JP4820470B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for an internal combustion engine, and is preferably applied to, for example, a fuel injection control device that controls fuel injection based on injection characteristics related to a fuel injection device that injects fuel into each cylinder of the internal combustion engine. Is.

  In recent years, in order to reduce harmful substances contained in exhaust gas from internal combustion engines (especially diesel engines) and to achieve low fuel consumption and high output operation of internal combustion engines, fuel injection performed in one combustion cycle has been staged in multiple stages, etc. A fuel injection device that executes automatically has been proposed (see Patent Documents 1 and 2, etc.).

  The techniques disclosed in Patent Documents 1 and 2 are so-called variable injection hole type fuel injection valves having a plurality of injection holes that can be sequentially opened at least at the initial stage of injection. An outer needle that opens and closes each nozzle hole and an inner needle that is accommodated in the outer needle are provided in a valve body having two nozzle holes. In this technique, the outer needle is lifted prior to the inner needle, and the inner needle is lifted by colliding with the inner needle with a predetermined lift HDo.

  In Patent Document 1, the inner needle is lifted simultaneously with the collision of the outer needle. Further, in Patent Document 2, after the preceding outer needle collides with the inner needle, the subsequent inner needle lifts against the urging force (set load) of the urging member (spring) that urges the inner needle. . The outer needle is in a full lift state from when it collides with the inner needle until the inner needle starts to lift.

Further, Patent Document 3 discloses a fuel injection control device that has one needle in a fuel injection valve and uses the full lift region of the needle, and has an inflection point that appears before and after the full lift. A technique for improving the control accuracy of the fuel injection amount near the inflection point with respect to the quantity characteristic (Q-Tq characteristic) is disclosed. In this technique, when the injection pulse Tq for driving the nozzle needle of the fuel injection valve is obtained from the required injection amount Q, it is directly obtained from an approximate expression in which an inflection point is defined.
JP 2001-241370 A JP 2005-320904 A Japanese Patent Laid-Open No. 2004-19602

  In the prior arts disclosed in Patent Documents 1 and 2, since the injection characteristics can be switched by selecting the injection hole to be at least one of the first injection hole and the second injection hole (hereinafter, switching the number of injection holes), By switching the injection characteristics depending on the operating conditions of the internal combustion engine, it is possible to control the injection amount to satisfy the injection characteristics required under all operating conditions.

  However, in the prior art, due to the structure of the variable injection hole type, the injection amount characteristic having an inflection point is obtained when the number of injection holes corresponding to the change of the injection characteristic is changed. In the vicinity of the inflection point, the control accuracy of the fuel injection amount is inevitably lowered. In particular, since a bounce or the like occurs between the needles due to a collision between the outer needle and the inner needle, there is a possibility that the injection amount becomes unstable in the region around the inflection point. For example, when the injection pulse for driving the fuel injection valve is set to a predetermined pulse value corresponding to the inflection point, the fuel injection amount injected from the fuel injection valve driven at the predetermined pulse value may vary. There is.

  Assuming that the conventional technique for controlling the injection amount using a fuel injection valve having only one needle according to Patent Document 3 is applied to the fuel injection control device that controls the injection amount using such a variable injection hole type fuel injection valve. However, even if the fuel injection valve is driven with the injection pulse determined for the required injection amount (required inflection point injection amount) in the region around the inflection point, the actual injection amount varies and the injection amount becomes unstable. It cannot be avoided.

  In particular, when switching the injection control so as to straddle the inflection point in an operating condition such as a transient operating state in which the injection amount continuously changes, there is a hysteresis in the injection characteristics, etc. Variations and variations between jets are likely to occur. Depending on the case, there is a possibility that the emission is deteriorated and the vibration noise of the internal combustion engine is increased.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine having a variable injection hole type fuel injection valve that can suppress the influence of an unstable region at the time of injection switching. A fuel injection control device is provided.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, according to the first aspect of the present invention, in the fuel injection control device for an internal combustion engine that controls the operation of the fuel injection valve so as to perform stepwise injection within one combustion cycle of the internal combustion engine, the fuel injection valve includes: A variable injection type fuel injection valve having a plurality of injection holes that can be sequentially opened in two stages at least in the initial stage of injection, wherein the valve body has a first injection hole and a second injection hole, and the valve body An outer needle that opens and closes the first nozzle hole, and an inner needle that is arranged inside the outer needle and opens and closes the second nozzle hole, and either one of the outer needle and the inner needle is: The first needle that is lifted prior to the other needle collides with the other needle, and the operating state including the rotational speed of the internal combustion engine and the accelerator opening is determined. The operation condition estimating means for predicting the transition of the operation condition based on the detected operation condition, and assuming the next operation area, and the injection condition basic information storage for storing the basic value of the injection condition corresponding to the operation area The unstable region where the injection characteristics become unstable is defined by step-by-step switching, and the stable region is divided by the unstable region. And determining whether or not an unstable region exists in the transition path to the next operation region based on the next operation region estimated by the injection region storage unit and the operation region assumption unit And an injection that corrects the basic value stored in the injection condition basic information storage means so as to reduce the degree of influence of the unstable region and determines the corrected injection condition based on the determination result by the means and the determination means A matter modifying means, the injection condition modifying means changes the next operating condition is determined to be in the unstable region by determining means, among the injection condition, the fuel injection pressure for the transition to the stable region The injection conditions are a fuel injection pressure, an injection pulse period, and a fuel injection amount or an index value corresponding thereto, and the injection pulse period is calculated and determined for a target injection amount corresponding to the fuel injection pressure. The operation of the fuel injection valve is controlled based on the command injection pulse period .

  According to this, the unstable region caused by the step-by-step switching of the fuel injection valve can be grasped experimentally in advance, for example, and this unstable region is related to the stable region in the entire operation region. It prescribes in. Then, a transition of the driving state is predicted from the detected current driving state, and it is determined whether or not an unstable region exists in the middle of the transition path for transitioning to the next driving state or the next driving state. Based on the determination result, the basic values (eg, fuel injection pressure, injection pulse period, etc.) stored in the injection condition basic information storage means such as the basic injection condition map are reduced so as to reduce the degree of influence of the unstable region. Correction is performed, and operation control of the fuel injection valve is performed under the corrected injection condition.

  As a result, for example, in the process of transitioning to the next operating state, the ratio of the unstable region to the operating time ratio of the stable region to the unstable region is reduced, such as shortening the control time in the operating state where the vehicle stays in the unstable region. As a result, the influence of the unstable region on the fuel injection characteristics of the injection from the fuel injection valve can be avoided in a relatively short stay time.

In addition, the fuel injection valve having an unstable region in the injection characteristics due to the stepwise switching of the injection by the above operation control is not limited to the variable injection hole type fuel injection valve for switching the injection hole, for example, the initial injection is stepwise. Any one that performs stepwise injection within one combustion cycle may be used.
In a fuel injection control device for an internal combustion engine, a fuel injection valve that suppresses the influence of an unstable region in the process of transitioning to the next operating state with respect to an unstable region caused by stepwise switching of a fuel injection valve Therefore, the present invention is suitable for application to a variable injection hole type fuel injection valve having a plurality of injection holes that can be sequentially opened at least in the initial stage of injection.
In the fuel injection control device for an internal combustion engine, the unstable region caused by the step-by-step switching of the fuel injection valve is defined in relation to the stable region in the entire operation region, so that at least the initial injection stage Are divided into two stages, and the first nozzle hole is opened first, the second nozzle hole is opened thereafter, and the second nozzle hole is opened first, and then the first nozzle is opened. It is suitable to apply to any of those having holes.
Furthermore, when the determination means determines that the next operating state is in the unstable region, the injection condition correction means includes an injection condition correction means that mainly changes the fuel injection pressure among the injection conditions. Even if the injection condition is corrected by changing the fuel injection pressure by the injection condition correcting means, the fuel injection amount is not changed for the purpose of transition to the stable region.
Therefore, the next operating state can be corrected from the unstable region to the stable region without changing the output torque of the internal combustion engine, and the unstable region can be avoided.
In the present invention, the injection conditions are the fuel injection pressure, the injection pulse period, and the fuel injection amount or an index value corresponding thereto, and the injection pulse period is calculated with respect to the target injection amount according to the fuel injection pressure. The operation of the fuel injection valve is controlled based on the determined command injection pulse period. In general, the unstable region caused by the step-by-step switching of the fuel injection valve occurs while the command injection pulse period is continuously changed, for example, in the increasing direction. On the other hand, in the present invention, even if the corrected injection condition changes any of the fuel injection pressure, the injection pulse period, and the fuel injection amount, the fuel injection is performed according to the corrected injection condition as a result. When the operation of the valve is controlled, the operation of the fuel injection valve can be controlled based on a command injection pulse period that avoids an unstable region.
According to a second aspect of the present invention, in the fuel injection control device for an internal combustion engine that controls the operation of the fuel injection valve so as to perform stepwise injection within one combustion cycle of the internal combustion engine, the fuel injection valve comprises: A variable injection type fuel injection valve having a plurality of injection holes that can be sequentially opened in two stages at least in the initial stage of injection, wherein the valve body has a first injection hole and a second injection hole, and the valve body An outer needle that opens and closes the first nozzle hole, and an inner needle that is arranged inside the outer needle and opens and closes the second nozzle hole, and either one of the outer needle and the inner needle is: The first needle that is lifted prior to the other needle collides with the other needle, and the operating state including the rotational speed of the internal combustion engine and the accelerator opening is determined. The operation condition estimating means for predicting the transition of the operation condition based on the detected operation condition, and assuming the next operation area, and the injection condition basic information storage for storing the basic value of the injection condition corresponding to the operation area The unstable region where the injection characteristics become unstable is defined by step-by-step switching, and the stable region is divided by the unstable region. And determining whether or not an unstable region exists in the transition path to the next operation region based on the next operation region estimated by the injection region storage unit and the operation region assumption unit And an injection that corrects the basic value stored in the injection condition basic information storage means so as to reduce the degree of influence of the unstable region and determines the corrected injection condition based on the determination result by the means and the determination means The injection condition correction means, with respect to the transition path that transitions from the detected operation state to the next operation region when the determination means determines that the next operation state crosses the unstable region, A detour transition path setting means for selecting a detour transition path that detours the crossing transition path across the unstable region to be shorter is provided, the selected detour transition path is set as a corrected injection condition, and the injection condition is fuel injection. Pressure, injection pulse period, and fuel injection amount or index values corresponding to these, the injection pulse period is calculated with respect to the target injection amount corresponding to the fuel injection pressure, and fuel is determined based on the determined command injection pulse period. The operation of the injection valve is controlled .
According to this, the unstable region caused by the step-by-step switching of the fuel injection valve can be grasped experimentally in advance, for example, and this unstable region is related to the stable region in the entire operation region. It prescribes in. Then, a transition of the driving state is predicted from the detected current driving state, and it is determined whether or not an unstable region exists in the middle of the transition path for transitioning to the next driving state or the next driving state. Based on the determination result, the basic values (eg, fuel injection pressure, injection pulse period, etc.) stored in the injection condition basic information storage means such as the basic injection condition map are reduced so as to reduce the degree of influence of the unstable region. Correction is performed, and operation control of the fuel injection valve is performed under the corrected injection condition.
As a result, for example, in the process of transitioning to the next operating state, the ratio of the unstable region to the operating time ratio of the stable region to the unstable region is reduced, such as shortening the control time in the operating state where the vehicle stays in the unstable region. As a result, the influence of the unstable region on the fuel injection characteristics of the injection from the fuel injection valve can be avoided in a relatively short stay time.
In addition, the fuel injection valve having an unstable region in the injection characteristics due to the stepwise switching of the injection by the above operation control is not limited to the variable injection hole type fuel injection valve for switching the injection hole, for example, the initial injection is stepwise. Any one that performs stepwise injection within one combustion cycle may be used.
In a fuel injection control device for an internal combustion engine, a fuel injection valve that suppresses the influence of an unstable region in the process of transitioning to the next operating state with respect to an unstable region caused by stepwise switching of a fuel injection valve Therefore, the present invention is suitable for application to a variable injection hole type fuel injection valve having a plurality of injection holes that can be sequentially opened at least in the initial stage of injection.
In the fuel injection control device for an internal combustion engine, the unstable region caused by the step-by-step switching of the fuel injection valve is defined in relation to the stable region in the entire operation region, so that at least the initial injection stage Are divided into two stages, and the first nozzle hole is opened first, the second nozzle hole is opened thereafter, and the second nozzle hole is opened first, and then the first nozzle is opened. It is suitable to apply to any of those having holes.
Further, when it is determined by the determining means that the next operating state crosses the unstable region, the injection condition correcting unit determines the unstable region with respect to the transition path from the detected operating state to the next operating region. Since there is a detour transition path setting means that selects a detour transition path that detours so that the crossing transition path is shortened, in the process of transitioning to the next operating state, the stay time of the unstable region that affects the fuel injection characteristics is reduced. Can be avoided with relatively short crossing times.
In the present invention, the injection conditions are the fuel injection pressure, the injection pulse period, and the fuel injection amount or an index value corresponding thereto, and the injection pulse period is calculated with respect to the target injection amount according to the fuel injection pressure. The operation of the fuel injection valve is controlled based on the determined command injection pulse period. In general, the unstable region caused by the step-by-step switching of the fuel injection valve occurs while the command injection pulse period is continuously changed, for example, in the increasing direction. On the other hand, in the present invention, even if the corrected injection condition changes any of the fuel injection pressure, the injection pulse period, and the fuel injection amount, the fuel injection is performed according to the corrected injection condition as a result. When the operation of the valve is controlled, the operation of the fuel injection valve can be controlled based on a command injection pulse period that avoids an unstable region.

Further, the invention according to claim 3 further includes an operation state storage means for storing the detected operation state, and the operation region assumption means includes the detected operation state and the operation state detected last time by the operation state storage means. The next operation state is estimated based on the deviation.

  In general, the switching of fuel injection valve injection is caused by executing injection step by step in the initial stage of injection, so that it is predicted in a transient operation state such as when the vehicle is stopped or when starting at low speed. There is an unstable region in the middle of the transition path that transitions to the next driving state or the next driving state.

On the other hand, in the invention according to claim 3 , since the next driving state is estimated based on the deviation between the detected current driving state and the previous driving state detected last time, for example, the transition direction based on the deviation, From the index value such as the transition amount, the next driving state can be instantaneously estimated when the current driving state is detected.

  Therefore, for example, it is possible to quickly determine whether or not the injection condition during the transition process to the next operation state in the transient operation state includes an injection condition for performing the injection control in the unstable region, Even in the transient operation state, the injection condition can be quickly corrected so as to reduce the degree of influence of the unstable region.

In the invention according to claim 4, the injection condition correcting means includes a gap between the stable region and the next operating region between the two stable regions existing across the unstable region and the next operating region. A small correction transition path with a small change amount of the fuel injection pressure is selected from among the correction transition paths that change due to the change of the fuel injection pressure, and the change direction and the change amount of the fuel injection pressure in the selected small correction transition path are determined according to the injection condition. Is a correction value for correcting.

According to this, the injection condition correction means selects a small correction transition path with a small change amount of the fuel injection pressure from among the correction transition paths in which the fuel injection pressure changes between the stable region and the next operation region, It is preferable that the change direction and the change amount of the fuel injection pressure in the selected small correction transition path be a correction value for correcting the injection condition.

As a result, the injection condition correction means selects the small correction transition path with a small change amount of the fuel injection pressure from among the correction transition paths in which the fuel injection pressure changes between the stable region and the next operation region. The correction of the relatively small injection condition of selecting a small correction transition path with a small change amount of the fuel injection pressure with respect to the injection condition of the next operation state that is the requested operation state of the internal combustion engine by the request of the user or the like is not possible. A stable region can be avoided.

In the invention according to claim 5 , the detour transition route setting means includes a first stable region in which the detected operating state is detected, and a next operating region among the two stable regions existing across the unstable region. In a second stable region, of the detour transition route, a detour transition route portion in at least one of the first stable region and the second stable region is changed to a first stable region and a second stable region corresponding to the detour transition route portion. It is characterized in that it is set longer than the transition path portion of the transition paths in at least one of the areas .

According to this, the detour transition route setting means includes a detour transition route in at least one of the detected first stable region having the current driving state and the second stable region having the next driving state among the detour transition routes. Can be set more redundantly than the transition path portion of the transition paths in at least one of the first stable region and the second stable region corresponding to the detour transition path portion. The setting of the detour path part can be performed in preference to the setting of each detour path part in the other first stable region and the second stable region. For example, the preferential setting of the detour path part in the unstable region makes it possible to avoid the stay time in the unstable region with the shortest crossing time.

Further, in the invention according to claim 6 , when the injection condition correcting means determines that the operating state and the next operating state detected by the determining means are in the same stable region without straddling the unstable region, The basic value is not corrected.

  According to this, when it is determined that the current operating state and the next operating state detected by the determining unit are in the same stable region without crossing the unstable region, the injection condition correcting unit corrects the basic value. do not do.

  In general, when detecting the current operating state, predicting the transition of the operating state based on the detected current operating state, and assuming the next operating region, for example, to the vehicle and the internal combustion engine mounted on the vehicle Based on the operation information of the driver who requests performance, the current driving state is formed and detected.

  Therefore, when predicting the next driving state, immediately after detecting the current driving state, the driver's operation information such as the accelerator opening degree and the gear position shift information related to the accelerator depression amount greatly changes. This is not expected.

On the other hand, in the invention according to claim 6 , the transition of the driving state is predicted from the detected current driving state, and there is an unstable region in the transition path of transition to the next driving state or the next driving state. The injection condition is corrected only when it is determined whether or not an unstable region exists based on the determination result. Thereby, it is possible to suppress the influence of the unstable region without improving excessive prediction accuracy for predicting the next operation state by the operation region assumption means.

The invention according to claims 7 to 8 is characterized in that the injection condition basic information storage means has a basic injection condition map in which basic values obtained by experiments are stored in advance and stored.

  According to this, for example, a basic value can be obtained by a conformity test of a fuel injection device including an internal combustion engine and a fuel injection valve, and the obtained basic value can be held in a map as map data information. This makes it easier to set the basic value before correcting the injection conditions, compared to a method represented by an approximate expression that prescribes the basic value obtained in advance through experiments such as a conformance test.

The invention according to claim 8 is characterized in that the basic value in the basic injection condition map is temporarily rewritten by the corrected injection condition.

  According to this, even when the degree of engagement with the unstable region in the next operating state changes according to the determination means obtained each time the operating state is detected when the operation control of the fuel injection valve is performed, the injection condition It is possible to easily switch between a basic injection condition map having a basic value before correction and a corrected basic injection condition map in which the basic value is temporarily rewritten.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a fuel injection control device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing the overall configuration of the fuel injection control apparatus according to this embodiment. FIG. 2 is a partial cross-sectional view showing a nozzle portion of the fuel injection valve in FIG. FIG. 3 is an example of a characteristic map stored in the ECU in FIG. 1, and is a characteristic diagram showing a relationship between a target injection amount and a command injection pulse period. FIG. 4 is an example of a characteristic map stored in the ECU in FIG. 1, and is a characteristic diagram showing a relationship between the target injection amount and the fuel injection pressure. FIG. 5 is a diagram illustrating a control method executed by the ECU in FIG. 1. It is determined whether or not there is an unstable region in the transition path that transitions to the predicted operating state, and based on the determination result. 5 is a flowchart showing a control process for avoiding an unstable region that suppresses the influence of the unstable region on the injection characteristics. FIG. 6 shows a method for correcting an injection condition for avoiding an unstable region and a correction corresponding thereto when it is determined that the transition path to the operation state predicted in the determination in FIG. 5 crosses the unstable region. It is a characteristic view explaining the setting method of the made correction | amendment transition path | route. FIG. 7 shows a method of correcting an injection condition for avoiding an unstable region and a corrected correction transition corresponding thereto when the operation state predicted in the determination in FIG. 5 is determined to stay in the unstable region. It is a characteristic view explaining the setting method of a path | route.

  A fuel injection device for an internal combustion engine (hereinafter referred to as a fuel injection device) is applied to a common rail fuel injection device for an internal combustion engine (hereinafter referred to as an engine) such as a multi-cylinder (4 cylinders in the present embodiment) diesel engine. As shown in FIG. 1, the fuel injection device includes a common rail 109 that stores fuel in a high pressure state, and a high-pressure pump (hereinafter referred to as a supply pump) 110 that pressurizes and pumps the fuel pumped from the fuel tank 111 to the common rail 109. The fuel injection valve 101 or the like for injecting high-pressure fuel supplied from the common rail 109 through the high-pressure pipe 114 into the cylinder of the diesel engine is controlled by a fuel injection control device (hereinafter referred to as ECU) 100.

  As shown in FIG. 1, the common rail 109 includes a pressure sensor 107 that detects a fuel pressure (hereinafter referred to as a common rail pressure) Pc corresponding to the fuel injection pressure in the common rail 109 and outputs it to the ECU 100, and a common rail pressure Pc in the common rail 109. A pressure limiter 108 is attached to limit the value so as not to exceed a preset upper limit value. The high-pressure pump 110 is provided with a solenoid valve (hereinafter referred to as an inlet metering valve) 110a in a fuel passage (not shown) for introducing fuel pumped from the fuel tank 111 into a pump chamber (not shown), and is built in the pump chamber. When the inlet metering valve 110a shuts off the fuel passage while the plunger is being pumped, the fuel in the pump chamber is pressurized by the plunger and pushes open a check valve (not shown) to pump the high pressure fuel to the common rail 109.

  As shown in FIG. 1, the fuel injection valve 101 includes a nozzle 101 a that houses two needles 1 and 8, and a drive valve 101 b that controls the back pressure of the needles 1 and 8 using an electromagnetic valve 30. When this drive valve 101b is energized, fuel is injected from the nozzle 101a. When the drive valve 101b is energized, the fuel pressure in the pressure control chamber 22 provided behind the nozzle 101a is lowered, so that the needles 1 and 8 are raised stepwise to start injection. Thereafter, when the energization to the drive valve 101b is stopped, the fuel pressure in the pressure control chamber 22 increases, so that the needles 1 and 8 are pushed down and the injection ends. Therefore, the injection timing is controlled by the energization timing to the drive valve 101b, and the injection amount is controlled by the energization period (command injection pulse period Tq) to the drive valve 101b.

  Specifically, the high-pressure fuel supplied from the supply pump 110 via the common rail 109 is supplied to the fuel reservoir chamber 3 via the fuel inlet 27 and the fuel introduction passage 28 and also to the pressure control chamber 22. . The high pressure fuel in the pressure control chamber 22 can be discharged to the fuel tank 111 by controlling the electromagnetic valve 30.

  As shown in FIGS. 1 and 2, an outer needle 1 is slidably accommodated in a valve body (hereinafter referred to as a nozzle body) 2 of a fuel injection valve 101, and a fuel reservoir chamber 3, a fuel are disposed under the sliding portion. A passage 4 is provided, and a valve seat (hereinafter referred to as a seat surface) 5 is provided downstream thereof. An inner needle 8 is slidably accommodated inside the outer needle 1.

  In addition, the outer needle 1 is slidable in the outer needle 1 and the bypass passage 10 passing through the inside of the outer needle 1 to the left and right so that the common rail pressure Pc can be applied to the upper end portion 9 of the inner needle 8. A valve closing chamber 11 communicating with the bypass passage 10 is provided. Further, the outer needle 1 communicates with a cylindrical portion 12 of the inner needle 8 and a slidable guide portion 13 and an adjustment hole 14 penetrating the outer needle 1 from side to side. A lift pin 15 inserted right and left in the inner needle 8 is positioned in the adjustment hole 14. The dimension between the lower end portion in the adjustment hole 14 and the lower end portion of the lift pin 15 defines an invalid lift amount (hereinafter referred to as an inner invalid lift amount) HD0 of the inner needle 8 with respect to the outer needle 1.

  An abutting portion that abuts against the seat surface 5 is provided at the tip of the outer needle 1, and the abutting portion of the outer needle 1 is seated on the seat surface 5, whereby the first valve seat 16 is placed on the seat surface 5. Is forming. The first valve seat 16 formed in this way blocks communication between the fuel passage 4 and the first injection hole 6.

  A contact portion that contacts the seat surface 5 is provided at the tip of the inner needle 8, and the contact portion of the inner needle 8 is seated on the seat surface 5, whereby the second valve seat 17 is placed on the seat surface 5. Is forming. The second valve seat 17 formed in this way blocks communication between the fuel passage 4 and the second injection hole 7.

  The first nozzle hole 6 is provided on the fuel downstream side of the fuel passage 4, and the second nozzle hole 7 is provided on the fuel downstream side of the first nozzle hole 6. The first valve seat 16 is provided between the fuel passage 4 and the first injection hole 6, and the second valve seat 17 is provided between the first injection hole 6 and the second injection hole 7. ing. A sac chamber 3 a communicating with the second injection hole 7 is formed on the fuel downstream side of the second valve seat 17, and initial injection is performed from the second injection hole 7 when the lift of the inner needle 8 is started. The planned fuel is temporarily stored.

  As shown in FIG. 1, a control piston 21 is connected to an end of the outer needle 1 on the side opposite to the injection side via a pressure pin 19, and the first spring 20 that biases the pressure pin 19 in the injection hole closing direction. It has.

  The electromagnetic valve 30 that controls the fuel pressure in the pressure control chamber 22 includes an electromagnetic coil 23, a control valve 24, a second spring 25, and an outlet throttle 26 that communicates a passage discharged from the pressure control chamber 22 to the fuel tank 111. The outlet throttle 26 is opened and closed by the control valve 24.

  When the energization of the electromagnetic coil 23 is turned off, the control valve 24 closes the outlet throttle 26 by the urging force of the second spring 25. When high pressure fuel is supplied to the pressure control chamber 22, the urging force that the outer needle 1 receives toward the first valve seat 16 by the first spring 20 (hereinafter referred to as the urging force of the outer needle spring) and pressure control. The sum of the force received from the fuel pressure in the chamber 22 toward the first valve seat 16 (hereinafter referred to as the back pressure of the pressure control chamber 22) is the force received in the lift direction by the fuel pressure in the fuel reservoir chamber 3 (hereinafter referred to as the lift pressure). Therefore, the outer needle 1 is seated on the first valve seat 16.

  When the electromagnetic coil 23 is energized, the control valve 24 opens the outlet throttle 26 and the high-pressure fuel in the pressure control chamber 22 is discharged to the fuel tank 111 through the outlet throttle 26. Then, as the fuel pressure in the pressure control chamber 22 decreases, the outer needle 1 is lifted away from the first valve seat 16.

  Here, the relationship with the inner needle 8 which lifts according to the lift of the outer needle 1 will be described. During the lift stroke of the inner invalid lift amount HD0, the outer needle 1 is separated from the first valve seat 16 and lifted, and injection is performed only from the first injection hole 6 to reduce the initial injection rate while reducing the initial injection rate. The injection pressure can be increased.

  When the outer needle 1 is further lifted, the lower end of the adjustment hole 14 comes into contact with the lower end of the lift pin 15, and the inner needle 8 is separated from the second valve seat 17. When the inner needle 8 is lifted even slightly due to separation, the high-pressure fuel is loaded on the entire inner needle conical surface 18, so that the inner needle 8 is lifted up instantaneously, and fuel injection is also started from the second injection hole 7. To do. Accordingly, the fuel injection rate from the first injection hole 6 and the second injection hole 7 can increase the injection rate in the middle injection period.

  The maximum lift amount HDmax of the outer needle 1 is determined by the axial dimension between the lower end of the regulating member 29 and the upper end face 1a of the outer needle 1 as shown in FIG. The lift amount of the inner needle 8 is HDmax−HD0. In this embodiment, a biasing member such as a spring for independently biasing the inner needle 8 to the second valve seat 17 is not provided, but the outer needle 1 is biased to the first valve seat 16. In addition to the first spring 20, a spring (hereinafter referred to as an urging spring) that urges the inner needle 8 to the second valve seat 17 independently may be provided. By setting various parameters such as the inner invalid lift amount HD0 and the like to predetermined values and switching the injection holes 6 and 7 for injecting fuel, it becomes possible to inject fuel with two-stage injection characteristics at the initial stage of injection.

  As described above, the injection characteristic that is changed into two stages by switching the injection holes 6 and 7 has a relationship between the fuel injection amount Q as shown in FIG. 3 and the injection pulse period Tq for driving and controlling the fuel injection valve 101. In FIG. 3, for the sake of convenience, a biasing spring that independently biases the inner needle 8 toward the second valve seat 17 is provided in order to explain the variation factors due to various parameters of the fuel injection valve 101. To do.

  As shown in FIG. 3, when the energization pulse period Tq for energization control of the solenoid valve 30 becomes the first energization pulse period Tq1, the pressure in the pressure control chamber 22 decreases due to energization, and the lift direction fuel receiving pressure of the outer needle 1 However, when the sum of the urging force of the outer needle spring and the back pressure of the pressure control chamber 22 is won, the injection is started (see point QTq1 in FIG. 3).

  Further, when the second energization pulse period Tq2 is reached, the outer needle 1 collides with the inner needle 8. Between the first energization pulse period Tq1 and the second energization pulse period Tq2, since there is a lift stroke of the inner invalid lift amount HD0, fuel corresponding to the lift amount of the outer needle 1 is injected from the first injection hole 6. .

  Since the urging spring for urging the inner needle 8 is provided, the pressure control for the lift direction fuel receiving pressure of the inner needle 8 to overcome the sum of the urging force of the urging spring and the back pressure of the pressure control chamber 22. When the third energization pulse period Tq2 is reached, which is an increment ΔTq corresponding to a decrease in the back pressure of the chamber 22, the inner needle 8 leaves the seat and the inner needle 8 starts to lift together with the outer needle 1. That is, during the second energization pulse period Tq2 and the third energization pulse period Tq3 between the increments ΔTq, the outer needle 1 is locked by the inner needle 8 and is in a pseudo full lift state (point QTq2 in FIG. 3). ~ See point QTq3). The pseudo full lift amount is a lift amount generated by the contact between the lower end portion in the adjustment hole 14 and the lower end portion of the lift pin 15, and corresponds to the inner invalid lift amount HD0.

  Further, when the increment ΔTq from the third energization pulse period Tq3, fuel is injected from both the first nozzle hole 6 and the second nozzle hole 7. The increment of the injection amount increases in accordance with the lift amount of the needles 1 and 8 of the first nozzle hole 6 and the second nozzle hole, and therefore, the increment of the injection amount during the energization pulse period Tq3 to Tq4 is energized. It is larger than Tq1 to Tq2 during the pulse period (see QTq3 point to QTq4 point in FIG. 3).

  When the increment ΔTq is further performed and the fourth energization pulse period Tq4 is reached, the outer needle 1 and the inner needle 8 are in a mechanical full lift state. The subsequent increment ΔQ of the injection amount Q is substantially proportional to the increment amount ΔTq.

  Here, in the above injection characteristics, at the point QTq2 shown in FIG. 3, bounce occurs between the needles 1 and 8 due to the collision between the outer needle 1 and the inner needle 8, so that the pseudo full lift amount and the inner The seating state of the needle may become unstable and fluctuate. For example, the seating state may be incomplete due to the bounce of the inner needle, and the seat may be temporarily separated slightly. Further, the lift amount of the outer needle 1 may be larger than the pseudo full lift amount due to the bounce at the time of collision.

Further, in the above injection characteristics, the outer needle 1 and the inner needle 8 are temporarily integrated by contact between the lower end of the adjustment hole 14 and the lower end of the lift pin 15 between the points QTq2 to QTq3 shown in FIG. Therefore, it is only in the pseudo full lift amount of the outer needle 1 against the urging force of the urging spring. For this reason, the injection characteristics between the QTq2 point and the QTq3 point (refer to the BTq region in FIG. 3) are unstable compared to other QTq1 to QTq2 or between QTq3 to QTq4, and the above-mentioned bounce of the QTq2 point and the QTq2 point Due to the influence of the temporary integration state between the needles 1 and 8 between the QTq3 points, on the injection amount Q on the vertical axis in FIG. 3, in the peripheral region (hereinafter referred to as unstable region) B of the QTq2 points to QTq3, The fuel injection amount Q fluctuates and becomes unstable. Specifically, for example, when the energization pulse value is set to any of the energization pulse periods Tq2 to Tq3 corresponding to the QTq2 point to QTq3, even if the fuel injection valve 101 is controlled to operate with the set energization pulse value, the fuel injection quantity injected from the injection valve 101 varies the target fuel injection amount Q _0, it may not be injection controlled to the target fuel injection amount Q _0.

  In the above description, the injection characteristic when the operation of the fuel injection valve 101 is controlled based on the correlation between the fuel injection amount Q and the injection pulse period Tq in FIG. 3, which is an example of the characteristic map stored in the ECU 100. However, the present invention is not limited to this, and even in the correlation between the fuel injection amount Q and the common rail pressure Pc in FIG. 4 in one example of the characteristic map stored in the ECU 100, the injection holes 6 and 7 are switched at the initial stage of injection. An unstable region B occurs.

  Further, in the fuel injection amount Q on the vertical axis in FIGS. 3 and 4, the unstable region B has a stable region where the injection amount is smaller than the unstable region B (hereinafter referred to as the first stable region) and the injection amount is large. It is sandwiched between stable regions (hereinafter referred to as second stable regions).

  Here, the ECU 100, which is a control means of the present embodiment, is configured with a known microcomputer as a main body, and executes various engine control programs stored in a built-in ROM (storage medium). Accordingly, the fuel injection amount Q and the common rail pressure Pc of the fuel injection valve 101 are controlled. Further, the supply pump 110 and the like are controlled via the inlet metering valve 110a based on the output signal of the ECU 100. Various arithmetic processes are performed based on sensors signals read into the ECU 100.

  Sensors connected to the ECU 100 include an accelerator sensor (not shown) for detecting the accelerator opening degree Accp, a rotation speed sensor (not shown) for detecting the engine speed Ne, and a water temperature for detecting the engine coolant temperature Tw. There are a sensor (not shown), a fuel temperature sensor (not shown) for detecting the fuel temperature Tf of the fuel sucked into the supply pump 110, a pressure sensor 107 for detecting the common rail pressure Pc, and other sensors.

  Further, the ECU 100 is supplied with, for example, a fuel injection valve 101 from a supply source, and an image reading device (not shown) such as a code reader when the fuel injection valve 101 is assembled to each cylinder of the engine in an engine assembly line or the like. Are electrically connected. The image reading device reads a storage medium (for example, QR code 32) such as a memory attached to each fuel injection valve 101.

  In this storage medium, an injection characteristic (hereinafter referred to as injection characteristic eigenvalue data) indicating a correlation between the injection amount Q and the injection pulse period Tq in accordance with the common rail pressure Pc is stored in a map (hereinafter referred to as a basic). It is stored separately from the injection map. In the injection characteristic eigenvalue data, data representative of individual injection characteristics of the fuel injection valve 101 is stored. The injection characteristic eigenvalue data may be a unique basic value stored in the map, or may represent the basic value by an approximate expression of the injection characteristic.

  Note that the injection characteristics stored in the ECU 100 include a map (hereinafter referred to as a first map) showing the correlation between the command injection amount Q and the command injection pulse period Tq shown in FIG. 3, or the command injection amount Q and the command shown in FIG. It is a basic injection map such as a map (hereinafter referred to as a second map) showing the correlation of the target common rail pressure Pc.

  Here, the ECU 100 controls the injection operation of the fuel injection valve 101, the common rail pressure control unit that controls the common rail pressure in the common rail 109 to the target fuel pressure (target common rail pressure), and the expected operating range. Control means (hereinafter referred to as injection characteristic correcting means) for correcting the injection characteristics in order to avoid the unstable region B on the injection characteristics in the course of the transition. The target common rail pressure Pc corresponds to the fuel injection pressure injected from the fuel injection valve 101, and is set to an optimum fuel pressure according to the engine operating state.

  The injection means includes target injection amount determination means, injection timing determination means, injection period determination means, and fuel injection valve drive means. The target injection amount determining means determines an optimal target injection amount Qfin according to the engine operating state detected by various sensors. The injection timing determining means determines a command injection timing (command injection pulse timing) Tfin based on the target injection amount Qfin and the engine speed Ne. The injection period determining means determines a command injection period (command injection pulse period) Tq based on the common rail pressure Pc and the target injection amount Qfin. The fuel injection valve drive means applies a substantially pulsed energization current to the electromagnetic valve 30 of the fuel injection valve 101 of each cylinder until the command injection pulse period (Tq) elapses from the command injection timing (Tfin). .

  The common rail pressure control means includes a discharge amount control means for controlling the discharge amount of the supply pump 110 to the common rail 109, and the actual fuel pressure in the common rail 109 (hereinafter referred to as the actual common rail pressure) is detected by the pressure sensor 107. Detect and feedback control is performed so that the actual common rail pressure Pcf substantially coincides with the target common rail pressure Pca.

  The discharge amount control means determines the basic drive signal to the inlet metering valve 110a based on the target common rail pressure Pca and the fuel temperature Tf and controls the supply pump 110 to control the detected actual common rail pressure Pca and the target common rail pressure. If Pca does not match, the basic drive signal is corrected according to the difference between the actual common rail pressure Pca and the target common rail pressure Pca, and the supply pump 110 is driven and controlled by the corrected drive signal after correction.

  Next, the injection characteristic correcting means determines whether or not there is an opportunity to pass through or stay in the unstable region B in the transition path that transitions to the predicted driving region based on the predicted driving region; Based on the determination result by the determination means, there is provided an injection condition correction means for correcting the basic value stored in the basic injection map so as to reduce the influence of the unstable region B and determining the corrected injection condition. . The determination means and the injection condition correction means will be described in detail in a control process (see FIG. 5) executed by the ECU 100 described later.

  Next, it is determined whether or not there is an unstable region B on the transition path to the predicted operating state executed by the ECU 100 described above, and control processing for avoiding the unstable region B based on the determination result ( Hereinafter, the unstable region avoidance control process) will be described with reference to FIG. 5, FIG. 6, FIG. 7, and the like.

  3 and 4, which are examples of characteristics stored in ECU 100, basic values such as fuel injection amount Q, injection pulse period Tq, and common rail pressure (fuel injection pressure) Pc are stored by a plurality of maps. It is what has been. Specifically, FIG. 3 shows, as one injection condition, a map MTq showing a Q-Tq characteristic when the common rail pressure Pc is a predetermined value (hereinafter also referred to as a map having a Q-Tq characteristic). For example, on the map MTq, using the common rail pressure Pc value as a parameter, a plurality (for example, N) of Q-Tq characteristics MTq1, MTq2,. A basic injection map is formed. Note that this basic injection map is not limited to such a map composed of N maps for each of a plurality (N) of Q-Tq characteristics MTq1 to MTqN, and a plurality (N) of Q-Tq characteristics MTq1. The map data of ~ MTqN may be collected on one map.

  FIG. 4 shows a basic injection map MPc (hereinafter also referred to as a basic injection map having a Q-Pc characteristic) indicated by a Q-Pc characteristic. Here, the regions A1, B, and A2 of the fuel injection amount Q on the vertical axis in FIG. 3 are the vertical axes as viewed from the III direction in which the common rail pressure Pc indicated by the horizontal axis is a predetermined value in FIG. This corresponds to each region A1, B, A2 of the fuel injection amount Q shown. In other words, a map MTq1 having a Q-Ta characteristic as shown in FIG. 3 shows one injection condition of the injection condition map MTq having the common rail pressure Pc value as a parameter, and has a Q-Pc characteristic as shown in FIG. The basic injection map MPc itself corresponds to the injection condition map MTq. That is, it is possible to determine whether the engine operating state is in the unstable region B, the stable region A1, or A2 based on the basic injection map MPc having the Q-Pc characteristic or the injection condition map MTq.

  Here, the relationship between the predicted next operation state and the unstable region B when shifting from the current operation state to the next operation state on the basic injection map MPc will be described with reference to FIG. In general, since the switching of the injection of the fuel injection valve 101 is caused by executing the injection stepwise in the initial stage of the injection, it is predicted in a transient operation state such as a stop of the vehicle or a start acceleration from a low speed traveling, for example. An unstable region B exists in the middle of the transition path TL that transitions to the next operation state or the next operation state. For this reason, it demonstrates below on the assumption that the present driving | running state exists in 1st stable area | region A1 corresponding to the small injection quantity area | region equivalent to a low load.

  On the basic injection map MPc of FIG. 4, 51 indicates the current operating state, and 52, 53, and 54 indicate the expected next operating state (hereinafter, the next operating state). In the case of the next operation state 52, the vehicle moves within the same first stable region A1 from the current operation state 51, and the transition path TL52 has an opportunity to cross or stay in the unstable region B. Absent.

  In the next operation state 53, the current operation state 51 moves from the first stable region A1 to the unstable region B and reaches the unstable region B, and the transition path TL53 has an unstable state. There is an opportunity to stay in the area B. Therefore, the transition route TL53 straddles at least the lower limit B1 of the unstable region B.

  In the case of the next operation state 54, the current movement state 51 moves from the first stable region A1 to the second stable region A2 across the unstable region B, and the transition path TL53 includes an unstable region. An opportunity to cross B has arisen. Therefore, the transition path TL54 straddles both the lower limit B1 and the upper limit B2 of the unstable region B.

  Therefore, in S501 (S is a step), the operation state of the engine is read in order to predict the next operation state. Specifically, the ECU 100 reads the driving state with various sensors and detects the current driving state. For example, the detection signal of the rotation speed sensor is input, the engine rotation speed Ne is read, the detection signal of the accelerator sensor is input, and the accelerator opening degree Accp is read. Further, the running state is read by a shift signal indicating the gear position state. From these operating states, it is possible to grasp basic operating state information as to whether or not the vehicle is in the stable region A1, A2 or the unstable region B at least when it is detected.

  In S502, the optimal injection condition according to the detected driving | running state is calculated. The injection conditions include basic values such as the target fuel injection amount Q, the common rail pressure Pc, and the command injection pulse period Tq, and an optimum basic value corresponding to the detected operating state is obtained. Specifically, the required engine load is calculated from the engine speed and the accelerator opening degree Accp, and the target fuel injection amount Qa corresponding to the required load is determined.

  In S501 and S502, the detected operating state and the areas A1, A2, and B corresponding to the operating state are stored for each detection.

  In S503 and S504, the injection condition in the previous operation state is compared with the detected injection condition in the current operation state, and the next expected operation state is estimated. Specifically, in S503, one target fuel injection amount of the injection condition is compared, and the previous target fuel injection amount Qp (command fuel injection amount Qfinp) and the current target fuel injection amount Qa are compared with the previous target fuel injection amount Qa. Find the deviation of the current operating state. That is, by obtaining the deviation between the previous and current injection conditions, the transition direction and the transition amount as the deviation direction constituting the deviation are calculated, and the next operation state is estimated based on the transition direction and the transition amount. And in S504, the area | region A1, A2, and A3 of the next driving | running state are assumed based on the predicted next driving | running state.

  In S505 and S506, it is determined whether or not there is an unstable region B in the transition path TL that transitions to the next operation state assumed in S503 and S504. Specifically, in S505, it is determined whether or not the next operation state maintains the same first stable region A1 as the current operation state. If the transition path TL of the next operation state is within the same first stable region A1 as the current operation state 51, the transition path TL52 of the next operation state 52 shown in FIG. Since there is no opportunity to cross or stay in the region B, the process proceeds to S509, and the fuel injection valve 101 is controlled to operate under the injection conditions by the normal control without performing correction to avoid the unstable region B (S510). .

  If the transition path TL of the next operating state is not within the same range of the first stable region A1 as the current operating state 51, the process proceeds to S506, and the range of the first stable region A1 of the transition path TL of the next operating state A determination is made to identify an outside state.

  In S506, it is determined whether or not the next operation state moves to the second stable region A2 and stays. If the transition path TL of the next operating state is within the range of the second stable region A2 across the unstable region B, it is the state of the transition route TL54 of the next operating state 54 shown in FIGS. In this transition route TL54, an opportunity to cross the unstable region B occurs and crosses both the lower limit B1 and the upper limit B2 of the unstable region B. Therefore, the process proceeds to S507, and the first unstable region avoidance control is performed. Execute.

  If the transition path TL of the next operating state does not transition into the range of the second stable region A2 across the unstable region B, the transition route TL53 of the next operating state 53 shown in FIGS. In this state, there is an opportunity to stay in the unstable region B, and at least the lower limit B1 of the unstable region B is crossed. Therefore, the process proceeds to S508, and the second unstable region avoidance control is executed. To do.

  In S507, as shown in FIG. 6, the predicted operation state is the state of the transition path TL54 of the next operation state 54. In this transition path TL54, there is an opportunity to cross the unstable region B, and Since both the lower limit B1 and the upper limit B2 of the stable region B are straddled, the transition path crossing the unstable region B is shortened. Specifically, the assumed transition path TL54 includes a transition path part TL54a in the first stable area A1, a transition path part TL54b in the unstable area B, and a transition path part TL54c in the second stable area A2. Has been. A transition path portion 59b that vertically traverses the unstable region B is selected with respect to the actual length Δp of the transition path portion TL54b in the unstable region B. The actual length Δa of the transition path portion 59b that traverses vertically can be shorter than the actual length Δp of the transition path portion TL54b.

  As a result, the transition path part 59b is connected to the transition path part TL59a in the first stable area A1 and the transition path part TL59c in the second stable area A2, and the selected transition path (hereinafter, referred to as the transition path part TL59a). Although the detour transition path TL59 is formed longer than the transition path TL54 in terms of the total transition path length, the transition path portion 59b crossing the unstable region B can be effectively shortened. Then, the process proceeds to S510, and the operation of the fuel injection valve 101 is controlled under the injection conditions corrected by the detour transition path TL59.

  In S508, as shown in FIG. 7, the predicted operating state is the state of the transition path TL53 of the next operating state 53, and an opportunity to stay in the unstable region B occurs, and at least unstable. Since the lower limit B1 of the region B is crossed, it is selected whether to return to the first stable region A1 across the lower limit B1 or to move to the second stable region A2 across the upper limit B2. Then, the process proceeds to S510, and the operation of the fuel injection valve 101 is controlled under the injection conditions corrected by the selected correction transition path TL58.

  Specifically, the transition path portion TL58bB that returns from the next assumed operating state 53 to the first stable region A1 across the lower limit B1 again is selected, or enters the second stable region A2 across the upper limit B2. A preferable selection method of selecting the moving path part TL58bA to be moved is determined.

  In this case, in this embodiment, it is preferable that the transition path part TL58bA and the transition path part TL58bB are modified transition paths that are modified mainly to change the common rail pressure Pc. Thereby, although the common rail pressure Pc is changed for the purpose of transition to the stable regions A1 and A2, the fuel injection amount Q is not changed for the purpose. Therefore, it is possible to avoid the unstable region B by correcting the next operating state from the unstable region B to the stable regions A1 and A2 with almost no change in the output torque of the engine.

  Further, in the present embodiment, it is preferable to determine, as the modified transition path TL58, the smaller one of the change amounts ΔPcu and ΔPcd of the common rail pressure Pc among the transition path part TL58bA and the transition path part TL58bB. In the example shown in FIG. 7 of the present embodiment, the change amount ΔPcd of the transition path part TL58bA is smaller than the change amount ΔPcu of the transition path part TL58bB, and the transition path part TL58bA is determined as the modified transition path TL58.

  As a result, a relatively small injection condition of selecting a small correction transition path with a small change amount of the common rail pressure Pc with respect to the injection condition of the next operation state 53 that is a requested operation state of the engine according to a request from the driver or the like. The unstable region can be avoided by the correction.

  In addition, as a storage method for storing the basic value information of the injection conditions, it is preferable to store basic values obtained in advance by experiments and store them in basic injection condition maps such as the stored basic injection maps MPc and MTq. According to this, for example, the basic value can be obtained by a conformity test of the fuel injection device including the engine and the fuel injection valve 101, and the obtained basic value can be held in the map MPc as map data information.

  Furthermore, the injection condition correction method for correcting the injection condition differs depending on the determination result of determining the relationship between the next operating states 52, 53, and 54 and the unstable region B described above, and the correction may not be performed. For this reason, when controlling the operation of the fuel injection valve 101 according to the injection conditions, it is preferable to temporarily rewrite the basic values in the basic injection condition map with the corrected injection conditions.

  Thereby, even if the degree of engagement with the unstable region B in the next operation state 52, 53, 54 changes according to the determination result obtained each time the operation state 51 is detected, the basic value before the injection condition correction is performed. And a corrected map in which the basic value is temporarily rewritten can be easily switched.

  In the present embodiment described above, the unstable region B generated by the stepwise switching of the fuel injection valve 101 can be experimentally grasped in advance, and this unstable region B is determined as the engine operating region. It is defined in relation to the stable regions A1 and A2 in the entire range. Then, the transition of the driving state is predicted from the detected current driving state 51, and in the middle of the transition path TL52, TL53, TL54 that transitions to the next driving state 52, 53, 54 or the next driving state 52, 53, 54. Then, it is determined whether or not the unstable region B exists. Based on the determination result, the basic value (for example, common rail pressure Pc) stored in the basic injection condition map such as the map MPc is corrected and corrected so as to reduce the degree of influence of the unstable region B. Operation control of the fuel injection valve 101 is performed under the injection conditions.

  Thereby, for example, in the process of transitioning to the next operation state 53, 54, the control time Δa in the operation state staying in the unstable region B is shortened, for example, the operation time ratio between the stable regions A1, A2 and the unstable region B By reducing the ratio of the unstable region B in the (transition path portion ratio), the influence of the unstable region B on the injection characteristics of the fuel injection valve 101 can be avoided in a relatively short stay time.

  In the present embodiment described above, the method for predicting the next operation state 52, 53, 54 is based on the deviation between the detected current operation state 51 and the stored operation state detected last time. The states 52, 53, and 54 are estimated.

  In general, since the switching of the injection of the fuel injection valve 101 occurs by executing the injection stepwise in the initial stage of the injection, it is predicted in a transient operation state such as when the vehicle is stopped or when starting at a low speed. The unstable region B exists in the middle of the transition path TL that changes to the next driving state or the next driving state.

  On the other hand, in this embodiment, since the next driving state 52, 53, 54 is estimated based on the deviation between the detected current driving state 51 and the previous driving state detected last time, for example, the transition is based on the deviation. From the index values such as the direction and the transition amount, the next driving state 52, 53, 54 can be instantaneously estimated when the current driving state 51 is detected.

  Therefore, for example, it is possible to quickly determine whether or not there is an injection condition for performing injection control in the unstable region B in the injection condition during the transition process to the next operation state in the transient operation state. Even in the transient operation state, the injection condition can be quickly corrected so as to reduce the degree of influence of the unstable region B.

  In the present embodiment described above, when it is determined that the next operation state 53 is in the unstable region B based on the determination result, the injection condition correction method mainly changes the common rail pressure Pc among the injection conditions. To correct. That is, the transition path portion TL58bA that moves to the second stable region and the transition route portion TL58bB that returns to the first stable region A1 with the next operating state 53 as a base point are mainly modified to change the common rail pressure Pc. A route is preferred. Thereby, although the common rail pressure Pc is changed for the purpose of transition to the stable regions A1 and A2, the fuel injection amount Q is not changed for the purpose. Therefore, it is possible to avoid the unstable region B by correcting the next operating state from the unstable region B to the stable regions A1 and A2 with almost no change in the output torque of the engine.

  In the present embodiment described above, it is preferable to determine, as the modified transition path TL58, the smaller one of the change amounts ΔPcu and ΔPcd of the common rail pressure Pc among the transition path part TL58bA and the transition path part TL58bB. As a result, a relatively small injection condition of selecting a small correction transition path with a small change amount of the common rail pressure Pc with respect to the injection condition of the next operation state 53 that is a requested operation state of the engine according to a request from the driver or the like. The unstable region B can be avoided by the correction.

  Further, in the present embodiment described above, when it is determined that the next operation state 54 crosses the unstable region B based on the determination result, the injection condition correction method is performed from the detected operation state 51 to the next operation region 54. With respect to the transition route TL54, a detour transition route TL59 that detours so as to shorten the crossing transition route portion TL59b straddling the unstable region B is selected, and the injection condition is corrected corresponding to this detour transition route TL59 ( to correct. Thereby, in the process of transitioning to the next operating state 54, the stay time (Δp) of the unstable region B that affects the injection characteristics can be avoided with a relatively short crossing time (Δa).

  Further, in the present embodiment described above, when it is determined that the current operation state 51 and the next operation state 52 detected by the determination result are in the same first stable region A1 without straddling the unstable region B. In the injection condition correction method, the basic value is not corrected for the purpose of avoiding an unstable region such as prevention of an unstable region shadow.

  In general, when the current driving state 51 is detected, the transition of the driving state is predicted based on the detected current driving state 51, and the next driving region 52, 53, 54 is assumed, for example, the vehicle and the vehicle The current driving state 51 is formed based on the operation information of the driver who requests the performance of the engine mounted on the vehicle, and this is detected.

  Therefore, when the next driving state 52, 53, 54 is predicted, immediately after detecting the current driving state 51, the accelerator opening degree Accp related to the accelerator depression amount, gear position shift information, etc. It is not assumed that the operation information will change greatly.

  On the other hand, in the present embodiment, a transition path TL52 that predicts a transition of the driving state from the detected current driving state 51 and transitions to the next driving state 52, 53, 54 or the next driving state 52, 53, 54. , TL53, and TL54, it is determined whether or not an unstable region exists. In addition, the injection condition is corrected only when it is determined that the unstable region B exists based on the determination result. Thereby, the influence of the unstable area | region B can be suppressed, without aiming at the improvement of the excessive prediction precision for predicting the next driving | running state 52,53,54.

  Further, in the present embodiment described above, as a storage method for storing information on basic values of injection conditions, basic values obtained by experiments in advance are stored, and basic injection condition maps such as stored basic injection maps MPc and MTq are stored. It is preferable to memorize. According to this, for example, the basic value can be obtained by a conformity test of the fuel injection device including the engine and the fuel injection valve 101, and the obtained basic value can be held in the map MPc as map data information. This makes it easier to set the basic value before correcting the injection conditions, compared to a method represented by an approximate expression that prescribes the basic value obtained in advance through experiments such as a conformance test.

  Further, in the present embodiment described above, the injection condition correction method for correcting the injection condition differs depending on the determination result of determining the relationship between the next operating states 52, 53, and 54 and the unstable region B. Sometimes not. For this reason, when controlling the operation of the fuel injection valve 101 according to the injection conditions, it is preferable to temporarily rewrite the basic values in the basic injection condition map with the corrected injection conditions. Thereby, even if the degree of engagement with the unstable region B in the next operation state 52, 53, 54 changes according to the determination result obtained each time the operation state 51 is detected, the basic value before the injection condition correction is performed. And a corrected map in which the basic value is temporarily rewritten can be easily switched.

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  In the first embodiment, the ECU 100 stores the basic injection condition map MPc in which basic values are stored and stored according to the determination result of determining the relationship between the predicted operating states 52, 53, and 54 and the unstable region B. The correction method for correcting the basic value on the corresponding map MPc of MTq is examined (selected), and the fuel injection valve 101 is operated according to the detour transition path TL59 and the corrected transition path TL58 obtained by the selection. The basic value of the injection condition to be controlled was directly corrected (direct correction).

  On the other hand, in the second embodiment, as shown in FIG. 8, a control map that defines engine characteristics (in this embodiment, governor characteristics) for satisfying the required engine characteristics is used to avoid unstable region B. A method of correcting the pseudo characteristics for the above. FIG. 8 is an example of a control map for satisfying the engine characteristics stored in the ECU according to the present embodiment. The control values in the control map are corrected for avoiding unstable regions. It is a characteristic view which shows the state substituted by the control value.

  In the control map MNe showing the Ne-Q characteristic shown in FIG. 8, QNe1, QNe2, and QNe3 show a part of one embodiment that specifies the partial load characteristic of the engine, and specify the remaining partial load characteristic. The portion is not shown. Further, the mountain-shaped engine characteristics shown in the upper part of the control map MNe define the full load characteristics.

  In the control map MNe defining such characteristics, as shown in FIG. 8, the common rail pressure Pc is increased on the high load side to increase the output, and the common rail pressure Pc is relatively low on the low load low speed side. Generally set to be low pressure.

  Here, in FIG. 8, it is predicted that the current operating state 51 will transit to the next operating state 54 across an unstable region (not shown) existing between the partial load characteristics QNe1 to QNe3. The broken line characteristics QNe11, QNe21, and QNe31 in the partial load characteristics QNe1 to QNe3 in the portion where the unstable region exists indicate the control value characteristics when the fuel injection valve 101 is normally controlled. .

  In this case, although the transition path TL54 is formed so as to traverse substantially perpendicular to the bandwidth between the broken line characteristics QNe11, QNe21, and QNe31, the crossing time across these bandwidth portions is an unstable region. There is a risk that the injection characteristics will be unstable due to the influence of the above.

  On the other hand, in the present embodiment, the partial load characteristics QNe12, QNe22, and QNe32 that are corrected by largely curving around the unstable region shown by the solid line in the drawing with respect to the partial load characteristics QNe11, QNe21, and QNe31 shown by broken lines. Thus, the control map MNe having the partial load characteristics QNe12, QNe22, and QNe32 that avoid the unstable region is temporarily rewritten.

  Even with this configuration, it is possible to ensure the function of correcting the basic value of the basic injection characteristic map performed in the first embodiment, so that the same effect as in the first embodiment can be obtained.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is limited to this embodiment and is not interpreted and can be applied to various embodiment in the range which does not deviate from the summary.

  (1) For example, in the above-described embodiment, in the map (basic injection map) MPc showing the Q-Pc characteristic, the unstable region B is a belt-like region having a constant width regardless of the common rail pressure Pc. The shape of the unstable amount region on the map MPc is not limited to this, and the common rail pressure Pc increases as the common rail pressure Pc increases compared to the width of the unstable amount region in the low pressure side portion. (Refer FIG. 9) and the width | variety (refer FIG. 10) may be sufficient.

  In other words, the width shape of the unstable region B is substantially equal, non-uniform in width, or substantially linear in the extending direction of the width, curved or bent. Any of non-linear ones may be used.

  (2) In the present embodiment described above, when it is determined by the determination result that the next operation state 54 crosses the unstable region B, the injection condition correction method is performed from the detected operation state 51 to the next operation region. With respect to the transition route TL54 to 54, the detour transition route TL59 that detours so that the intermediate crossing transition route portion TL59b across the unstable region B is shortened is selected.

  The crossing transition path part TL59b straddling the unstable region B is not limited to the intermediate part in the detour transition path T59 as described above, and the crossing transition path part directly straddling the unstable region B based on the current motion state 51. Any of those that form the TL 59b (see FIG. 11) and those that form the crossing transition path portion TL 59b that directly crosses the unstable region B with the next operation state 54 as a base point as a result (see FIG. 12) may be used.

  (3) In the above case, at least one of the detour transition path section TL59a and the detour transition path section TL59c among the detour transition path TL59 is a transition in an area corresponding to this in the assumed transition path TL54. It is set longer than the route part.

  Thereby, as a setting method for setting the detour transition route TL59, at least one of the detected first stable region A1 in the current operating state and the second stable region A2 in the next operating state in the detour transition route TL59. The detour transition path part in Kana can be set more redundantly than the transition path part in the area corresponding to this in the transition path TL54. Therefore, the setting of the crossing transition path part in the unstable area B can be performed in preference to the setting of each detour path part in the other first stable area A1 and second stable area A2. Thus, by preferential setting of the crossing transition path portion in the unstable region B, the staying time of the unstable region B can be avoided with the shortest crossing time.

  (4) In the present embodiment described above, description has been made by applying to the variable injection hole type fuel injection valve 101 having a plurality of injection holes 6 and 7 that can be sequentially opened at least at the initial stage of injection. In the ECU 100 of the present embodiment, the unstable region B generated by the step-by-step switching of the fuel injection valve 101 is defined in relation to the stable regions A1 and A2 in the entire operation region. The injection valve is any one of the first nozzle hole 6 opened first and then the second nozzle hole 7 opened, and the second nozzle hole opened first and the first nozzle hole opened thereafter. It is also suitable to apply.

  (5) In the present embodiment described above, in the map MPc showing the Q-Pc characteristic, a set of the first stable region A1, the unstable region B, and the second stable region A2 exists on the map MPc. It was explained as being. Not limited to this, a plurality of sets may exist on the map MPc.

It is a typical sectional view showing the whole fuel injection control device composition concerning a 1st embodiment of the present invention. It is a fragmentary sectional view which shows the nozzle part of the fuel injection valve in FIG. FIG. 4 is an example of a characteristic map stored in the ECU in FIG. 1, and is a characteristic diagram showing a relationship between a target injection amount and a command injection pulse period. FIG. 2 is an example of a characteristic map stored in an ECU in FIG. 1, and is a characteristic diagram showing a relationship between a target injection amount and a fuel injection pressure. It is a figure which shows the control method performed by ECU in FIG. 1, Comprising: It is determined whether there exists an unstable area in the transition path | route which changes to the driving | running state predicted, Based on the determination result, it is an unstable area 5 is a flowchart showing a control process for avoiding an unstable region that suppresses the influence on the injection characteristics. In the case where it is determined that the transition path to the predicted operating state in the determination in FIG. 5 crosses the unstable region, the injection condition correction method for avoiding the unstable region and the corresponding corrected correction transition It is a characteristic view explaining the setting method of a path | route. When it is determined that the operation state predicted in the determination in FIG. 5 stays in the unstable region, the injection condition correction method for avoiding the unstable region and the correction correction path setting method corresponding thereto are corrected. FIG. It is an example of the control map for satisfying the engine characteristics stored in the ECU according to the second embodiment, and the control value in this control map is corrected to the control value for avoiding the unstable region. It is a characteristic view which shows the state replaced by. It is an example of the characteristic map memorize | stored in ECU by other embodiment, Comprising: It is a characteristic view which shows the relationship between target injection quantity and fuel injection pressure. It is an example of the characteristic map memorize | stored in ECU by other embodiment, Comprising: It is a characteristic view which shows the relationship between target injection quantity and fuel injection pressure. In the case where it is determined that the transition path to the operation state predicted by the determination result according to the other embodiment crosses the unstable region, the injection condition correction method for avoiding the unstable region and the corresponding corrected It is a characteristic view explaining the setting method of a correction | amendment transition path | route. In the case where it is determined that the transition path to the operation state predicted by the determination result according to the other embodiment crosses the unstable region, the injection condition correction method for avoiding the unstable region and the corresponding corrected It is a characteristic view explaining the setting method of a correction | amendment transition path | route.

Explanation of symbols

100 ECU (control means, fuel injection control device)
DESCRIPTION OF SYMBOLS 101 Fuel injection valve 101a Nozzle part 101b Drive valve 1 Outer needle 2 Nozzle body (valve body)
6 First injection hole 7 Second injection hole 8 Inner needle 21 Control piston 22 Pressure control chamber 30 Solenoid valve 109 Common rail 110 Supply pump (high pressure pump)

Claims (8)

In a fuel injection control device for an internal combustion engine that controls operation of a fuel injection valve so as to perform stepwise injection within one combustion cycle of the internal combustion engine,
The fuel injection valve is a variable injection type fuel injection valve having a plurality of injection holes that can be sequentially opened at least in the initial stage of injection, and has a first injection hole and a second injection hole. An outer needle that is accommodated in the valve body and opens and closes the first nozzle hole, and an inner needle that is disposed inside the outer needle and opens and closes the second nozzle hole, and the outer needle and the One of the inner needles is lifted prior to the other needle, and the one needle that has been lifted collides with the other needle,
An operation region estimation means for detecting an operation state including the rotational speed of the internal combustion engine and an accelerator opening, predicting a transition of the operation state based on the detected operation state, and assuming a next operation region;
Injection condition basic information storage means for storing a basic value of the injection condition corresponding to the operation region;
In the entire range of the operation region, an unstable region where the injection characteristic becomes unstable is defined by the stepwise switching of the injection, and the stable region is divided by the unstable region. Injection characteristic storage means for storing a stable region in advance;
Based on the next driving region estimated by the driving region assumption unit, a determination unit that determines whether or not the unstable region exists in a transition path that transitions to the next driving region;
Injection that corrects the basic value stored in the injection condition basic information storage means so as to reduce the degree of influence of the unstable region based on the determination result by the determination means, and determines the corrected injection condition Condition correction means,
When the determination means determines that the next operation state is in an unstable region, the injection condition correction means changes a fuel injection pressure for transition to the stable region among the injection conditions ,
The injection conditions are a fuel injection pressure, an injection pulse period, and a fuel injection amount or an index value corresponding thereto, and a command determined by calculating an injection pulse period for a target injection amount corresponding to the fuel injection pressure A fuel injection control apparatus for an internal combustion engine, wherein the operation of the fuel injection valve is controlled based on an injection pulse period . In a fuel injection control device for an internal combustion engine that controls operation of a fuel injection valve so as to perform stepwise injection within one combustion cycle of the internal combustion engine,
The fuel injection valve is a variable injection type fuel injection valve having a plurality of injection holes that can be sequentially opened at least in the initial stage of injection, and has a first injection hole and a second injection hole. An outer needle that is accommodated in the valve body and opens and closes the first nozzle hole, and an inner needle that is disposed inside the outer needle and opens and closes the second nozzle hole, and the outer needle and the One of the inner needles is lifted prior to the other needle, and the one needle that has been lifted collides with the other needle,
An operation region estimation means for detecting an operation state including the rotational speed of the internal combustion engine and an accelerator opening, predicting a transition of the operation state based on the detected operation state, and assuming a next operation region;
Injection condition basic information storage means for storing a basic value of the injection condition corresponding to the operation region;
In the entire range of the operation region, an unstable region where the injection characteristic becomes unstable is defined by the stepwise switching of the injection, and the stable region is divided by the unstable region. Injection characteristic storage means for storing a stable region in advance;
Based on the next driving region estimated by the driving region assumption unit, a determination unit that determines whether or not the unstable region exists in a transition path that transitions to the next driving region;
Injection that corrects the basic value stored in the injection condition basic information storage means so as to reduce the degree of influence of the unstable region based on the determination result by the determination means, and determines the corrected injection condition Condition correction means,
The injection condition correction means, when the determination means determines that the next operation state crosses the unstable region, the transition condition that transitions from the detected operation state to the next operation region, Comprising a detour transition path setting means for selecting a detour transition path for detouring so as to shorten the crossing transition path across the unstable region, the selected detour transition path as the corrected injection condition ,
The injection conditions are a fuel injection pressure, an injection pulse period, and a fuel injection amount or an index value corresponding thereto, and a command determined by calculating an injection pulse period for a target injection amount corresponding to the fuel injection pressure A fuel injection control apparatus for an internal combustion engine, wherein the operation of the fuel injection valve is controlled based on an injection pulse period . Comprising an operation state storage means for storing the detected operation state;
The said driving | running area assumption means estimates the said following driving | running state based on the deviation of the driving | running state detected and the driving | running state detected last time by the said driving | running state memory | storage means. Item 3. A fuel injection control device for an internal combustion engine according to Item 2.   The injection condition correction means changes between the stable region and the next operating region by changing the fuel injection pressure in the two stable regions existing across the unstable region and the next operating region. Among the correction transition paths, a small correction transition path with a small change amount of the fuel injection pressure is selected, and the change direction and the change amount of the fuel injection pressure in the selected small correction transition path are corrected with the correction value for correcting the injection condition. The fuel injection control device for an internal combustion engine according to claim 1, wherein:   The detour transition route setting means includes a first stable region having the detected operating state and a second stable region having the next operating region among the two stable regions existing across the unstable region. The detour transition path portion in at least one of the first stable region and the second stable region of the detour transition route is defined as the first stable region and the second stable region corresponding to the detour transition path portion. The fuel injection control device for an internal combustion engine according to claim 2, wherein the fuel injection control apparatus is set to be longer than a transition path portion of the transition paths in at least one of the following.   The injection condition correcting unit corrects the basic value when it is determined that the operation state and the next operation state detected by the determination unit are in the same stable region without crossing the unstable region. The fuel injection control device for an internal combustion engine according to claim 1 or 2, wherein the fuel injection control device is not used.   The said injection condition basic information storage means has memorize | stored the said basic value calculated | required beforehand by experiment, and has the stored basic injection condition map, It is any one of Claims 1-6 characterized by the above-mentioned. Fuel injection control device for internal combustion engine.   8. The fuel injection control device for an internal combustion engine according to claim 7, wherein the basic value in the basic injection condition map is temporarily rewritten according to the corrected injection condition.

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