JP6260473B2 - 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.

  2. Description of the Related Art Conventionally, an in-cylinder internal combustion engine that directly injects fuel into a cylinder is known. For example, an electromagnetically driven fuel injection valve is mounted on a direct injection internal combustion engine, and the amount of fuel supplied to the internal combustion engine is controlled by driving a valve body (needle) by energization control of the electromagnetic part. (See, for example, Patent Document 1). Patent Document 1 discloses a fuel injection valve having a two-piece structure in which a movable core and a valve body can be relatively displaced. By configuring the fuel injection valve as described above, when the fuel injection valve is closed, the bounce of the valve body when the tip of the valve body is seated on the valve seat is suppressed. .

JP 2010-138886 A

  The rebound of the valve body is a phenomenon that can occur even when the fuel injection valve is opened. For example, in the fuel injection valve of Patent Document 1, the movable core collides with the fixed core when the electromagnetic unit is energized, so that the valve body rebounds. May occur. In addition, there is a concern that such a rebound of the valve body may temporarily cause an unstable position of the valve body, resulting in a case where the injection amount control cannot be performed with high accuracy.

  The present invention has been made to solve the above-described problems, and provides a fuel injection control device for an internal combustion engine that can accurately control the fuel injection amount in a direct injection internal combustion engine. Main purpose.

  The present invention employs the following means in order to solve the above problems.

  The present invention includes a valve body (43) that opens and closes a nozzle hole (49) by reciprocating in a housing (42), an electromagnetic unit (44) that drives the valve body in an axial direction by energization, and the jet The invention is applied to an internal combustion engine (10) that directly injects fuel into a cylinder from a fuel injection valve (23) provided with a positioning portion (47) that determines a stop position of the valve body in a valve open state, and to the electromagnetic portion The present invention relates to a fuel injection control device for an internal combustion engine that controls the supply power of the engine with an injection pulse signal.

In the first configuration , in the injection amount characteristic indicating the change in the fuel injection amount according to the elapsed time from the start of energization of the electromagnetic unit, the movement of the valve body in the valve opening direction is restricted by the positioning unit. A bounce region where the bounce of the valve body occurs is determined in advance, and based on the operating state of the internal combustion engine, a required amount calculation means for calculating a required injection amount within one combustion cycle of the internal combustion engine; The end timing of the injection pulse signal for each injection of the fuel injection valve determined based on the required injection amount calculated by the required amount calculation means and the number of injections performed in the one combustion cycle includes a predetermined range including the bounce region A bounce determination means for determining whether or not the fuel gas enters within the range, and the bounce determination means determines that the end timing of the injection pulse signal for each injection falls within the predetermined range. In this case, the fuel injection is performed by changing the pulse width of the injection pulse signal for each injection while holding the fuel injection amount in the one combustion cycle at the required injection amount calculated by the required amount calculation means. And an injection control means.

  When the fuel injection valve is opened, the stop position of the valve body is determined by the positioning portion that determines the stop position of the valve body, and the fuel injection amount is adjusted according to the valve opening time at the stop position. Here, when the fuel injection valve is opened, the movement of the valve body in the valve opening direction is restricted by the positioning portion, so that the valve body bounces by inertial force and then stops. Further, while the bounce of the valve body is occurring, the amount of fuel injected from the fuel injection valve is not stable, and variations in the injection amount are likely to occur. For this reason, if the ratio of the bounce period to the injection time (pulse width of the injection pulse signal) per injection of the fuel injection valve is large, it is considered that the injection amount control cannot be performed with high accuracy.

  In view of this point, in the above configuration, when it is determined that the end timing of the injection pulse signal for each injection of the fuel injection valve falls within a predetermined range including the bounce region, the amount of fuel injected in one combustion cycle is determined. Fuel injection is performed by changing the pulse width of the injection pulse signal for each injection while maintaining the required injection amount according to the operating state. That is, the fuel injection is performed so as to actively avoid the use of the region where the injection amount is not stable among the entire region on the injection amount characteristic. According to such a configuration, it is possible to accurately control the fuel injection amount.

The block diagram which shows the whole engine control system outline. Sectional drawing which shows the outline of an injector. The figure which shows an example of the map for injection mode setting. The figure which shows the injection quantity characteristic. The flowchart which shows the process sequence of fuel-injection control. The flowchart which shows the process sequence of a bounce determination process. The figure showing the injection quantity characteristic and bounce area according to fuel pressure.

  Hereinafter, the present embodiment will be described with reference to the drawings. In this embodiment, an engine control system is constructed for an in-cylinder in-vehicle multi-cylinder four-cycle gasoline engine that is an internal combustion engine. In this control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the fuel injection amount, control the ignition timing, and the like. FIG. 1 shows an overall schematic configuration diagram of the engine control system.

  In the engine 10 shown in FIG. 1, the intake pipe 11 is provided with an air flow meter 12 for detecting the intake air amount. A throttle valve 14 whose opening degree is adjusted by a throttle actuator 13 such as a DC motor is provided on the downstream side of the air flow meter 12. The opening of the throttle valve 14 (throttle opening) is detected by a throttle opening sensor built in the throttle actuator 13. A surge tank 15 is provided on the downstream side of the throttle valve 14. The surge tank 15 is provided with an intake pressure sensor 16 for detecting the pressure in the intake pipe. The surge tank 15 is connected to an intake manifold 17 that introduces air into each cylinder of the engine 10. The intake manifold 17 is connected to an intake port of each cylinder.

  An intake valve 18 and an exhaust valve 19 are provided at the intake port and the exhaust port of the engine 10, respectively. The air in the surge tank 15 is introduced into the combustion chamber 21 by the opening operation of the intake valve 18, and the exhaust gas after combustion is discharged to the exhaust pipe 22 by the opening operation of the exhaust valve 19.

  An injector 23 that directly supplies fuel to the combustion chamber 21 is attached to the upper part of each cylinder of the engine 10. The injector 23 is connected to a fuel tank 25 via a fuel pipe 24. The fuel in the fuel tank 25 is pumped up by the low pressure pump 26 and then pressurized by the high pressure pump 27. The high-pressure fuel is pumped from the high-pressure pump 27 to the delivery pipe 28 and supplied from the delivery pipe 28 to the injectors 23 of the respective cylinders. Thereafter, the fuel is injected into the combustion chamber 21 by the injector 23.

  A spark plug 29 is attached to the cylinder head of the engine 10 for each cylinder. A high voltage is applied to the ignition plug 29 at a desired ignition timing through an ignition device (not shown) including an ignition coil. By applying this high voltage, a spark discharge is generated between the counter electrodes of each spark plug 29. Thereby, the air-fuel mixture in the combustion chamber 21 is ignited and used for combustion.

  The exhaust pipe 22 is provided with a catalyst 31 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas. In addition, an air-fuel ratio sensor 32 for detecting the air-fuel ratio (oxygen concentration) of the air-fuel mixture with exhaust gas as a detection target is provided upstream of the catalyst 31.

  In addition, the engine 10 includes a cooling water temperature sensor 33 that detects a cooling water temperature, a crank angle sensor 34 that outputs a rectangular crank angle signal at every predetermined crank angle of the engine (for example, at a cycle of 10 ° CA), and a delivery pipe 28. A fuel pressure sensor 35 for detecting the internal fuel pressure is attached.

  Next, the injector 23 will be described in detail. FIG. 2 is a cross-sectional view showing the injector 23. The injector 23 includes a housing 42 in which an injection hole 49 is formed, a needle 43 as a valve body, and a coil 44 as an electromagnetic part. In the description of FIG. 2, for convenience, the direction toward the injection hole 49 in the injector 23 is defined as a downward direction or a valve closing direction, and the direction toward the opposite side of the injection hole 49 is defined as an upward direction or a valve opening direction.

  The housing 42 has a hollow portion, and a needle 43 is accommodated in the hollow portion so as to be capable of reciprocating in the axial direction. A fuel passage 45 communicating with the injection hole 49 is formed between the outer peripheral surface of the needle 43 and the inner peripheral surface of the housing 42. An inlet (not shown) connected to the fuel pipe 24 is formed at the upper end of the housing 42, and high-pressure fuel in the delivery pipe 28 is supplied into the fuel passage 45 through the inlet. The upper end portion of the needle 43 is fixed to the housing 42 via a first spring 51 that biases the needle 43 in the valve closing direction.

  The lower end portion of the needle 43 has a cross-sectional shape larger than the opening area of the injection hole 49. Then, when the lower end portion of the needle 43 comes into contact with the valve seat 46, the injection hole 49 is closed by the needle 43, and fuel injection is prevented. Further, when the lower end portion of the needle 43 is separated from the valve seat 46, the injection hole 49 is opened, and the fuel in the fuel passage 45 is injected from the injection hole 49.

  A fixed core 47 that generates a magnetic force when the coil 44 is energized is provided in the housing 42. A movable core 48 is disposed at a position facing the lower end surface of the fixed core 47. The movable core 48 is fixed to the housing 42 via the second spring 52 and is urged in the valve opening direction by the second spring 52. An insertion hole is formed in the movable core 48, and the needle 43 is slidably inserted into the insertion hole. An enlarged diameter portion 53 having an outer diameter larger than that of the lower portion is formed at the upper end portion of the needle 43. Accordingly, the needle 43 can be displaced integrally with the movable core 48 as the movable core 48 moves in the valve opening direction.

  The force f1 of the first spring 51 in the valve closing direction is set to be larger than the force f2 of the second spring 52 in the valve opening direction. Therefore, when the coil 44 is not energized, the needle 43 is displaced and seated on the side of the injection hole 49 by the biasing force of the first spring 51, so that the closed state of the injection hole 49 is maintained.

  On the other hand, when the coil 44 is energized, a magnetic attractive force is generated between the fixed core 47 and the movable core 48. When the sum f3 of the magnetic attractive force and the force f2 of the second spring 52 in the valve opening direction is larger than the force f1 of the first spring 51 in the valve closing direction (f3> f1), the movable core 48 opens in the valve opening direction. And the needle 43 moves in the valve opening direction. When the movable core 48 contacts the fixed core 47, the movement of the movable core 48 and the needle 43 in the valve opening direction is restricted, and the stop position of the needle 43 when the nozzle hole 49 is opened is determined. The fixed core 47 corresponds to a “positioning portion” that determines the stop position of the valve body when the nozzle hole 49 is in the valve open state. The fuel injection amount injected from the injector 23 in one injection is adjusted by the valve opening time of the injection hole 49, that is, the energization time of the coil 44.

  As is well known, the ECU 40 is mainly composed of a microcomputer (hereinafter referred to as a microcomputer) 41 composed of a CPU, ROM, RAM, and the like, and executes various control programs stored in the ROM, so that the engine operation state can be changed each time. In response, various controls of the engine 10 are performed. That is, the microcomputer 41 of the ECU 40 receives detection signals from the various sensors described above and calculates the fuel injection amount, ignition timing, and the like based on the various detection signals. Moreover, the drive of the injector 23 and the spark plug 29 is controlled based on the calculation result.

  Regarding the fuel injection control, the microcomputer 41 uses a variety of data (for example, engine speed, engine load, fuel pressure, etc.) relating to the operating state of the engine 10 to perform one combustion cycle of the engine 10 (intake stroke → compression stroke → expansion stroke → The required injection amount Qrq is calculated as the fuel injection amount required in the exhaust stroke). Then, an injection pulse signal is generated according to the calculated required injection amount Qrq. In the present embodiment, a pulse signal map defined corresponding to the required injection amount Qrq is stored in the ECU 40 in advance. The microcomputer 41 determines the pulse width of the injection pulse signal and the output timing for outputting the injection pulse signal to the injector 23 with reference to this pulse signal map.

  In this system, the fuel injection mode is switched in accordance with the engine operating state every time. Specifically, the injection mode is switched between a single injection mode in which fuel is injected once in one combustion cycle and a split injection mode in which fuel is injected a plurality of times (in this embodiment, twice) within one combustion cycle. ing. Note that the split injection uses the intake-intake injection mode in which fuel injection is performed twice in the intake stroke, but is applied to the engine 10 that adopts the intake-compression injection mode in which injection is performed in the intake stroke and the compression stroke. May be.

  FIG. 3 is a diagram illustrating an example of a correspondence relationship between the engine rotation speed, the engine load, and the injection mode. In FIG. 3, the split injection mode is selected in the engine operation region of high rotation and high load, and the single injection mode is selected in the engine operation region of low rotation or low load. In this embodiment, the injection mode is switched according to the engine temperature. Specifically, the split injection mode is selected when the engine temperature is equal to or lower than a predetermined warm-up determination temperature, and the injection mode is selected based on the map of FIG. 3 when the engine temperature is higher than the warm-up determination temperature.

  In the split injection, the fuel injection amount for each injection is calculated by dividing the required injection amount Qrq in one combustion cycle according to the split ratio α, and each injection time is calculated based on the calculated fuel injection amount. An injection pulse signal is generated. Specifically, when fuel injection is performed twice for each fuel cycle, the previous fuel injection amount is Qrq × α, and the subsequent fuel injection amount is Qrq × (1−α). Then, for each of the previous fuel injection and the subsequent fuel injection, the pulse width and pulse output timing of the injection pulse signal are determined with reference to the pulse signal map. In the present embodiment, a constant value (for example, 50%) is set for the division rate.

  Here, in the injector 23, the stop position of the needle 43 in the valve open state is determined by the movable core 48 coming into contact with the fixed core 47 by supplying power to the coil 44. At this time, the needle 43 is not immediately stopped, and a rebound phenomenon (bounce phenomenon) of the needle 43 occurs due to inertial force. Further, while the needle 43 is bounced, the state where the fuel injection amount of the injector 23 is unstable continues. The sensitivity to the bounce phenomenon varies depending on the length of the injection period for each injection of the injector 23. Further, it is conceivable that the fuel injection amount cannot be accurately controlled in a situation that is easily affected by bounce.

  FIG. 4 is a pulse signal map showing the correspondence between the pulse width of the injection pulse signal and the fuel injection amount. FIG. 4 is also a diagram illustrating an injection amount characteristic indicating a change in the fuel injection amount in accordance with an elapsed time (pulse width) from the start of coil energization. In FIG. 4, a period TZ from the start of energization (t 0) to time t 1 is a dead zone in which the needle 43 is not displaced even when power is supplied to the coil 44. When the coil 44 is energized for a time longer than the time t1, the movable core 48 is attracted to the fixed core 47 and the needle 43 moves in the valve opening direction. The period t1 to t2 until the movable core 48 contacts the fixed core 47 is a period in which the opening area of the injection hole 49 increases as the elapsed time from the start of energization becomes longer. The fuel injection amount from the injector 23 increases.

  When the energization time of the coil 44 is TA or more, the movable core 48 comes into contact with the fixed core 47, and the needle 43 bounces along with the contact. Therefore, after the movable core 48 contacts the fixed core 47, the state where the position of the needle 43 is unstable continues for a predetermined time. Thereafter, the needle 43 stops at a predetermined stop position and becomes stable. At this time, at the point P that is out of the bounce region on the injection amount characteristic of FIG. 4, the ratio of the time that the needle 43 bounces (bounce period) to the pulse width T1 of the injection pulse signal is small. The effect on the accuracy of the injection amount is small. On the other hand, the influence of the bounce is large at the point Q in the bounce region, and as a result, the variation in the injection amount becomes large.

  The injector 23 of the present embodiment has a structure in which the movable core 48 and the needle 43 can be relatively displaced. When the injector 23 is opened, the lower end surface 55 of the enlarged diameter portion 53 and the upper end surface of the movable core 48 are provided. The needle 43 further moves in the valve opening direction when it comes into contact with 54. Therefore, immediately after the movable core 48 comes into contact with the fixed core 47, the injection amount is excessive, and thereafter, the needle 43 is displaced in the valve closing direction due to the elastic force, so that the injection amount tends to be excessive.

  Therefore, in the present embodiment, it is determined whether or not the end timing of the injection pulse signal for each injection of the injector 23 falls within a predetermined range (bounce occurrence determination region) including the bounce region. When it is determined that the end timing of the injection pulse signal for each injection does not fall within the bounce occurrence determination region, fuel injection is performed using the injection pulse signal generated based on the required injection amount Qrq. On the other hand, when it is determined that the end timing of the injection pulse signal for each injection falls within the bounce occurrence determination region, the fuel amount to be injected in one combustion cycle is held at the required injection amount, and Fuel injection is performed by changing the pulse width of the injection pulse signal.

  In the present embodiment, the bounce region is set by using whether or not the actual air-fuel ratio of the engine 10 converges to the target value in the air-fuel ratio feedback control. Specifically, the actual air-fuel ratio can be converged to the target value by the air-fuel ratio feedback control from the point A corresponding to the timing when the movable core 48 contacts the fixed core 47 among the points on the injection amount characteristic. A bounce area is set in an area between points B corresponding to the lower limit of the pulse width range. Further, the bounce occurrence determination area is set to a range including the entire predetermined bounce area from the viewpoint of ensuring the injection amount accuracy more reliably.

  FIG. 5 is a flowchart showing the processing procedure of the fuel injection control of the present embodiment. This process is executed at predetermined intervals by the microcomputer 41 of the ECU 40.

  In FIG. 5, in step S101, the required injection amount Qrq is calculated based on the engine operating state. In the subsequent step S102, a fuel injection mode is set. Specifically, data relating to the engine speed, engine load, and engine water temperature is input, and an injection mode corresponding to the input data is selected using the map of FIG. The process for setting the injection mode corresponds to the “number of times setting means”.

  In step S103, it is determined whether or not the set injection mode is the single injection mode. When the single injection mode is set, the process proceeds to step S104, where the requested injection amount Qrq and the fuel pressure Pi detected by the fuel pressure sensor 35 are input, and an injection pulse signal (pulse width and output timing) is obtained from these input data. To decide. Then, it progresses to step S107 and performs the bounce determination process of FIG. Further, in step S108, based on the injection pulse signal determined by the bounce determination process, power is supplied to the coil 44 from a battery (not shown) to drive the injector 23.

  On the other hand, when the divided injection mode is set, a negative determination is made in step S103, and the process proceeds to step S105. In step S105, the required injection amount Qrq and the division ratio α are input, and the fuel injection amount for each injection in one combustion cycle is calculated from the input data. In the subsequent step S106, the required injection amount Qrq and the fuel pressure Pi detected by the fuel pressure sensor 35 are input, and the injection pulse signal at each injection time is determined from these input data. Thereafter, the process proceeds to step S107, the bounce determination process of FIG. 6 is executed, and the injector 23 is driven in step S108.

  Next, the bounce determination process will be described. In FIG. 6, in step S <b> 201, a bounce occurrence determination region is determined based on the fuel pressure Pi detected by the fuel pressure sensor 35. Here, the bounce region varies depending on the fuel pressure Pi, and the lower the fuel pressure Pi, the bounce occurs in a region where the elapsed time from the start of energization of the coil 44 is shorter (see FIGS. 7, B1 and B2). Therefore, in this embodiment, the bounce occurrence determination region is determined according to the fuel pressure Pi. Specifically, the ECU 40 stores a pulse signal map corresponding to the fuel pressure Pi, and a bounce occurrence determination region is preset for each map. The microcomputer 41 determines the bounce occurrence determination region by referring to the pulse signal map corresponding to the current fuel pressure Pi.

  In subsequent step S202, it is determined whether or not the end timing of the injection pulse signal falls within the bounce occurrence determination region for each of the injection pulse signals for each injection (bounce determination means). In the present embodiment, the determination is made using the pulse width of the ejection pulse signal as an index. Specifically, the determination is made based on whether the pulse width of the injection pulse signal is larger than the lower limit determination value TH1 and smaller than the upper limit determination value TH2. Here, the lower limit determination value TH1 is set based on the time required for the movable core 48 to contact the fixed core 47 after the coil energization is started. In this embodiment, TA in FIG. 4 is set. Further, the upper limit determination value TH2 is set based on the time required until the bounce of the needle 43 disappears after the start of coil energization, and in this embodiment, TB in FIG. 4 is set.

  When it is determined that the end timing of the injection pulse signal is out of the bounce occurrence determination region, this routine is ended as it is. On the other hand, if it is determined that the end timing of the injection pulse signal falls within the bounce occurrence determination region, the process proceeds to step S203. In the case of split injection, determination is made for each injection pulse signal at each injection time, and if it is determined that the end timing of the injection pulse signal falls within the bounce occurrence determination region at at least one of the injection times Proceed to step S203.

  In step S203, it is determined whether or not the single injection mode is selected. When the single injection mode is selected, the process proceeds to step S204, and it is determined whether or not the divided injection can be performed. Here, the determination is made based on whether or not the execution condition including that the fuel injection amount when the required injection amount Qrq is divided by the division ratio α is larger than the minimum injection amount of the injector 23 is satisfied.

  If it is determined in step S204 that the split injection can be performed, the process proceeds to step S205, and the fuel injection mode is switched from the single injection mode to the split injection mode. Further, along with the switching of the injection mode, the fuel injection amount to be injected at each injection time in one combustion cycle is reset, and each injection speed is determined from the reset fuel injection amount and the fuel pressure Pi detected by the fuel pressure sensor 35. The injection pulse signals at are determined respectively. Then, this subroutine is finished.

  On the other hand, if it is determined in step S203 that the divided injection mode is set, the process proceeds to step S206, where it is possible to remove the end timing of the injection pulse signal from the bounce occurrence determination region by changing the division ratio α. Determine whether or not. In the injector 23, the minimum injection amount is determined to ensure the injection amount accuracy. However, in some cases, if the end timing of the injection pulse signal for each injection is to be removed from the bounce occurrence determination region, one combustion is performed. An injection amount that is lower than the minimum injection amount may be set at any injection time in the cycle. Therefore, in the present embodiment, by performing the determination process in step S206, the change of the division ratio α when the injection amount accuracy cannot be ensured is prohibited.

  That is, if an affirmative determination is made in step S206, the process proceeds to step S207, where the change of the split ratio α is permitted, and the fuel injection amount for each injection is based on the changed split ratio and the required injection amount Qrq. To reset. Further, the injection pulse signal at each injection time is determined. On the other hand, if a negative determination is made in step S206, the process proceeds to step S208, and the fuel injection mode is switched from the split injection mode to the single injection mode. Further, along with the switching of the injection mode, the fuel injection amount to be injected within one combustion cycle is reset, and the injection pulse signal is determined from the reset fuel injection amount and the fuel pressure Pi detected by the fuel pressure sensor 35. Then, this subroutine is finished.

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  When it is determined that the end timing of the injection pulse signal for each injection by the injector 23 falls within a predetermined range including the bounce region, the amount of fuel injected in one combustion cycle is a required injection amount Qrq according to the operating state. The fuel injection is performed by changing the pulse width of the injection pulse signal while holding the fuel. In this case, the fuel injection is performed so as to actively avoid the use of the region where the injection amount is not stable among the entire region on the injection amount characteristic. It can be carried out with high accuracy.

  As one aspect of the configuration of changing the pulse width of the injection pulse signal for each injection, when it is determined that the end timing of the injection pulse signal for each injection falls within the bounce occurrence determination region, within one combustion cycle The number of injections was changed. Specifically, when the single injection mode is selected as the fuel injection mode, switching to the split injection mode prevents the end timing of the injection pulse signal for each injection from entering the bounce occurrence determination region. I made it. In addition, when the split injection mode is selected, the end timing of the injection pulse signal for each injection does not fall within the bounce occurrence determination region by switching to the single injection mode in a situation where the split ratio cannot be changed. I did it. According to the change in the number of injections, fuel injection mainly using the bounce region can be avoided without changing the required injection amount and the injection rate within one combustion cycle.

  As one aspect of the configuration for changing the pulse width of the injection pulse signal for each injection, the split injection mode is selected, and when the end timing of the injection pulse signal for each injection of the injector 23 falls within the bounce occurrence determination region If determined, the division ratio α is basically changed. According to this configuration, it is possible to prevent the end timing of the injection pulse signal for each injection from entering the bounce occurrence determination region while continuing the fuel injection control by the divided injection.

  When trying to avoid fuel injection using the bounce zone, the division ratio α is changed on condition that the minimum injection amount is ensured at each injection. Otherwise, the injection mode is changed to the single injection mode. It was set as the structure switched. From the viewpoint of the injection amount accuracy and the like, normally, the injection amount range that can be injected from the injector 23 is limited, and the minimum injection amount is set. Further, as a result of trying to avoid fuel injection using the bounce area, there is a concern that inconvenience such as misfire may occur when an injection amount smaller than the minimum injection amount is set. In view of these points, as described above, by prohibiting the change of the division ratio in a situation where the minimum injection amount cannot be ensured, it is possible to suitably suppress a decrease in engine controllability due to misfire or the like.

  Paying attention to the point that the injection amount characteristic differs according to the fuel pressure supplied to the injector 23 and the range where the bounce area is generated, the bounce occurrence determination area is variably set according to the fuel pressure detected by the fuel pressure sensor 35. It was set as the structure to do. According to such a configuration, it is possible to perform the control so that the end timing of the injection pulse signal for each injection does not fall within the bounce occurrence determination region, and to perform the injection amount control with high accuracy. Can do.

(Other embodiments)
The present invention is not limited to the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, when the split injection mode is selected and it is determined that the end timing of the injection pulse signal for each injection falls within the bounce occurrence determination region, each injection cycle after the change of the split ratio α is performed. If the minimum injection amount can be ensured, the division ratio α is changed. Otherwise, the single injection mode is switched. When the divided injection mode is selected and it is determined that the end timing of the injection pulse signal for each injection falls within the bounce occurrence determination region, the configuration is always switched to the single injection mode. Also good.

  In the above embodiment, the determination is made as to whether or not the end timing of the injection pulse signal for each injection falls within the bounce generation determination region, using the pulse width of the injection pulse signal as an index. It is good also as a structure determined using the fuel injection amount for every as an index. Specifically, in step S202 of FIG. 6, it is determined whether or not the fuel injection amount of one injection by the injector 23 is a value within a predetermined injection amount range. For example, the lower limit value of the injection amount range is a value corresponding to the injection amount when the pulse width is TA, and the upper limit value is a value corresponding to the injection amount when the pulse width is TB, for example.

  In the above embodiment, the range including the entire predetermined bounce area is set as the bounce occurrence determination area, but the bounce occurrence determination area is not limited to this. For example, a part of the bounce area is set as the bounce occurrence determination area. It may be set. Further, in the above embodiment, from the point A corresponding to the timing when the movable core 48 contacts the fixed core 47, it corresponds to the lower limit of the pulse width range in which the actual air-fuel ratio can be converged to the target value by the air-fuel ratio feedback control. Although the area between the points B to be set is set as the bounce occurrence determination area, the present invention is not limited to this. For example, an area having a pulse width smaller than that of the point A may be included in the bounce occurrence determination area.

  In the above embodiment, the split ratio α in the split injection mode is a constant value, but may be applied to an engine in which the split ratio α is variably set according to the engine operating state.

  In the above embodiment, the case where the number of injections in the split injection mode is two has been described, but the present invention can also be applied to the engine 10 to which three or more times are applied. In the configuration in which fuel injection is performed three times or more within one combustion cycle, the fuel injection stroke is arbitrary, and the fuel injection may be performed in the intake stroke or in the intake stroke and the compression stroke.

  In the above-described embodiment, the case where the needle 43 and the movable core 48 are applied to the engine 10 including the injector 23 having a two-body structure capable of relative displacement is described. However, the needle 43 and the movable core 48 are integrated. You may apply to an engine provided with the injector of structure.

  In the above embodiment, the case where the present invention is applied to a direct injection type gasoline engine has been described, but the present invention may be applied to a diesel engine.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 23 ... Injector (fuel injection valve), 28 ... Delivery pipe, 35 ... Fuel pressure sensor, 40 ... ECU, 41 ... Microcomputer, 42 ... Housing, 43 ... Needle (valve body), 44 ... Coil (electromagnetic part) , 47 ... fixed core (positioning part), 48 ... movable core, 49 ... injection hole.

Claims (6)

A valve body (43) that opens and closes the nozzle hole (49) by reciprocating in the housing (42), an electromagnetic part (44) that drives the valve body in the axial direction by energization, and the valve opening of the nozzle hole Applied to an internal combustion engine (10) that directly injects fuel into a cylinder from a fuel injection valve (23) including a positioning portion (47) that determines a stop position of the valve body in a state, and supplies electric power to the electromagnetic unit A fuel injection control device for an internal combustion engine controlled by an injection pulse signal,
In the injection amount characteristic indicating the change in the fuel injection amount according to the elapsed time from the start of energization of the electromagnetic unit, the valve body bounces by restricting the movement of the valve body in the valve opening direction by the positioning unit. The bounce area where
A required amount calculating means for calculating a required injection amount in one combustion cycle of the internal combustion engine based on an operating state of the internal combustion engine;
End timing of the injection pulse signal for each injection of the fuel injection valve determined based on the required injection amount calculated by the required amount calculation means and the number of injections performed in the one combustion cycle is a predetermined value including the bounce region Bounce determination means for determining whether or not to fall within the range;
The request calculated by the request amount calculation means when the bounce determination means determines that the end timing of the injection pulse signal for each injection falls within the predetermined range. Injection control means for performing fuel injection by changing the pulse width of the injection pulse signal for each injection while maintaining the injection amount;
Number setting means for setting the number of injections to be performed within the one combustion cycle based on the operating state of the internal combustion engine;
Equipped with a,
In the injection control means, the number of injections performed in the one combustion cycle is set to one by the number setting means, and the end timing of the injection pulse signal for each injection is set to the predetermined time by the bounce determination means. A fuel injection control device for an internal combustion engine, which performs fuel injection by split injection that divides and injects the required injection amount calculated by the required amount calculation means when it is determined to fall within the range . In the injection control means, the number of injections carried out within the one combustion cycle is set to a plurality of times by the number setting means, and the end timing of the injection pulse signal for each injection is set to the predetermined time by the bounce determination means. If it is determined to fall within the scope, the fuel injection control apparatus for an internal combustion engine according to claim 1, implementing a fuel injection by one injection for injecting the required injection amount calculated by the required amount calculating means in one . A valve body (43) that opens and closes the nozzle hole (49) by reciprocating in the housing (42), an electromagnetic part (44) that drives the valve body in the axial direction by energization, and the valve opening of the nozzle hole Applied to an internal combustion engine (10) that directly injects fuel into a cylinder from a fuel injection valve (23) including a positioning portion (47) that determines a stop position of the valve body in a state, and supplies electric power to the electromagnetic unit A fuel injection control device for an internal combustion engine controlled by an injection pulse signal,
In the injection amount characteristic indicating the change in the fuel injection amount according to the elapsed time from the start of energization of the electromagnetic unit, the valve body bounces by restricting the movement of the valve body in the valve opening direction by the positioning unit. The bounce area where
A required amount calculating means for calculating a required injection amount in one combustion cycle of the internal combustion engine based on an operating state of the internal combustion engine;
End timing of the injection pulse signal for each injection of the fuel injection valve determined based on the required injection amount calculated by the required amount calculation means and the number of injections performed in the one combustion cycle is a predetermined value including the bounce region Bounce determination means for determining whether or not to fall within the range;
The request calculated by the request amount calculation means when the bounce determination means determines that the end timing of the injection pulse signal for each injection falls within the predetermined range. Injection control means for performing fuel injection by changing the pulse width of the injection pulse signal for each injection while maintaining the injection amount;
Equipped with a,
A number-of-times setting means for setting the number of injections to be performed within the one combustion cycle based on the operating state of the internal combustion engine;
In the injection control means, the number of injections carried out within the one combustion cycle is set to a plurality of times by the number setting means, and the end timing of the injection pulse signal for each injection is set to the predetermined time by the bounce determination means. An internal combustion engine characterized in that when it is determined that the fuel injection falls within a range, fuel injection is performed by changing a division ratio in the divided injection in which the required injection amount calculated by the required amount calculation means is divided and injected . Fuel injection control device. A minimum injection amount is predetermined as a lower limit value of a fuel amount range that can be injected by one injection of the fuel injection valve;
The injection control means, when the minimum injection amount is ensured in each injection time after changing the split ratio, changes the split ratio in the split injection, performs fuel injection, and changes the split ratio 4. The internal combustion engine according to claim 3 , wherein when the minimum injection amount is not ensured at each injection time after the injection, fuel injection is performed by a single injection that injects the required injection amount calculated by the required amount calculation unit at a time. Engine fuel injection control device. A valve body (43) that opens and closes the nozzle hole (49) by reciprocating in the housing (42), an electromagnetic part (44) that drives the valve body in the axial direction by energization, and the valve opening of the nozzle hole Applied to an internal combustion engine (10) that directly injects fuel into a cylinder from a fuel injection valve (23) including a positioning portion (47) that determines a stop position of the valve body in a state, and supplies electric power to the electromagnetic unit A fuel injection control device for an internal combustion engine controlled by an injection pulse signal,
In the injection amount characteristic indicating the change in the fuel injection amount according to the elapsed time from the start of energization of the electromagnetic unit, the valve body bounces by restricting the movement of the valve body in the valve opening direction by the positioning unit. The bounce area where
A required amount calculating means for calculating a required injection amount in one combustion cycle of the internal combustion engine based on an operating state of the internal combustion engine;
End timing of the injection pulse signal for each injection of the fuel injection valve determined based on the required injection amount calculated by the required amount calculation means and the number of injections performed in the one combustion cycle is a predetermined value including the bounce region Bounce determination means for determining whether or not to fall within the range;
The request calculated by the request amount calculation means when the bounce determination means determines that the end timing of the injection pulse signal for each injection falls within the predetermined range. Injection control means for performing fuel injection by changing the pulse width of the injection pulse signal for each injection while maintaining the injection amount;
Equipped with a,
The injection amount characteristic and the bounce area are predetermined according to the pressure of fuel supplied to the fuel injection valve,
Comprising fuel pressure detecting means for detecting the pressure of fuel supplied to the fuel injection valve;
The bounce determination means determines the predetermined range based on the fuel pressure detected by the fuel pressure detection means, and whether or not the end timing of the injection pulse signal for each injection is within the determined predetermined range. A fuel injection control device for an internal combustion engine, characterized in that The injection amount characteristic and the bounce area are predetermined according to the pressure of fuel supplied to the fuel injection valve,
Comprising fuel pressure detecting means for detecting the pressure of fuel supplied to the fuel injection valve;
The bounce determination means determines the predetermined range based on the fuel pressure detected by the fuel pressure detection means, and whether or not the end timing of the injection pulse signal for each injection is within the determined predetermined range. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4 .

Images