JP2009068461A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of smoothly driving an internal combustion engine without causing torque variation in changing the number of injection times or fuel pressure of a fuel injection valve. <P>SOLUTION: This fuel injection control device to control the fuel injection valve free to inject fuel in a combustion chamber of the cylinder injection type internal combustion engine is furnished with an injection times changing means free to change the injection times of the fuel injection valve in accordance with changing of a driving region of the internal combustion engine and an injection finish timing control means to coincide injection finish timing of the fuel injection valve in a combustion cycle after the changing with injection finish timing of the fuel injection valve in a combustion cycle before the changing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection control device that controls a fuel injection valve capable of injecting fuel into a combustion chamber of an internal combustion engine.

  As a conventional fuel injection control device, a fuel injection valve disposed in a combustion chamber is controlled to inject a required amount of fuel from the fuel injection valve in a lump (collective injection), and a required amount of fuel from the fuel injection valve Is known to be injected in a plurality of times (divided injection) (see Patent Document 1).

JP 2000-104609 A

  By the way, in the conventional fuel injection control device, when the fuel injection valve is controlled to switch from the batch injection to the split injection without changing the fuel injection amount, the injection period from the injection start timing to the injection end timing in the split injection Is longer than the injection period from the injection start timing to the injection end timing in the batch injection.

  At this time, if the fuel injection is performed by matching the injection start timing of the divided injection after the switching with the injection start timing of the batch injection before the switching, the injection end timing of the divided injection is delayed with respect to the injection end timing of the batch injection. I horn. If the injection end timing differs before and after switching, the mixture formation in the combustion chamber changes before and after switching. For this reason, if the air-fuel mixture is combusted with the injection start timings before and after the switching being matched, the combustion state of the air-fuel mixture changes, so that the torque obtained from the internal combustion engine before the switching and the internal combustion engine after the switching are obtained. A large torque step is generated between the torque and the generated torque.

  Similarly, when the fuel injection valve is controlled to change from low fuel pressure injection to high fuel pressure injection without changing the fuel injection amount, the injection period in high fuel pressure injection is shorter than the injection period in low fuel pressure injection. Become. For this reason, if the air-fuel mixture is combusted in a state where the injection start timings before and after the switching are made coincident, a large torque step between the torque obtained from the internal combustion engine before the switching and the torque obtained from the internal combustion engine after the switching. Will occur.

  As a result, if the fuel injection pattern from the fuel injection valve is switched between batch injection and split injection, or switched between low fuel pressure injection and high fuel pressure injection, torque fluctuation will occur. There was a fear.

  Therefore, the fuel injection control device of the present invention can smoothly operate the internal combustion engine without causing torque fluctuation when switching the number of injections of the fuel injection valve or switching the fuel pressure of the fuel injection valve. It is an object to provide a fuel injection control device.

  A fuel injection control device according to the present invention is a fuel injection control device that controls a fuel injection valve capable of injecting fuel into a combustion chamber of a direct injection internal combustion engine. When the number of injections of the fuel injection valve is switched by the injection number switching means that can switch the number of injections of the valve and the injection number switching means, the injection end timing of the fuel injection valve in the combustion cycle before the switching is An injection end timing control means for matching the injection end timing of the fuel injection valve in the combustion cycle is provided.

  Another fuel injection control device of the present invention is a fuel injection control device that controls a fuel injection valve capable of injecting fuel into a combustion chamber of a direct injection internal combustion engine. When the fuel pressure of the fuel injection valve is switched by the fuel pressure switching means that can switch the fuel pressure of the fuel injection valve between the high fuel pressure and the low fuel pressure, and the fuel pressure switching means, And an injection end timing control means for matching the injection end timing of the fuel injection valve in the combustion cycle after switching with the injection end timing.

  In these cases, there is further provided an injection start timing determining means for determining whether or not the injection start timing calculated from the injection end timing after switching is advanced from a preset injection start timing. When it is determined by the determining means that the injection start timing is advanced from the set injection start timing, the injection end timing control means is configured to change the injection after switching so that the injection start timing coincides with the set injection start timing. It is preferable to retard the end timing.

  The fuel injection control device according to the present invention suppresses torque fluctuation by matching the injection end timing of the fuel injection valve before and after switching the number of injections of the fuel injection valve or before and after switching the fuel pressure of the fuel injection valve. Thus, the internal combustion engine can be operated smoothly.

  Hereinafter, an engine ECU to which a fuel injection control device according to the present invention is applied will be described with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

  Here, FIG. 1 is a schematic configuration diagram of an in-cylinder injection type gasoline engine, and FIG. 2 is an explanatory diagram regarding an operation region of the engine. FIG. 3 is an explanatory diagram of control related to injection switching of a conventional fuel injection valve, and FIG. 4 is a graph relating to engine speed and torque when the injection start timings are matched. Further, FIG. 5 is an explanatory diagram of control relating to injection switching of the fuel injection valve in the first embodiment, and FIG. 6 is a graph relating to engine speed and torque when the injection end timings are matched. FIG. 7 is an explanatory diagram of the control when the injection start timing is set with an advance from the set injection start timing, and FIG. 8 is a series of flowchart diagrams regarding the injection switching control of the fuel injection valve. .

  First, an internal combustion engine (hereinafter referred to as an engine) controlled by the engine ECU 2 according to the first embodiment will be described with reference to FIG. This engine 1 is an in-cylinder injection type gasoline engine, and is controlled by an engine ECU 2.

  The engine 1 has a crankcase 10 from the bottom, a cylinder block 11 provided at the top of the crankcase 10, and a cylinder head 12 provided at the top of the cylinder block 11 via a head gasket (not shown). Is formed. A piston 13 is housed in an upper part of the cylinder block 11 so as to be movable up and down, and a crankshaft 14 is housed in a housing part formed by the lower part of the cylinder block 11 and the crankcase 10. The piston 13 and the crankshaft 14 are connected by a connecting rod 15, and the vertical movement of the piston 13 is transmitted to the crankshaft 14. A pent roof type combustion chamber 16 is formed by the cylinder block 11, the cylinder head 12 and the piston 13.

  The crankcase 10 is provided with a crank angle sensor 20 that detects the rotation angle of the crankshaft 14. The crank angle sensor 20 is connected to the engine ECU 2, and the engine ECU 2 starts an ignition timing by an ignition plug 44 described later and a fuel injection valve 45 described later based on a detection result of the crank angle sensor 20. The timing and the injection end timing are controlled.

  The cylinder block 11 is formed with a cylinder bore 24 for accommodating the piston 13 therein. The piston 13 is formed in a cylindrical shape so as to be fitted to the cylinder bore 24, and is supported in the cylinder bore 24 so as to be vertically movable between a top dead center and a bottom dead center. Further, a piston cavity 25 is formed in the head surface of the piston 13 so as to be immersed. Further, a water jacket 26 serving as a cooling water circulation passage for cooling the engine 1 is formed inside the cylinder block 11, and the water jacket 26 is disposed so as to surround the cylinder bore 24. The cylinder block 11 is provided with an engine water temperature detection sensor 27 that detects the coolant temperature, and the engine water temperature detection sensor 27 is connected to the engine ECU 2.

  The cylinder head 12 has an intake port 30 communicating with the combustion chamber 16 and an exhaust port 31 disposed facing the intake port 30 and communicating with the combustion chamber 16 therein.

  An intake valve 34 is provided at the intake side communication port 32 between the combustion chamber 16 and the intake port 30, and an exhaust side communication port 33 between the combustion chamber 16 and the exhaust port 31 is provided at the exhaust side communication port 33. An exhaust valve 35 is provided.

  The intake valve 34 and the exhaust valve 35 are formed in a trumpet-shaped conical shape having a wide end, an open position (lower end position) where the intake side communication port 32 and the exhaust side communication port 33 are opened, and an intake side communication port. 32 and the closed position (rising end position) where the exhaust side communication port 33 is closed. An intake side camshaft 40 is disposed at the base end portion of the intake valve 34, and an exhaust side camshaft 41 is disposed at the base end portion of the exhaust valve 35. The intake valve 34 and the exhaust valve 35 can be opened and closed by rotating.

  A spark plug 44 is disposed at the top of the combustion chamber 16 so that the tip portion protrudes, and fuel that injects fuel from the wall surface of the combustion chamber 16 below the intake port 30 of the cylinder head 12. An injection valve 45 is provided.

  Here, the combustion operation of one combustion cycle in the engine 1 will be described. In the combustion cycle, an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are sequentially performed.

  In the intake stroke, the piston 13 starts moving from the top dead center to the bottom dead center, and the intake valve 34 is moved downward to open the intake side communication port 32. Then, air is sucked into the combustion chamber 16 through the intake side communication port 32 due to the negative pressure of the combustion chamber 16, and thereafter, the intake valve 34 is moved upward to close the intake side communication port 32. At this time, fuel injection is started from the fuel injection valve 45, and the sucked air and the fuel are mixed to become an air-fuel mixture.

  In the compression stroke, the piston 13 moves from the bottom dead center to the top dead center. When the piston 13 moves to the top dead center, the air-fuel mixture is compressed along with this movement. When the piston 13 reaches near the top dead center, the spark plug 44 is sparked to ignite the air-fuel mixture. The fuel injection from the fuel injection valve 45 is configured to end before the spark plug 44 is discharged.

  In the expansion stroke, the air-fuel mixture expands (explodes) due to the combustion of the air-fuel mixture by ignition. As a result, the piston 13 moves from the top dead center toward the bottom dead center.

  In the exhaust stroke, the piston 13 that has reached the bottom dead center moves again toward the top dead center due to inertia. At this time, the exhaust valve 35 is moved downward to open the exhaust side communication port 33, and the exhaust gas after combustion is discharged from the exhaust side communication port 33 as the piston 13 moves to the top dead center. After the exhaust gas is discharged, the exhaust valve 35 is moved upward to close the exhaust side communication port 33.

  By repeating the above combustion cycle, the piston 13 is moved up and down, and this power is transmitted to the crankshaft 14 via the connecting rod 15, whereby the engine 1 can obtain a driving force.

  Next, the engine ECU 2 will be described. The engine ECU 2 is mainly configured by a CPU 70, a ROM 71, a RAM 72, an input port 73, an output port 74, and the like, and are connected to each other via an internal bus 75. The CPU 70 performs arithmetic processing based on various detection signals input from various sensors or the like. The ROM 71 stores various programs and data. The RAM 72 is a work area for executing various programs.

  The ignition plug 44 and the fuel injection valve 45 are controllably connected to the engine ECU 2, and the engine ECU 2 is inhaled from the outside in addition to the crank angle sensor 20 and the engine water temperature detection sensor 27 described above. Various sensors such as an air flow sensor 79 for detecting the amount of intake air to be detected are connected.

  Various programs such as a fuel injection control program 80, an ignition control program 81, an operation region setting program 82, and an operation region switching determination program 83 are stored in the ROM 71 of the engine ECU 2, and the CPU 70 stores various programs from the ROM 71. Is read out and expanded in the RAM 72, and the expanded program is executed, whereby the spark plug 44 and the fuel injection valve 45 can be controlled.

  The ignition control program 81 controls the discharge operation of the spark plug 44 based on the crank angle input from the crank angle sensor 20.

  The operation region setting program 82 sets the operation region of the engine 1 based on the engine speed and the engine load. The engine load is detected by the intake air amount detected by the air flow sensor 79 and the engine water temperature detection sensor 27. Obtained from the engine water temperature.

  Here, as shown in FIG. 2, the operating region of the engine 1 is divided into, for example, four according to the engine speed and the engine load, and fuel injection from the fuel injection valve 45 is performed once (single after-mentioned single A first operation region E1 performed in injection), a second operation region E2 in which fuel injection from the fuel injection valve 45 is performed twice, and a third operation region E3 in which fuel injection from the fuel injection valve 45 is performed three times. , And a fourth operation region E4 in which fuel injection from the fuel injection valve 45 is performed four times.

  Therefore, when the engine ECU 2 executes the operation region setting program 82, one operation region is set from the four operation regions E1, E2, E3, and E4 based on the engine speed and the engine load.

  The operation region switching determination program 83 determines whether or not the one operation region set by the operation region setting program 82 is the same as the operation region set last time, that is, different from the one operation region set last time. It is discriminate | determined whether it switched to the driving | operation area | region.

  The fuel injection control program 80 controls the fuel injection operation of the fuel injection valve 45 based on the crank angle input from the crank angle sensor 20 and the number of injections in the set operation region. The engine ECU 2 (fuel injection control device) can control the fuel injection valve 45 by executing the fuel injection control program 80 stored in the ROM 71.

  Specifically, when a predetermined crank angle is reached in the intake stroke, fuel injection is started from the fuel injection valve 45, and when a predetermined crank angle is reached in the intake stroke or the compression stroke, the fuel is injected from the fuel injection valve 45. Is stopped.

  Here, the engine ECU 2 can control the fuel injection valve 45 by the fuel injection control program 80 and cause the fuel injection valve 45 to perform single injection and multi-pilot injection. In the single injection, the fuel to be injected into the combustion chamber 16 is injected at a time (once) during one combustion cycle. In the multi-pilot injection, fuel injected into the combustion chamber 16 is injected in a plurality of times during one combustion cycle.

  The fuel injection control program 80 includes an injection number switching program 85 that switches the number of injections of the fuel injection valve 45 in accordance with the switching of the operation region of the engine 1. When the engine ECU 2 executes the injection number switching program 85, the number of injections of the fuel injection valve 45 is switched based on one operation region set by the operation region setting program 82 (injection number switching means). That is, the engine ECU 2 selects one of the four operation regions E1, E2, E3, and E4, thereby selecting single injection or multi-pilot injection and selecting the number of injections in multi-pilot injection. ing.

  By the way, as described above, when the number of injections of the fuel injection valve 45 is switched by the injection number switching program 85, if the injection amount of the fuel to be injected is substantially the same amount, the fuel injection timing of the fuel injection valve 45 starts. The injection period leading to the injection end time changes. That is, as shown in FIG. 3, in the case of single injection (single injection), multi-pilot injection (double injection), and multi-pilot injection (three injections), for example, the injection start timing S1 to the injection end timing of single injection The injection period T2 from the injection start timing S2 of multi-pilot injection (twice) to the injection end timing D2 is longer than the injection period T1 reaching D1. Further, the injection period T3 from the injection start timing S3 of the multipilot injection (three times) to the injection end timing D3 is longer than the injection period T2 of the multipilot injection (twice). That is, there is a relationship of injection period T1 <injection period T2 <injection period T3.

  At this time, when switching the number of injections of the fuel injection valve 45, for example, when switching from single injection to multi-pilot injection (twice), the predetermined crank angle K1 is set to the injection start timing S1 of single injection, and multi-pilot injection (2 ) Injection start timing S2 is made to coincide with the injection start timing S1. Then, the multi-pilot injection (twice) injection end timing D2 becomes the crank angle K3, and the single injection injection end timing D1 becomes the crank angle K2. For this reason, the injection end timing D2 is retarded as compared with the injection end timing D1.

  Similarly, when switching from multi-pilot injection (2 times) to multi-pilot injection (3 times), the predetermined crank angle K1 is set as the injection start timing S2 of multi-pilot injection (2 times), and multi-pilot injection (3 times) The injection start time S3 is made to coincide with the injection start time S2. Then, the multipilot injection (3 times) injection end timing D3 becomes the crank angle K4, and the multipilot injection (2 times) injection end timing D2 becomes the crank angle K3. For this reason, the injection end timing D3 is retarded as compared with the injection end timing D2.

  At this time, if the injection end timing differs before and after the switching, the mixture formation in the combustion chamber 16 changes greatly. In this state, the spark plug 44 discharges to ignite and burn the mixture. And it turned out that a big torque level | step difference will arise as shown in the graph of FIG. In addition, the graph of FIG. 4 is a torque level difference at the time of switching from single injection to multi-pilot injection. As a result, torque fluctuation occurs when the number of injections of the fuel injection valve 45 is switched. Therefore, in this embodiment, the fuel injection is performed before and after the switching of the number of injections of the fuel injection valve 45 in order to suppress the torque fluctuation. The injection end timings of the valve 45 are matched. Hereinafter, the control operation for matching the injection end timing of the fuel injection valve 45 will be described in detail.

  The fuel injection control program 80 has an injection end timing control program 84 in addition to the above injection number switching program 85. The injection end timing control program 84 matches the injection end timing of the fuel injection valve 45 in the combustion cycle after switching with the injection end timing of the fuel injection valve 45 in the combustion cycle before switching. Therefore, when the engine ECU 2 executes the injection end timing control program 84, the injection end timing of the fuel injection valve 45 in the combustion cycle after switching is matched with the injection end timing of the fuel injection valve 45 in the combustion cycle before switching. (Injection end timing control means).

  Specifically, when switching from single injection to multi-pilot injection (twice), the engine ECU 2 executes the injection end timing control program 84. As shown in FIG. 5, when the predetermined crank angle K1 is the injection start timing S1 of the single injection, the injection end timing D1 of the single injection is the crank angle K2. Then, the injection end timing D2 of the multi-pilot injection (twice) is made to coincide with the injection end timing D1. Then, the injection start timing S2 of multi-pilot injection (twice) becomes the crank angle K5. For this reason, the injection start timing S2 advances with respect to the injection start timing S1.

  Similarly, when switching from multi-pilot injection (2 times) to multi-pilot injection (3 times), the engine ECU 2 executes the injection end timing control program 84. Assuming that the predetermined crank angle K5 is the injection start timing S2 of multi-pilot injection (twice), the injection end timing D2 of multi-pilot injection (twice) is the crank angle K2. Then, the injection end timing D3 of the multi-pilot injection (three times) is made to coincide with the injection end timing D2. Then, the injection start timing S3 of multi-pilot injection (three times) becomes the crank angle K6. For this reason, the injection start timing S3 advances with respect to the injection start timing S2.

  At this time, when the injection end timings of the fuel injection valve 45 before and after the switching coincide, the mixture formation in the combustion chamber 16 can be made substantially the same. For this reason, when the spark plug 44 is discharged in this state to ignite and burn the mixture, the torque step shown in the graph of FIG. 6 is smaller than the torque step shown in the graph of FIG. I understood. In other words, it was found that torque fluctuation can be suppressed by making the injection end timings coincide before and after switching the number of injections of the fuel injection valve 45. In addition, the graph of FIG. 6 is also a torque level difference when switching from single injection to multi-pilot injection.

  By the way, as shown in FIG. 7, for example, when switching from single injection to multi-pilot injection (twice), after the switching in the state where the injection end timing D1 of the single injection before the switching becomes the predetermined crank angle K2. If the injection end timing D2 of the multi-pilot injection (twice) is matched, the injection start timing S2 of the multi-pilot injection (twice) becomes the crank angle K5 as described above. At this time, when the preset set injection start timing S4 is set to a crank angle K7 between the crank angle K5 and the crank angle K1, the injection start timing S2 for multi-pilot injection (twice) is set. The fuel is injected at an earlier timing (advanced) than the injection start timing S4.

  When the fuel is injected from the fuel injection valve 45 at an angle advanced from the set injection start timing S4, the injected fuel may adhere to the upper part of the piston or the wall surface of the cylinder bore 24. If fuel adheres to the upper part of the piston, smoke may increase, and if fuel adheres to the wall surface of the cylinder bore 24, the fuel may enter the engine oil and dilute the engine oil. .

  Therefore, the fuel injection control program 80 includes an injection start timing determination program that determines whether or not the injection start timing of the fuel injection valve 45 after switching is advanced from a preset injection start timing S4. 86 is stored. When the engine ECU 2 executes the injection start timing determination program 86 and determines that the post-switching injection start timing is advanced from the set injection start timing S4, the injection end timing control program 84 sets the injection start timing. The injection end timing after switching is retarded so that becomes the set injection start timing S4.

  Specifically, when the engine ECU 2 executes the injection start time determination program 86, the engine ECU 2 sets the injection start time S2 of the multi-pilot injection (two times) after switching to be higher than the preset injection start time S4. It is determined whether or not it is angular (injection start time determining means). If it is determined that the engine ECU 2 has advanced, the multipilot injection (twice) injection end timing D2 so that the multipilot injection (twice) injection start timing S2 coincides with the set injection start timing S4. Is retarded. That is, the injection start timing S2 and the set injection start timing S4 are made to coincide with each other by retarding the injection period T2 of multi-pilot injection (twice).

  As a result, the fuel is not injected from the fuel injection valve 45 at an angle earlier than the set injection start timing S4, so that smoke does not increase and engine oil dilution does not occur.

  Hereinafter, a series of control flows for switching the number of injections of the fuel injection valve 45 will be described with reference to the flowchart of FIG. First, the engine ECU 2 detects the operation state of the engine 1 by various sensors such as the air flow sensor 79 and the engine water temperature detection sensor 27, and based on the detection result, the operation region setting program 82 determines the operation region of the engine 1. Set (S1). At this time, the engine ECU 2 executes the operation region switching determination program 83 to determine whether or not the operation region has been switched to a different operation region from the previously set operation region (S2). When it is determined that the operation region of the engine 1 is switched, the engine ECU 2 executes the injection number switching program 85 to switch to the number of injections of the fuel injection valve 45 corresponding to the operation region of the engine 1 (S3). ).

  When the number of injections is switched, the engine ECU 2 executes the injection end timing control program 84, and the injection of the fuel injection valve 45 in the combustion cycle after switching at the injection end timing of the fuel injection valve 45 in the combustion cycle before switching. The end times are set to coincide (S4). Thereafter, the engine ECU 2 executes the injection start timing determination program 86 to determine the injection start timing after switching from the set injection end timing after switching (S5), and the determined injection start timing is set in advance. It is determined whether or not the set injection start timing S4 is advanced (S6). If the engine ECU 2 determines that the injection start timing after switching is advanced from the set injection start timing S4, the engine ECU 2 executes the injection end timing control program 84, and the injection start timing is set to the set injection start timing S4. The injection end timing after switching is delayed and set so as to match (S7).

  Then, the engine ECU 2 injects fuel from the fuel injection valve 45 based on the set injection end timing (S8), returns to S1 again, and repeats the control flow. In S2, when the operation region of the engine 1 is not switched, that is, when the set operation region is the same as the previously set operation region, the number of injections from the fuel injection valve 45 does not change. The fuel is injected from the fuel injection valve 45 with the same setting as the above. Further, when the engine ECU 2 determines in S6 that the injection start timing after switching is not advanced from the set injection start timing S4, the fuel injection valve 45 takes fuel from the fuel injection valve 45 based on the injection end timing set in S4. Is injected.

  According to the above configuration, when the number of injections of the fuel injection valve 45 is switched, the injection end timing of the fuel injection valve in the combustion cycle after switching is different from the injection end timing of the fuel injection valve 45 in the combustion cycle before switching. Can be matched. Therefore, as is clear from the graph shown in FIG. 6, there is no large torque step between the torque obtained from the engine 1 before switching and the torque obtained from the engine 1 after switching. Torque fluctuations can be suppressed.

  Conventionally, since the torque fluctuation was large before and after the switching of the fuel injection valve 45, at least two different engine torque maps had to be prepared before and after the switching. However, in this embodiment, torque fluctuations can be suppressed before and after switching of the fuel injection valve 45, so that two different engine torque maps before and after switching can be unified to form one engine torque map. Thereby, the prepared engine torque map can be reduced.

  In addition, when the injection start timing of the fuel injection valve 45 obtained from the injection end timing after switching is advanced from the preset injection start timing S4, the injection start timing is set to the set injection start timing S4. By retarding the injection end timing in this way, smoke does not increase due to fuel adhesion, oil dilution or the like does not occur. In this embodiment, when the injection start timing after switching is advanced from the set injection start timing S4, the injection end timing is retarded so that the injection start timing and the set injection start timing S4 coincide. However, the injection start timing may be delayed from the set injection start timing S4.

  Next, the fuel injection control apparatus (engine ECU 2) according to the second embodiment will be described with reference to FIGS. Only different parts will be described in order to avoid duplicate descriptions. FIG. 9 is an explanatory diagram of control related to injection switching of the fuel injection valve in the second embodiment, and FIG. 10 is an explanatory diagram related to an engine operating region. FIG. 11 is a series of flowcharts related to the injection switching control of the fuel injection valve.

  The engine ECU 2 according to the second embodiment is configured such that the fuel injection valve 45 is controlled by the fuel injection control program 80 so that the fuel injection valve 45 can execute low fuel pressure injection and high fuel pressure injection. At this time, as shown in FIG. 9, since the fuel pressure in the low fuel pressure injection is lower than that in the high fuel pressure injection, the injection period T4 from the low fuel pressure injection start timing S4 to the injection end timing D4 is high fuel pressure. It is longer than the injection period T5 from the injection start timing S5 to the injection end timing D5.

  Here, as shown in FIG. 10, the operation region of the engine 1 includes a low fuel pressure operation region EL that performs low fuel pressure injection from the fuel injection valve 45, and a high fuel pressure operation region EH that performs high fuel pressure injection from the fuel injection valve 45. , Is composed of. For this reason, when the engine ECU 2 executes the operation region setting program 82, the engine ECU 2 sets the operation region of the engine 1 to the low fuel pressure operation region EL or the high fuel pressure operation region EH based on the engine speed and the engine load.

  The fuel injection control program 80 includes a fuel pressure switching program 90 that switches the fuel pressure (fuel pressure) of the fuel injection valve 45 between the low fuel pressure and the high fuel pressure in accordance with the switching of the operation region of the engine 1. is doing. When the engine ECU 2 executes the fuel pressure switching program 90, the fuel pressure of the fuel injection valve 45 is switched according to the operating region of the engine 1 (fuel pressure switching means). As an example of specifically switching the fuel pressure, when the engine ECU 2 executes the fuel pressure switching program 90, although not shown, the fuel in the delivery pipe is returned to the fuel tank to the delivery pipe communicating with the fuel injection valve 45. A relief valve is provided, and the fuel pressure from the fuel injection valve 45 is switched by performing opening / closing control of the relief valve.

  Hereinafter, a series of control flows for switching the fuel pressure of the fuel injection valve 45 will be described with reference to the flowchart of FIG. Since only the control in S3 is different, description of other parts is omitted. If it is determined in S2 that the operation region of the engine 1 is switched, the engine ECU 2 executes the fuel pressure switching program 90 to switch to the fuel pressure of the fuel injection valve 45 corresponding to the operation region of the engine 1 (S10). . Thereafter, in S4, the injection end timing of the fuel injection valve 45 in the combustion cycle before switching is set to coincide with the injection end timing of the fuel injection valve 45 in the combustion cycle after switching.

  Even in the above configuration, when the fuel pressure of the fuel injection valve 45 is switched, the injection end timing of the fuel injection valve 45 in the combustion cycle after the switching coincides with the injection end timing of the fuel injection valve 45 in the combustion cycle before the switching. Therefore, a large torque step does not occur between the torque obtained from the engine before the switching and the torque obtained from the engine after the switching. For this reason, the torque fluctuation at the time of switching can be suppressed. Note that the first embodiment and the second embodiment may be combined.

  As described above, the fuel injection control device according to the present invention is useful for an in-cylinder injection type gasoline engine, and is particularly suitable when torque fluctuation occurs.

It is a schematic block diagram of a cylinder injection type gasoline engine. It is explanatory drawing regarding the driving | operation area | region of an engine. It is explanatory drawing of the control regarding the injection switching of the fuel injection valve in the past. It is a graph regarding an engine speed and torque when the injection start timings are matched. It is explanatory drawing of the control regarding the injection switching of the fuel injection valve in Example 1. FIG. It is a graph regarding an engine speed and torque when the injection end timings are matched. It is explanatory drawing of the control in case the injection start time is set ahead of the set injection start time. It is a series of flowcharts regarding injection switching control of a fuel injection valve. It is explanatory drawing of the control regarding the injection switching of the fuel injection valve in Example 2. FIG. It is explanatory drawing regarding the driving | operation area | region of the engine in Example 2. FIG. FIG. 6 is a series of flowcharts relating to injection switching control of a fuel injection valve in Embodiment 2.

Explanation of symbols

1 Engine 2 Engine ECU
16 Combustion chamber 20 Crank angle sensor 45 Fuel injection valve 80 Fuel injection control program 82 Operation region setting program 83 Operation region switching determination program 84 Injection end timing control program 85 Injection number switching program 86 Injection start timing determination program 90 Fuel pressure switching program D1 Injection End time D2 Injection end time D3 Injection end time

Claims (3)

In a fuel injection control device for controlling a fuel injection valve capable of injecting fuel into a combustion chamber of an in-cylinder injection internal combustion engine,
With the switching of the operation region of the internal combustion engine, an injection number switching means capable of switching the number of injections of the fuel injection valve;
When the number of injections of the fuel injection valve is switched by the injection number switching means, the injection end timing of the fuel injection valve in the combustion cycle after switching is different from the injection end timing of the fuel injection valve in the combustion cycle before switching. A fuel injection control device comprising: an injection end timing control means for matching the two. In a fuel injection control device for controlling a fuel injection valve capable of injecting fuel into a combustion chamber of an in-cylinder injection internal combustion engine,
A fuel pressure switching means capable of switching the fuel pressure of the fuel injection valve between a high fuel pressure and a low fuel pressure in accordance with the switching of the operation region of the internal combustion engine,
When the fuel pressure of the fuel injection valve is switched by the fuel pressure switching means, the injection end timing of the fuel injection valve in the combustion cycle after switching coincides with the injection end timing of the fuel injection valve in the combustion cycle before switching. A fuel injection control device comprising: an injection end timing control unit for controlling the fuel injection timing. An injection start timing determining means for determining whether or not the injection start timing obtained from the injection end timing after switching is advanced from a preset injection start timing;
When it is determined by the injection start timing determination means that the injection start timing is advanced from the set injection start timing, the injection end timing control means is configured such that the injection start timing is set to the set injection start timing. The fuel injection control device according to claim 1 or 2, wherein the injection end timing after switching is retarded so as to coincide.

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