JP4292717B2 - Accumulated fuel injection system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure-accumulating fuel injection device including an injector that injects high-pressure fuel accumulated in a common rail into each cylinder of a multi-cylinder internal combustion engine. The present invention relates to a pressure accumulation type fuel injection device capable of performing multistage injection three or more times during a cycle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a pressure accumulation type fuel injection device (for example, JP-A-6-101552) that supplies high pressure fuel accumulated in a common rail into a combustion chamber of each cylinder of a multi-cylinder internal combustion engine is known. In this accumulator fuel injection device, the main injection (main injection) is performed by opening the injector twice in order to perform stable combustion from the start of main injection and suppress noise vibration of the multi-cylinder internal combustion engine. Before this, a small amount of high-pressure fuel is injected in advance (pilot injection).
[0003]
Here, in the two-stage injection (pilot-main) described in JP-A-6-101552, the pilot injection ends from the common rail pressure: NPC, the pilot injection energization period: TQP, and the pilot interval: TINT after the end of the previous cylinder injection. Delay time: TDEP and main injection start delay time: TDM are calculated, and from the main injection timing: TFIN, pilot injection end delay time: TDEP and main injection start delay time: TDM calculated using the detected value of the operating state Main injection energization start time: TTMF is obtained. Here, TTPF in FIG. 7 is the pilot injection start timing.
[0004]
[Problems to be solved by the invention]
However, in the conventional technique, as shown in the operation timing chart of FIG. 7, the injection is performed twice at maximum in one cycle (one stroke) of the engine in each cylinder of a multi-cylinder (4 cylinders in this example) diesel engine. Recently, in each cylinder of a multi-cylinder (4 cylinders in this example) diesel engine as shown in the lowermost stage of FIG. 7, three-stage injection (pilot) is performed during one cycle (one stroke) of the engine. There is a demand to improve the exhaust gas performance by suppressing the discharge of smoke by burning unburned gas in the main injection by performing (main-after-injection). Here, TQPF in FIG. 7 is a pilot injection energization period, and TQMF is a main injection energization period.
[0005]
However, since the common rail pressure is significantly lower at the start of after injection than at the start of main injection, after injection energization start time: TTAF is calculated using pilot injection end delay time: TDEP and main injection start delay time: TDM. Then, the error of the injection start timing to the solenoid valve of the injector after the third time is large, and the control accuracy of the injection start timing after the third time is deteriorated, so that smoke emission increases and the effect of improving the exhaust gas performance is reduced. Problem arises.
[0006]
OBJECT OF THE INVENTION
  In the specific cylinder of the multi-cylinder internal combustion engine according to the present invention, the third and subsequent multi-stage injections are performed three or more times during one cycle of the multi-cylinder internal combustion engine.AfterAn object of the present invention is to provide a pressure accumulation type fuel injection device capable of improving exhaust gas performance by improving the control accuracy of the injection start timing.
[0007]
[Means for Solving the Problems]
  According to the first aspect of the present invention, in a specific cylinder of a multi-cylinder internal combustion engine, during one cycle of the multi-cylinder internal combustion engine.3 steps3 times when jettingEye afterThe injection start timeAfter the last cylinder injectionDetection value of injection pressure immediately before injector injectionAnd the mainInjectionMaineInjection periodWithParametersOn the basis of theFirst 2D mapFromCalculatedMaineInjection end delay time of injection and detected value of operating condition of multi-cylinder internal combustion engineFrom map or arithmetic expression based onCalculatedMaineInjection andAfterinjectionBetweenTarget interval ofAfter the last cylinder injectionDetection value of injection pressure immediately before injector injectionAnd the mainInjection andAfterinjectionBetweenTarget intervalWithParametersOn the basis of the main injection, which is lower than at the start of the main injectionA second two-dimensional map that takes into account the drop in injection pressure at the end of injectionFromCalculatedAfterThe calculation is performed using the injection start delay time of the injection.
  Here, the injection start delay time of the after injection is set to a longer time than the main injection start delay time when the second two-dimensional map is used.
[0008]
  It was calculated by itMaineInjection andAfterinjectionBetweenThe actual interval follows the target interval ofMaineBy jettingInjection pressure at the start of after-injection (Common rail pressure)3 times caused by a significant drop inEye afterThe error in the injection start timing is reduced. ThisPerformed after the first pilot injection and the second main injection3rdAfter salesSince the control accuracy of the injection start timing of the injector at the time of injection can be improved, 3 timesOcularFuel injection(After injection)BySecond fuelinjection(Main injection)Unburned gas can be burned reliably. Therefore, smoke emission can be suppressed and the black smoke density can be reduced. Therefore, the exhaust gas performance can be improved. According to the invention of claim 2, the second two-dimensional map of claim 1 is:After-determining the after-injection delay time of the after-injection using the detected value of the injection pressure immediately before the injector injection and the target interval between the main injection and the after-injection as parametersIt is an injection start delay time map.Thereby, the injection start delay time of the after injection is set to a longer time than the main injection start delay time.
[0009]
  According to the invention of claim 3, in a specific cylinder of the multi-cylinder internal combustion engine, during one cycle of the multi-cylinder internal combustion engine.3 steps3 times when jettingEye afterThe injection start time is the detected value of the injection pressure after the end of the previous cylinder injection.And the mainInjectionMaineInjection periodWithParametersOn the basis of theFirst 2D mapFromCalculatedMaineInjection end delay time of injection and detected value of operating condition of multi-cylinder internal combustion engineFrom map or arithmetic expression based onCalculatedMaineInjection andAfterinjectionBetweenTarget interval and detected value of injection pressure after end of previous cylinder injectionAnd the mainInjectionMaineInjection amountWhenDetected value of operating condition of multi-cylinder internal combustion engineAnd from maps or arithmetic expressions based on parametersCalculatedAfterPredicted value of injection pressure at the start of injection,AfterPredicted value of injection pressure at the start of injectionAnd the mainInjection andAfterinjectionBetweenTarget intervalWithParametersOn the basis of the,Second 2D mapFromCalculatedAfterThe calculation is performed using the injection start delay time of the injection.
[0010]
  It was calculated by itMaineInjection andAfterinjectionBetweenThe actual interval follows the target interval ofMaineBy jettingInjection pressure at the start of after-injection (Common rail pressure)3 times caused by a significant drop inEye afterThe error in the injection start timing is reduced. ThisPerformed after the first pilot injection and the second main injection3rdAfter salesSince the control accuracy of the injection start timing of the injector at the time of injection can be improved, 3 timesOcularFuel injection(After injection)BySecond fuelinjection(Main injection)Unburned gas can be burned reliably. Therefore, smoke emission can be suppressed and the black smoke density can be reduced. Therefore, the exhaust gas performance can be improved.
[0011]
  According to the invention described in claim 4, the second two-dimensional map described in claim 3 is:Main for determining the injection start delay time of the main injection with the detected value of the injection pressure after the end of the previous cylinder injection and the pilot interval between the pilot injection and the main injection as parametersIt is an injection start delay time map. ThisSince the injection start delay time of the after injection can be accurately calculated using the main injection start delay time map,Cost can be reduced. Furthermore, according to the invention described in claim 5, the operating state detecting means described in any one of claims 1 to 4 is at least.ManyEngine rotational speed detecting means for detecting the rotational speed of the cylinder internal combustion engine, andManyEngine load detecting means for detecting the load of the cylinder internal combustion engine is provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
[Configuration of First Embodiment]
1 to 4 show a first embodiment of the present invention, and FIGS. 1 and 2 show a common rail type fuel injection device.
[0013]
The common rail fuel injection device of the present embodiment is an electronically controlled pressure accumulation fuel injection device, in which high-pressure fuel is injected into the combustion chamber of each cylinder of a multi-cylinder diesel engine (hereinafter referred to as engine) as a multi-cylinder internal combustion engine. A plurality of injectors 1 for injection supply, a common rail 2 which is a kind of surge tank for accumulating high-pressure fuel, a known low-pressure supply pump (feed pump) 4 for pumping fuel from the fuel tank 3, and the low-pressure supply pump 4 A variable discharge amount type high-pressure supply pump 5 that pressurizes more sucked fuel to a high pressure, and an electronic control type control unit (hereinafter referred to as ECU) 6 that electronically controls the plurality of injectors 1 and the high-pressure supply pump 5. .
[0014]
Each injector 1 includes a fuel injection nozzle including a nozzle needle 10, a nozzle body 11, a hydraulic piston 12, a nozzle holder 13, and the like, and an electromagnetic valve 7 as an electromagnetic actuator that drives the fuel injection nozzle. An injection hole 21 for injecting fuel into the combustion chamber of each cylinder of the engine is formed at the tip of the nozzle body 11.
[0015]
Here, 15 is a fuel reservoir to which high-pressure fuel is always supplied, 16 is a coil spring for urging the nozzle needle 10 in the valve closing direction, 17 is a control chamber for controlling the back pressure of the hydraulic piston 12, and 18 and 19 are passed through. It is an orifice (throttle) that adjusts the flow rate of the fuel to be used. Each injector 1 is connected to a plurality of branch pipes 22 communicating with the common rail 2 via check valves 23, respectively.
[0016]
The fuel injection from the injector 1 to the engine is electronically controlled by a solenoid valve control signal to an injector drive circuit (not shown) that drives the solenoid valve 7. Since the fuel in the control chamber 17 is leaked through the orifice 19 while the electromagnetic valve 7 is open, the nozzle needle 10 is lifted from the valve seat of the nozzle body 11, so that the injection hole 21 and the fuel are discharged. The reservoir 15 communicates. Thereby, the high-pressure fuel supplied from the common rail 2 is injected into the combustion chamber of each cylinder of the engine.
[0017]
A high pressure corresponding to the injection pressure needs to be continuously accumulated in the common rail 2, and for this purpose, a high-pressure supply pump 5 is connected via a fuel pipe 24 and a discharge valve 25. In addition, the fuel return pipes 26 and 27 from the injectors 1, the common rail 2 and the high-pressure supply pump 5 to the fuel tank 3 allow the pressure to be released from the pressure limiter 28 so that the internal pressure does not exceed the limit accumulated pressure. It is comprised so that.
[0018]
The high-pressure supply pump 5 includes a feed pump 4 that pumps up the fuel in the fuel tank 3 through the fuel pipe 29 by rotating with the rotation of the crankshaft of the engine, and the fuel sucked out by the feed pump 4. This is a supply pump that pressurizes and feeds high-pressure fuel. A cam chamber 31 is formed at the lower end of the pump housing 30 in the drawing of the high-pressure supply pump 5. A cam shaft 32 that rotates at a rotational speed that is half the engine rotational speed is inserted into the cam chamber 31, and a cam 33 is formed on the cam shaft 32.
[0019]
A cylinder 34 is attached to the upper end of the pump housing 30 in the figure, and a plunger 35 is inserted into the cylinder 34 so as to reciprocate and slide freely. The plunger 35 has a cylindrical shape with no leads. In addition, a plunger chamber 36 constituting a pump chamber of a pump element constituted by the cylinder 34 and the plunger 35 is provided between the illustrated upper end surface of the plunger 35, the inner peripheral surface of the cylinder 34, and the illustrated lower end surface of the solenoid valve 9. Is formed.
[0020]
The lower end of the plunger 35 is connected to a slider 37, and the slider 37 is pressed against the cam roller 39 by a return spring 38. The cam roller 39 is in sliding contact with the cam 33. Therefore, when the cam 33 is rotated by the rotation of the cam shaft 32, the plunger 35 is reciprocated through the cam roller 39 and the slider 37. The reciprocating stroke of the plunger 35 is determined by the height difference of the cam 33.
[0021]
An electromagnetic valve 9 as an electromagnetic actuator is attached to the high-pressure supply pump 5. The electromagnetic valve 9 is configured such that a pump drive circuit (not shown) is electronically controlled by an electromagnetic valve control signal from the ECU 6, thereby discharging a high-pressure fuel from the high-pressure supply pump 5 to the common rail 2 via the fuel pipe 24 ( Adjust the pumping amount. Therefore, the solenoid valve 9 constitutes an injection pressure variable means for changing the injection pressure at which fuel is injected from each injector 1 into the combustion chamber of each cylinder of the engine.
[0022]
In order to electronically control the solenoid valves 7 and 9 for controlling the injection amount: QFIN, the injection timing: TFIN, and the injection pressure: PFIN to the optimum values, as shown in FIG. A cam position sensor 41, which is a known electromagnetic pickup, is disposed opposite to the timing rotor 41a. The cam position sensor 41 is a crank angle detecting means for detecting the crank angle of the engine (= cam angle of the high-pressure supply pump 5) shown in the operation time chart of FIG.
[0023]
In the present embodiment, the timing rotor 41a is generated so that 90 crank angle signals (1 pulse 7.5 ° CA) are generated during one cycle of the engine, that is, the crankshaft rotates twice (720 °). 45 tooth-like portions (projections) are provided on the outer peripheral surface of the plate. The NE pulse No. 20 and no. A missing tooth portion is provided between 0 (see FIG. 7).
[0024]
A cylinder discrimination sensor 42 and a rotor 42a are also coaxially attached to the camshaft 32. Seven teeth (protrusions, one extra tooth) are formed on the outer peripheral surface of the rotor 42a. Therefore, the microcomputer receives seven signals from the cylinder discrimination sensor 42 for one rotation of the pump. From the cylinder discrimination sensor 42 and the crank angle signal (NE pulse signal) of the cam position sensor 41, the ECU 6 can accurately determine and obtain the bottom dead center signal of the pump specific cylinder.
[0025]
The ECU 6 that electronically controls the common rail fuel injection device corresponds to the injector control means of the present invention. The CPU 51 performs control processing and arithmetic processing, the ROM 52 that stores various control programs and control maps, and input data. A microcomputer including functions of the RAM 53, the input port 54, the output port 55, and the like to be stored is incorporated.
[0026]
Here, the ECU 6 receives the crank angle signal, the cylinder discrimination signal, the accelerator opening signal, and the cooling water temperature signal from the cam position sensor 41, the cylinder discrimination sensor 42, the accelerator opening sensor 43, and the cooling water temperature sensor 44, for example. The ECU 6 applies the injector drive current to the electromagnetic coil of the solenoid valve 7 so that the optimum injection timing and the optimum injection amount that are input after the conversion and determined from the engine information and the calculated engine speed are obtained. A solenoid valve control (energization pulse) signal is output to the injector drive circuit. The ECU 6 and the cam position sensor 41 correspond to the operating state detection means of the present invention and are engine rotation speed detection means for detecting the engine rotation speed. The accelerator opening sensor 43 corresponds to the operating state detecting means of the present invention, and is an engine load detecting means for detecting the amount of depression of the accelerator pedal (accelerator opening).
[0027]
More preferably, the fuel pressure sensor (corresponding to the injection pressure detecting means of the present invention) detects the injection pressure at which fuel is injected into the combustion chamber of each cylinder of the engine, that is, the common rail pressure (NPC) after the end of previous cylinder injection. ) 45 is arranged on the common rail 2 so that the common rail pressure (Rail pressure) signal from the fuel pressure sensor 45 becomes an optimum injection pressure (common rail pressure) set in advance corresponding to the engine load and the engine speed. The ECU 6 outputs a solenoid valve control (energization pulse) signal to a pump drive circuit that supplies a pump drive current to the solenoid coil of the solenoid valve 9. An intake air temperature sensor 46, an intake air pressure sensor 47, a fuel temperature sensor (not shown), and the like may be provided.
[0028]
Here, in the common rail fuel injection device of this embodiment, in each cylinder of the engine, during one cycle of the engine (1 stroke: intake stroke-compression stroke-explosion stroke-exhaust stroke), that is, the crankshaft of the engine rotates twice ( 720 °), it is possible to perform multistage injection three or more times. That is, as shown in the operation timing chart of FIG. 3, it is possible to perform three-stage injection (pilot injection-main injection-after-injection) during one cycle of the engine in each cylinder of the engine.
[0029]
[Control Method of First Embodiment]
Next, a control method for the common rail fuel injection device according to the present embodiment will be briefly described with reference to FIGS. Here, FIG. 4 is a flowchart showing the calculation process of the after-injection energization start time (TTAF).
[0030]
First, the engine speed: NE is detected by measuring the interval time of the crank angle signal (NE pulse signal) input from the cam position sensor 41. Further, an accelerator opening signal from the accelerator opening sensor 43 is input to detect an engine load such as accelerator opening: ACCP. Also, a coolant temperature signal from the coolant temperature sensor 44 is input to detect engine coolant temperature: THW (operating state detection means: step S1). In addition, the intake air temperature from the intake air temperature sensor 46, the intake air pressure from the intake air pressure sensor 47, the fuel temperature from the fuel temperature sensor, and the like may be detected.
[0031]
Next, a main injection amount: QMAIN and an after injection amount: QAFTER are calculated from a two-dimensional map or an arithmetic expression based on control parameters of engine speed: NE and accelerator opening: ACCP (injection amount calculation means: step S2) ). The injection amount may be corrected according to engine operating conditions such as engine cooling water temperature: THW, intake pressure, intake air temperature, or fuel temperature.
[0032]
  Next, it is determined whether or not three-stage injection (pilot-main-after-injection) is performed in each cylinder of the engine during one cycle of the engine. That is, it is determined whether or not the third and subsequent injections (after-injection) when performing three-stage injection are performed (step S3). If this determination result is NO, that is, if it is not at the time of the after-injection energization command, the arithmetic processing in FIG. 4 is terminated.Here, at the time of the three-stage injection in which the number of injections in the multi-stage injection is set to three, if the second injection that is the immediately preceding injection is the main injection, the first injection that is the preceding injection before the main injection is the main injection Injection amount: pilot injection is smaller than QMAIN, and the third fuel injection, which is the current injection, is after injection smaller than main injection amount: QMAIN.
[0033]
If the determination result in step S3 is YES, that is, if the after-injection energization command is received, the common rail pressure signal from the fuel pressure sensor 45 is input to detect the common rail pressure: NPC immediately before the injector 1 injection. (Injection pressure detecting means: step S4).
[0034]
  Next, a main injection energization period: TQM is calculated from a two-dimensional map or an arithmetic expression based on the control parameters of the main injection amount: QMAIN and the detected value of the common rail pressure: NPC, and the engine speed: NE and accelerator opening: After interval: TINTA (in accordance with the present invention)MaineInjection andAfterinjectionBetween(Corresponding to the target interval) is calculated (step S5).
[0035]
  Next, the main injection end delay time: TDEM is calculated from the first two-dimensional map: MTDEM based on the control parameter of the common rail pressure detection value: NPC and the main injection energization period: TQM (main injection end delay time calculation) Means: Step S6). Next, based on the control parameters of the common rail pressure detection value: NPC and the after interval: TINTA,Significantly lower than the common rail pressure at the start of main injection,The after injection start delay time: TDA is calculated from the second two-dimensional map: MTDA (new map) that anticipates the decrease in common rail pressure at the start of after injection (after injection start delay time calculating means: step S7).
  Here, when the second two-dimensional map: MTDA is used, the decrease in the common rail pressure at the end of the main injection, that is, after the start of the after injection, which is significantly lower than the common rail pressure at the start of the main injection, is considered. The after injection start delay time: TDA is set longer than the main injection start delay time: TDM.
[0036]
Next, after injection energization start timing: TTAF is calculated from the following equation (1) (after injection energization start timing calculating means: step S10). Thereafter, the calculation process of FIG. 4 is terminated.
[0037]
  [Equation 1]
  TTAF = TTM + TQM +TDEM+ TINTA-TDA
  Here, TTM is the main injection energization start timing, TQM is the main injection energization period,TDEMIs the main injectionFinishIn the delay time, TINTA is an after interval, and TDA is an after injection start delay time.
[0038]
Here, when performing three-stage injection (pilot-main-after-injection) in one cycle (one stroke) of the engine in each cylinder of the engine, the engine speed (NE), the accelerator opening (ACCP), etc. From the engine load, a pilot injection energization period: TQP, a main injection energization period: TQM, an after injection energization period: TQA, a pilot interval: TINT, and an after interval: TINTA are calculated.
[0039]
Then, a pilot injection end delay time: TDEP is calculated from a two-dimensional map of common rail pressure: NPC and pilot injection energization period: TQP before the start of injector injection (after the end of injection of the immediately preceding cylinder), and the common rail before the start of injector injection A main injection end delay time: TDEM is calculated from a two-dimensional map of pressure: NPC and main injection energization period: TQM.
[0040]
  Then, a main injection start delay time: TDM is calculated from a two-dimensional map of common rail pressure: NPC and pilot interval: TINT before the start of injector injection, and common rail pressure: NPC and after interval: TINT2 before the start of injector injection. Dimensional map, that isAt the start of after injectionCommon rail pressure dropMinMTDA map created with the expectation ofUsingAfter injection start delay time: TDA is calculated.
[0041]
Then, the main injection energization start time: TTM is calculated from the main injection amount: QMAIN and the common rail pressure: NPC before the start of the injector injection, and the after injection energization start time: TTAF using the above equation (1). Is calculated. Thus, by supplying an injector drive current from the ECU 6 to the solenoid valve 7 of the injector 1 via the injector drive circuit, three-stage injection, that is, pilot-main, is performed in one cycle (one stroke) of the engine in each cylinder of the engine. -After-injection is made.
[0042]
That is, for example, at a predetermined crank angle before top dead center, during the pilot injection energization period: TQP, by supplying an injector drive current to the solenoid valve 7 of the injector 1, pilot injection starts from the pilot injection energization start timing TTP. Delay time: After TDEP, the nozzle needle 10 is lifted, and a small amount of fuel injection corresponding to the pilot injection amount: QPILOT is made in the combustion chamber of a specific cylinder of the engine. The injection rate waveform at the time of pilot injection is shown in the operation timing chart of FIG.
[0043]
Next, when the main injection energization start time: TTM comes after the end of pilot injection, during the main injection energization period: TQM, the injector drive current is supplied to the solenoid valve 7 of the injector 1 to start main injection from the start of main injection energization. After the start delay time: TDM, the nozzle needle 10 is lifted, and fuel injection corresponding to the main injection amount: QMAIN is performed in the combustion chamber of a specific cylinder of the engine. The injection rate waveform during the main injection is shown in the operation timing chart of FIG.
[0044]
Next, after the main injection ends, when the after injection energization start time: TTAF comes, during the after injection energization period: TQA, the injector drive current is supplied to the electromagnetic valve 7 of the injector 1 to start the after injection from the start of the after injection energization. After the start delay time: TDA, the nozzle needle 10 is lifted, and fuel injection corresponding to the after injection amount: QAFTER is performed in the combustion chamber of a specific cylinder of the engine. The injection rate waveform at the time of this after injection is shown in the operation timing chart of FIG.
[0045]
[Effects of First Embodiment]
The common rail fuel injection device according to the present embodiment is provided to the solenoid valve 7 of the injector 1 in order to accurately match the third injection start timing at the time of performing the three-stage injection with a desired timing under all operating conditions. The energization start time at the time of after injection is calculated from (1) main injection end delay time: TDEM and (2) after injection start delay time: TDA and (3) after interval: TINTA. The signal is commanded.
[0046]
Then, as shown in the operation timing chart of FIG. 3, the common rail pressure: NPC and the main injection are avoided in order to avoid the deterioration of the control accuracy of the energization start time at the time of the after injection, which is caused by the decrease of the common rail pressure in the main injection. Energization period: Main injection end delay time based on control parameter with TQM: First two-dimensional map for calculating TDEM: MTDEM, common rail pressure: NPC and after interval: After injection start delay time with control parameter of TINTA : A second two-dimensional map for calculating TDA: MTDA is newly set for calculating the energization start time at the time of after injection.
[0047]
Then, at the time of after-injection energization command for sending an energization pulse signal from the output port 55 of the ECU 6 to the injector drive circuit and supplying the injector drive current from the injector drive circuit to the electromagnetic valve 7 of the injector 1, those first two-dimensional maps By searching the second two-dimensional map, the after injection start time can be calculated with high accuracy.
[0048]
As a result, the calculated after interval: TINTA follows the actual interval, and the start of energization at the time of after-injection to the solenoid valve 7 of the injector 1 at the time of after-injection is the optimum time. : The error in the after injection start timing caused by a significant decrease in NPC is reduced. As a result, the control accuracy of the injection start timing of the solenoid valve 7 of the injector 1 at the time of after injection can be improved, so that a desired injection rate waveform is formed as shown by the solid line in the operation timing chart of FIG. The
[0049]
Then, by performing three-stage injection (pilot-main-after-injection) in one cycle (one stroke) of the engine in the specific cylinder of the engine, the main cylinder is injected from the injector 1 into the combustion chamber of the specific cylinder of the engine. Unburned gas in the fuel can be reliably burned together with the fuel injected from the injector 1 into the combustion chamber of the specific cylinder of the engine at the time of after injection. Thereby, since the discharge | emission of smoke can be suppressed, the deterioration of an emission can be suppressed.
[0050]
[Second Embodiment]
5 and 6 show a second embodiment of the present invention. FIG. 5 is a flowchart showing a calculation process of after-injection energization start timing (TTAF), and FIG. 6 (a) is a main injection start delay time. FIG. 6B is an operation timing chart of the common rail fuel injection device.
[0051]
  Only arithmetic processing different from the flowchart of FIG. 4 will be described. After calculating the main injection end delay time (TDEM) in step S6, the after-order is calculated from the two-dimensional map or the calculation formula based on the control parameters of the common rail pressure (NPC), the main injection amount (QMAIN), and the engine speed (NE). At the start of injectionofPredicted value of common rail pressure: NPCA is calculated (after-injection start common rail pressure predicted value calculating means: step S8).
[0052]
Next, the after injection start delay time (TDA) is calculated from the two-dimensional map: MTDM (existing map) based on the control parameters of the predicted value of common rail pressure at the start of after injection: NPCA and after interval: TINTA (after injection) Start delay time calculating means: Step S9). After that, the process proceeds to step S10.
[0053]
  Here, the after injection start delay time is determined by the common rail pressure at the start of the after injection and the after interval. Therefore, if the common rail pressure at the start of after injection: NPCA can be accurately predicted or estimated, the main injection start delay time map as shown in FIG. 6A: MTDM (existing map)UsingSince the after injection start delay time: TDA can be calculated with high accuracy, the existing map can be used as compared with the first embodiment, so that the cost can be reduced.
[0054]
In FIGS. 6 (a) and 6 (b), NPC (2) is the common rail pressure after the previous cylinder injection (after main injection), TINT (2) is the pilot interval, and NPCA (2) is after the start of after-injection. TINTA (2) is the after interval, TDM is the main injection start delay time, and TDA is the after injection start delay time.
[0055]
[Other Embodiments]
In the present embodiment, the injection pressure immediately before the injector injection is detected by the fuel pressure sensor 45 disposed on the common rail 2, but the injection pressure immediately before the injector injection is detected in the fuel piping system from the high-pressure supply pump 5 to each injector 1. It may be detected by a fuel pressure sensor for detecting the fuel pressure. Further, the common rail pressure (the injection pressure immediately before the injector injection) may be calculated from the discharge amount of the high-pressure supply pump 5. Further, the common rail pressure (the injection pressure immediately before the injector injection) may be calculated from the injection pressure command value to the electromagnetic valve 9 of the high pressure supply pump 5.
[0056]
In the present embodiment, the example in which the present invention is applied to a common rail fuel injection device capable of performing three-stage injection (pilot-main-after-injection) in one cycle of the engine in a specific cylinder of the engine has been described. Even if the present invention is applied to an accumulator fuel injection device capable of performing four injections, five injections, six injections, or seven or more multistage injections in one cycle of the engine in a specific cylinder of the engine. good.
[0057]
In this embodiment, the first injection start timing (pilot injection energization start timing) of the three-stage injection is controlled to be BTDC 37.5 ° CA. However, the first injection start timing of the three-stage injection is controlled. It is desirable to control (pilot injection energization start timing) so that the fuel is injected before top dead center (TDC). For example, it may be controlled to be BTDC 10 ° CA to 40 ° CA, or BTDC 25 ° CA. You may control so that it may become -35 degreeCA.
[0058]
  In the present embodiment, the first and third injections of the three-stage injection are set to substantially the same injection amount, but the ratio may be changed.. MaIn addition, the first injection amount of multistage injection is 5% to 25% of the total injection amount in the first stroke, the second injection amount of multistage injection is 50% to 75% of the total injection amount in the first stroke, and the multistage injection. The third and subsequent injection amounts may be controlled to be 5% to 25% of the total injection amount in one stroke.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a common rail fuel injection device (first embodiment).
FIG. 2 is a block diagram showing a common rail fuel injection device (first embodiment).
FIG. 3 is a timing chart showing the operation of the common rail fuel injection device (first embodiment).
FIG. 4 is a flowchart showing a calculation process of after-injection energization start timing (first embodiment).
FIG. 5 is a flowchart showing a calculation process of after-injection energization start timing (second embodiment).
6A is a diagram showing a main injection start delay time map, and FIG. 6B is a timing chart showing the operation of the common rail fuel injection device (second embodiment).
FIG. 7 is a timing chart showing the operation of the common rail fuel injection device.
[Explanation of symbols]
1 Injector
2 Common rail
3 Fuel tank
4 Low pressure supply pump
5 High pressure supply pump
6 ECU (injector control means, engine speed detection means)
7 Solenoid valve
9 Solenoid valve
41 Cam position sensor (operating state detection means, engine rotation speed detection means)
43 Accelerator opening sensor (operating state detection means, engine load detection means)
45 Fuel pressure sensor (Injection pressure detection means)

Claims (5)

A common rail for accumulating high-pressure fuel discharged from the high-pressure supply pump;
An injector for injecting high-pressure fuel accumulated in the common rail into each cylinder of the multi-cylinder internal combustion engine;
Injector control which has an operation state detection means for detecting an operation state of the multi-cylinder internal combustion engine, calculates an injection timing and an injection amount according to a detection value of the operation state of the multi-cylinder internal combustion engine, and controls the injector Means and
A pressure accumulation type fuel injection device capable of performing multi-stage injection three or more times in one cycle of the multi-cylinder internal combustion engine in a specific cylinder of the multi-cylinder internal combustion engine,
The injector control means has an injection pressure detection means for detecting an injection pressure immediately before the injector injection after the end of the previous cylinder injection,
If the second injection that is the immediately preceding injection is the main injection when performing at least three-stage injection, the first injection that is the preceding injection before the main injection is a pilot injection that is smaller than the main injection amount. The third injection, which is an injection, is an after injection that is a smaller amount than the main injection amount,
The third after- injection start time when performing the three-stage injection,
(A) an injection end delay time of the main injection calculated from the first two-dimensional map based on a parameter of a detected value of the injection pressure immediately before the injector injection and a main injection period of the main injection;
(B) a target interval between the main injection and the after injection calculated from a map or an arithmetic expression based on a detected value of an operating state of the multi-cylinder internal combustion engine;
(C) based on the parameters of the detected value and the previous Symbol targets interval of the injector injection immediately before injection pressure is lower than at the time of the main injection start, considering decrement the injection pressure during the main injection ends An accumulator fuel injection apparatus that performs calculation using an after injection start delay time calculated from a second two-dimensional map. The pressure accumulation type fuel injection device according to claim 1,
The second two-dimensional map is an after injection start delay time map for obtaining an injection start delay time of the after injection using the detected value of the injection pressure immediately before the injector injection and the target interval as parameters. An accumulator fuel injection device. A common rail for accumulating high-pressure fuel discharged from the high-pressure supply pump;
An injector for injecting high-pressure fuel accumulated in the common rail into each cylinder of the multi-cylinder internal combustion engine;
Injector control which has an operation state detection means for detecting an operation state of the multi-cylinder internal combustion engine, calculates an injection timing and an injection amount according to a detection value of the operation state of the multi-cylinder internal combustion engine, and controls the injector Means and
In the accumulator fuel injection device capable of performing multi-stage injection three or more times in one cycle of the multi-cylinder internal combustion engine in a specific cylinder of the multi-cylinder internal combustion engine,
The injector control means includes an injection pressure detection means for detecting an injection pressure after completion of the previous cylinder injection,
If the second injection that is the immediately preceding injection is the main injection when performing at least three-stage injection, the first injection that is the preceding injection before the main injection is a pilot injection that is smaller than the main injection amount. The third injection, which is an injection, is an after injection that is a smaller amount than the main injection amount,
The third after- injection start time when performing the three-stage injection,
(A) and the immediately preceding cylinder injection after the end of the injection pressure detected value and the injection end time delay of the main injection which is calculated from the first two-dimensional map based on the parameters of the main injection period of main injection,
(B) a target interval between the main injection and the after injection calculated from a map or an arithmetic expression based on a detected value of an operating state of the multi-cylinder internal combustion engine;
(C) After injection calculated from a map or an arithmetic expression based on parameters of the detected value of the injection pressure after the end of the immediately preceding cylinder injection, the main injection amount of the main injection, and the detected value of the operating state of the multi-cylinder internal combustion engine The predicted value of the starting injection pressure,
And (d) for calculating using said after-injection at the start of the injection pressure predictive value and the after-injection of the injection starting delay time calculated from the second two-dimensional map based on the parameters of the previous SL objectives interval An accumulator fuel injection device characterized by the above. The pressure accumulation type fuel injection device according to claim 3,
The second two-dimensional map obtains the injection start delay time of the main injection using the detected value of the injection pressure after the end of the immediately preceding cylinder injection and the pilot interval between the pilot injection and the main injection as parameters. A pressure-accumulation fuel injection device characterized by being a main injection start delay time map. The pressure accumulation type fuel injection device according to any one of claims 1 to 4,
The operating state detection means includes at least engine rotation speed detection means for detecting a rotation speed of the multi-cylinder internal combustion engine, and engine load detection means for detecting a load of the multi-cylinder internal combustion engine. Accumulated fuel injection system.

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