 As shown, the end surface 302 of the movable member 202 contacts the valve core 214, and the movable member 202 is stationary. The valve core 214 and the movable member 202 are configured to be relatively displaceable and are internally housed in the nozzle holder 201. The nozzle holder 201 has an end surface 303 that serves as a spring seat for the return spring 212. The force of the spring 210 is adjusted during assembly by the amount of pressure applied to the spring pressure plate 224 fixed to the inner surface of the stator (core) 207.

[0028] In addition, the fuel injection device 101 forms a magnetic circuit through the stator 207, the movable part 202, the nozzle holder 201 and the housing 203. A gap 301 is provided between the movable part 202 and the stator 207. A yoke 211 is formed in a portion of the nozzle holder 201 corresponding to the gap 301 between the movable part 202 and the stator 207. The solenoid 205 is mounted on the outer peripheral side of the nozzle holder 201 in a state of being wound on the winding bobbin 204. A guide rod 215 is provided near the top end portion of the valve seat 218 side of the valve core 214 in a manner fixed to the nozzle holder 201. The valve core 214 is oriented in the valve axis direction ( Figure 3 A throttle hole 216 having a valve seat 218 and a fuel injection hole 219 is fixed to the top end of the nozzle holder 201, and the internal space (fuel passage) between the movable part 202 and the valve core 214 is sealed from the outside.

[0029] The fuel supplied to the fuel injection device 101 is supplied from the rail piping provided upstream of the fuel injection device 101, flows to the top end of the valve core 214 through the fuel passage hole 231, and seals the fuel through the top end portion of the valve seat 218 side of the valve core 214 and the valve seat 218. In the closed valve state, the fuel pressure generates a pressure difference between the upper and lower parts of the valve core 214, and the pressure difference force obtained by multiplying the fuel pressure by the pressure area of ​​the inner diameter of the position of the valve seat 218, and the force of the spring 210, push the valve core 214 in the valve closing direction. When the driving current is supplied to the solenoid 205 from the closed valve state, a magnetic field is generated in the magnetic circuit, and the magnetic flux passes between the stator 207 and the movable part 202, exerting a magnetic attraction on the movable part 202. At the moment when the magnetic attraction acting on the movable part 202 exceeds the pressure difference force and the force of the spring 210, the movable part 202 begins to move in the direction of the stator 207 ( Figure 3 ) displacement above.

[0030] After the valve core 214 begins the valve opening action, the movable part 202 moves to the position of the stator 207 and collides with the stator 207. After the movable part 202 collides with the stator 207, the movable part 202 receives the reaction force from the stator 207 and rebounds (rebounds). However, due to the magnetic attraction acting on the movable part 202, the movable part 202 is attracted by the stator 207 and eventually stops. At this time, since the return spring 212 acts strongly on the movable part 202 in the direction of the stator 207, the time until the rebound converges can be shortened. Due to the small rebound, the time for the gap 301 between the movable part 202 and the stator 207 to increase is shortened, and stable operation can be performed even for a smaller injection pulse width.

[0031] Having thus completed the valve opening operation, movable member 202 and valve core 214 remain stationary in the valve-open state. In this state, a gap is created between valve core 214 and valve seat 218, allowing fuel to be injected from fuel injection hole 219. Fuel flows downstream through the center hole provided in stator 207 and fuel passage hole 305 provided in movable member 202.

[0032] When the power to solenoid 205 is cut off, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attraction also disappears. By eliminating the magnetic attraction acting on movable element 202, movable element 202 and valve core 214 are pressed back to the closed valve position in contact with valve seat 218 by the force of spring 210 and the pressure difference.

[0033] When the valve core 214 closes the valve from the open state, after the valve core 214 contacts the valve seat 218, the movable part 202 separates from the valve core 214 and the stator 207 and moves in the valve closing direction. After moving for a certain period of time, it returns to the initial position of the valve closing state through the return spring 212.

[0034] At the moment the valve core 214 collides with the valve seat 218 and completes valve closing, the movable member 202 separates from the valve core 214. Thus, the fuel injection device 101 can reduce the mass of the movable member at the moment the valve core 214 collides with the valve seat 218 by the mass of the movable member 202. Consequently, the fuel injection device 101 can reduce the collision energy when the valve core 214 collides with the valve seat 218, thereby suppressing the rebound of the valve core 214 caused by the collision between the valve core 214 and the valve seat 218.

[0035] In the fuel injection device 101, the valve element 214 and the movable element 202 undergo relative displacement at the moment of collision between the movable element 202 and the stator 207 during valve opening, and at the moment of collision between the valve element 214 and the valve seat 218 during valve closing. This allows the fuel injection device 101 to suppress rebound of the movable element 202 relative to the stator 207 and rebound of the valve element 214 relative to the valve seat 218.

[0036] Figure 5 This diagram shows the relationship among the injection pulse output from the ECU 104 , the drive voltage applied to the solenoid 205 of the fuel injection device 101 , the drive current supplied to the solenoid 205 , and the displacement amounts of the valve element 214 and the movable element 202 .

[0037] When an injection pulse is input to the drive circuit 103, the drive circuit 103 applies a high voltage 401 to the solenoid 205 from a voltage source VH that has been boosted to a voltage higher than the battery voltage VB, thereby starting to supply a drive current to the solenoid 205. When the drive current reaches a peak current value Ipeak preset by the ECU 104, the drive circuit 103 stops applying the high voltage 401. Consequently, the drive current supplied to the solenoid 205 is returned to the voltage source VH due to the back electromotive force generated by the inductance of the solenoid 205, causing it to rapidly decrease from the peak current value Ipeak, as shown by current 402. When the drive current falls below a specified current value 404, the drive circuit 103 controls the solenoid 205 so that the specified current 403 is maintained while the battery voltage VB is applied to the solenoid 205.

[0038] As the fuel pressure supplied to the fuel injection device 101 increases, the differential pressure acting on the valve core 214 increases, prolonging the time it takes for the valve core 214 to reach the target opening. As a result, the target opening may be reached later than the peak current value Ipeak. If the drive current is rapidly reduced, as in current 402, the magnetic attraction acting on the movable element 202 also decreases rapidly, causing the valve core 214 to become unstable, and in some cases, the valve may begin to close without being energized.

[0039] During the transition period from peak current value Ipeak to current 403, drive circuit 103 directs the current generated by the back electromotive force toward the ground potential, regenerating the current within the circuit. This reduces the applied voltage to solenoid 205 to approximately 0V, allowing current 402 to gradually decrease. This allows drive circuit 103 to gradually reduce the magnetic attraction acting on movable element 202, stabilizing the operation of valve element 214 under high fuel pressure. Consequently, drive circuit 103 can suppress variations in injection amount.

[0040] The fuel injection device 101 is driven by this driving current distribution. From the time high voltage 401 is applied until the peak current value Ipeak is reached, the movable member 202 and the valve core 214 begin to displace at time t41. Subsequently, the movable member 202 and the valve core 214 reach a predetermined maximum height position. At time t42, when the movable member 202 reaches the maximum height position, it collides with the stator 207 and rebounds. Because the valve core 214 is configured to be displaceable relative to the movable member 202, it separates from the movable member 202, causing the displacement of the valve core 214 to exceed the maximum height position and overshoot. Subsequently, the magnetic attraction generated by the current 403 and the valve-opening force of the return spring 212 cause the movable member 202 to displace in the valve-opening direction, coming to rest at the maximum height position at time t44. The valve core 214 seats on the movable member 202 at time t43 and displaces in the valve-opening direction, coming to rest at the maximum height position at time t44, thus entering the valve-open state. In the case of a fuel injection device in which the valve core 214 and the movable part 202 are integrally formed, the displacement of the valve core 214 will not be greater than the maximum height position, and the displacements of the movable part 202 and the valve core 214 are equal after reaching the maximum height position (after time t42).

[0041] In addition, the so-called height position of the valve core 214 and the movable part 202 refers to the position of the valve core 214 and the movable part 202 in the valve-closing state with the valve core 214 seated on the valve seat 218 as the reference position, and the position of the valve core 214 and the movable part 202 in the valve-opening direction from this reference position. In other words, the displacement of the valve core 214 and the movable part 202 is the displacement of the valve core 214 and the movable part 202 from this reference position. The maximum height position of the valve core 214 and the movable part 202 is predetermined by the position of the stator 207 with which the movable part 202 collides. The displacement of the valve core 214 is also referred to as the lift of the valve core 214. In this embodiment, the displacement of the valve core 214 when the valve core 214 reaches the maximum height position is also referred to as the maximum lift.

[0042] Figure 6 This is a diagram explaining fuel injection control performed during operation in the catalyst warm-up mode.

[0043] Figure 6 The horizontal axis represents the angle of the crankshaft 710. Figure 6 In the intake stroke, the angle of the crankshaft 710 at the top dead center (TDC) of the piston 609 is -360 degrees, the angle of the crankshaft 710 at the bottom dead center (BDC) of the piston 609 is -180 degrees, and the angle of the crankshaft 710 at the TDC of the piston 609 in the compression stroke is 0 degrees. Figure 6 The dotted line represents the lift amount of the intake valve 605. Figure 6 The dotted line represents the average value of the turbulent velocity 615 in the cylinder. Figure 6 The solid line represents the tumble flow within the cylinder 615. Figure 6 The hatched portion indicates a period during which fuel injection is performed.

[0044] When operating in the catalyst warm-up mode, the control device 150 controls the fuel injection device 101 so as to perform multiple fuel injections in one combustion cycle. In this case, the control device 150 may also control the fuel injection device 101 so as to perform two or more fuel injections in the intake stroke 802 and one or more fuel injections in the expansion stroke 804. Figure 6 In the example of FIG, the control device 150 controls the fuel injection device 101 so as to perform two fuel injections in the intake stroke 802 and one fuel injection in the expansion stroke 804. Figure 6 In the example shown, the control device 150 delays the ignition timing to time t86 within the expansion stroke 804. Furthermore, ignition timing t86 varies depending on the catalyst temperature increase requirement and environmental conditions and is preset. The control device 150 needs to control the fuel injection device 101 to appropriately inject fuel at the desired ignition timing t86.

[0045] Specifically, at time t81 when piston 609 reaches TDC, that is, just before or at the same time as exhaust valve 610 closes, control device 150 starts opening intake valve 605, allowing air to flow into cylinder 615. At time t82, between the start of intake valve 605 opening and the moment it reaches maximum lift, control device 150 starts first fuel injection 805. Then, at time t83, before piston 609 reaches BDC, control device 150 starts second fuel injection 806. After piston 609 reaches BDC and enters compression stroke 803, and then reaches TDC, control device 150 starts third fuel injection 807 at time t84, just before ignition timing t86. During this third fuel injection 807, the control device 150 controls the start time t84 and end time t85 of fuel injection so that the spray injected from the fuel injection device 101 forms a rich mixture around the spark plug 604 that is richer than the theoretical air-fuel ratio (stoichiometric ratio). The control device 150 sets the fuel split ratio between the intake stroke 802 and the expansion stroke 804 so that the fuel in the intake stroke 802 is greater. For example, the control device 150 may set the ratio to approximately 6:4, 7:3, 8:2, or 9:1 for the intake stroke 802:expansion stroke 804.

[0046] At time t86, when a rich mixture is formed between and around the negative electrode 612 and the positive electrode 613 of the spark plug 604, the control device 150 performs ignition to ignite the mixture. To maintain the mixture around the spark plug 604 at ignition time t86, it is preferable to bring the end time t85 of the fuel injection immediately before ignition time t86 closer to ignition time t86. Specifically, the control device 150 controls the fuel injection device 101 so that the later the ignition time t86 is, the shorter the period from the end time t85 of the fuel injection immediately before ignition time t86 to ignition time t86 becomes.

[0047] Figure 7 It is a projection diagram of the spray injected from the fuel injection device 101 . Figure 7 Indicates the direction of the fuel injection device 101 Figure 1 The projection diagram of the spray at the AA' cross section of the spray is shown.

[0048] Fuel injection device 101 is a multi-hole type fuel injection device in which fuel injection hole 219 is composed of a plurality of holes. The spray injected from fuel injection device 101 is composed of, for example, eight sprays: sprays D1 and D2 injected toward spark plug 604, sprays D3 and D4 injected toward piston 609, and sprays D5 to D8 injected toward intake valve 605 relative to sprays D3 and D4.

[0049] The concept of this embodiment is to form a mixture between and around the negative electrode 612 and positive electrode 613 of spark plug 604 using sprays D1 and D2 during fuel injection immediately before ignition. Fuel injection device 101 injects sprays D1 and D2 so that they sandwich negative electrode 612 and positive electrode 613. This allows fuel injection device 101 to form a mixture richer than stoichiometric between and around negative electrode 612 and positive electrode 613, ensuring combustion stability.

[0050] Figure 8 This is a diagram showing the relationship between the penetration force of the spray injected from the fuel injection device 101 and the pressure in the cylinder 615 .

[0051] The penetration of the spray injected from the fuel injection device 101 is easily changed due to the change of the pressure in the cylinder 615. Figure 8 As shown, the lower the pressure in the cylinder 615 is, the longer the spray penetration is. When the spray penetration is longer, the spray is easy to spread into the cylinder 615, and it is difficult to maintain the mixed gas around the spark plug 604 at the ignition time.

[0052] Figure 9 This is a diagram illustrating a first embodiment of the fuel injection control immediately before the ignition timing during operation in the catalyst warm-up mode. Figure 9 (a) indicates a small ignition delay. Figure 9 (b) shows the case where the ignition delay is large. Figure 9 The dotted line represents the pressure in the cylinder 615. Figure 9 (a) and Figure 9 In (b), the load on the internal combustion engine 10 during operation in the catalyst warm-up mode is made constant.

[0053] The ignition delay amount refers to the amount by which the ignition timing is delayed from the optimal ignition timing for optimal fuel efficiency. The larger the ignition delay amount, the greater the ignition timing delay.

[0054] like Figure 9 As shown in (a), when the ignition delay is small, the pressure in cylinder 615 is high because the start time t91 of fuel injection is close to TDC. In this case, the spray's penetration is difficult to increase, making it difficult for the air-fuel mixture to diffuse into cylinder 615. In this case, control device 150 increases the penetration of the spray by extending fuel injection period 901, that is, by increasing the injection amount, thereby facilitating the spray's diffusion into cylinder 615. This allows control device 150 to easily maintain the air-fuel mixture around spark plug 604 at ignition time t93.

[0055] like Figure 9 As shown in (b), when the ignition delay is large, the pressure ratio of the cylinder 615 at the start time t94 of the fuel injection is Figure 9 In case (a), the fuel injection pressure is low. In this case, the spray's penetrating force tends to be longer, making it easier for the mixture to diffuse into cylinder 615. In this case, control device 150 shortens fuel injection period 902, that is, reduces the injection amount, thereby reducing the spray's penetrating force and suppressing the diffusion of the spray. This allows control device 150 to easily maintain the mixture around spark plug 604 at ignition time t96. As a result, control device 150 can stably ignite the mixture, thereby ensuring combustion stability.

[0056] Furthermore, in Figure 9 In the case shown in (b), since the penetration of the spray tends to be longer, the fuel tends to adhere to the piston 609 and the wall surface in the cylinder 615, and PN tends to increase. However, since the control device 150 reduces the injection amount, it is possible to suppress the adhesion of fuel to the piston 609 and the like, and thus suppress PN.

[0057] In this way, the control device 150 controls the fuel injection device 101 so that the more delayed the ignition timing is, the smaller the injection amount of fuel injected immediately before the ignition timing is. As a result, the control device 150 can maintain the air-fuel mixture around the spark plug 604 at the ignition timing and suppress the adhesion of fuel to the piston 609 and other parts. Therefore, the control device 150 can achieve both ensuring combustion stability and suppressing PN.

[0058] In addition, in Figure 9 (a) and Figure 9 In cases where the injection amount of the fuel injection performed immediately before ignition during the expansion stroke varies depending on the ignition retard amount, as shown in (b), control device 150 can adjust the injection amount of the fuel injection during the intake stroke to maintain the air-fuel ratio at the stoichiometric ratio or a constant value. Specifically, due to the large ignition retard amount, while reducing the injection amount of the fuel injection performed immediately before ignition during the expansion stroke, control device 150 controls fuel injection device 101 so that the injection amount of the fuel injection performed during the intake stroke is increased in response to this reduction in injection amount. This allows control device 150 to maintain the air-fuel ratio at the stoichiometric ratio or a constant value while suppressing PN, thereby reliably ensuring combustion stability.

[0059] In addition, when two or more fuel injections are performed during the intake stroke, the control device 150 may control the fuel injection device 101 so that the injection amount of the fuel injection performed after the second intake stroke is increased. For example, the control device 150 may extend the fuel injection period or increase the injection pulse width so that the fuel injection performed after the second intake stroke (for example Figure 6 The injection quantity of the fuel injection 806) is increased by the amount by which the injection quantity performed immediately before the ignition moment in the expansion stroke is reduced.

[0060] The first fuel injection during the intake stroke (e.g. Figure 6 Compared with the fuel injection 805 of the intake stroke, the second fuel injection (eg Figure 6 The mixture of the fuel injection 806 (in the second intake stroke) is difficult to diffuse. Therefore, increasing the injection amount of the second fuel injection during the intake stroke can further enhance the effect of forming a rich mixture over a wide area within the cylinder 615, thereby ensuring combustion stability. Furthermore, compared to the first fuel injection during the intake stroke, the injection timing of the second fuel injection during the intake stroke is later, so the time for air and fuel to mix is ​​longer, making it difficult for the air and fuel to mix. Therefore, increasing the injection amount of the second fuel injection during the intake stroke can further enhance the effect of easily forming a rich mixture over a wide area around the spark plug 604, thereby ensuring combustion stability.

[0061] [Implementation Method 2] use Figures 10 to 12 Next, the control device 150 of the fuel injection device 101 according to the second embodiment will be described. In the control device 150 of the fuel injection device 101 according to the second embodiment, descriptions of the same configuration and operation as those of the first embodiment will be omitted.

[0062] Figure 10 This is a diagram illustrating a second embodiment of the fuel injection control immediately before the ignition timing performed during operation in the catalyst warm-up mode. Figure 10 (a) indicates a small ignition delay. Figure 10 (b) shows the case where the ignition delay is large. Figure 10 The dotted line represents the pressure in the cylinder 615. Figure 10 (a) and Figure 10 In (b), the load on the internal combustion engine 10 during operation in the catalyst warm-up mode is made constant.

[0063] In addition to the fuel injection control of Embodiment 1, which controls the fuel injection device 101 so that the injection amount of the fuel injected immediately before the ignition timing decreases as the ignition delay increases, the control device 150 of Embodiment 2 further performs the following fuel injection control. Specifically, the control device 150 of Embodiment 2 controls the fuel injection device 101 so that the period from the end time of the fuel injection immediately before the ignition timing to the ignition timing decreases as the ignition delay increases, that is, the more delayed the ignition timing becomes. Specifically, the control device 150 controls the fuel injection device 101 so that, when the ignition delay is large, the period 1202 from the end time t25 of the fuel injection to the ignition timing t96 is shorter than the period 1201 from the end time t23 of the fuel injection to the ignition timing t93 when the ignition delay is small.

[0064] When the ignition retard amount is large, the pressure in the cylinder 615 at the start time t24 of fuel injection is lower than when it is small, so the penetration of the spray is prolonged, making it easier for the air-fuel mixture to diffuse into the cylinder 615. As a result, it is difficult to maintain a rich air-fuel mixture around the spark plug 604 at the ignition time t96.

[0065] The control device 150 of the second embodiment shortens the period 1202 from fuel injection end time t25 to ignition time t96 as the ignition delay increases, thereby stably forming a rich mixture around the spark plug 604 and ensuring combustion stability. However, if this period 1202 is too short, the fuel injection end time t25 approaches ignition time t96, shortening the time the spray can vaporize, potentially causing the mixture to ignite before the spray vaporizes. However, the control device 150 of the second embodiment can shorten the time required for spray vaporization by reducing the injection amount. This reduces fuel adhesion to the piston 609 and other components at ignition time t96, enabling PN to be suppressed while ensuring combustion stability. Furthermore, by suppressing extremely rich mixtures with an equivalence ratio of 2 or greater, for example, PN can be further suppressed.

[0066] Figure 11 This diagram shows the relationship among the injection pulse output from the ECU 104 , the drive voltage applied to the solenoid 205 of the fuel injection device 101 , the drive current supplied to the solenoid 205 , and the displacement of the valve element 214 in the second embodiment. Figure 11 is with Figure 5 The corresponding figure. Figure 11 The dotted line indicates Figure 5 The waveforms of the embodiment 1 shown are Figure 11 The solid lines represent the waveforms of the second embodiment.

[0067] The control device 150 of the second embodiment is configured to control the valve element 214 to be in a state of being ... Figure 11 The valve element 214 is controlled so that the displacement transition 1301 shown in FIG. Specifically, the control device 150 controls the valve element 214 so that, during fuel injection immediately before ignition, the valve element 214 is displaced within a range of height positions lower than the maximum height position. In other words, the control device 150 of Embodiment 2 controls the lift amount of the valve element 214 during fuel injection immediately before ignition within a range smaller than a predetermined maximum lift amount.

[0068] Furthermore, control device 150 controls fuel injection device 101 so that the greater the ignition delay, that is, the more delayed the ignition timing, the smaller the lift of valve core 214. By reducing the lift of valve core 214, the pressure loss of the fuel flowing between valve core 214 and valve seat 218 increases, slowing the flow rate of the spray. Therefore, even if the ignition timing is delayed and the pressure in cylinder 615 decreases at the time of fuel injection, the mixture can be easily formed near spark plug 604, ensuring combustion stability.

[0069] Furthermore, the greater the ignition retard amount, the smaller the control device 150 reduces the lift of the valve core 214. However, when the ignition retard amount is small, the control device 150 may be controlled so that the valve core 214 reaches its maximum height position. As a result, the upper limit of the lift of the valve core 214 can be greatly changed according to the ignition retard amount, making it easier to maintain the air-fuel mixture around the spark plug 604 in response to changes in the pressure in the cylinder 615 caused by the ignition retard amount.

[0070] Figure 12 1 is a diagram showing the relationship between the injection pulse width Ti and the injection amount of the fuel injection device 101 . Figure 12 Indicates use Figure 11 Injection amount characteristics Q141 in the case of each waveform shown.

[0071] If the injection pulse width Ti does not reach the specified time, and the combined force of the magnetic attraction force acting on the movable member 202 and the valve opening direction as the return spring 212 does not exceed the force of the spring 210, the valve core 214 does not start to open the valve, and fuel is not injected. Alternatively, if the movable member 202 does not ensure the magnetic attraction force required for sliding in the gap 301 even if it starts to move, and the movable member 202 does not contact the valve core 214, the valve core 214 does not start to open the valve, and fuel is not injected. In addition, when the injection pulse width Ti is short, for example, Figure 12 In the case of point 1401, movable member 202 collides with valve element 214, causing valve element 214 to separate from valve seat 218 and begin displacement. However, since valve closing begins before valve element 214 reaches its maximum height, the injection amount decreases relative to a single-dot chain line 1420 extrapolated from a linear region 1430 in which the relationship between injection pulse width Ti and injection amount is a substantially straight line.

[0072] Furthermore, with the injection pulse width Ti at point 1402, valve closing begins immediately after valve core 214 reaches its maximum height, and the trajectory of valve core 214 exhibits parabolic motion. In this case, valve core 214 possesses a large amount of kinetic energy in the valve-opening direction, and the magnetic attraction acting on movable element 202 is strong. Therefore, the time required for valve closing increases, and the injection volume increases compared to that shown by the dot-dash line 1420.

[0073] In this embodiment, in the injection amount characteristic Q141, a region 1440 in which the movable member 202 does not collide with the stator 207, that is, the valve element 214 does not reach its maximum height position and the trajectory of the valve element 214 is a parabolic motion, is also referred to as a "half-lift region 1440." In this embodiment, in the injection amount characteristic Q141, a region 1441 in which the movable member 202 collides with the stator 207, that is, the valve element 214 reaches its maximum height position, is also referred to as a "full-lift region 1441." Figure 11 The solid line indicates that the valve core 214 is displaced in the half-lift region 1440 .

[0074] The injection pulse width Ti at point 1403 indicates that valve closing begins when the rebound of valve element 214 caused by the collision between movable element 202 and stator 207 reaches its maximum. Consequently, the reaction force from the collision between movable element 202 and stator 207 acts on movable element 202, shortening the valve closing delay time from the termination of the injection pulse to the closing of valve element 214. Consequently, the injection amount is less than that indicated by the dot-dash line 1420.

[0075] The injection pulse width Ti at point 1404 represents the situation where valve closing begins just after the rebound of the valve core 214 converges. For injection pulse widths Ti greater than point 1404, the injection amount increases approximately linearly as the injection pulse width Ti increases. In the region from the start of fuel injection to the injection pulse width Ti at point 1404, even if the valve core 214 has not yet reached its maximum height position or even if the valve core 214 has reached its maximum height position, the rebound of the valve core 214 is unstable, and thus the injection amount fluctuates. Fuel injection performed immediately before ignition during the expansion stroke has a significant impact on combustion stability if the injection amount fluctuates. Therefore, the control device 150 can adjust the injection pulse width Ti so that the valve core 214 is displaced within the half-lift region 1440 or the linear region 1430. As a result, the control device 150 can more easily ensure combustion stability.

[0076] [Implementation Method 3] use Figure 13 and Figure 14 The control device 150 of the fuel injection device 101 according to Embodiment 3 will be described. In the control device 150 of the fuel injection device 101 according to Embodiment 3, descriptions of the same configurations and operations as those of Embodiments 1 and 2 will be omitted.

[0077] Figure 13 : is a graph showing the relationship between the ignition delay amount, fuel pressure, injection amount, the rotation speed of the internal combustion engine 10, and the elapsed time from the start of the internal combustion engine 10. Figure 13 In FIG, the case where the ignition delay amount is 0 means that the ignition timing is set to the time of TDC of the compression stroke. Figure 13 In the case where the ignition delay amount is a retarded angle, it means that the ignition timing is set to the retarded angle side of TDC in the compression stroke. Figure 13 In FIG. 1 , the case where the ignition retard amount is the advanced angle means that the ignition timing is set on the advanced angle side of TDC in the compression stroke.

[0078] During a startup period 1501, from start time t51 of the internal combustion engine 10 until combustion stabilizes, the control device 150 sets the ignition retard amount to the advanced angle side (ignition timing is advanced relative to TDC of the compression stroke), thereby achieving stable combustion and raising the temperature in the cylinder 615. After time t52, when the engine 10 is complete, the control device 150 shifts the ignition retard amount to the retarded angle side (ignition timing is retarded relative to TDC of the compression stroke), thereby increasing exhaust losses and raising the temperature of the exhaust gas discharged from the cylinder 615 to the exhaust port 608. As a result, the control device 150 can activate the catalyst of the catalyst device 703 at an early stage, thereby reducing HC.

[0079] Furthermore, during the startup period 1501, the transition period 1502 until the ignition retard amount shifts to the retarded side, and the catalyst warm-up mode operation period 1503 (the period after the ignition retard amount shifts to the retarded side), there is a transition period 1504 in which the fuel pressure (hereinafter also referred to as "fuel pressure") supplied to the fuel injection device 101 changes (increases). The fuel pump that supplies high-pressure fuel to the fuel injection device 101 supplies high-pressure fuel to the fuel pipe connected to the fuel injection device 101 through the compression action of a plunger synchronized with the camshaft of the internal combustion engine 10. Therefore, when the speed of the internal combustion engine 10 is low, it takes a certain amount of time for the fuel pressure to reach the target pressure 1505. Specifically, the transition period 1504 in which the fuel pressure changes occurs between the startup time t51 of the internal combustion engine 10 and the completion time t56 of the catalyst warm-up. In particular, in hybrid vehicles (HEV, SHEV, PHEV) equipped with the internal combustion engine 10 and an electric motor, the frequency of starting and stopping the internal combustion engine 10 increases compared to vehicles equipped with only the internal combustion engine 10. Therefore, the fuel pressure when the internal combustion engine 10 is started frequently changes.

[0080] Figure 14 This is a diagram illustrating a third embodiment of the fuel injection control immediately before the ignition timing performed during operation in the catalyst warm-up mode. Figure 14 (a) indicates the case of low fuel pressure. Figure 14 (b) shows the case where the fuel pressure is high. Figure 14 (a) and Figure 14 In (b), the ignition retard amount is made the same.

[0081] When the fuel pressure is low, the spray's penetrating force is reduced, making it difficult for the spray to spread within the cylinder 615. When the fuel pressure is high, the spray's penetrating force is increased, making it easier for the spray to spread within the cylinder 615. Therefore, when the fuel pressure changes, it is preferable to adjust at least one of the end timing and injection amount of fuel injection immediately before ignition.

[0082] The control device 150 of the third embodiment controls the fuel injection device 101 so that the lower the fuel pressure supplied to the fuel injection device 101 at the start time of the fuel injection immediately before the ignition timing, the longer the period from the end time of the fuel injection immediately before the ignition timing to the ignition timing. Furthermore, the control device 150 controls the fuel injection device 101 so that the lower the fuel pressure, the greater the injection amount of the fuel injection immediately before the ignition timing.

[0083] Specifically, control device 150 controls the fuel injection system so that, when fuel pressure is low, the period 1601 from the end time t62 of fuel injection to the ignition time t63 is longer than the period 1602 from the end time t65 of fuel injection to the ignition time t66 when fuel pressure is high. This allows control device 150 to easily diffuse the spray within cylinder 615, allowing the air-fuel mixture to easily reach the vicinity of spark plug 604, thereby ensuring combustion stability. Furthermore, control device 150 controls the fuel injection period 906 when fuel pressure is low to be longer than the fuel injection period 907 when fuel pressure is high. This increases the penetration of the spray, facilitating diffusion, allowing the air-fuel mixture to easily reach the vicinity of spark plug 604, further ensuring combustion stability.

[0084] On the other hand, the control device 150 of the third embodiment controls the fuel injection device 101 so that the higher the fuel pressure supplied to the fuel injection device 101 at the start time of the fuel injection immediately before the ignition timing, the smaller the injection amount of the fuel injection immediately before the ignition timing. Furthermore, the control device 150 controls the fuel injection device 101 so that the higher the fuel pressure, the shorter the period from the end time of the fuel injection immediately before the ignition timing to the ignition timing.

[0085] Specifically, control device 150 controls the fuel injection period 907 when fuel pressure is high to be shorter than fuel injection period 906 when fuel pressure is low. This reduces the penetration of the spray and suppresses its diffusion, thereby preventing fuel from adhering to piston 609 and other components, ensuring combustion stability while also suppressing PN. Furthermore, control device 150 controls the fuel injection period 1602 from the end of fuel injection t65 to ignition t66 when fuel pressure is high to be shorter than the period 1601 from the end of fuel injection t62 to ignition t63 when fuel pressure is low. This prevents the spray from spreading within cylinder 615, allowing the mixture to be easily maintained around spark plug 604 and preventing fuel from adhering to piston 609 and other components, thus achieving a high degree of balance between ensuring combustion stability and suppressing PN.

[0086] In this way, control device 150 can adjust at least one of the end timing and injection amount of fuel injection immediately before ignition based on changes in fuel pressure. Therefore, even under conditions of fuel pressure fluctuations, a mixture can be formed around spark plug 604, ensuring combustion stability. While adjusting the end timing and injection amount of fuel injection immediately before ignition is effective alone, adjusting both allows for greater control over the diffusion of the spray within cylinder 615, further enhancing combustion stability and PN suppression.

[0087] Furthermore, in hybrid vehicles (HEVs, SHEVs, and PHEVs) equipped with internal combustion engine 10 and an electric motor, the fuel pressure fluctuates frequently when starting internal combustion engine 10, as described above. Therefore, the control device 150 of the third embodiment is particularly effective when applied to hybrid vehicles, further enhancing the combustion stability and PN suppression effects of hybrid vehicles.

[0088] Furthermore, the present invention is not limited to the above-described embodiments and includes various variations. For example, the above-described embodiments are detailed for the purpose of easily understanding the present invention and are not necessarily limited to embodiments having all the described configurations. Furthermore, configurations from other embodiments may replace portions of the configurations of certain embodiments, and configurations from other embodiments may be added to the configurations of certain embodiments. Furthermore, other configurations may be added, deleted, or replaced with portions of the configurations of each embodiment.

[0089] Furthermore, each of the aforementioned components, functions, processing units, or the like may also be implemented in hardware, for example, by designing a portion or all of them using an integrated circuit. Furthermore, each of the aforementioned components or functions may also be implemented in software by having a processor interpret and execute a program that implements the respective function. Information such as programs, tables, or files that implement the respective functions may be stored in a storage device such as a memory, a hard disk, or an SSD (solid state drive), or a recording medium such as an IC card, an SD card, or a DVD.

[0090] In addition, the control lines and information lines are those considered necessary for the purpose of explanation, and do not necessarily represent all control lines and information lines in the product. In reality, it can be assumed that almost all components are connected to each other. Explanation of symbols

[0091] 10 ...internal combustion engine, 101 ...fuel injection device, 150 ...control device, 214 ...valve core, 219 ...fuel injection hole, 615 ...inside the cylinder.

Claims

1. A control device for a fuel injection device that directly injects fuel into a cylinder of an internal combustion engine operating in a catalyst warm-up mode, wherein the catalyst warm-up mode warms up a catalyst by retarding ignition timing to ignition delay in an expansion stroke, the control device for the fuel injection device being characterized by: When operating in the catalyst preheating mode, the fuel injection device is controlled in the following manner: the fuel injection just before the ignition timing among the multiple fuel injections performed in one combustion cycle is performed in the expansion stroke, and the more delayed the ignition timing is, the smaller the injection amount of the fuel injection just before the ignition timing is.

2. The control device for the fuel injection device according to claim 1, characterized in that: The fuel injection device is controlled so that the more retarded the ignition timing is, the shorter the period from the end timing of the fuel injection immediately before the ignition timing to the ignition timing is.

3. The control device for the fuel injection device according to claim 1, characterized in that: The fuel injection device is controlled in such a manner that fuel injection is performed two or more times in an intake stroke, and an injection amount of the fuel injection performed second and subsequent times in the intake stroke is increased in accordance with a decrease in the injection amount of the fuel injection immediately before the ignition timing.

4. The control device for the fuel injection device according to claim 1, wherein: The fuel injection device includes a valve element for closing or opening a fuel injection hole for injecting the fuel. The control device controls the lift amount of the valve element during the fuel injection immediately before the ignition timing within a range smaller than a predetermined maximum lift amount, and controls the valve element so that the lift amount decreases as the ignition timing is retarded.

5. A control device for a fuel injection device that directly injects fuel into a cylinder of an internal combustion engine operating in a catalyst preheating mode, wherein the catalyst is preheated by retarding the ignition timing to the ignition delay of the expansion stroke, the control device for the fuel injection device being characterized in that: When operating in the catalyst preheating mode, the fuel injection device is controlled as follows: the fuel injection just before the ignition timing among the multiple fuel injections performed in one combustion cycle is performed in the expansion stroke, and the higher the fuel pressure supplied to the fuel injection device at the start timing of the fuel injection just before the ignition timing, the shorter the period from the end timing of the fuel injection just before the ignition timing to the ignition timing.

6. The control device for the fuel injection device according to claim 5, characterized in that: The fuel injection device is controlled in such a manner that, at the start timing of the fuel injection immediately before the ignition timing, the higher the fuel pressure is, the smaller the injection amount of the fuel injection immediately before the ignition timing is.

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