Control device for a compression self-ignition internal combustion engine

Abstract

To provide a control device of a compression self-ignition type internal combustion engine which can calculate a further-accurate estimation ignition delay time.SOLUTION: A control device of a compression self-ignition type internal combustion engine has: a normal multistage injection execution unit for executing multistage injection including main injection and pilot injection to a one-time combustion stroke of the internal combustion engine by controlling an injector; an estimated ignition delay time calculation unit for acquiring an estimated ignition delay time until the main injection is generated after a start of the main injection on the basis of an operation state of the internal combustion engine; a confirmation single-stage injection execution unit for executing confirmation single-stage injection for injecting a prescribed quantity of fuel by the single-stage injection by only the main injection to the internal combustion engine whose rotation number is decreased due to a fuel cut; a torque equivalent amount detection unit for detecting a torque equivalent amount corresponding to torque which is generated in the internal combustion engine by the confirmation single-stage injection; a correction time calculation unit for calculating a correction time for correcting the estimated ignition delay time on the basis of the detected torque equivalent amount; and an estimated ignition delay time correction unit for correcting the estimated ignition delay time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a compression self-ignition type internal combustion engine that controls an injector for injecting fuel into the compression self-ignition type internal combustion engine.

Background Art

[0002] Conventionally, in a compression self-ignition type internal combustion engine mounted on an automobile or the like, for one combustion stroke, multi-stage injection including main injection which is the main fuel injection and pilot injection which is the fuel injection performed prior to the main injection is carried out. When performing multi-stage injection, the control device for the internal combustion engine estimates the ignition delay time (the delay time from the start of the main injection until the main combustion which is the main combustion occurs) based on the operating state, and calculates combustion parameters based on the estimated ignition delay time.

[0003] The combustion parameters are parameters related to multi-stage injection performed in a compression self-ignition type internal combustion engine. Based on the parameters, the control device distributes, for example, the total injection amount from the injector for one combustion stroke of the internal combustion engine into the main injection amount by the main injection and the pilot injection amount by the pilot injection which is the fuel injection performed prior to the main injection. According to the multi-stage injection based on the combustion parameters that realize the estimated ignition delay time, ideal combustion can be generated.

[0004] In a compression ignition internal combustion engine as described above, in order to determine combustion parameters based on the estimated ignition delay time, it is necessary to obtain a sufficiently high estimation accuracy of the ignition delay time. For example, in Patent Document 1, it is assumed that the ignition delay includes a physical ignition delay (the time required for fuel droplet evaporation and mixing) and a chemical ignition delay (the time required for chemical bond formation, decomposition, and oxidation heat generation of fuel vapor), and the total ignition delay period is obtained based on these ignition delay periods. Specifically, the physical ignition delay period is obtained as the period from the start time of pilot injection until the in-spray equivalence ratio drops below the in-spray combustible equivalence ratio, and the chemical ignition delay is calculated based on the temperature and pressure in the combustion chamber at the time when the in-spray equivalence ratio of the fuel injected by the pilot injection reaches the in-spray combustible equivalence ratio after the pilot injection is started. The total ignition delay period is calculated from this physical ignition delay and chemical ignition delay.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in an environment where the intake manifold (intake manifold, hereinafter referred to as in-mani) temperature is low, for example, in an environment of 10°C or lower, the error between the calculated estimated ignition delay time and the actual ignition delay time may exceed the allowable range. Therefore, if the method of determining combustion parameters on the premise that the estimated ignition delay time is accurately calculated (for example, the error with respect to the actual ignition delay time is within the range of -10% to 10%) is used, there is a risk of misfire when injection is performed based on the combustion parameters in a low in-mani environment.

[0007] Therefore, conventionally, preventing misfire has been prioritized over ideal combustion, and a method for determining combustion parameters has been used on purpose, assuming that the estimated ignition delay time varies with respect to the actual ignition delay time. While this achieves the effect of preventing misfire, it results in combustion that is slightly deviated from ideal combustion. For example, combustion noise may increase slightly. If an accurate estimated ignition delay time can be obtained regardless of the in-cylinder temperature, there is no need to prioritize misfire prevention, and ideal combustion without the risk of misfire can be realized.

[0008] The present invention was conceived in view of such a point, and an object thereof is to provide a control device for a compression self-ignition type internal combustion engine that can calculate a more accurate estimated ignition delay time and realize combustion closer to ideal.

Means for Solving the Problem

[0009] To solve the above problems, a control device for a compression self-ignition type internal combustion engine according to the present disclosure includes a normal multi-stage injection execution unit that controls an injector to perform multi-stage injection including a main injection, which is a main fuel injection, and a pilot injection, which is a fuel injection performed prior to the main injection, for one combustion stroke of the internal combustion engine; an estimated ignition delay time calculation unit that obtains an estimated ignition delay time, which is an estimated value of the ignition delay time, which is the delay time from the start of the main injection until main combustion, which is the main combustion, occurs, based on the operating state of the internal combustion engine; a confirmation single-stage injection execution unit that controls the injector to perform a confirmation single-stage injection in which a predetermined amount of fuel is injected by a single-stage injection of only the main injection to the internal combustion engine that is idling while the rotational speed decreases due to fuel cut during deceleration; a torque equivalent amount detection unit that detects a torque equivalent amount corresponding to the torque generated in the internal combustion engine by the confirmation single-stage injection; a correction time calculation unit that calculates a correction time for correcting the estimated ignition delay time based on the detected torque equivalent amount and the intake temperature, which is the temperature of the intake manifold of the internal combustion engine or the temperature of the intake air of the internal combustion engine; and an estimated ignition delay time correction unit that corrects the estimated ignition delay time using the correction time.

[0010] According to this, if the ignitability in the cylinder where air is compressed and heated is good, the fuel by the single-stage injection for confirmation burns in a short period, so the torque equivalent amount becomes large. If the ignitability is bad, it burns slowly, so the torque equivalent amount becomes small. Therefore, regarding the torque equivalent amount obtained by the single-stage injection for confirmation, it can be an index of ignitability. Also, the temperature of the intake manifold and the intake air temperature are directly related to the ignitability in the cylinder. Therefore, by focusing on two values correlated with the actual ignitability in the cylinder and correcting the estimated ignition delay time, a more accurate estimated ignition delay time can be calculated.

[0011] In the control device for the compression self-ignition type internal combustion engine, the torque equivalent amount detection unit may obtain the torque equivalent amount based on the rotational speed of the internal combustion engine immediately before executing the single-stage injection for confirmation and the amount of change in the rotational speed increased by the single-stage injection for confirmation.

[0012] According to this, for example, the rotational speed that rises as a result of performing the single-stage injection for confirmation at 2,000 rpm (for example, 10 rpm) is different from the rotational speed that rises as a result of performing the single-stage injection for confirmation at 1,000 rpm (for example, 20 rpm). However, when multiplying both (the rotational speed immediately before the single-stage injection for confirmation and the rotational speed increase amount), it becomes almost the same value (for example, 20,000 rmp^2). Therefore, the torque equivalent amount obtained in this way is suitable as an index of ignitability, and a more accurate estimated ignition delay time can be calculated.

[0013] In the control device for the compression self-ignition type internal combustion engine, the single-stage injection for confirmation execution unit executes the single-stage injection for confirmation a plurality of times and continuously for the internal combustion engine that is idling while the rotational speed is decreasing due to fuel cut during deceleration, without generating combustion. The torque equivalent amount detection unit obtains the torque equivalent amount for each of the plurality of times, and the torque equivalent amount for calculating the correction time is obtained by averaging the obtained torque equivalent amounts for the plurality of times.

[0014] According to this, by taking the average, the variation in the torque equivalent amount obtained for each single-stage injection for confirmation is suppressed, so that a more accurate estimated ignition delay time can be calculated as compared with the case of correcting the estimated ignition delay time based on the torque equivalent amount obtained by a single confirmation single-stage injection.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0016] ●[Overall Configuration of Diesel Engine System 1 (FIG. 1)] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. First, with reference to FIG. 1, an example of the overall configuration of a diesel engine system 1 having a compression self-ignition type diesel engine 10 will be described. In the description of the present embodiment, the diesel engine system 1 mounted on a vehicle will be described as an example.

[0017] Hereinafter, the entire system will be described in order from the intake side to the exhaust side. An air cleaner (not shown) and intake air flow rate detecting means 21 (for example, an intake air flow rate sensor) are provided on the inflow side of the intake pipe 11A. The intake air flow rate detecting means 21 outputs a detection signal corresponding to the flow rate of the air inhaled by the diesel engine 10 to the control device 50. Further, the intake air flow rate detecting means 21 is provided with intake air temperature detecting means 28A (for example, an intake air temperature sensor). The intake air temperature detecting means 28A outputs a detection signal corresponding to the temperature of the intake air passing through the intake air flow rate detecting means 21 to the control device 50.

[0018] The outflow side of the intake pipe 11A is connected to the inflow side of the compressor 35, and the outflow side of the compressor 35 is connected to the inflow side of the intake pipe 11B. The turbocharger 30 includes a compressor 35 having a compressor impeller 35A and a turbine 36 having a turbine impeller 36A. The compressor impeller 35A is rotationally driven by the turbine impeller 36A that is rotationally driven by the energy of the exhaust gas, and supercharges by pumping the intake air flowing in from the intake pipe 11A to the intake pipe 11B.

[0019] An intake pipe 11A upstream of the compressor 35 is provided with a compressor upstream pressure detection means 24A. The compressor upstream pressure detection means 24A is, for example, a pressure sensor, and outputs a detection signal corresponding to the pressure of the intake air in the intake pipe 11A upstream of the compressor 35 to the control device 50. An intake pipe 11B downstream of the compressor 35 (at a position between the compressor 35 and the intercooler 16 in the intake pipe 11B) is provided with a compressor downstream pressure detection means 24B. The compressor downstream pressure detection means 24B is, for example, a pressure sensor, and outputs a detection signal corresponding to the pressure of the intake air in the intake pipe 11B downstream of the compressor 35 to the control device 50.

[0020] An intercooler 16 is arranged upstream of the intake pipe 11B, and a throttle device 48 is arranged downstream of the intercooler 16. The intercooler 16 is arranged downstream of the compressor downstream pressure detection means 24B, and lowers the temperature of the intake air supercharged by the compressor 35. An intake air temperature detection means 28B (for example, an intake air temperature sensor) is provided between the intercooler 16 and the throttle device 48. The intake air temperature detection means 28B outputs a detection signal corresponding to the temperature of the intake air whose temperature has been lowered by the intercooler 16 to the control device 50.

[0021] The throttle device 48 drives a throttle valve that adjusts the opening degree of the intake pipe 11B based on a control signal from the control device 50, and can adjust the intake air flow rate. The control device 50 can output a control signal to the throttle device 48 to adjust the opening degree of the throttle valve provided in the intake pipe 11B based on a detection signal from the throttle opening detection means 48S (for example, a throttle opening sensor) and a target throttle opening degree. The control device 50 obtains a target throttle opening degree based on the depression amount of the accelerator pedal detected based on a detection signal from the accelerator pedal depression amount detection means 25 and the operating state of the diesel engine 10.

[0022] The accelerator pedal depression amount detection means 25 is, for example, an accelerator pedal depression angle sensor, and is provided on the accelerator pedal. The control device 50 can detect the depression amount of the accelerator pedal by the driver based on the detection signal from the accelerator pedal depression amount detection means 25.

[0023] On the downstream side of the throttle device 48 in the intake pipe 11B, the outflow side of the EGR pipe 13 is connected. And the outflow side of the intake pipe 11B is connected to the inflow side of the intake manifold 11C, and the outflow side of the intake manifold 11C is connected to the inflow side of the diesel engine 10. And the intake manifold 11C is provided with intake manifold pressure detection means 24C. The intake manifold pressure detection means 24C is, for example, a pressure sensor, and outputs a detection signal corresponding to the pressure of the intake air in the intake manifold 11C to the control device 50. Also, from the outflow side (connection part with the intake pipe 11B) of the EGR pipe 13, the EGR gas flowing in from the inflow side (connection part with the exhaust pipe 12B) of the EGR pipe 13 is discharged into the intake pipe 11B. The path through which the EGR gas flows formed by the EGR pipe 13 corresponds to the EGR path.

[0024] The diesel engine 10 (diesel engine) has a plurality of cylinders 45A to 45D, and injectors 43A to 43D are provided in the respective cylinders. Fuel is supplied to the injectors 43A to 43D via the common rail 41 and the fuel pipes 42A to 42D. The injectors 43A to 43D are driven by control signals from the control device 50, and fuel is injected into the respective cylinders 45A to 45D.

[0025] The diesel engine 10 is provided with a crank angle detection means 22A and a cylinder detection means 22B. The crank angle detection means 22A is, for example, a rotation sensor provided near the crankshaft, and outputs a detection signal corresponding to the rotation angle of the crankshaft of the diesel engine 10 to the control device 50. The cylinder detection means 22B is a rotation sensor provided near the camshaft, and outputs a detection signal to the control device 50 when, for example, the piston of the first cylinder reaches the compression top dead center. The control device 50 can detect, based on the detection signal from the crank angle detection means 22A and the detection signal from the cylinder detection means 22B, that the piston of the first cylinder, for example, is at the top dead center position, and can determine whether the top dead center position is the compression top dead center position or the intake top dead center position.

[0026] The diesel engine 10 is also provided with a coolant temperature detection means 28C. The coolant temperature detection means 28C is, for example, a temperature sensor, detects the temperature of the coolant for cooling circulated in the diesel engine 10, and outputs a detection signal corresponding to the detected temperature to the control device 50.

[0027] On the exhaust side of the diesel engine 10, the inflow side of the exhaust manifold 12A is connected, and on the outflow side of the exhaust manifold 12A, the inflow side of the exhaust pipe 12B is connected. The outflow side of the exhaust pipe 12B is connected to the inflow side of the turbine 36, and the outflow side of the turbine 36 is connected to the inflow side of the exhaust pipe 12C.

[0028] On the exhaust pipe 12B, the inflow side of the EGR pipe 13 is connected. The EGR pipe 13 communicates the exhaust pipe 12B and the intake pipe 11B, and it is possible to reflux a part of the exhaust gas in the exhaust pipe 12B to the intake pipe 11B. The EGR pipe 13 is also provided with an EGR cooler 15 and an EGR valve 14.

[0029] The EGR valve 14 (EGR valve) is provided on the downstream side of the EGR cooler 15 in the EGR pipe 13. And the EGR valve 14 adjusts the flow rate of the EGR gas flowing in the EGR pipe 13 by adjusting the opening degree of the EGR pipe 13 based on a control signal from the control device 50.

[0030] The EGR cooler 15 is provided in the EGR pipe 13. The EGR cooler 15 is a so-called heat exchanger, to which a coolant for cooling is supplied, and which cools the inflowing EGR gas and discharges it.

[0031] With the above-described EGR pipe 13, (EGR cooler 15), and EGR valve 14, an EGR system capable of returning a part of the exhaust gas to the intake path is configured. Note that the EGR system may or may not include the EGR cooler 15.

[0032] The outflow side of the exhaust pipe 12B is connected to the inflow side of the turbine 36, and the outflow side of the turbine 36 is connected to the inflow side of the exhaust pipe 12C. The turbine 36 is provided with a variable nozzle 33 (capable of adjusting the opening degree of the flow path guiding the exhaust gas to the turbine) capable of controlling the flow velocity of the exhaust gas guiding to the turbine impeller 36A, and the opening degree of the variable nozzle 33 is adjusted by the nozzle driving means 31. The control device 50 can output a control signal to the nozzle driving means 31 based on the detection signal from the nozzle opening degree detection means 32 (for example, a nozzle opening degree sensor) and the target nozzle opening degree to adjust the opening degree of the variable nozzle 33.

[0033] On the exhaust pipe 12B upstream of the turbine 36, a turbine upstream pressure detection means 26A is provided. The turbine upstream pressure detection means 26A is, for example, a pressure sensor, and outputs a detection signal corresponding to the pressure of the exhaust gas in the exhaust pipe 12B upstream of the turbine 36 to the control device 50. On the exhaust pipe 12C downstream of the turbine 36, a turbine downstream pressure detection means 26B is provided. The turbine downstream pressure detection means 26B is, for example, a pressure sensor, and outputs a detection signal corresponding to the pressure of the exhaust gas in the exhaust pipe 12C downstream of the turbine 36 to the control device 50.

[0034] The exhaust pipe 12C is provided with an oxidation catalyst 61 and a particulate filter 62. A selective reduction catalyst may be provided on the downstream side of the particulate filter 62. An exhaust temperature detection means 28D is provided on the upstream side of the oxidation catalyst 61, and an exhaust temperature detection means 28E is provided on the downstream side of the oxidation catalyst 61. The exhaust temperature detection means 28D and 28E are, for example, exhaust temperature sensors, and output detection signals corresponding to the exhaust temperature to the control device 50. Further, the particulate filter 62 is provided with a differential pressure detection means 26C for detecting the pressure difference between the upstream side and the downstream side of the particulate filter 62. The differential pressure detection means 26C is, for example, a pressure sensor, and outputs a detection signal corresponding to the differential pressure between the pressure of the exhaust gas on the upstream side of the particulate filter 62 and the pressure of the exhaust gas on the downstream side of the particulate filter 62 to the control device 50.

[0035] The atmospheric pressure detection means 23 is, for example, an atmospheric pressure sensor, and is provided in the control device 50. The atmospheric pressure detection means 23 outputs a detection signal corresponding to the atmospheric pressure around the control device 50 to the control device 50.

[0036] The vehicle speed detection means 27 is, for example, a vehicle speed detection sensor, and is provided on the wheels of the vehicle or the like. The vehicle speed detection means 27 outputs a detection signal corresponding to the rotational speed of the vehicle wheels to the control device 50.

[0037] The control device 50 is a fuel property detection device, and has at least a CPU 51 and a storage device 53. As described above, the inputs to the control device 50 (CPU 51) include detection signals from the intake air flow rate detection means 21, the crank angle detection means 22A, the cylinder detection means 22B, the atmospheric pressure detection means 23, the accelerator pedal depression amount detection means 25, the compressor upstream pressure detection means 24A, the compressor downstream pressure detection means 24B, the intake manifold pressure detection means 24C, the turbine upstream pressure detection means 26A, the turbine downstream pressure detection means 26B, the differential pressure detection means 26C, the vehicle speed detection means 27, the intake air temperature detection means 28A and 28B, the coolant temperature detection means 28C, the exhaust temperature detection means 28D and 28E, the nozzle opening degree detection means 32, the throttle opening degree detection means 48S, etc.

[0038] In addition, as described above, the outputs from the control device 50 (CPU 51) include control signals for the injectors 43A to 43D, the EGR valve 14, the nozzle drive means 31, the throttle device 48, and the like. Note that the inputs and outputs of the control device 50 are not limited to the above-described detection means and actuators. Further, the temperature, pressure, etc. of each part may be calculated by estimation calculation without mounting a sensor. The control device 50 detects the operating state and environmental state of the diesel engine 10 based on detection signals from various detection means including the above-described detection means, and controls various actuators including the above-described actuators. The storage device 53 is a storage device such as a Flash-ROM, and stores programs, data, etc. for executing control and self-diagnosis of the diesel engine 10.

[0039] Note that the control device 50 (CPU 51) has a normal multi-stage injection execution unit 51A, an estimated ignition delay time calculation unit 51B, a confirmation single-stage injection execution unit 51C, a torque equivalent amount detection unit 51D, a correction time calculation unit 51E, and an estimated ignition delay time correction unit 51F. Details thereof will be described later.

[0040] ● [Multi-stage injection including pilot injection and main injection and estimated ignition delay time (Fig. 2)] Fig. 2 is a diagram showing an example of multi-stage injection. The horizontal axis represents the crank angle (shown as time for convenience regarding the injection timing), and the vertical axis represents the execution of injection and the heat generation rate, respectively. The control device 50 injects, into the cylinder (cylinders 45A to 45D) where air is compressed and heated, a main injection which is the main fuel injection and one or more pilot injections which are fuel injections before the main injection, for one combustion stroke based on the operating state of the diesel engine 10. In the description of the present embodiment, all injections before the main injection in one combustion stroke are collectively referred to as "pilot injection".

[0041] For example, as shown in FIG. 2, in normal multi-stage injection, the control device 50 executes pilot injections 101A and 102A before the main injection 103A to generate pilot combustions 101B and 102B, and then executes the main injection 103A to generate the main combustion 103B.

[0042] The time from the start time t1 of the main injection 103A to the start time t2 of the main combustion 103B is the actual ignition delay time (actual ignition delay time Tr). In contrast, the control device 50 calculates an estimated ignition delay time Te based on the operating state of the diesel engine 10 (for example, based on the detection signals input from the intake air temperature detection means 28A to 28B, the pressure detection means 24A to 24C, the coolant temperature detection means 28C, etc.). However, the estimated ignition delay time Te calculated in an environment with a low in-cylinder temperature may deviate significantly from the actual ignition delay time Tr. Therefore, as described below, the control device 50 calculates a correction time Tc to correct (add) the estimated ignition delay time Te so that it approaches the actual ignition delay time Tr, and calculates combustion parameters based on the corrected estimated ignition delay time (Te + Tc).

[0043] ● [Processing procedure of the overall process (FIG. 3) in the processing procedure of the first embodiment (FIGS. 3 to 7)] Next, the processing procedure for calculating the correction time of the estimated ignition delay time by the control device 50 will be described using the flowcharts shown in FIGS. 3 to 7. The control device 50 (CPU 51) starts the process shown in FIG. 3, for example, at every predetermined crank angle (for example, every 15 [°CA], see FIG. 8), and proceeds to step S110. For example, the crank angle detection means 22A (see FIG. 1) outputs a detection signal every time the crankshaft rotates 15 [°CA], and the cylinder detection means 22B outputs a detection signal immediately before the position where the first cylinder reaches top dead center of compression. Then, the process shown in FIG. 3 is started every time a detection signal from the crank angle detection means 22A is input. Note that the confirmation single-stage injection may be executed for any cylinder, but in this embodiment, an example of executing the confirmation single-stage injection for the first cylinder will be described. Also, in this embodiment, an example where the ignition timing = P [°CA] is 7 [°CA] will be described.

[0044] In step S110, the control device 50 updates the value of the crank angle counter (00 to 47 (see FIG. 8)), obtains the time when the current crank angle signal is input, stores it corresponding to the value of the crank angle counter (00 to 47), and proceeds to step S115 for processing.

[0045] For example, in step S110, when the cylinder detection signal from the cylinder detection means 22B (see FIG. 1) is detected, the control device 50 initializes the value of the crank angle counter to (00) (see FIG. 8), and when the cylinder detection signal from the cylinder detection means 22B is not detected, the control device 50 increments the value of the crank angle counter by 1 (see FIG. 8). As a result, the value of the crank angle counter is updated to one of the values (00 to 47) every 15 [°CA]. For example, during the period when the value of the crank angle counter is (00), it indicates that the crank angle is between 0 [°CA] and 15 [°CA] at the compression top dead center of the first cylinder, and during the period when the value of the crank angle counter is (24), it indicates that the crank angle is between 360 [°CA] and 375 [°CA] at the intake top dead center of the first cylinder.

[0046] In step S115, the control device 50 determines whether it is the schedule timing of normal multi-stage injection. If it is established (Yes), the process proceeds to step S120, and if it is not established (No), the process proceeds to step S125. For example, during the period when the value of the crank angle counter is (47), the crank angle is between -15 [°CA] before the compression top dead center and 0 [°CA] at the compression top dead center of the first cylinder, which corresponds to the schedule timing of normal multi-stage injection. In addition, for example, during the period when the value of the crank angle counter is (11), etc., the crank angle is between 165 [°CA] before the compression top dead center and 180 [°CA] at the compression top dead center of the third cylinder, which also corresponds to the schedule timing of normal multi-stage injection.

[0047] When the process proceeds to step S120, the control device 50 executes process SA000 and proceeds to step S125. Note that the process of process SA000 is a process of calculating and correcting the estimated ignition delay time and a process of performing scheduling of normal multi-stage injection based on the combustion parameters calculated from the corrected estimated ignition delay time. Details of process SA000 will be described later.

[0048] When the process proceeds to step S125, the control device 50 determines whether or not the execution condition for the confirmation single-stage injection is satisfied. If it is satisfied (Yes), the process proceeds to step S130. If it is not satisfied (No), the process proceeds to step S175. The execution condition for the confirmation single-stage injection is satisfied when the accelerator pedal depression amount is 0 and during fuel cut during deceleration. For example, when the foot is lifted from the accelerator pedal after acceleration, the execution condition for the confirmation single-stage injection is satisfied. At that time, the diesel engine 10 is in a state where the rotational speed gradually decreases while idling.

[0049] When the process proceeds to step S130, the control device 50 determines whether or not the value of the current crank angle counter is (00). If the value of the current crank angle counter is (00) (Yes), the process proceeds to step S133. If the value of the current crank angle counter is not (00) (No), the process proceeds to step S150. In this way, by proceeding to the execution of the confirmation single-stage injection when the crank angle counter = 00, the combustion of the confirmation single-stage injection is prevented from being continuous. In the present embodiment, the confirmation single-stage injection is performed only on the first cylinder.

[0050] When the process proceeds to step S133, the control device 50 determines whether the confirmation completion flag is ON. If it is not ON (NO), the process proceeds to step S135. If it is ON (Yes), the process shown in FIG. 3 ends. The confirmation completion flag is a flag set to avoid wasted firing of the single-stage injection for confirmation. That is, after the averaging execution condition of the torque equivalent amount is satisfied and the average torque equivalent amount is calculated, if the execution condition of the single-stage injection for confirmation still holds (the diesel engine 10 is in a state where the rotational speed gradually decreases while idling), and the execution of the single-stage injection for confirmation continues regardless, it is a waste of fuel. Therefore, in such a case, it is set to ON once.

[0051] When the process proceeds to step S135, the control device 50 executes process SA200 and then proceeds to step S140. The process of process SA200 is a process of measuring the rotational speed (Ne[previous], see FIG. 6) immediately before executing the single-stage injection for confirmation. Details of process SA200 will be described later.

[0052] At step S140, the control device 50 executes the single-stage injection for confirmation and ends the process shown in FIG. 3. Specifically, the control device 50 drives the injector 43A provided in the cylinder 45A as the first cylinder with a control signal and injects a predetermined amount of fuel only by the main injection.

[0053] When the process proceeds to step S150, the control device 50 determines whether the value of the current crank angle counter is (03). If the value of the current crank angle counter is (03) (Yes), the process proceeds to step S155. If the value of the current crank angle counter is not (03) (No), the process proceeds to step S175.

[0054] When the process proceeds to step S155, the control device 50 executes process SA300 and proceeds to the process in step S160. The process of process SA300 is a process of calculating and integrating the torque equivalent amount based on the rotational speed immediately after the execution of the single-stage injection for confirmation (Ne[immediately after], see Fig. 3), the rotational speed immediately before the execution of the single-stage injection for confirmation (Ne[immediately before], see Fig. 6), and the amount of change in the rotational speed increased by the single-stage injection for confirmation (Ne[immediately before] - Ne[immediately after]). The details of process SA300 will be described later.

[0055] In step S160, the control device 50 determines whether the averaging execution condition of the torque equivalent amount is satisfied. If it is satisfied (Yes), the process proceeds to step S165. If it is not satisfied (No), the process proceeds to step S175. For example, when the calculation of the torque equivalent amount is performed 10 times or more (when the integration counter ≥ 10), the averaging execution condition is satisfied.

[0056] When the process proceeds to step S165, the control device 50 executes process SA400 and proceeds to the process in step S170. The process of process SA400 is a process of calculating the average torque equivalent amount. The details of process SA400 will be described later.

[0057] When the process proceeds to step S170, the control device 50 sets the confirmation end flag to ON and ends the process shown in Fig. 3.

[0058] When the process proceeds to step S175, the control device 50 sets the confirmation end flag to OFF and ends the process shown in Fig. 3.

[0059] The control device 50 (CPU 51) that executes the processes of steps S125 to S140 controls the injector to perform a confirmation single-stage injection for injecting a predetermined amount of fuel by single-stage injection of only the main injection into an internal combustion engine that is coasting while the rotational speed decreases due to fuel cut during deceleration. This corresponds to the confirmation single-stage injection execution unit 51C (see FIG. 1). Also, it corresponds to the confirmation single-stage injection execution unit 51C (see FIG. 1) that executes the confirmation single-stage injection a plurality of times and continuously without generating combustion for an internal combustion engine that is coasting while the rotational speed decreases due to fuel cut during deceleration.

[0060] ● [Processing procedure of process SA200 (FIG. 4)] Next, the details of process SA200 in step S135 in the flowchart shown in FIG. 3 will be described using the flowchart shown in FIG. 4. Process SA200 is a process for measuring Ne[previous] (see FIG. 8), which is the rotational speed immediately before the confirmation single-stage injection. When the control device 50 executes process SA200 in step S135 shown in FIG. 3, the process proceeds to step SA210 shown in FIG. 4.

[0061] In step SA210, the control device 50 calculates (measures) Ne[previous] (see FIG. 8), which is the rotational speed immediately before the confirmation single-stage injection, based on the difference (the time of 15 [°CA]) between the time when the crank angle signal with the value of the (current) crank angle counter being (00) is input and the time when the crank angle signal with the value of the (previous) crank angle counter being (47) is input. Then, the process shown in FIG. 4 ends and returns. The process proceeds immediately after step S135 shown in FIG. 3, and the process shown in FIG. 4 ends.

[0062] ● [Processing procedure of process SA300 (FIG. 5)] Next, the details of process SA300 in the flowchart shown in FIG. 3 will be described using the flowchart shown in FIG. 5. Process SA300 is a process of measuring the rotational speed Ne[immediately after] (see FIG. 8) immediately after the single-stage injection for confirmation, and a process of calculating and integrating the torque equivalent amount based on the Ne[immediately after] and Ne[immediately before] that has already been measured in process SA200. When the control device 50 executes process SA300 in step S155 shown in FIG. 3, the process proceeds to step SA310 shown in FIG. 5.

[0063] In step SA310, the control device 50 calculates (measures) Ne[immediately after] (see FIG. 8), which is the rotational speed immediately after the combustion generated by the single-stage injection for confirmation, based on the difference (the time of 15[°CA]) between the time when the crank angle signal with the value of the (current) crank angle counter being (03) is input and the time when the crank angle signal with the value of the (previous) crank angle counter being (02) is input, and then proceeds to step SA320.

[0064] In step SA320, the control device 50 obtains ΔNe (see FIG. 8), which is the difference between Ne[immediately after], which is the rotational speed immediately after the single-stage injection for confirmation, and Ne[immediately before], which is the rotational speed immediately before the single-stage injection for confirmation. Then, the control device 50 calculates the torque equivalent amount TQ based on the obtained ΔNe and Ne[immediately before], and proceeds to step SA330. Specifically, the control device 50 calculates the torque equivalent amount TQ by multiplying ΔNe and Ne[immediately before]. Therefore, the unit of the torque equivalent amount TQ is rpm^2.

[0065] In step SA330, the control device 50 adds the torque equivalent amount TQ to the integrated value and proceeds to step SA320. The initial value of the integrated value is set to zero.

[0066] In step SA340, the control device 50 increments the integration counter and ends the process shown in FIG. 5. The initial value of the integration counter is set to zero.

[0067] The control device 50 (CPU 51) that executes the processes of steps SA310 to SA320 corresponds to a torque equivalent amount detection unit 51D (see FIG. 1) that obtains a torque equivalent amount based on the rotational speed of the internal combustion engine immediately before executing the single-stage injection for confirmation and the amount of change in the rotational speed increased by the single-stage injection for confirmation.

[0068] ● [Processing procedure of process SA400 (FIG. 6)] Next, the details of the process SA400 in step S165 in the flowchart shown in FIG. 3 will be described using the flowchart shown in FIG. 6. The process SA400 is a process of calculating an average torque equivalent amount. When the control device 50 executes the process SA400 in step S165 shown in FIG. 3, the control device 50 proceeds to step SA410 shown in FIG. 6.

[0069] In step SA410, the control device 50 calculates an average torque equivalent amount TQav based on the integrated value calculated in the process SA400 and the integration counter value, and proceeds to the process in step SA410. For example, when the calculation of the torque equivalent amount is performed 10 times, the integration counter value is 10. Therefore, the control device 50 divides the integrated value by 10 and calculates it as the average torque equivalent amount TQav.

[0070] In step SA410, the control device 50 initializes the integrated value and the integration counter and ends the process shown in FIG. 5.

[0071] The control device 50 (CPU 51) that executes the process of step SA410 corresponds to a torque equivalent amount detection unit 51D (see FIG. 1) that obtains a torque equivalent amount in each of a plurality of times, averages the obtained torque equivalent amounts of the plurality of times, and uses it as a torque equivalent amount for calculating a correction time.

[0072] ● [Processing procedure of process SA000 (FIG. 7)] Next, the details of process SA000 in step S120 of the flowchart shown in FIG. 3 will be described using the flowchart shown in FIG. 7. Process SA000 is a process of calculating and correcting an estimated ignition delay time, and a process of performing scheduling of normal multi-stage injection based on combustion parameters calculated from the corrected estimated ignition delay time. When the control device 50 executes process SA000 in step S120 shown in FIG. 3, the process proceeds to step SA010 shown in FIG. 7.

[0073] In step SA010, the control device 50 calculates an estimated ignition delay time based on detection signals input from, for example, intake air temperature detection means 28A to 28B, pressure detection means 24A to 24C, coolant temperature detection means 28C, etc., and proceeds to step SA020. Since the estimated ignition delay time can be obtained by an existing calculation method, detailed description thereof will be omitted.

[0074] In step SA020, the control device 50 obtains the intake manifold temperature T and proceeds to step SA030. The control device 50 estimates the intake manifold temperature T from the detection signals from the intake air temperature detection means 28A and 28B.

[0075] In step SA030, the control device 50 calculates and updates a correction time according to the combination of the average torque equivalent amount TQav and the intake manifold temperature T, and proceeds to step SA040. For example, in the storage device 53 of the control device 50, as shown in FIG. 9, a torque equivalent amount - intake manifold temperature - correction time characteristic in which a correction time (Δt*) is set according to the average torque equivalent amount (TQ*) and the intake manifold temperature (T*) is stored. The control device 50 obtains the correction time of the estimated ignition delay time based on the torque equivalent amount - intake manifold temperature - correction time characteristic. The control device 50 appropriately interpolates to obtain the correction time. For example, when the calculated average torque equivalent amount is in the middle of TQ1 and TQ2 and the intake manifold temperature is T1, the middle of Δt11 and Δt21 is calculated as the correction time. It is desirable that an appropriate initial value of the average torque equivalent amount TQav is set for each vehicle.

[0076] In step SA040, the control device 50 adds a correction time to the estimated ignition delay time and advances the process to step SA050. The correction time is changed each time the above-described process SA400 (see FIG. 6) is performed and the average torque equivalent amount is updated.

[0077] In step SA050, the control device 50 calculates combustion parameters based on the estimated ignition delay time. Since the combustion parameters can be obtained by an existing calculation method based on the estimated ignition delay time, detailed description thereof is omitted. Based on the calculated combustion parameters, the control device 50 drives the injectors 43A to 43D by a control signal and determines the combustion mode, the number of injection stages, the injection amount of each stage, etc. For example, for the pilot injection that is sprayed before the main injection, the timing, the amount, and the number of stages of spraying are determined.

[0078] In step SA060, the control device 50 performs scheduling of normal multi-stage injection based on the combustion parameters and ends the process shown in FIG. 7.

[0079] The control device 50 (CPU 51) that executes the processes of steps SA010 to SA030 corresponds to a correction time calculation unit 51E (see FIG. 1) that calculates based on the detected torque equivalent amount and the intake temperature, which is the temperature of the intake manifold of the internal combustion engine or the temperature of the intake air of the internal combustion engine.

[0080] The control device 50 (CPU 51) that executes the process of step SA040 corresponds to an estimated ignition delay time correction unit 51F (see FIG. 1) that corrects the estimated ignition delay time using the correction time.

[0081] The exhaust pipe of the internal combustion engine of the present invention is not limited to the appearance, configuration, structure, etc. described in the present embodiment, and various changes, additions, and deletions are possible without changing the gist of the present invention. Also, the numerical values used in the description of the present embodiment are examples and are not limited to these numerical values.

[0082] In the description of this embodiment, an example where a detection signal from the crank angle detection means is output every time the crankshaft rotates by 15 [°CA] has been described, but it is not limited to every 15 [°CA]. Also, an example where a signal of the compression top dead center position of the first cylinder is output from the cylinder discrimination means has been described, but it is not limited to this. There are various types of crank angle signals and cylinder discrimination signals.

[0083] In the description of this embodiment, an example where the ignition timing of fuel by the single-stage injection for confirmation is 7 [°CA] has been described, but the ignition timing is not limited to this and can be various values.

[0084] In the description of this embodiment, after calculating the torque equivalent amount a plurality of times (10 times), the average torque equivalent amount is obtained. However, it is also possible to calculate the torque equivalent amount only once and calculate the correction time based on the calculated torque equivalent amount. Also, even when averaging is performed, the number of calculations is not limited to 10 times. If the accuracy of the estimated ignition delay time after correction calculated based on the average torque equivalent amount can be guaranteed, it may be reduced to, for example, 5 times.

[0085] In the description of this embodiment, it has been described that the single-stage injection for confirmation is executed in the first cylinder. However, if the combustion of the single-stage injection for confirmation is not continuous, the single-stage injection for confirmation may be executed in other cylinders. Also, it is not limited to the same cylinder, and the single-stage injection for confirmation may be executed in a plurality of different cylinders.

Description of Reference Numerals

[0086] 1 Diesel engine system 10 Diesel engine 11A, 11B Intake pipe 11C Intake manifold 12A Exhaust manifold 12B, 12C Exhaust pipe 13 EGR pipe 14 EGR valve 15 EGR cooler 21 Intake air flow rate detection means 22A Crank angle detection means 22B Cylinder detection means 23 Atmospheric pressure detection means 24A Compressor upstream pressure detection means 24B Compressor downstream pressure detection means 24C Intake manifold pressure detection means 25 Accelerator pedal depression amount detection means 26A Turbine upstream pressure detection means 26B Turbine downstream pressure detection means 26C Differential pressure detection means 27 Vehicle speed detection means 28A, 28B Intake air temperature detection means 28C Coolant temperature detection means 28D, 28E Exhaust gas temperature detection means 30 Turbocharger 31 Nozzle drive means 32 Nozzle opening degree detection means 33 Variable nozzle 35 Compressor 35A Compressor impeller 36 Turbine 36A Turbine impeller 41 Common rail 43A~43D Injector 45A~45D Cylinder 48 Throttle device 48S Throttle opening degree detection means 50 Control device (fuel property detection device) 51 CPU Tr Actual ignition delay time Te Estimated ignition delay time Tc Correction time

Claims

1. A control device for a compression ignition type internal combustion engine that controls an injector for injecting fuel into the compression ignition type internal combustion engine, wherein the control device, a normal multi-stage injection execution unit that controls the injector to perform multi-stage injection including a main injection that is a main fuel injection and a pilot injection that is a fuel injection performed prior to the main injection for one combustion stroke of the internal combustion engine; an estimated ignition delay time calculation unit that obtains an estimated ignition delay time that is an estimated value of an ignition delay time, which is a delay time from the start of the main injection until main combustion, which is the main combustion, occurs, based on the operating state of the internal combustion engine; a confirmation single-stage injection execution unit that controls the injector to perform a confirmation single-stage injection in which a predetermined amount of fuel is injected by a single-stage injection of only the main injection to the internal combustion engine that is idling while the rotational speed decreases due to fuel cut during deceleration; a torque equivalent amount detection unit that detects a torque equivalent amount corresponding to the torque generated in the internal combustion engine by the confirmation single-stage injection; a correction time calculation unit that calculates a correction time for correcting the estimated ignition delay time based on the detected torque equivalent amount and the intake temperature, which is the temperature of the intake manifold of the internal combustion engine or the temperature of the intake air of the internal combustion engine; an estimated ignition delay time correction unit that corrects the estimated ignition delay time using the correction time; and has, a control device for a compression ignition type internal combustion engine.

2. The control device for a compression ignition type internal combustion engine according to claim 1, wherein the control device, the torque equivalent amount detection unit obtains the torque equivalent amount based on the rotational speed of the internal combustion engine immediately before executing the confirmation single-stage injection and the amount of change in the rotational speed increased by the confirmation single-stage injection. a control device for a compression ignition type internal combustion engine.

3. The control device for a compression ignition type internal combustion engine according to claim 1 or 2, wherein the control device, the confirmation single-stage injection execution unit executes the confirmation single-stage injection a plurality of times and continuously for the internal combustion engine that is idling while the rotational speed decreases due to fuel cut during deceleration so as not to generate combustion, the torque equivalent amount detection unit obtains the torque equivalent amount at each of the plurality of times, and the torque equivalent amount obtained by averaging the plurality of torque equivalent amounts obtained is used as the torque equivalent amount for calculating the correction time. a control device for a compression ignition type internal combustion engine.

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