JP2005163559A - Accumulator fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accumulator fuel injection device injecting fuel multiple times during a combustion stroke and capable of improving injection precision of post-injection irrespective of magnitude of injection quantity of previous injection. <P>SOLUTION: In the accumulator fuel injection device provided with a accumulator 17 accumulating fuel under a high pressure condition, an injector 2 injecting high pressure fuel supplied from the accumulator 17 to an internal combustion engine 1, and a control means 10 controlling injector 2 according to an operation state of the internal combustion engine 1, and performing multiple time injection during a combustion stroke of the internal combustion engine 1, a pressure detection means 18 detecting pressure PCF of the accumulator 17 is provided, and when the control means 10 calculates an index value TQM indicating magnitude of injection quantity of previous injection QM performed previously in the multiple time injection and calculates injection period TQA for demand injection quantity Q3 of the post-injection QA performed after the previous injection QM, correction is performed based on interval TINTA between the previous injection QM and the post injection QA, accumulator pressure NPC2 just before post injection QA and the index value TQM. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure-accumulation fuel injection device, and is particularly suitable for application to a pressure-accumulation fuel injection device that injects high-pressure fuel stored in a common rail from an injector to an internal combustion engine at least twice during one combustion stroke. .

  2. Description of the Related Art Conventionally, a pressure accumulation type fuel injection device that supplies high pressure fuel accumulated in a common rail as a pressure accumulation chamber having a predetermined volume from a injector to a diesel engine is known. In this type of accumulator fuel injection device, due to restrictions on mounting in a diesel engine, etc., the volume of high-pressure fuel that is accumulated on the common rail is limited, so if you try to inject multiple times during one combustion stroke, Pressure fluctuation (pressure pulsation) occurs after injection. This pressure pulsation affects the injection amount to be post-injected from the injector.

On the other hand, in the technique disclosed in Patent Document 1, a signal (injection command value) related to the post-injection is corrected according to the common rail pressure before the post-injection and the interval between the pre-injection and the post-injection. Note that the pressure pulsation in the common rail caused by the pre-injection is predicted from the interval. A map stored in advance for this interval is provided, and a correction value is obtained from this map, and the post-injection amount and the post-injection timing are controlled to be a predetermined target injection amount and a predetermined target injection timing.
Japanese Patent Application Laid-Open No. 10-2668888

However, since the above-described prior art is a method of determining the correction value by estimating the pressure pulsation, the correction accuracy of the post-injection may be insufficient depending on the injection conditions or the like where it is difficult to grasp the actual state of the pressure pulsation. For example, in the case of three injections (pilot injection, main injection, and after injection) during one combustion stroke, if the pre-injection and post-injection are the main injection and after-injection, as shown in FIG. The change amount ΔP _{CM of the} average pressure that occurs in the post-injection period after the end of the pre-injection changes according to the magnitude of the amount (hereinafter referred to as the pre-injection amount) Q. That is, the magnitude and intensity of pressure pulsation (increase / decrease in pulsation frequency) generated during the post-injection period change according to the magnitude of the pre-injection amount. In the conventional method, since the common rail pressure immediately before the post-injection is measured and the pressure pulsation is estimated to determine the correction value, the pressure pulsation that fluctuates around the average value obtained from the average pressure value in the post-injection period. It is difficult to get close to the value.

  The present invention has been made in consideration of such circumstances, and its purpose is to inject a plurality of times during one combustion stroke, regardless of the amount of pre-injection. An object of the present invention is to provide a pressure accumulation type fuel injection device capable of improving the injection accuracy of injection.

  According to claim 1 of the present invention, a pressure accumulating chamber for storing fuel in a high pressure state, an injector for injecting high pressure fuel supplied from the pressure accumulating chamber into a cylinder of the internal combustion engine, and controlling the injector according to the operating state of the internal combustion engine And a pressure detecting means for detecting the pressure in the pressure accumulating chamber in the pressure accumulating fuel injection apparatus that performs injection a plurality of times during one combustion stroke of the internal combustion engine with respect to the cylinder. When calculating an index value indicating the magnitude of the injection amount of the pre-injection performed before the plurality of injections, and calculating the injection period for the required injection amount of the post-injection performed after the pre-injection, Correction is performed based on the interval between the pre-injection and the post-injection, the pressure accumulation chamber pressure immediately before the post-injection, and the index value.

  The influence value obtained by estimating the pressure accumulation chamber pressure average value during the post-injection period only with the two detected values of the pressure accumulation chamber pressure value immediately before the post-injection and the interval between the pre-injection and the post-injection. In contrast to the current situation where the correction accuracy of the post-injection is not sufficient in the concept of the conventional method of correcting the basic injection period of the post-injection, the inventor It has been found that the calculation accuracy can be improved by adding an index value representing the size of the previous injection.

  Inferring the reason for the improvement in accuracy detection, an index value indicating the size of the previous injection, for example, the larger the injection amount, the larger the amount of fuel taken out from the pressure accumulator chamber. The intensity (the magnitude of the amplitude value) of the pulsation (disturbance) of the high-pressure fuel in the pressure accumulating chamber at the time of post-injection is due to showing a certain tendency (substantially proportional). That is, for example, when this index value is large, the injection period that becomes the injection amount targeting the post-injection period can be corrected in consideration of the tendency that the pressure accumulation chamber pressure average value during the post-injection period tends to be low.

  Therefore, even if the magnitude or intensity of pressure fluctuation (pressure pulsation) during the post-injection period changes depending on the magnitude of the pre-injection injection quantity, the post-injection injection quantity can be accurately corrected. Is possible.

  According to a second aspect of the present invention, the control means is configured to calculate during the post-injection injection period from at least three data of the interval between the pre-injection and the post-injection, the pressure accumulation chamber pressure immediately before the post-injection, and the index value. An estimated average pressure value of the pressure accumulating chamber is calculated.

  According to claim 3 of the present invention, the calculation of the average pressure expected value of the pressure accumulating chamber has a relationship between the index value indicating the magnitude of the injection amount of the pre-injection and the average pressure expected value in the map data, or is calculated It is characterized by correcting.

  According to claim 4 of the present invention, the estimated average pressure value is corrected by adding three data and the pressure value of the high-pressure fuel measured before the injection of the pre-injection.

  According to claim 5 of the present invention, the index value is a target injection value for determining the injection amount to be injected in the first injection calculated by the control means from the operating state of the internal combustion engine, and the injector is based on the target injection value. The command injection amount value to be controlled, the injector drive pulse period value calculated based on the command injection amount value, the measured pressure value of the high-pressure fuel immediately before the injection of the pre-injection, and the pressure value immediately after the end of the injection of the pre-injection Is one of the differential pressure values.

  According to claim 6 of the present invention, a pressure accumulating chamber for storing fuel in a high pressure state, an injector for injecting high pressure fuel supplied from the pressure accumulating chamber into a cylinder of the internal combustion engine, and controlling the injector according to the operating state of the internal combustion engine In the accumulator type fuel injection apparatus, the control means includes: a control means for detecting the pressure in the pressure accumulating chamber; and a pressure detecting means for detecting the pressure in the pressure accumulating chamber. An index value calculating means for calculating an index value representing the magnitude of the amount of pre-injection performed earlier among a plurality of injections, and an injection period for the required injection amount of post-injection performed after the previous injection. When calculating, it has an average pressure correcting means for estimating an average pressure value of the pressure accumulation chamber pressure during the injection period of the post-injection after the end of the previous injection based on the index value.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a vehicle control device according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing the overall configuration of the pressure accumulation fuel injection system of the present embodiment. FIG. 2 is a flowchart showing a control method for injecting a plurality of times during one combustion stroke in the ECU in FIG. FIG. 3 is a flowchart showing a control method in which the ECU in FIG. 1 injects a plurality of times during one combustion stroke. FIG. 4 is a time chart showing the operation of the pressure accumulation type fuel injection device of the present embodiment.

  As shown in FIG. 1, an accumulator fuel injection device includes an operating state or operating conditions of a multi-cylinder (for example, 4-cylinder) diesel engine (hereinafter referred to as an engine) 1 mounted on a vehicle such as an automobile, The driving state and the operation amount (will) of the driver are detected by various sensors and transmitted to an engine control unit (engine control unit) (hereinafter referred to as an ECU) 10, and an optimum target is detected by sensor signals from the various sensors. A plurality of (4 in the present embodiment) that calculate an injection amount (command injection amount), a target injection timing (command injection timing), a target injection period (command injection period), and a target injection pressure (command injection pressure) are controlled. Are configured to instruct an injector (electromagnetic fuel injection valve) 2 and a high-pressure supply pump (fuel supply pump) (hereinafter referred to as supply pump) 3. To have.

  The engine 1 is a four-cycle four-cylinder engine that includes a cylinder, a cylinder head, an oil pan, and the like. The intake port of each cylinder of the engine 1 is opened and closed by an intake valve (intake valve) 11, and the exhaust port is opened and closed by an exhaust valve (exhaust valve) 12. In each cylinder, a piston 14 connected to the crankshaft 13 via a connecting rod is slidably disposed.

  The injector 2 is attached to the cylinder head of the engine 1 corresponding to each cylinder. These injectors 2 include a fuel injection nozzle in which a nozzle needle for opening and closing the injection hole is slidably accommodated in a nozzle body in which the injection hole is formed, and an electromagnetic valve (needle drive means, Solenoid actuator) and needle biasing means such as a spring for biasing the nozzle needle in the valve closing direction.

  The fuel injection from the injector 2 to the engine 1 energizes and energizes a solenoid valve (not shown) that controls the fuel pressure in the back pressure control chamber (pressure control chamber) of the command piston connected to the nozzle needle. Electronically controlled by stopping (ON / OFF). While the solenoid valve of the injector 2 of each cylinder is open, the high-pressure fuel accumulated in the common rail 17 as the pressure accumulation chamber is injected into the combustion chamber of each cylinder of the engine 1. In addition, the fuel leaked from the internal leak of the injector 2 or the fuel discharged from the pressure control chamber (the fuel used to open the injector 2) is returned to the fuel tank 15 via the return pipe 33.

  The supply pump 3 is a high-pressure supply pump that pressurizes sucked fuel and pumps high-pressure fuel from the discharge port to the common rail 17, and includes a feed pump (low-pressure supply pump) 6 that pumps fuel from the fuel tank 15. The fuel path from the feed pump 6 to the pressurization chamber of the supply pump 3 is adjusted by adjusting the degree of opening of the fuel path (valve opening or opening area) so that the amount of fuel discharged from the supply pump 3 to the common rail 17 ( A suction metering valve (linear solenoid actuator) 7 is attached as an electromagnetic actuator for changing the pump discharge amount and the pump pumping amount.

  The intake metering valve 7 is electronically controlled by a pump drive signal from the ECU 10 via a pump drive circuit (not shown), thereby adjusting the amount of fuel sucked from the feed pump 6 into the pressurized chamber of the supply pump 3. A fuel injection pressure (hereinafter referred to as a common rail pressure) supplied from each injector 2 into each cylinder of the engine 1 is changed. The supply pump 3 sucks fuel from the fuel tank 15 and pressurizes it, and pumps the fuel discharge amount commanded by the ECU 10 to the common rail 17. The common rail pressure in the common rail 17 is measured by a fuel pressure sensor 18 as a fuel pressure detecting means, and a pump drive command value (pump drive current value) and an injection amount command value (pulsed injector drive current, injector injection command pulse). ) Is calculated by the ECU 10.

  The common rail 17 continuously supplies high-pressure fuel corresponding to the fuel injection pressure, and high-pressure fuel stored in the common rail 17 is supplied from the support pump 3 via a supply pipe (hereinafter referred to as high-pressure pipe) 20. The A return pipe 21 for returning fuel from the common rail 17 to the fuel tank 15 is provided. The common rail 17 is provided with a normally closed pressure reducing valve 22 that can adjust the degree of opening of the return pipe 21. The pressure reducing valve 22 is electronically controlled by a pressure reducing valve driving current value applied from the ECU 10 via a pressure reducing valve driving circuit, so that the common rail pressure in the common rail 17 is quickly reduced from a high pressure to a low pressure, for example, when decelerating or when the engine is stopped. It has a function to reduce pressure. Instead of the pressure reducing valve 22, a pressure limiter for releasing the fuel pressure in the common rail 17 between the common rail 17 and the return pipe 21 so that the common rail pressure in the common rail 17 does not exceed the limit set pressure. May be attached.

  Here, the injector 2, the supply pump 3 and the common rail 17 constitute fuel injection means for supplying fuel to the engine 1.

  The ECU 10 includes a CPU for performing control processing and arithmetic processing, a storage device (memory such as ROM and RAM) for storing various programs and data, an input circuit, an output circuit, a power supply circuit, an injector drive circuit, a pump drive circuit, and the like. A microcomputer having a known structure configured to include functions is provided. The detection signal (voltage signal) output from the fuel pressure sensor 18, the detection signal output from the fuel temperature sensor 34, and the sensor signals from other various sensors are A / D converted by the A / D converter. Later, it is configured to be input to a microcomputer built in the ECU 10. Further, the ECU 10 returns the engine key to the IG position after cranking the engine 1 and when an ignition switch (not shown) is turned on (ON), for example, the electromagnetic of the injector 2 is controlled based on a control program stored in the memory. The actuator of each control component such as the valve, the intake metering valve 7 of the supply pump 3, the actuator 40 for driving the throttle valve 39, and the EGR valve 42 for adjusting the exhaust gas recirculation amount (EGR amount) is electronically controlled. Has been.

  The ECU 10 receives the crankshaft rotation pulse and the camshaft rotation pulse from the crank angle sensor 4 attached to the crankshaft (crankshaft) 13 and the cam angle sensor 5 attached to the camshaft (camshaft) 23. The actual fuel pressure in the common rail 17 (actual common rail pressure) is held at the command injection pressure by determining the injection timing of the injector 2 and the pumping period of the supply pump 3 for each cylinder based on the signal. The crank angle sensor 4 includes a magnetic timing rotor (signal rotor) 24 fixed to the crankshaft 13 of the engine 1, an electromagnetic pickup coil disposed so as to face the peripheral surface of the timing rotor 24, and a magnetic flux. It is an electromagnetic rotation sensor composed of a permanent magnet (magnet) to be generated, and detects the rotation angle of the crankshaft 13. The ECU 10 detects the engine rotation speed (NE) by measuring the interval time of the crank angle signal (NE pulse signal). A plurality of convex teeth are formed on the timing rotor 24 at predetermined angles (for example, 10 °). When the timing rotor 24 rotates, the convex teeth approach and move away from the electromagnetic pickup coil, so that a crank angle signal (NE pulse signal) is output from the electromagnetic pickup coil by electromagnetic induction. The cam angle sensor 5 includes a magnetic timing rotor (signal rotor) 27 fixed to the cam shaft 23 of the engine 1, an electromagnetic pickup coil disposed so as to face the peripheral surface of the timing rotor 27, and An electromagnetic rotation sensor composed of a permanent magnet (magnet) or the like that generates magnetic flux, and detects the rotation angle of the cam shaft 23. In the timing rotor 27, a plurality of convex teeth are arranged for each predetermined angle.

  Further, the ECU 10 receives sensor signals from an accelerator opening sensor 30 that measures the amount of depression of the accelerator pedal (accelerator operation amount, accelerator opening), a cooling water temperature sensor 31 that detects the cooling water temperature of the engine 1, and the like. It is configured. Then, the ECU 10 calculates an optimal command injection pressure (= target fuel pressure: PFIN) according to the operating conditions of the engine 1, and discharges the intake metering valve 7 of the supply pump 3 via the pump drive circuit. It has a control means. Specifically, the ECU 10 calculates the target fuel pressure (PFIN) according to the engine speed (NE) and the command injection amount (QFIN), and in order to achieve the target fuel pressure (PFIN), The pump drive signal (pump drive current value) to the suction metering valve 7 of the supply pump 3 is adjusted to control the pumping amount (pump discharge amount) of fuel discharged from the supply pump 3.

  Further, the ECU 10 has a function of individually controlling the fuel injection amount injected from the injector 2 of each cylinder. Specifically, the ECU 10 includes basic injection amount determining means, command injection amount determining means, injection timing determining means, injection period determining means, and injector driving means. The basic injection amount determination means has a function of calculating an optimum basic injection amount (Q) based on the engine speed (NE), the accelerator opening (ACCP), and a characteristic map created by measurement in advance through experiments or the like. The command injection amount determination means takes into account the cooling water temperature (THW) detected by the cooling water temperature sensor 31 or the fuel leak temperature (fuel temperature: THF) detected by the fuel temperature sensor 34 in the basic injection amount (Q). It has a function of calculating the command injection amount (QFIN) in consideration of the injection amount correction amount. The injection timing determining means has a function of calculating a command injection timing (TFIN) from a command injection amount (QFIN), an engine rotation speed (NE), and a characteristic map created by measurement in advance through experiments or the like. The injection period determining means calculates the common pulse pressure (NPC), the command injection amount (QFIN), and the energization pulse time (injection command pulse time: TQ) to the injector 2 from the characteristic map created by measurement in advance through experiments or the like. Have The injector drive means applies a pulsed injector drive current (injector injection command pulse) to the solenoid valve of the injector 2 of each cylinder until the injection command pulse time (TQ) elapses from the command injection timing (TFIN). It has the function to do.

  For the purpose of improving the control accuracy of the fuel injection amount, the common rail pressure (NPC) in the common rail 17 detected by the fuel pressure sensor 18 is a target fuel pressure (PFIN) set according to the operating state of the engine 1. It is preferable to perform feedback control of the pump drive current value to the supply pump 3 so as to substantially match. The pump drive current value to the intake metering valve 7 is preferably controlled by duty (DUTY) control. For example, by adjusting the pump drive signal ON / OFF ratio (energization time ratio, duty ratio) per unit time according to the deviation (ΔP) between the common rail pressure (NPC) and the target fuel pressure (PFIN) High-precision digital control is possible by using duty control that changes the valve opening of the quantity 7.

  Next, the injection correction control of the present embodiment having the above-described configuration will be described with reference to FIGS. 2, 3, and 4.

  As shown in FIG. 2, in S201 (S is a step), signals output from the accelerator opening sensor 30 and the various sensors 4, 5 are input to the ECU 10, and the accelerator opening ACCP indicating the engine operating state and the engine rotation are displayed. The speed NE is detected.

  In S202, an optimal injection rate profile is obtained from the engine operating state read in S201. Specifically, from the accelerator opening ACCP and the engine rotational speed NE, a required injection pattern corresponding to the engine load state and the engine rotational speed is used as one injection during one combustion stroke, two injections, three injections, or the like. It is determined whether or not to inject a plurality of times, and an injection amount to be injected is determined for each injection from a map or an arithmetic expression. (Q = ΣQi, Qi = f (NE, ACCP)). For example, if the required injection pattern is three injections, each target injection amount Q = pilot target injection amount Q1 + main target injection amount Q2 + after target injection amount is obtained from the calculation formula of the accelerator opening ACCP and the engine speed NE. .

  Hereinafter, the number of injections during one combustion stroke of the present embodiment is three times (pilot injection QP, main injection QM, and after injection QA).

  In S203, a target common rail pressure NPC (see FIG. 4) for realizing an optimum fuel injection pressure in accordance with the engine operating state is calculated.

  In S204, an optimum interval TINTi is obtained according to the engine operating state. For example, the after interval TINTA between the main injection QM and the after injection QA will be described. A time interval ta between the start timing of the main injection QM and the start timing of the after injection is calculated from a two-dimensional map of the engine speed NE and the after injection amount QA. The actual injection period tb of the main injection QM is calculated from the target common rail pressure NPC and the main injection amount Q2. Then, an after interval TINTA is calculated by subtracting the actual injection period tb of the main injection QM from the calculated time interval ta. In FIG. 4, FIG. 4 (a) shows command injection periods TQP, TQM, and TQA in which the ECU 10 controls the injector 2 with respect to the pilot injection QP, the main injection QM, and the after injection QA. FIG. 4B shows an optimum injection pattern according to the engine operating state. FIG. 4C shows the common rail pressure for each injection. The interval TINT between the pilot injection QP and the main injection QM is similarly calculated.

  FIG. 3 shows the target injection amounts Q1, Q2, and Q3, the target common rail pressure NPC (see FIG. 4C), and the intervals TINT and TINTA according to the engine operating state in the control processing from S201 to S204. As described above, the correction process is performed for each target injection amount Q1, Q2, and Q3 in the control process from S301 to S308.

  In S301, Q = ΣQi obtained in S201 (in this embodiment, each target injection amount Q1, Q2, Q3) is read out in order to be corrected in order. For the sake of simplicity of explanation, here, it is assumed that correction processing of the pilot injection Q1 and the main injection Q2 is performed, and this time the after injection Q3 is performed.

  In S302, it is determined whether or not the current injection Q3 has a pre-injection. If there is no pre-injection, the process proceeds to S307. Conversely, if there is pre-injection, the process proceeds to S303, and the target injection amount Q2, which is the attribute value of the pre-injection (main injection) Q2, or the command injection amount QFIN corrected by the pre-injection Q2, the command injection period TQM, etc. are read. Then, the process proceeds to S304.

  In S304, as in S307, the basic correction amount TDANB is calculated from a map or characteristic equation in which the relationship between the target common rail pressure NPC (see FIG. 4C) and the after interval TINTA is obtained in advance through experiments or the like, and the process proceeds to S305. Transition. Specifically, the basic correction amount TDANB is calculated by performing four-point interpolation or the like based on the two-dimensional map information of the target common rail pressure NPC and the after interval TINTA.

  In S305, the pre-injection is determined from the map or characteristic equation obtained in advance through experiments or the like in relation to the command injection period TQM as the index value indicating the magnitude of the injection amount of the pre-injection Q2 read in S302 and the target common rail pressure NPC. The correction coefficient CTNAN is calculated, and the process proceeds to S306. Specifically, the pre-injection correction coefficient CTNAN is calculated by performing four-point interpolation or the like based on the two-dimensional map information of the command target period TQM and the target common rail pressure NPC.

  Here, S305 constitutes correction means (hereinafter referred to as pressure fluctuation correction means) that estimates the pressure average value of the common rail pressure generated during the post-injection period after the end of pre-injection.

  In S306, the signal output from the fuel temperature sensor 34 is input to the ECU 10 to detect the fuel temperature THL. The after-injection fuel temperature correction coefficient TDANTHL is calculated from a map or characteristic equation in which the relationship between the detected fuel temperature THL and the after-interval TINTA is obtained in advance through experiments or the like, and the process proceeds to S308. Specifically, the after injection amount fuel temperature correction coefficient TDANTHL is calculated by performing four-point interpolation or the like based on the two-dimensional map information of the fuel temperature THL and the after interval TINTA.

  Here, S306 constitutes a correction means (hereinafter referred to as a propagation speed correction means) for considering the propagation speed of pressure pulsation from the fuel temperature THL and the length of the high-pressure pipe 20 between the common rail 17 and the injector 2. To do.

  In S308, the correction coefficients CTNAN and TDANTHL obtained in S304 to S306 and the correction amount TDAN1 are multiplied (TDAN = TDANNB × TDANTHL × CTNAN). The injection amount command value (injection command period) TQA and the injection timing command value TFIN are corrected using these multiplied final correction values TDAN.

  Note that the target of the control process in S307 is applicable only to the pilot injection Q1. The basic correction amount TDPNB is calculated and processed from a map or a characteristic equation in which the relationship between the target common rail pressure NPC and the basic correction amount TDPNB is obtained in advance through experiments or the like. In S308, an injection amount command is used using the basic correction amount TDPNB. The value (injection command period) TQP and the injection timing command value TFIN are corrected.

  Note that the target of the control process from S303 to S306 corresponds to the main injection QM, the after injection QA, and the like other than the pilot injection QP.

  In order to improve the injection amount accuracy, the injection amount correction amount may be added using the fuel temperature THL in consideration of the injection flow rate that affects the fuel temperature THL.

  Next, operations and effects of the present embodiment will be described. (1) When the post-injection QA is corrected by the ECU 10 according to the interval TINTA between the pre-injection QM and the post-injection QA, the post-injection QA after the end of the pre-injection QM Pressure fluctuation correction means S305 for estimating the pressure average value of the common rail pressure generated during the injection period of the first injection QM, so that the pressure fluctuation (pressure) in the subsequent injection period depends on the magnitude of the injection amount Q2 of the previous injection QM. Even if the magnitude or intensity of the pulsation changes, it is possible to accurately correct the post-injection by considering the influence of the pressure fluctuation by the average pressure value.

  (2) The pressure fluctuation correction means S305 maps the relationship between the command injection period TQM as an index value indicating the magnitude of the injection amount Q2 of the previous injection QM and the previous injection correction coefficient CTNAN indicating the expected value of the average pressure. It is configured to have data or to correct calculation. For this reason, the relationship between the index value and the expected value of the average pressure can be calculated and corrected as a correction coefficient or a correction amount from a characteristic map or a characteristic equation obtained in advance through experiments or the like.

  (3) The pre-injection correction coefficient CTNAN indicating the expected value of the average pressure takes into account the common rail value NPC measured before injection of the pre-injection and the index value, so that the pre-injection amount QA is compared with the conventional correction method. The influence of pressure fluctuation can be reduced regardless of

(Other embodiments)
In the embodiment described above, the command injection period TQM has been described as an index value indicating the magnitude of the injection amount Q2 of the pre-injection QM. However, the present invention is not limited to the command injection period TQM as a command injection amount signal for controlling the injector. Even if the target injection amount Q2 is optimal in accordance with the operating state, or the pressure difference NPC1 between the pressure value NPC1 immediately before injection and the pressure value NPC2 immediately after injection is measured (see FIG. 4C). It is preferable to apply the present invention.

  In the embodiment described above, the pre-injection and the post-injection have been described with the main injection QM and the after injection QA. However, not only the relationship between the main injection QM and the after injection QA but also the relationship between the pilot injection QP and the main injection QM. However, it is preferable to apply the present invention.

  In the embodiment described above, the target common rail pressure NPC is used as the common rail pressure before the post-injection is injected when obtaining the correction coefficient TDANTHL and the correction amount TDAN1, but the pressure value NPC1 immediately before the injection of the pre-injection QM is used. Alternatively, the pressure value NPC2 immediately after the pre-injection QM or the pressure value before the post-injection MA may be used.

It is a lineblock diagram showing the whole pressure accumulation type fuel injection system composition of an embodiment of the present invention. 2 is a flowchart showing a control method for injecting a plurality of times during one combustion stroke in the ECU in FIG. 1. 2 is a flowchart showing a control method for injecting a plurality of times during one combustion stroke in the ECU in FIG. 1. It is a time chart which shows the action | operation of the pressure accumulation type fuel injection apparatus of embodiment of this invention. It is a time chart which shows the action | operation of the conventional pressure accumulation type fuel injection apparatus.

Explanation of symbols

1 engine (internal combustion engine)
2 Injector (fuel injection valve, electromagnetic fuel injection valve)
3 Supply pump (high pressure supply pump, fuel supply pump)
7 Suction metering valve 10 ECU (Engine control unit, control means, correction means)
17 Common rail (accumulation chamber)
20 High-pressure piping (supply piping)

Claims (6)

A pressure accumulation chamber for storing fuel in a high pressure state;
An injector for injecting high-pressure fuel supplied from the accumulator into a cylinder of an internal combustion engine;
Control means for controlling the injector according to the operating state of the internal combustion engine,
In the accumulator fuel injection device that performs injection a plurality of times during the combustion stroke of the internal combustion engine to the cylinder,
Pressure detecting means for detecting the pressure in the pressure accumulating chamber,
The control means calculates an index value indicating the magnitude of the injection amount of the pre-injection that is performed earlier of the plurality of injections,
When calculating the injection period for the required injection amount of the post injection performed after the pre-injection, the interval between the pre-injection and the post-injection, the pressure accumulation chamber pressure immediately before the post-injection, and the index A pressure-accumulating fuel injection device that corrects based on a value. The said control means is the said accumulator chamber in the said post-injection injection period from the at least three data of the interval between the said pre-injection and the said post-injection, the said accumulator pressure immediately before the said post-injection, and the said index value. The pressure accumulation type fuel injection device according to claim 1, wherein an estimated average pressure value is calculated. The calculation of the average pressure estimate value of the pressure accumulating chamber has a relationship between an index value representing the magnitude of the injection amount of the pre-injection and the average pressure estimate value in map data or is calculated and corrected. The pressure accumulation type fuel injection device according to claim 2. The pressure accumulation type according to claim 2, wherein the estimated average pressure value is corrected by adding the three data and the pressure value of the high-pressure fuel measured before the injection of the pre-injection. Fuel injection device. The index value is a target injection value for determining an injection amount to be injected in the first injection calculated by the control means from an operating state of the internal combustion engine, and a command for controlling the injector based on the target injection value An injection amount value, an injector drive pulse period value calculated based on the command injection amount value, a measured pressure value of the high-pressure fuel immediately before the injection of the pre-injection, and a pressure value immediately after the end of the injection of the pre-injection The pressure accumulation type fuel injection device according to any one of claims 1 to 4, wherein the pressure accumulation value is any one of the differential pressure values. A pressure accumulation chamber for storing fuel in a high pressure state;
An injector for injecting high-pressure fuel supplied from the accumulator into a cylinder of an internal combustion engine;
Control means for controlling the injector according to the operating state of the internal combustion engine;
Pressure detecting means for detecting the pressure in the pressure accumulating chamber,
In the accumulator fuel injection device that performs injection a plurality of times during the combustion stroke of the internal combustion engine to the cylinder,
The control means is an index value calculation means for calculating an index value indicating the magnitude of the injection amount of the pre-injection that is performed earlier of the plurality of injections;
When calculating the injection period for the required injection amount of the post injection performed after the pre-injection, the average pressure value of the pressure accumulation chamber pressure during the injection period of the post-injection after the end of the previous injection is the index value A pressure accumulating fuel injection device comprising: a correcting means for estimating the pressure on the basis of the pressure.

Images