JP2010007619A - Fuel injection control device and fuel injection control method for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device capable of shortening total combustion period without increasing smoke even if a plurality of times of divided injection are performed during one cycle. <P>SOLUTION: This device is provided with a fuel supply device 10 capable of directly injecting fuel by dividing it into a plurality of times into a combustion chamber near compression top dead center of each cylinder during one cycle, and a flame position control means 21 controlling flame position by previous stage injection and flame position by next stage injection by using the fuel supply device 10 in such a manner that the flame position by the previous stage and the flame position by the next stage injection do not spatially overlap while a period of time when flame by the previous stage injection exists and a period of time when flame by the next stage injection exists overlap. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device and a fuel injection control method for a diesel engine.

In order to achieve both combustion noise and exhaust emission reduction, fuel is divided into multiple times near the compression top dead center of each cylinder and directly injected into the combustion chamber so that fuel spray is burnt intermittently by each injection. By controlling the fuel injection pressure and fuel injection amount, it is possible to perform combustion in a state where fresh air is sufficiently introduced for each of the fuel sprays by multiple injections, thereby reducing smoke. (See Patent Document 1).
JP 2005-291116 A

  By the way, the technique of the above-mentioned patent document 1 starts combustion of the fuel spray by the post-stage injection after the combustion of the fuel spray by the pre-stage injection is completed so that each of the combustion by the multiple injections in one cycle is intermittently performed. In other words, since the flame position for each injection is controlled so that the flame positions for each injection do not overlap in time, the entire combustion period by a plurality of injections is longer than the conventional one. For this reason, in the prolonged combustion period, the application range cannot be expanded to the high load side where the entire combustion is not established, and the application range is limited.

  Accordingly, an object of the present invention is to provide an apparatus and a method capable of shortening the entire combustion period by a plurality of injections without increasing smoke even if a plurality of divided injections are performed in one cycle. .

  The present invention includes a fuel supply device that can divide the fuel into a plurality of times near the compression top dead center of each cylinder during one cycle and directly inject the fuel into the combustion chamber. The flame position by the next stage injection and the flame by the next stage injection are used so that the flame position by the next stage injection does not spatially overlap the flame position by the previous stage injection while overlapping with the time when the flame by Configure to control position.

  Further, the present invention has an injection direction variable mechanism that can divide the fuel into a plurality of times in the vicinity of the compression top dead center of each cylinder and inject it directly into the combustion chamber during one cycle, and can change the fuel injection direction. With a fuel injection valve, the time when the flame due to the previous stage injection and the time when the flame due to the next stage injection overlap, while the flame position due to the next stage injection does not spatially overlap the flame position due to the previous stage injection, The fuel injection valve is used to control the flame position by the previous stage injection and the flame position by the next stage injection.

  According to the present invention, the fuel supply device is provided that can divide the fuel into a plurality of times in the vicinity of the compression top dead center of each cylinder during one cycle and directly inject the fuel into the combustion chamber. The flame position and the next stage injection by the preceding stage injection using the fuel supply device so that the flame position by the next stage injection overlaps the time at which the flame by the stage injection exists and does not spatially overlap the flame position by the previous stage injection. Since the flame position is controlled, it is possible to shorten the entire combustion period by a plurality of injections without increasing the smoke, and the application range can be expanded to a higher load side than the conventional apparatus.

  Further, according to the present invention, the injection direction variable mechanism that can divide the fuel into a plurality of times in the vicinity of the compression top dead center of each cylinder and inject it directly into the combustion chamber during one cycle and change the fuel injection direction. The time when the flame due to the previous stage injection and the time when the flame due to the next stage injection overlap overlap with each other so that the flame position due to the next stage injection does not spatially overlap the flame position due to the previous stage injection. In addition, because the fuel injection valve is used to control the flame position by the pre-stage injection and the flame position by the next-stage injection, it becomes possible to shorten the entire combustion period by the multiple injections without increasing the smoke. The application range can be expanded to a higher load side than the conventional device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a diesel engine (hereinafter also simply referred to as “engine”) provided with a fuel injection control device of the present invention.

  In FIG. 1, a stepping motor 5 is driven by a control signal from a control unit 21 in an EGR passage 4 that connects an exhaust passage 2 of an engine 1 and a collector portion 3a of an intake passage 3. A predetermined EGR rate is obtained.

  The engine 1 includes a common rail fuel injection device 10 as a fuel supply device. This fuel injection device 10 is mainly composed of a fuel tank 11, a supply pump 12, a common rail (accumulation chamber) 13, and a fuel injection valve 15 provided for each cylinder, and the fuel pressurized by the supply pump 12 is common rail. Once stored in 13, the high-pressure fuel in the common rail 13 is distributed to the fuel injection valve 15 of each cylinder.

  The common rail 13 is provided with a fuel pressure sensor 34 and a fuel temperature sensor 35 in order to detect the fuel pressure and fuel temperature in the common rail 13. Further, in order to control the fuel pressure in the common rail 13 to the target value, a part of the fuel discharged from the supply pump 12 is returned to the fuel supply passage 16 through the overflow passage 17 provided with the one-way valve 18. It is supposed to be. Specifically, a pressure control valve 19 for changing the flow passage area of the overflow passage 17 is provided, and the pressure control valve 19 changes the flow passage area of the overflow passage 17 in accordance with a duty signal from the engine control unit 21. Let Thereby, the substantial fuel discharge amount from the supply pump 12 to the common rail 13 is adjusted, and the fuel pressure in the common rail 13 is controlled to the target value.

  The fuel injection valve 15 is an electronic injection valve that is opened and closed by an ON-OFF signal from the engine control unit 21, and injects fuel into the combustion chamber by the ON signal and stops injection by the OFF signal. The fuel injection amount increases as the period of the ON signal applied to the fuel injection valve 15 increases, and the fuel injection amount increases as the fuel pressure of the common rail 13 increases.

  A characteristic of such a common rail fuel injection device 10 is that it is possible to divide the fuel into a plurality of times in the vicinity of the compression top dead center of each cylinder and inject it directly into the combustion chamber during one cycle. Further, the common rail fuel injection device 10 has an injection timing variable mechanism that can change the fuel injection timing for each of the plurality of injections, and an arrival distance variable mechanism that can change the arrival distance of the fuel spray for each of the plurality of injections. Have.

  In addition to the signal of the common rail pressure (fuel pressure of the common rail 14) Pcr from the fuel pressure sensor 34 and the signal of the fuel temperature Tf from the fuel temperature sensor 35, the engine control unit 21 includes the coolant temperature Tw from the water temperature sensor 31. , A crank angle signal from the crank angle detection crank angle sensor 32 (which is the basis of the engine speed Ne), a cylinder discrimination signal Cyl from the cylinder discrimination crank angle sensor 33, and an accelerator opening sensor 36 A signal of opening degree (depressing amount of the accelerator pedal) L (equivalent to engine load) and a signal of intake air amount Qa from the air flow meter 7 are inputted, and the engine control unit 21 responds to the engine speed and the accelerator opening degree. The main fuel injection amount is calculated and the fuel corresponding to the calculated main fuel injection amount is calculated. In addition to controlling the ON time of the injection valve 15, by controlling the switching phase of the ON of the fuel injection valve 15, so as to obtain the predetermined injection start timing according to the operating conditions (injection timing).

  A variable capacity turbocharger 25 is provided in the exhaust passage 2 downstream of the opening of the EGR passage 4. This is a variable nozzle 27 driven by an actuator 28 at the scroll inlet of the exhaust turbine 26. The engine control unit 21 allows the variable nozzle 27 to obtain a predetermined supercharging pressure from a low rotational speed range. In addition, the nozzle opening degree is controlled to increase the flow rate of the exhaust gas introduced into the exhaust turbine 26 on the low rotation speed side, and to the nozzle opening degree to introduce the exhaust gas into the exhaust turbine 26 without resistance on the high rotation speed side.

  A post-treatment device (for example, an oxidation catalyst or a NOx trap catalyst) 41 is provided downstream of the exhaust turbine 26. An intake throttle valve 45 is driven by an actuator.

  By the way, in order to achieve both combustion noise and exhaust emission reduction, fuel injection is performed in multiple times near the compression top dead center of each cylinder, and fuel injection is performed so that combustion of fuel spray by each injection is performed intermittently. There is a combustion system that enables simultaneous reduction of smoke and combustion noise by controlling pressure and fuel injection amount.

  However, this combustion method cannot be applied to the high-load side because the entire combustion period by multiple injections is prolonged in time compared with single-stage injection (only one fuel injection in one cycle). Only a limited range of operation is possible.

  Now, the fuel injection valve 15 is on the piston shaft and directly faces the combustion chamber. When there are six injection holes, the fuel from one injection is equally divided in six directions from the injection hole toward the periphery of the combustion chamber. As shown in FIG. 2, each of the fuel sprays injected in the six directions entrains the surrounding air to form a spray lump 48, and swirls (gas flow) in the combustion chamber to center the piston central axis. And rotate in the circumferential direction. FIG. 2 (A) shows that the spray mass by the first injection has moved by a predetermined amount Ls radially outward from the nozzle hole and rotated in the circumferential direction (clockwise) by a predetermined amount Lr1 from the injection direction. ing. The spray mass 48 is vaporized and self-ignited by the pressure increase in the combustion chamber accompanying the upward movement of the piston to form a flame. Then, the spray lump 48 (or flame) by the first injection is spatially unevenly distributed in the combustion chamber, and the spray lump 48 (flame) by the first injection rather than where the spray lump 48 (flame) by the first injection exists. It can be seen that there are more areas with no symbol.

  Therefore, in the present invention, the position of the flame formed by the fuel spray lump by each injection multiple times (the position of the flame formed by the fuel spray lump by each injection) is hereinafter referred to as "flame position for each injection" The flame formed by the fuel spray lump by the first injection (hereinafter, the flame formed by the fuel spray lump by the first injection is simply referred to as “flame by the first injection”). And the flame formed by the fuel spray lump by the second injection (hereinafter, the flame formed by the fuel spray lump by the second injection is simply referred to as “flame by the second injection”). The position of the flame formed by the fuel spray lump by the second injection (the position of the flame formed by the fuel spray lump by the second injection is The position of the flame formed by the fuel spray lump by the first injection is simply referred to as “the position of the flame formed by the fuel spray lump by the first injection”. The flame position by the first injection and the flame position by the second injection are controlled so as not to spatially overlap with the “flame position by the first injection”. For example, in FIG. 2A, the spray mass by the second injection is vaporized in a state where it is rotated clockwise by a predetermined amount Lr2 from the injection direction, and is self-ignited to form a flame.

  When the third injection is performed when the number of injections in one cycle is 3, it is formed by the time during which the flame by the first injection exists, the time by which the flame by the second injection exists, and the lump of fuel spray by the third injection. (The flame formed by the fuel spray lump by the third injection is hereinafter simply referred to as “flame by the third injection”) and overlapped by the time of the fuel spray lump by the third injection. The position of the flame to be generated (the position of the flame formed by the fuel spray lump by the third injection is hereinafter simply referred to as “the flame position by the third injection”) is the flame position by the second injection and the flame by the first injection The flame position by the third injection is controlled so as not to spatially overlap the position. For example, in FIG. 2A, the spray mass by the third injection is vaporized in a state where it rotates clockwise by a predetermined amount Lr3 from the injection direction, and self-ignites to form a flame. In FIG. 2A, only one spray mass by the third injection and the above-mentioned spray mass by the second injection are shown.

  Here, a plurality of injections performed near the compression top dead center of each cylinder is also referred to as multistage injection. When the number of injections in one cycle is two, the first injection is referred to as the pre-stage injection, while the second injection is referred to as the next-stage injection. When the number of injections in one cycle is 3, the first injection is the preceding injection, while the second injection and the third injection are the next injection.

  Next, the difference in operating conditions will be further described with reference to FIG. 2. FIG. 2A shows that the first injection is performed under high penetration (high injection pressure, low intake pressure) and high swirl conditions. In the radial direction, the six spray lumps 48 have reached the point where they have reached the piston crown surface peripheral portion 43 beyond the cavity 44 in the radial direction, and in the circumferential direction, they are greatly moved clockwise from the injection direction by the high swirl. It is shown that. In such a case, when performing the second injection and the third injection, there is no spray lump 48 due to the first injection in the injection direction, so the injection start timing of the second injection and the injection of the third injection from the injection start timing of the first injection. Each injection interval until the injection start timing is reduced, that is, the second injection and the third injection are started without delay from the first injection start timing.

  On the other hand, FIG. 2 (B) shows that when the first injection is performed under the low penetration (low injection pressure, high intake pressure) and low swirl conditions, the spray mass 48 by the first injection stays in the cavity 44 in the radial direction, and In the circumferential direction, it is shown that there is little movement from the injection direction due to low swirl. In such a case, when performing the second injection and the third injection, there is a spray lump 48 by the first injection in the injection direction, so the injection start timing of the second injection from the injection start timing of the first injection, Each injection interval up to the injection start timing is increased, that is, the second injection and the third injection are started after the spray mass 48 from the first injection stops moving.

  In this way, the flame position for each injection is controlled so that the flame positions for each injection do not overlap spatially even under the same operating conditions or even if the operating conditions are different. However, each combustion is caused to overlap in time, thereby shortening the entire combustion period by a plurality of injections as compared with the conventional apparatus, thereby making it applicable even on the high load side.

  This control executed by the engine control unit 21 will be described in detail based on the following flowchart.

  FIG. 3 is a main flowchart. FIG. 3 shows the flow of processing and is not executed repeatedly at regular intervals.

  In step 1, the engine rotational speed Ne detected by the crank angle sensor and the load L detected by the accelerator opening sensor 36 are read. In step 2, the target fuel injection amount Q0 and the number of injections in one cycle are read based on these values. Ni is determined. The target fuel injection amount Q0 determines the amount of fuel required per combustion cycle at the engine speed Ne and load L at that time.

  In the present invention, divided injection (multistage injection) is performed a plurality of times centering around the compression top dead center, and the number of injections Ni determines the number of divided injections. The number of injections Ni is at least twice. Here, the case where the number of injections is 3 will be described. When the number of injections is three, the target fuel injection amount Q0 is divided into three, and divided injection is divided into three parts around the compression top dead center. Whether to increase or decrease the number of injections Ni when the load increases under a constant engine speed, or whether to increase or decrease the number of injections Ni when the engine speed increases under a constant load Determined by conformance.

  In step 3, the flame position for each injection, that is, the flame position by the first injection, the flame position by the second injection, and the flame position by the third injection are calculated (predicted).

  For simplicity, it is assumed that the injection start timing of the first injection is determined in advance. The calculation of the flame position for each injection is performed before the first injection. That is, as will be described later, after determining the injection start timing of the second injection and the injection timing of the third injection prior to the first injection, the first injection is performed when the injection start timing of the first injection is reached. After the first injection, the second injection and the third injection are performed according to the determined injection start timing of the second injection and the injection timing of the third injection.

  The calculation of the flame position for each injection will be described with reference to the flow of FIG. In FIG. 4 (subroutine of step 3 in FIG. 3), in step 11, the in-cylinder state and the fuel injection state at the injection timing (injection start timing) are calculated or detected. Specifically, at least one parameter of the in-cylinder pressure Pic, the swirl ratio Sr, the intake air amount Qa, the common rail pressure (injection pressure) Pcr, the EGR rate Regr, the fuel property Cf, the intake air temperature Ta, and the piston position Pp is calculated or To detect. Here, the intake air amount Qa may be obtained by detecting the air flow meter 7 and the common rail pressure Pcr by the fuel pressure sensor 34.

  The in-cylinder pressure Pic, the fuel property Cf, and the intake air temperature Ta may be obtained by detection by a sensor (not shown). The swirl ratio Sr can be determined by the engine specifications and the swirl valve control method. For example, if the swirl valve is controlled to a fully open state and a half open state, the swirl ratio is zero when the swirl valve is fully open, and a predetermined value that is not zero when the swirl valve is half open. Since it is known that the EGR rate Regr is calculated with a first-order lag of the target EGR rate Megr, this known method may be used. In addition, it is not essential to provide a sensor. If the parameter can be calculated by a known method, the parameter may be calculated by the known method.

  In step 12, the flame position for each injection is calculated based on at least one parameter detected or calculated in step 11.

  As described above with reference to FIG. 2, each of the six spray masses 48 by one injection moves in a radial direction and a circumferential direction around the piston central axis on a plane orthogonal to the piston axis. Because it vaporizes and generates a flame by self-ignition, from the position of the spray mass in the radial direction (that is, the radial flame position) and the position of the spray mass in the circumferential direction (the rotational direction) (that is, the flame position in the rotational direction) The flame position on the plane can be determined. In this case, since each of the six spray masses (flame) moves substantially the same around the piston central axis, it is sufficient to focus on one spray mass (flame) and determine its position.

  Here, the position of the spray mass in the radial direction (flame position) is determined by the penetration Ls, and the position (flame position) (angle) of the spray mass in the rotational direction is determined by the rotation amount Lr. The above penetration Ls is the spray reach distance. When the number of injections in one cycle is 3, the penetration Ls of each injection is substantially the same as shown in FIGS. 2 (A) and 2 (B). Factors affecting the penetration Ls are the intake air amount Qa, the in-cylinder pressure Pic, the common rail pressure Pcr, the EGR rate Regr, the fuel property Cf, the intake air temperature Ta, and the piston position Pp as shown in FIG.

  Further, the spray mass for each injection rotates around the piston shaft by a swirl generated in the combustion chamber immediately after the injection. The amount of movement Lr in the rotational direction is an angle by which the sprayed mass is rotated by the swirl until the spray lump generates a flame with the injection direction as a reference position. As shown in FIG. 2A, when the number of injections in one cycle is three, there are three rotation direction movement amounts Lr (first rotation direction movement amount Lr1, second rotation direction movement amount Lr2). , The third rotation direction movement amount Lr3), the first rotation direction movement amount Lr1 is the maximum, the second rotation direction movement amount Lr2 is smaller than the first rotation direction movement amount Lr1, and the third rotation direction movement amount Lr3 is the second rotation amount. The direction moving amount is smaller than Lr2. Therefore, here, the first rotation direction movement amount Lr1 that is the maximum rotation direction movement amount (angle) is adopted as the rotation direction movement amount Lr. When there is no swirl, the rotational movement amount Lr is zero. As shown in FIG. 5, the swirl ratio Sr is the only factor that affects the rotational movement amount Lr.

  FIG. 5 shows the intake air amount Qa, the in-cylinder pressure Pic, the common rail pressure Pcr, the EGR rate Regr, the fuel property Cf, the intake air temperature Ta, the swirl ratio Sr, the penetration Ls, the rotational movement amount Lr, and the spray angle depending on the piston position Pp. This is a summary of how θs changes. In FIG. 5, “?” Indicates that it cannot be determined which side to change unless an experiment is performed. Here, the piston position Pp is a substitute value for the in-cylinder pressure Pic. The piston position can be obtained from the crank angle.

  Now, by determining the injection start timing of the first injection in advance, the penetration Ls (= radial flame position) of each injection is determined from the parameters at that time, and the rotation direction of each injection is determined from the swirl ratio Sr at that time. Since the movement amount Lr (= rotational direction flame position) is determined, the flame position for each injection is determined.

  In step 13, the spray angle θs is calculated based on at least one parameter detected or calculated in step 11. The spray angle θs is an angle at which spray spreads from one nozzle hole when attention is paid to one nozzle hole. The six nozzle holes are configured in the same manner, and therefore the spray angle is common to the six nozzle holes. Here, since the spray angle changes depending on parameters such as the intake air amount as shown in FIG. 5, the changing spray angle is obtained.

  When the flame position and spray angle θs for each injection are thus calculated (predicted), the flow returns to FIG. The flame position is controlled so as not to overlap. This flame position control will be described with reference to the flowchart of FIG.

  In FIG. 6 (subroutine of step 4 in FIG. 3), in step 21, the penetration Ls, the rotational movement amount Lr, and the injection angle θs are read (calculated in step 12 of FIG. 4). The injection interval is determined by searching a map having the contents shown in FIG. When the number of injections in one cycle is 3, the injection interval is the interval from the injection start timing of the first injection to the injection start timing of the second injection and the injection of the third injection from the injection start timing of the second injection This is the interval until the start timing. Here, for simplicity, it is assumed that the interval from the injection start timing of the first injection to the injection start timing of the second injection is equal to the interval from the injection start timing of the second injection to the injection start timing of the third injection. For example, [degCA] may be adopted as the unit of the injection interval.

  In FIG. 7, when the radial flame position (= penetration Ls) on the vertical axis is the same, the larger the rotational flame position (= rotation amount Lr) on the horizontal axis, the shorter the injection interval, and the horizontal axis rotation. When the directional flame position is the same, the larger the radial flame position on the vertical axis, the shorter the injection interval. This is because the flame position by the second injection is formed in an area where the flame position by the second injection does not spatially overlap the flame position by the first injection, and the flame position by the third injection is the flame position by the first injection and the second time. This is because a flame caused by the third injection is formed in a region that does not spatially overlap with the flame position caused by the injection.

  In FIG. 7, when the radial flame position on the vertical axis exceeds the cavity radius Rc (see FIG. 8), the injection interval is shortened immediately before exceeding the cavity radius Rc. The effect of the step between the cavity 44 and the piston crown surface peripheral portion 43 is taken into consideration.

  In FIG. 7, when the rotational flame position on the horizontal axis exceeds the nozzle hole interval θn (see FIG. 8), the characteristic from the time when the rotational flame position is zero is repeated from the adjacent nozzle hole. This is in consideration of overlapping with spraying. Here, the nozzle hole interval θn is an angle between adjacent nozzle holes as shown in FIG. 8 (60 ° when there are six nozzle holes). FIG. 8 shows an example in which six nozzle holes are provided at equal intervals. The present invention is not limited to this, and the present invention is also applicable to those having 7 to 10 nozzle holes.

  In FIG. 7, the range of the horizontal axis is only described up to about 1.5 times the nozzle hole interval θn, but to what extent the horizontal axis is to be described is determined by the maximum value of the rotational flame position. Note that the map characteristics differ if the specifications of the fuel injection valve 15 and the engine 1 differ.

  Actually, the target injection interval is calculated by correcting the spray angle with respect to the injection interval obtained in FIG. 7, that is, the target injection interval is calculated by the following equation.

Target injection interval = injection interval × spray angle correction coefficient 1 (1)
Here, the spray angle correction coefficient 1 is necessary for the following reason. For example, consider a case where the intake air amount is the first predetermined value Qa1 and a case where the intake air amount is a second predetermined value Qa2 larger than this. From FIG. 5, the spray angle in the case of the second predetermined value Qa2 is smaller than the spray angle in the case of the first predetermined value Qa1. If the size of the spray mass in the case of the second predetermined value Qa2 is smaller than the size of the spray mass in the case of the first predetermined value Qa1 due to the difference in the spray angle, the case of the second predetermined value Qa2 by the reduced amount is assumed. Since the region where there is no flame is wider than when the first predetermined value Qa1, the injection interval for the second predetermined value Qa2 can be made smaller than the injection interval for the first predetermined value Qa1. Thus, since the spray angle affects the injection interval, the flame position for each injection can be controlled with higher accuracy by introducing the spray angle correction coefficient 1 and correcting the injection interval. The spray angle correction coefficient 1 is finally determined by conformance. Since no experiment has been performed at this stage, the spray angle correction coefficient 1 = 1.0, that is, the target injection interval = injection interval will be described here.

  When the injection interval is determined in this manner, the flow returns to FIG. 3, and in step 5, fuel injection control of each injection is performed using this injection interval. That is, since the injection start timing of the first injection is determined in advance, the value that is retarded by the injection interval from the injection start timing of the first injection is used as the injection start timing of the second injection, and the injection start of the second injection is further started. The value on the retard side by the injection interval from the timing is determined as the injection start timing of the third injection. The fuel injection amount per injection is 1/3 of the target fuel injection amount. Fuel injection is performed by intermittently opening the fuel injection valve 15 three times at the injection start timing for each injection determined in this way. The common rail fuel injection device 10 has an injection timing variable mechanism that can change the fuel injection timing for each injection.

  Here, the effect of this embodiment is demonstrated with reference to FIG.

  FIG. 9 shows how the heat generation pattern differs between this embodiment and the conventional apparatus when the number of injections in one cycle is three. In the conventional apparatus shown on the left side, the heat generation pattern by the first injection and the heat generation pattern by the second injection are temporally (that is, the horizontal axis represents the heat generation pattern by the second injection and the heat generation pattern by the third injection). In the direction), so that the overall combustion period of the three injections is prolonged.

  On the other hand, according to this embodiment shown on the right side, the heat generation pattern by the first injection and the heat generation pattern by the second injection, the heat generation pattern by the second injection, and the heat generation pattern by the third injection Are greatly overlapped in time (in the direction of the horizontal axis), so that the entire combustion period by three injections is shortened. This is because in this embodiment, the heat generation patterns by the respective injections are overlapped in time by spatially dividing and causing the combustion by the respective injections. Note that R. on the vertical axis. O. H. R is the heat generation rate.

  Thus, according to this embodiment shown on the right side compared to the conventional device shown on the left side, the entire combustion period by three injections can be shortened compared to the conventional device, so that it is applied to the higher load side than the conventional device. can do.

  As described above, according to the present embodiment (inventions according to claims 1 and 10), the common rail fuel injection device 10 (in which a fuel is divided into a plurality of times near the compression top dead center of each cylinder during one cycle). A fuel supply device that can be directly injected into the combustion chamber), a time during which a flame is present by the first injection (previous stage injection) and a time during which a flame is present by the second injection (next stage injection), and the second injection ( The flame position by the first injection (previous stage injection) and the flame position by the second stage injection (next stage injection) while the time during which the flame by the next stage injection) and the time by which the flame by the third injection (next stage injection) exists overlap each other The flame position by the first injection (previous stage injection) and the second injection (next stage injection) using the fuel supply device 10 so that the flame position by the third injection (next stage injection) does not spatially overlap each other. ) Since the flame position by the third injection (next stage injection) is controlled (see Step 4 in FIG. 3 and Steps 21 and 22 in FIG. 6), the entire combustion period by a plurality of injections can be increased without increasing the smoke. It becomes possible to shorten the range, and the application range can be expanded to a higher load side than the conventional apparatus.

  According to this embodiment (the invention described in claim 2), the in-cylinder pressure detecting / calculating means for detecting or calculating the in-cylinder pressure, the swirl ratio detecting / calculating means for detecting or calculating the swirl ratio, Intake air amount detection / calculation means for detecting or calculating intake air amount, injection pressure detection / calculation means for detecting or calculating injection pressure, and EGR rate detection / calculation for detecting or calculating EGR rate Means, fuel property detection / calculation means for detecting or calculating fuel properties, intake air temperature detection / calculation means for detecting or calculating intake air temperature, and piston position for detecting or calculating piston position And at least one of detection / calculation means and flame position calculation means for calculating the flame position for each of a plurality of injections (see step 3 in FIG. 3 and steps 11 and 12 in FIG. 4). The flame position calculation detection means is configured for each injection based on at least one of the detected or calculated in-cylinder pressure, swirl ratio, intake air amount, injection pressure, EGR rate, fuel property, intake air temperature, and piston position. Since the flame position is calculated (see steps 11 and 12 in FIG. 4), each injection is performed even if the in-cylinder pressure, swirl ratio, intake air amount, injection pressure, EGR rate, fuel property, intake air temperature, and piston position are different. Each flame position can be calculated with high accuracy.

  According to the present embodiment (the invention described in claim 3), the fuel supply device 10 has an injection timing variable mechanism capable of changing the fuel injection timing for each of a plurality of injections, and the flame position control means performs this injection. Since the fuel injection timing for each of a plurality of injections is controlled using the timing variable mechanism (see step 5 in FIG. 3), it can be configured using a known fuel supply device 10.

  According to this embodiment (the invention described in claim 4), the flame position control means is configured such that the flame position by the second injection (next stage injection), the flame position by the third injection (next stage injection) is the first injection ( Since the fuel injection timing of the first injection (previous injection) and the fuel injection timing of the second injection and the third injection (next injection) are controlled so as to be in a flame-free region due to (pre-stage injection) (step 5 in FIG. 3). See), and sufficient air introduction for each fuel spray by each injection reduces smoke.

  10 and 11 show the second embodiment, which replaces FIGS. 3 and 6 of the first embodiment, respectively. 10 and 11, the same step numbers are assigned to the same portions as those in FIGS.

  In the second embodiment, the reach distance is determined instead of the injection interval of the first embodiment. If the concept of 2nd Embodiment is demonstrated with reference to FIG. 13, 2nd Embodiment will mainly target the engine in which a swirl does not arise. The spray mass (flame) by the first injection moves in the radial direction from the nozzle hole to a distance determined by penetration as shown in FIG. This means that if the penetration of the first injection is made somewhat long, the flame formed by the fuel spray lump by the first injection in front of the spray lump by the first injection, that is, the injection hole side (the fuel by this first injection) The flame formed by the mass of spray is hereinafter simply referred to as “flame by the first injection”). Therefore, if the flame by the second injection and the flame by the third injection come in the region where the flame by the first injection does not exist, the flame position by the first injection, the flame position by the second injection, and the flame position by the third injection And do not overlap spatially. That is, the arrival distance (S2) of the second injection is determined so that the distance from the nozzle hole to the flame position by the second injection is shorter than the distance from the nozzle hole to the flame position by the first injection. In addition, when the number of injections in one cycle is 3, the distance from the nozzle hole to the flame position by the second injection when the flame position by the second injection is in front of the flame position by the first injection (on the injection hole side) The third injection range (S3) is determined so that the distance from the nozzle hole to the flame position by the third injection becomes shorter.

  According to the second embodiment, in particular, even in an engine in which no swirl is generated in the combustion chamber, it is possible to burn without overlapping the flame positions for each injection spatially. In addition, 2nd Embodiment is applicable independently with respect to the engine in which a swirl arises. Further, the first embodiment can be further combined with the second embodiment for an engine in which a swirl is generated.

  The difference from the first embodiment will be mainly described. In step 31 of FIG. 10, the flame position for each injection is controlled so that the flame positions for each injection do not overlap spatially and temporally. . The control of the flame position for each injection will be described with reference to the flowchart of FIG.

  In FIG. 11 (subroutine of step 31 in FIG. 10), in step 21, the penetration Ls, the rotation direction movement amount Lr, and the injection angle θs are read (calculated in step 12 in FIG. 4), among these the penetration Ls and the rotation direction movement amount Lr. The reach distance is determined by searching a map having the contents shown in FIG. Here, the reach distance is the distance that is reached immediately before the spray lump by each injection self-ignites. When the number of injections in one cycle is three, there are three such reach distances (first reach distance S1, second reach distance S2, and third reach distance S3) as shown in FIG. The arrival distance S1 is the maximum, the second arrival distance S2 is smaller than the first arrival distance S1, and the third arrival distance S3 is smaller than the second arrival distance S2. Therefore, here, the first reachable distance S1, which is the maximum reachable distance, is adopted as the reachable distance.

  In FIG. 12, when the radial flame position (= penetration Ls) on the vertical axis is the same, the reach distance increases as the rotational flame position (= rotational movement amount Lr) on the horizontal axis increases, and the horizontal axis rotates. When the directional flame position is the same, the reach distance is increased as the radial flame position on the vertical axis is larger. This is because the flame position by the second injection is formed in a region where the flame position by the second injection does not spatially overlap the flame by the first injection, and the flame position by the third injection is caused by the flame by the first injection and the second injection. This is because a flame caused by the third injection is formed in an area that does not spatially overlap with the flame.

  In FIG. 12, when the radial flame position on the vertical axis exceeds the cavity radius Rc (see FIG. 8), the reach distance is increased from immediately before the cavity radius Rc is exceeded. The effect of the step between the cavity 44 and the piston crown surface peripheral portion 43 is taken into consideration.

  In FIG. 12, when the rotational flame position on the horizontal axis exceeds the nozzle hole interval θn (see FIG. 8), the characteristics from the time when the rotational flame position is zero are repeated from the adjacent nozzle holes. This is in consideration of overlapping with spraying. Here, the nozzle hole interval θn is an angle between adjacent nozzle holes as shown in FIG. 8 (60 ° when there are six nozzle holes).

  Also in FIG. 12, the range of the horizontal axis is only described up to about 1.5 times the nozzle hole interval θn, but to what extent the horizontal axis is to be described is determined by the maximum value of the rotational flame position. Note that the map characteristics differ if the specifications of the fuel injection valve 15 and the engine 1 differ.

  Actually, the target arrival distance is calculated by correcting the spray angle with respect to the arrival distance obtained by FIG. 12, that is, the target arrival distance is calculated by the following equation.

Target reach distance = arrival distance × spray angle correction coefficient 2 (2)
Here, the reason why the spray angle correction coefficient 2 is required is as follows. For example, consider a case where the intake air amount is the first predetermined value Qa1 and a case where the intake air amount is a second predetermined value Qa2 larger than this. The spray angle for the second predetermined value Qa2 is smaller than the spray angle for the first predetermined value Qa1. If the size of the spray mass in the case of the second predetermined value Qa2 is smaller than the size of the spray mass in the case of the first predetermined value Qa1 due to the difference in the spray angle, the case of the second predetermined value Qa2 by the reduced amount is assumed. Since the region having no flame is wider than that in the case of the first predetermined value Qa1, the reach distance in the case of the second predetermined value Qa2 can be made smaller than the reach distance in the case of the first predetermined value Qa1. Thus, since the spray angle affects the reach distance, the flame position for each injection can be controlled more accurately by introducing the spray angle correction coefficient 2 and correcting the reach distance. The spray angle correction coefficient 2 is finally determined by conformity. Since no experiment has been performed at this stage, the spray angle correction coefficient 2 = 1.0, that is, the target reaching distance = the reaching distance will be described here.

  When the reach distance is determined in this way, the flow returns to FIG. 10 and in step 32, fuel injection control of each injection is performed using this reach distance. The common rail fuel injection device 10 has a variable reach mechanism that can change the reach of the spray mass (fuel spray) for each injection. That is, by changing the injection pressure, the arrival distance of the spray lump for each injection can be changed, so that the injection pressure at the first injection (this injection pressure is referred to as “first injection pressure”) according to the arrival distance. ). The injection pressure at the second injection (this injection pressure is referred to as “second injection pressure”) is set lower than the first injection pressure. The injection pressure at the time of the third injection (this injection pressure is referred to as “third injection pressure”) is set lower than the second injection pressure. How much the second injection pressure is made lower than the first injection pressure and how much the third injection pressure is made lower than the second injection pressure are finally determined by adaptation. In the second embodiment, the injection interval is basically constant. That is, the injection start timing for each injection is determined in advance. The fuel injection amount per injection is 1/3 of the target fuel injection amount. Accordingly, the fuel is in the state of the first injection pressure at the injection start timing of the first injection, in the state of the second injection pressure at the injection start timing of the second injection, and in the state of the third injection pressure at the injection start timing of the third injection. Each injection valve 15 is opened. In this way, fuel injection is performed by intermittently opening the fuel injection valve 15 three times using the injection pressure for each injection.

  According to the second embodiment (inventions according to claims 1 and 10), the common rail fuel injection device 10 (in one cycle, fuel is divided into a plurality of times near the compression top dead center of each cylinder and is divided into the combustion chamber. A fuel supply device capable of direct injection), a time during which a flame is present by the first injection (previous stage injection) and a time during which a flame is present by the second injection (next stage injection), and the second injection (next stage injection) ) The flame position by the first injection (previous stage injection) and the flame position by the second injection (next stage injection) while the time when the flame by the third stage (second stage injection) exists overlaps the time when the flame by The flame position by the first injection (previous injection) and the flame by the second injection (next stage injection) using the fuel supply device 10 so that the flame positions by the third injection (next stage injection) do not overlap each other spatially. Position, third time Since the flame position by the shot (next stage injection) is controlled (see step 31 in FIG. 10 and steps 21 and 41 in FIG. 11), the entire combustion period by multiple injections is shortened without increasing the smoke. Therefore, the application range can be expanded to a higher load side than the conventional device.

  According to the second embodiment (the invention described in claim 5), the fuel supply device 10 has a variable reach distance mechanism capable of changing the reach distance of the fuel spray for each of a plurality of injections, and flame position control means Since this reaching distance variable mechanism is used to control the reaching distance for each of a plurality of injections (see step 32 in FIG. 10), it can be configured using a known fuel supply device 10.

  According to the second embodiment (the invention described in claim 6), the flame position control means is configured such that the flame position by the second injection (next stage injection), the flame position by the third injection (next stage injection) is the first injection. Since the fuel spray reach distance by the first injection (previous stage injection) and the fuel spray reach distance by the second injection and the third injection (next stage injection) are controlled so as to come to a region where there is no flame by (pre-stage injection) ( Smoke is reduced because sufficient air is introduced into each fuel spray by each injection.

  FIG. 14 is a cross-sectional view of the tip portion of the fuel injection valve 51 of the third embodiment. The fuel injection valve 51 has a bevel angle variable mechanism (injection direction variable mechanism) that can change the bevel angle. Since this bevel angle varying mechanism itself is known from Japanese Patent Application Laid-Open No. 2006-118370, it will be outlined below.

  59 is a needle holder formed at the tip of the fuel injection valve 51, 54 is a hollow needle-shaped second needle valve that is slidably inserted into the needle holder 59 in the direction of the axis AA, and 52 is a second needle valve. The first needle valve is coaxially inserted inside the needle valve 14. A fuel chamber 60 is formed between the needle holder 59 and the second needle valve 54 and between the first needle valve 52 and the second needle valve 54 and is filled with fuel.

  The fuel chamber 60 is connected to a fuel supply passage (not shown), and fuel is supplied in a state where a predetermined pressure is applied by a fuel pump (not shown). When a first nozzle hole 53 or a second nozzle hole 55, which will be described later, is opened by driving the first needle valve 52 or the second needle valve 54, a predetermined value is directed from the opened nozzle hole toward the combustion chamber. Fuel is ejected by pressure.

  The first needle valve 52 and the second needle valve 54 are each driven by an electromagnetic actuator, and the valve opening time is controlled by changing the energization time to the actuator. The actuator may be driven by a fluid force such as pneumatic pressure or hydraulic pressure.

  A tapered surface 52 a is formed at the distal end portion of the first needle valve 52, and this tapered surface 52 a is seated at a first seat position 57 formed in a tapered shape inside the distal end portion of the needle holder 59. The first seat position 57 is provided with a first injection hole 53 that allows the outside of the fuel injection valve 51 to communicate with the fuel chamber 60, and this first injection hole 53 is formed when the first needle valve 52 is seated. Closed. On the other hand, a tapered surface 54 a is similarly formed at the distal end portion of the second needle valve 54, and the tapered surface 54 a is seated at a second seat position 58 formed in a tapered shape inside the distal end portion of the needle holder 59. The second seat position 58 is provided with a second injection hole 55 that allows the outside of the fuel injection valve 51 to communicate with the fuel chamber 60, and this second injection hole 55 is formed when the second needle valve 54 is seated. Closed.

  The first injection hole 53 is provided on the tip side of the second injection hole 55, and the angle of the first injection hole 53 is larger than that of the second injection hole 55 with respect to the axis AA. The size of the first nozzle hole 53 and the size of the second nozzle hole 55 are the same.

  Next, fuel spraying of the fuel injection valve 51 will be described with reference to FIG. 15. FIG. 15A shows fuel injection at a wide bevel angle, and FIG. 15B shows fuel injection at a narrow bevel angle. The case where is performed is shown. Here, the bevel angle is the spread angle of the fuel spray formed in the combustion chamber from the axis A-A, and when it is large, it is called the wide bevel angle, and when it is small, it is called the narrow bevel angle.

  When fuel injection is performed at a wide bevel angle, the first needle valve 52 is lifted and fuel is injected from the first injection holes 53 as shown in FIG. At this time, an angle between the fuel spray and the axis AA is θ1. On the other hand, when fuel injection is performed at a narrow bevel angle, the second needle valve 54 is lifted and fuel is injected from the second injection hole 55 as shown in FIG. At this time, an angle between the fuel spray and the axis AA is θ2. At the time of fuel injection, the first needle valve 52 and the second needle valve 54 are held at predetermined positions where the first injection hole 53 and the second injection hole 55 are opened, respectively. Thereby, the bevel angle is kept substantially constant during fuel injection.

  This completes the outline of the fuel injection valve 51.

  In the third embodiment, the time at which the flame by the first injection exists and the time at which the flame by the second injection exists overlap, and the flame position by the second injection and the flame position by the first injection are spatially separated. In order not to overlap, the above-described fuel injection valve 51 is used to control the flame position by the first injection and the flame position by the second injection.

  The concept of the third embodiment will be described with reference to FIG. 16. FIG. 16 shows a cross section of the combustion chamber 62 when the piston 61 is in the vicinity of the compression top dead center, and the shape of fuel spray by wide bevel angle injection, The shape of fuel spray by narrow umbrella angle injection is shown in an overlapping manner. The angle from the piston central axis to the spray direction of the wide bevel angle injection is the first bevel angle θ1, and the angle from the piston central axis to the spray direction of the narrow bevel angle injection is the second bevel angle θ2. However, the wide umbrella angle injection and the narrow umbrella angle injection are never performed simultaneously.

  When a boundary is provided between the two angles of the first bevel angle θ1 and the second bevel angle θ2, as indicated by a one-dot chain line, the combustion chamber volume when the piston 61 is near the compression top dead center at the boundary. Is defined so that the first volume Va and the second volume Vb are substantially divided into two. Then, when the wide umbrella angle injection is performed on the first volume Va located on the upper side of the combustion chamber volume divided into two, and the narrow umbrella angle injection is performed on the second volume Vb located on the lower side. The position of the flame formed by the fuel spray lump by the wide umbrella angle injection (hereinafter, the position of the flame formed by the fuel spray lump by the wide umbrella angle injection is simply referred to as “flame position by the wide umbrella angle injection”). Is the position of the flame formed only by the first volume Va and by the fuel spray lump by the narrow umbrella angle injection (hereinafter, the position of the flame formed by the fuel spray lump by the narrow umbrella angle injection is simply referred to as “narrow umbrella The flame position by angular injection ") exists only in the second volume Vb, and the flame position by wide umbrella angle injection and the flame position by narrow umbrella angle injection do not overlap spatially. In other words, the combustion chamber volume when the piston 61 is in the vicinity of the compression top dead center is approximately divided into the first volume Va and the second volume Vb, and the first one located above the combustion chamber volume divided into two. The first bevel angle θ1 and the second bevel angle θ2 are set so that the wide bevel angle injection is performed on the volume Va and the narrow bevel angle injection is performed on the second volume Vb located on the lower side. Set it.

  Therefore, by using the fuel injection valve 51 having such a bevel angle varying mechanism, it is possible to perform multi-stage injection so that the flame positions of the respective injections do not overlap spatially while the flames of the respective injections overlap. Can do. However, this fuel injection valve 51 can divide the fuel into a plurality of times near the compression top dead center of each cylinder and inject it directly into the combustion chamber during one cycle.

  FIG. 17 is a main flowchart of the third embodiment, which replaces FIG. 3 of the first embodiment. The same steps as those in FIG. 3 are given the same step numbers.

  Here, if the number of injections in one cycle is described as two, step 51 performs umbrella angle injection control. Here, it is assumed that the injection start timing for each injection is determined in advance. Then, when the injection start timing of the first injection is reached, 1/2 of the target fuel injection amount Q0 is supplied by making the first injection a wide bevel angle injection, and the injection start timing of the second injection is reached By setting the second injection to be a narrow umbrella angle injection, ½ of the target fuel injection amount Q0 is supplied. On the contrary, when the injection start timing of the first injection is reached, 1/2 of the target fuel injection amount Q0 is supplied by setting the first injection to be a narrow bevel angle injection, and the injection start timing of the second injection is reached. In this case, ½ of the target fuel injection amount Q0 may be supplied by setting the second injection as a wide bevel angle injection.

  Thus, according to the third embodiment (the invention described in claim 9), the fuel injection valve 51 having the bevel angle variable mechanism (the injection direction variable mechanism capable of changing the fuel injection direction) is provided. The flame position by the second injection (next stage injection) is the first injection (previous stage injection) while the time when the flame by the injection (previous stage injection) and the time by which the flame by the second injection (next stage injection) exists overlap. Since the fuel injection valve 51 is used to control the flame position by the first injection (previous injection) and the flame position by the second injection (subsequent injection) so that they do not spatially overlap with each other (step 51 in FIG. 17). Reference), the entire combustion period by a plurality of injections can be shortened without increasing the smoke, and the application range can be expanded to a higher load side than the conventional apparatus.

  The multistage injection performed using the fuel injection valve 51 having the bevel angle varying mechanism is not limited to this case. For example, an engine in which no swirl is generated in the combustion chamber can be applied to the case where the number of injections in one cycle is three by performing the following. In other words, the injection start timing for each injection is also determined in advance here.

  <1> When the injection start timing of the first injection is reached, 1/3 of the target fuel injection amount Q0 is supplied by making the first injection a wide bevel angle injection.

  <2> At the injection start timing of the second injection, 1/3 of the target fuel injection amount Q0 is supplied by setting the second injection to be a narrow bevel angle injection.

  <3> When the injection start timing of the third injection is reached, 1/3 of the target fuel injection amount Q0 is supplied by setting the third injection to wide bevel angle injection.

  In this case, the first injection and the third injection are the same wide-angle injection, that is, the injection direction is the same for the first injection and the third injection, so the second injection is the second for the first injection and the third injection. The embodiment is applied. That is, for the engine in which no swirl is generated in the combustion chamber, the reach of the spray mass by the third injection is controlled so that the flame position by the third injection is in a region where there is no flame by the first injection. Specifically, the arrival distance of the fuel spray by the third injection is determined to be 3 so that the distance from the nozzle hole to the flame position by the third injection is shorter than the distance from the nozzle hole to the flame position by the first injection. By performing the second injection, the flame position by the first injection (= wide umbrella angle injection) and the flame position by the third injection (= wide umbrella angle injection) are prevented from spatially overlapping.

Moreover, it can apply also to the case where the frequency | count of injection in 1 cycle is 3 by doing as follows with respect to the engine in which a swirl is produced | generated in a combustion chamber. However, here, it is assumed that the injection start timings of the first injection and the second injection are determined in advance.
.

  <4> When the predetermined injection start timing of the first injection is reached, 1/3 of the target fuel injection amount Q0 is supplied by setting the first injection to the wide bevel angle injection.

  <5> When the predetermined injection start timing of the second injection is reached, the second injection is set to the narrow bevel angle injection to supply 1/3 of the target fuel injection amount Q0.

  <6> Supplying 1/3 of the target fuel injection amount Q0 by setting the third injection to the wide bevel angle injection.

In this case, the first injection and the third injection are the same wide-angle injection, that is, the injection direction is the same for the first injection and the third injection, so the first injection and the third injection are the first. The embodiment is applied. That is, for the engine in which the swirl is generated in the combustion chamber, the flame position by the first injection and the flame position by the third injection are calculated, and the flame position by the third injection is in an area where there is no flame by the first injection. By controlling the fuel injection timing of the third injection, the flame position by the first injection (= wide umbrella angle injection) and the flame position by the third injection (= wide umbrella angle injection) are not spatially overlapped. It is.
.

  Thus, according to the third embodiment (the invention described in claim 7), the fuel supply device 10 has a fuel injection valve 51 having a bevel angle variable mechanism (an injection direction variable mechanism capable of changing the fuel injection direction). The flame position control means uses the fuel injection valve 51 to control the injection direction after each of a plurality of injections, so that it can be configured using a known fuel injection valve 51.

  According to the third embodiment (the invention described in claim 8), the flame position control means causes the flame position by the third injection (next stage injection) to be in an area where there is no flame by the first injection (previous stage injection). In addition, since the injection direction of the first injection (previous injection) and the injection direction of the third injection (next injection) are controlled, smoke is reduced because sufficient air introduction is performed for each fuel spray by each injection. .

  In claim 1, the function of the flame position control means is performed by step 4 in FIG. 3 and steps 21 and 22 in FIG.

  In claim 10, the flame position control processing procedure is performed by step 4 in FIG. 3 and steps 21 and 22 in FIG.

  In claim 9, the function of the flame position control means is performed by step 51 of FIG.

The schematic block diagram of the diesel engine provided with the fuel-injection control apparatus of this invention. The model figure which shows the behavior of the spray lump for every injection of 1st Embodiment. The main flowchart of 1st Embodiment. The flowchart for demonstrating the calculation of the flame position for every injection of 1st Embodiment. The table which shows the relationship between each parameter, penetration, rotational direction movement amount, and spray angle. The flowchart for demonstrating the flame position control of 1st Embodiment. The characteristic diagram of an injection interval. The top view of a piston crown surface. The figure which shows the heat generation pattern of 1st Embodiment. The main flowchart of 2nd Embodiment. The flowchart for demonstrating the flame position control of 2nd Embodiment. The characteristic diagram of the reach. The model figure which shows the behavior of the spray lump for every injection of 2nd Embodiment. The partial expanded sectional view of the fuel injection valve of 3rd Embodiment. The partial expanded sectional view of the fuel injection valve at the time of wide umbrella angle injection and narrow umbrella angle injection. The schematic longitudinal cross-sectional view of a combustion chamber. The main flowchart of 3rd Embodiment.

Explanation of symbols

10 Fuel Injection Device 21 Engine Control Unit 51 Fuel Injection Valve

Claims (10)

A fuel supply device capable of dividing the fuel into a plurality of times near the compression top dead center of each cylinder and directly injecting the fuel into the combustion chamber during one cycle;
The fuel supply device is used so that the time when the flame due to the previous stage injection and the time when the flame due to the next stage injection overlap, the flame position due to the next stage injection does not spatially overlap the flame position due to the previous stage injection. And a flame position control means for controlling the flame position by the preceding stage injection flame and the next stage injection, and a fuel injection control device for a diesel engine. In-cylinder pressure detection / calculation means for detecting or calculating in-cylinder pressure;
Swirl ratio detection / calculation means for detecting or calculating the swirl ratio;
Intake air amount detection / calculation means for detecting or calculating the intake air amount;
Injection pressure detection / calculation means for detecting or calculating the injection pressure;
EGR rate detection / calculation means for detecting or calculating the EGR rate;
Fuel property detection / calculation means for detecting or calculating the fuel property;
Intake air temperature detection / calculation means for detecting or calculating the intake air temperature;
At least one of piston position detection / calculation means for detecting or calculating the piston position;
Flame position calculating means for calculating the flame position for each injection of a plurality of times,
The flame position calculation detecting means is configured to detect or calculate each of the injections based on at least one of the detected or calculated in-cylinder pressure, swirl ratio, intake air amount, injection pressure, EGR rate, fuel property, intake air temperature, and piston position. The fuel injection control device for a diesel engine according to claim 1, wherein a flame position for each is calculated. The fuel supply device includes an injection timing variable mechanism capable of changing a fuel injection timing for each of the plurality of injections.
2. The fuel injection control device for a diesel engine according to claim 1, wherein the flame position control means controls the fuel injection timing for each of the plurality of injections using the injection timing variable mechanism.   The flame position control means controls the fuel injection timing of the preceding stage injection and the fuel injection timing of the next stage injection so that the flame position by the next stage injection comes in a region where there is no flame by the preceding stage injection. The fuel injection control device for a diesel engine according to claim 3. The fuel supply device has an arrival distance variable mechanism capable of changing an arrival distance of fuel spray for each of the plurality of injections,
2. The fuel injection control device for a diesel engine according to claim 1, wherein the flame position control unit controls an arrival distance for each of the plurality of injections using the arrival distance variable mechanism.   The flame position control means controls an arrival distance of the fuel spray by the previous stage injection and an arrival distance of the fuel spray by the next stage injection so that the flame position by the next stage injection comes in a region where there is no flame by the previous stage injection. The fuel injection control device for a diesel engine according to claim 5. The fuel supply device includes a fuel injection valve having an injection direction variable mechanism capable of changing a fuel injection direction,
2. The fuel injection control device for a diesel engine according to claim 1, wherein the flame position control means controls the injection direction after each of the plurality of injections using the fuel injection valve.   The flame position control means controls the injection direction of the previous stage injection and the injection direction of the next stage injection so that the flame position by the next stage injection is in a region where there is no flame by the previous stage injection. Item 8. A fuel injection control device for a diesel engine according to Item 7. A fuel injection valve having an injection direction variable mechanism capable of changing the injection direction of the fuel while allowing the fuel to be divided into a plurality of times near the compression top dead center of each cylinder and injected directly into the combustion chamber during one cycle;
The fuel injection valve is used so that the time when the flame due to the previous stage injection and the time when the flame due to the next stage injection overlap, the flame position due to the next stage injection does not spatially overlap the flame position due to the previous stage injection. And a flame position control means for controlling the flame position by the pre-stage injection and the flame position by the next-stage injection. A fuel supply device capable of dividing the fuel into a plurality of times near the compression top dead center of each cylinder and directly injecting the fuel into the combustion chamber during one cycle;
The fuel supply device is used so that the time when the flame due to the previous stage injection and the time when the flame due to the next stage injection overlap, the flame position due to the next stage injection does not spatially overlap the flame position due to the previous stage injection. And a flame position control processing procedure for controlling the flame position by the pre-stage injection and the flame position by the next-stage injection.