JP7283290B2 - Fuel property detector - Google Patents

Description

The present invention relates to a fuel property detection device for detecting properties of fuel (fuel properties) used in diesel engines.

In a diesel engine, in order to reduce the amount of combustion noise and the amount of NOx emissions, multi-stage injection control is performed in which secondary injections of fuel are performed before and after the main injection of fuel into the cylinder. Diffusion combustion shown in FIG. 20 and premixed combustion shown in FIG. 21 are known as types of combustion methods for multi-stage injection control, and diffusion combustion is generally used in diesel engines mounted on vehicles. ing.

FIG. 20 is a diagram showing an example of diffusion combustion, in which the horizontal axis indicates the crank angle (rotational angle of the crankshaft) and the vertical axis indicates the execution of injection and the heat release rate, respectively. As shown in FIG. 20, in diffusion combustion, secondary injections 101A and 102A are executed prior to main injection 103A to generate secondary combustions 101B and 102B to diffuse the intake air (oxygen) in the combustion chamber. 103A is executed to generate main combustion 103B. Note that the combustion speed of the main combustion 103B in the diffusion combustion shown in FIG. 20 is slower than that in the premixed combustion shown in FIG. 21 (longer in the crank angle direction).

FIG. 21 is a diagram showing an example of premixed combustion. Similar to FIG. 20, the horizontal axis indicates the crank angle, and the vertical axis indicates the execution of injection and the heat release rate. As shown in FIG. 21, in premixed combustion, the ignition timing of secondary combustions 111B and 112B by secondary injections 111A and 112A performed prior to main injection 113A and the ignition timing of main combustion 113B by primary injection 113A are substantially the same. A superimposed combustion 110B is generated in which the sub-combustions 111B and 112B and the main combustion 113B are overlapped. Note that the combustion speed of the superimposed combustion 110B in the premixed combustion shown in FIG. 21 is faster than the diffusion combustion shown in FIG. 20 (the length in the crank angle direction is short).

Premixed combustion is known to improve fuel efficiency and reduce NOx emissions as compared to diffusion combustion. However, in order to use premixed combustion in a diesel engine, it is important to appropriately correct the injection timing and injection amount of the sub-injection and main injection according to the cetane number of the fuel compared to diffusion combustion. It is essential to detect the cetane number with higher accuracy. The cetane number of fuel used in diesel engines varies from country to country around the world, and even within the same country, depending on the region and season. of fuel is used in countries and regions around the world.

FIG. 22 shows an example of using a low cetane number fuel, a medium cetane number fuel, and a high cetane number fuel in the diffusion combustion shown in FIG. . There is no change in ignition timing according to the cetane number, but in the case of the cetane number (low), there is an abnormality in the heat release rate, indicating that some kind of correction is necessary in the case of the cetane number (low). ing. When diffusion combustion is used, if the cetane number is (low), by performing a relatively simple correction such as increasing the fuel pressure in the common rail, as shown in FIG. can be properly corrected. In other words, in the case of diffusive combustion, it is sufficient to detect only the low cetane number within the range of low cetane number to high cetane number, and high cetane number detection accuracy is not required.

FIG. 24 shows an example of using a low cetane number fuel, a medium cetane number fuel, and a high cetane number fuel in the case of using the premixed combustion shown in FIG. there is When the cetane number is high, the ignition timing is early, and when the cetane number is low, the ignition timing is late, and stable combustion cannot be obtained. FIG. 25 shows a case in which the injection timing and the injection amount are corrected according to the cetane number with respect to FIG. Combustion with a stable ignition timing can be obtained by appropriately correcting the injection timing and the injection amount according to the cetane number. In other words, in order to utilize premixed combustion in a diesel engine, it is necessary to appropriately correct the injection timing and injection amount according to the cetane number. In order to appropriately correct the injection timing and injection amount according to the cetane number, it is necessary to detect the cetane number in a wider range from low cetane number to high cetane number with higher accuracy.

Therefore, Patent Document 1 discloses a fuel property detection device capable of further improving the detection accuracy of the cetane number of the fuel used. In the fuel property detection device described in Patent Document 1, two levels of injection amount are prepared as the injection amount of the secondary injection during normal operation, and the amount of change, which is the amount of change in the injection amount of the secondary injection, is used to detect generated torque, etc. A rate of change (change sensitivity) of a specific amount of change in is derived, and the cetane number of the used fuel is detected based on the change sensitivity.

JP 2009-144528 A

FIG. 20 shows a case in which the method described in Patent Document 1, in which the cetane number is detected based on the amount of change in generated torque by changing the injection amount of the secondary injection during normal operation of the diesel engine, is applied to diffusion combustion. Torques of the secondary combustions 101B and 102B are measured. In order to further improve the detection accuracy of the cetane number, it is necessary to generate a larger secondary combustion 101B. It is not preferable to increase it because it may cause damage to the engine.

Further, when the method described in Patent Document 1 is applied to premixed combustion, the torque generated in secondary combustion 111B and 112B must be extracted from the torque generated in superimposed combustion 110B shown in FIG. not. In this case, the torque (superimposed torque) due to the superimposed combustion 110B is measured, the torque (main torque) due to the main combustion 113B is obtained by calculation or the like, and the main torque is obtained by subtracting the main torque from the superimposed torque. This increases the error in the detected torque and the cetane number, so there is a possibility that the expected accuracy cannot be obtained.

In addition, even if the method described in Cited Document 1 is applied to either diffusion combustion or premixed combustion, it is obtained from the torque fluctuation amount during normal operation of the diesel engine, so very stable operation If detection is not performed in a state (such as when driving at a constant speed with a constant number of revolutions on a flat, level road surface), the error in the detected cetane number will increase.

The present invention has been invented in view of such a point, and can detect the cetane number of fuel used in diesel engines in a wider range from low cetane number to high cetane number with higher accuracy. An object of the present invention is to provide a fuel property detection device capable of

In order to solve the above-mentioned problems, the first invention of the present invention provides a detection injection to a predetermined cylinder during a detectable period in which the diesel engine stops fuel injection and gradually decreases the rotation speed while coasting. and detecting the cetane number of the fuel used in the diesel engine based on the torque equivalent amount corresponding to the torque generated by the detection injection, wherein n is 2 or more A first crank angle position to an n-th crank angle position are set in advance as crank angle positions at which the injected fuel ignites when an integer is used. An operating state including an intake air amount of the diesel engine so that the fuel injected by the first detection injection to the n-th detection injection is ignited at each of the first crank angle position to the n-th crank angle position. estimating an in-cylinder state including an in-cylinder temperature and an in-cylinder oxygen concentration-related quantity estimated based on the estimated in-cylinder state, and based on the estimated in-cylinder state, each of the first detection injection to the n-th detection injection a detection injection timing related quantity calculation unit for calculating each injection timing related quantity related to the injection timing of the When the fuel is injected based on the injection timing-related quantity and ignited at each of the first crank angle position to the n-th crank angle position, each of the above corresponding to the torque generated by each combustion following each ignition Detection for calculating the respective injection amounts of the first detection injection to the n-th detection injection so that the torque equivalent amount becomes the preset first reference torque equivalent amount to the nth reference torque equivalent amount, respectively and a first cetane number/torque equivalent set for each of the first detection injection to the n-th detection injection, in which the torque equivalent amount corresponding to the cetane number is set. When the fuel having the reference cetane number is used, each of the first reference torque equivalent to the nth reference torque equivalent is calculated. a storage device storing each of the first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic set as follows; On the other hand, each injection amount calculated by the injection amount calculation unit for detection is injected at each injection timing based on each injection timing related amount calculated by the injection timing related amount calculation unit for detection. and the torque actually generated in each of the first detection injection to the nth detection injection. A cetane number for detecting a cetane number based on a first actual torque equivalent amount to an n-th actual torque equivalent amount and each of the first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic. and a detection unit. Each of the first cetane number/torque equivalent amount characteristic to the nth cetane number/torque equivalent amount characteristic corresponding to each of the first detection injection to the nth detection injection is determined by the difference in cetane number. and a discriminable cetane number range in which the torque equivalent amount varies according to the difference in the cetane number with respect to the indistinguishable cetane number range. , wherein each of the first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic is a cetane number that is a detection lower limit cetane number required to be detected to a detection upper limit cetane number A part of the detection range is defined as the discriminable cetane number range, and the first cetane number/torque equivalent amount characteristic to the nth cetane number/torque equivalent amount characteristic are the first cetane number/torque equivalent amount. The fuel property is set so that when the discriminable cetane number ranges of the characteristic to the n-th cetane number/torque equivalent characteristic are superimposed, the entirety of the detection lower limit cetane number to the detection upper limit cetane number is covered. detection device.

Next, a second invention of the present invention is the fuel property detection device according to the first invention, wherein at a predetermined period after refueling the diesel engine or after starting the diesel engine, In a cetane number initial detection period, the detection injection execution unit executes the first detection injection to the n-th detection injection at least once, and the cetane number detection unit detects the cetane number, In the detectable period after the cetane number initial detection period, when m is an integer of 2 or more and n or less, based on the cetane number detected after the cetane number initial detection period, the first cetane number m-th cetane number/torque detected after the cetane number initial detection period is close to the center of the distinguishable cetane number range from the m-th cetane number/torque equivalent characteristic to the n-th cetane number/torque equivalent characteristic The equivalent amount characteristic is selected, the m-th detection injection corresponding to the m-th cetane number/torque equivalent amount characteristic is selected from the first detection injection to the n-th detection injection, and the selected m-th injection is selected. It is a fuel property detection device , wherein the injection for detection is executed by the injection for detection execution unit .

Next, a third invention of the present invention is a fuel property detection device according to the first invention or the second invention, wherein each of the first detection injection to the nth detection injection is injected. , until the cetane number detection unit corresponding to each of the first detection injection to the n-th detection injection detects the cetane number, the intake and exhaust system of the diesel engine is provided with It is a fuel property detection device that maintains the operating state of the actuator without changing it .

According to the first aspect of the invention, the detection injection in which the injection timing and the injection amount are appropriately corrected is executed on the diesel engine that is coasting with the fuel injection stopped, and the Detect torque equivalent. Compared to the method of detecting the amount of change in torque due to sub-injection with two levels of injection amounts described in Patent Document 1, there is no need to subtract the torque equivalent amount for the main injection from the detected torque equivalent amount. A torque equivalent can be detected with high accuracy. Therefore, the cetane number can be detected with higher accuracy. In the case of the reference cetane number, since the cetane number is detected based on the cetane number/torque equivalent characteristic, which is the reference torque equivalent amount, and the actual torque equivalent amount, the cetane number/torque equivalent has an appropriate cetane number detection range. By using the quantitative characteristic, the cetane number can be detected with higher accuracy in a wider range from low cetane number to high cetane number.

According to the first invention, a plurality of cetane number/torque equivalent amount characteristics are provided, and the cetane number is detected with higher accuracy by executing detection injection corresponding to each cetane number/torque equivalent amount characteristic. be able to.

According to the first invention, when the cetane number detection range from the detection lower limit cetane number to the detection upper limit cetane number is very wide, one cetane number/torque equivalent amount characteristic cannot cover the entire cetane number detection range. Sometimes. Even in such a case, by performing a plurality of cetane number/torque equivalent amount characteristics to which the discriminable cetane number range is appropriately assigned and detection injection corresponding to each cetane number/torque equivalent amount characteristic, a low The cetane number can be detected with higher accuracy in a wider range from cetane number to high cetane number.

According to the second invention, since the detection injection selected from the first detection injection to the n-th detection injection is performed according to the cetane number, fuel consumption and detection time due to unnecessary detection injection can be suppressed.

It is a figure explaining the example of the schematic structure of the whole diesel engine system. FIG. 5 is a diagram for explaining how the shape of the ignition timing and heat release rate with respect to the injection for detection varies depending on the operating state and the environmental state; FIG. 3 is a diagram for explaining an example of how the shapes of the ignition timing and the heat release rate can be made the same by correcting the injection timing and the injection amount according to the operating state and the environmental state with respect to FIG. 2 . 3, when the injection timing and the injection amount are corrected according to the operating state and the environmental state, the ignition timing is the same but the shape of the heat release rate is different when the cetane number is different. is. In contrast to FIG. 4, the amount of temporary rotation speed increase (detection FIG. 10 is a diagram for explaining how the amount of torque equivalent to injection) varies depending on the cetane number. FIG. 5 is a diagram illustrating an example of cetane number/torque equivalent amount characteristics; FIG. 4 is a diagram for explaining a cetane number/torque equivalent amount characteristic (P) in the first embodiment; 4 is a flowchart for explaining an example of processing (crank angle synchronization processing) of the control device in the first embodiment; FIG. 9 is a flowchart for explaining details of processing SA100 in the flowchart of FIG. 8. FIG. FIG. 9 is a flowchart for explaining details of processing SA200 in the flowchart of FIG. 8. FIG. FIG. 10 is a flowchart illustrating details of processing SA300 in the flowchart of FIG. 8; FIG. 9 is an operation waveform for explaining an example of operation by the processing of the flow chart shown in FIG. 8; Cetane number/torque equivalent characteristics (P1), cetane number/torque equivalent characteristics (P2), cetane number/torque equivalent characteristics (P3), cetane number/torque equivalent characteristics (P4) in the second embodiment It is a figure explaining the example of. 9 is a flowchart for explaining an example of processing (crank angle synchronization processing) of the control device in the second embodiment; FIG. 15 is a flow chart describing the details of processing in step SB100 in the flow chart of FIG. 14; FIG. FIG. 15 is a flow chart describing the details of the processing of step SB200 in the flow chart of FIG. 14; FIG. FIG. 15 is a flow chart describing the details of the processing of step SB300 in the flow chart of FIG. 14; FIG. FIG. 15 is a flow chart describing the details of the processing of step SB400 in the flow chart of FIG. 14; FIG. 15 is an operation waveform for explaining an example of operation by the processing of the flowchart shown in FIG. 14; It is a figure explaining the example of diffusion combustion. FIG. 4 is a diagram illustrating an example of premixed combustion; FIG. 3 is a diagram illustrating an example of the difference in heat release rate between fuels of low cetane number, medium cetane number, and high cetane number in the case of diffusion combustion. FIG. 23 is a diagram illustrating an example in which correction is added to FIG. 22 in the case of fuel with a cetane number (low). FIG. 4 is a diagram illustrating an example of a difference in heat release rate between fuels of low cetane number, medium cetane number, and high cetane number in the case of premixed combustion. FIG. 25 is a diagram illustrating an example of a case where the injection timing and the injection amount are appropriately corrected for the fuel of each cetane number with respect to FIG. 24 ;

● [Overall configuration of diesel engine system 1 (Fig. 1)]
Embodiments for carrying out the present invention will be described below 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 diesel engine 10 will be described. In the description of the present embodiment, a diesel engine system 1 mounted on a vehicle will be described as an example.

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

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 a turbine impeller 36A that is rotationally driven by the energy of the exhaust gas, and supercharges the intake air that has flowed in from the intake pipe 11A to the intake pipe 11B.

The intake pipe 11A on the upstream side of the compressor 35 is provided with 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 on the upstream side of the compressor 35 to the control device 50 . A compressor downstream pressure detection means 24B is provided in the intake pipe 11B downstream of the compressor 35 (a position between the compressor 35 and the intercooler 16 in the intake pipe 11B). 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 on the downstream side of the compressor 35 to the control device 50 .

An intercooler 16 is arranged upstream of the intake pipe 11</b>B, 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 . Between the intercooler 16 and the throttle device 48, an intake air temperature detection means 28B (for example, an intake air temperature sensor) is provided. 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 .

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 flow rate. The control device 50 outputs a control signal to the throttle device 48 based on a detection signal from the throttle opening detection means 48S (for example, a throttle opening sensor) and a target throttle opening to operate the throttle provided in the intake pipe 11B. The valve opening can be adjusted. The control device 50 obtains the target throttle opening based on the depression amount of the accelerator pedal detected based on the detection signal from the accelerator pedal depression amount detection means 25 and the operating state of the diesel engine 10 .

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 amount of depression of the accelerator pedal by the driver based on the detection signal from the accelerator pedal depression amount detection means 25 .

The outflow side of the EGR pipe 13 is connected to the downstream side of the throttle device 48 in the intake pipe 11B. 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. 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 to the control device 50 according to the pressure of the intake air in the intake manifold 11C. EGR gas that has flowed in from the inflow side of the EGR pipe 13 (the connection portion with the exhaust pipe 12B) is discharged into the intake pipe 11B from the outflow side of the EGR pipe 13 (the connection portion with the intake pipe 11B). . A path through which EGR gas flows formed in the EGR pipe 13 corresponds to an EGR path.

The diesel engine 10 (diesel engine) has a plurality of cylinders 45A-45D, each of which is provided with an injector 43A-43D. Fuel is supplied to the injectors 43A-43D via a common rail 41 and fuel pipes 42A-42D. The injectors 43A-43D are driven by control signals from a control device 50, and are injected into the respective cylinders 45A-45D. Inject fuel.

The diesel engine 10 is provided with crank angle detection means 22A and 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, for example, when the piston of the first cylinder reaches compression top dead center. Based on the detection signal from the crank angle detection means 22A and the detection signal from the cylinder detection means 22B, the control device 50 can detect, for example, that the piston of the first cylinder is at the top dead center position. It is possible to determine whether the dead center position is the compression top dead center position or the intake top dead center position.

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

An inflow side of an exhaust manifold 12A is connected to the exhaust side of the diesel engine 10, and an inflow side of an exhaust pipe 12B is connected to an outflow side of the exhaust manifold 12A. 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 inflow side of the EGR pipe 13 is connected to the exhaust pipe 12B. The EGR pipe 13 allows the exhaust pipe 12B and the intake pipe 11B to communicate with each other, and allows part of the exhaust gas in the exhaust pipe 12B to be recirculated to the intake pipe 11B. An EGR cooler 15 and an EGR valve 14 are provided in the EGR pipe 13 .

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

The EGR cooler 15 is provided on the EGR pipe 13 . The EGR cooler 15 is a so-called heat exchanger, is supplied with cooling coolant, cools the EGR gas that has flowed in, and discharges the EGR gas.

The EGR pipe 13, the EGR cooler 15, and the EGR valve 14 constitute an EGR system capable of returning part of the exhaust gas to the intake path. Note that the EGR system may or may not include the EGR cooler 15 .

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 controlling the flow velocity of the exhaust gas led to the turbine impeller 36A (adjusting the opening degree of the flow path leading the exhaust gas to the turbine). The opening is adjusted by the nozzle drive means 31 . The control device 50 outputs a control signal to the nozzle driving means 31 to adjust the opening of the variable nozzle 33 based on the detection signal from the nozzle opening detection means 32 (for example, a nozzle opening sensor) and the target nozzle opening. Adjustable.

Turbine upstream pressure detection means 26A is provided in the exhaust pipe 12B on the upstream side of the turbine 36 . 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 inside the exhaust pipe 12B on the upstream side of the turbine 36 to the control device 50 . A turbine downstream pressure detection means 26B is provided in the exhaust pipe 12C on the downstream side of the turbine 36 . 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 on the downstream side of the turbine 36 to the control device 50 .

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

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 .

The vehicle speed detection means 27 is, for example, a vehicle speed detection sensor, and is provided on the wheels of the vehicle. The vehicle speed detection means 27 outputs a detection signal corresponding to the rotation speed of the wheels of the vehicle to the control device 50 .

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 the intake 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, compressor downstream pressure detection means 24B, intake manifold pressure detection means 24C, turbine upstream pressure detection means 26A, turbine downstream pressure detection means 26B, differential pressure detection means 26C, vehicle speed detection means 27, intake temperature detection means 28A, 28B , coolant temperature detection means 28C, exhaust temperature detection means 28D and 28E, nozzle opening detection means 32, throttle opening detection means 48S and the like.

Outputs from the control device 50 (CPU 51) include control signals to the injectors 43A to 43D, the EGR valve 14, the nozzle driving means 31, the throttle device 48, etc., as described above. The input/output of the control device 50 is not limited to the detection means and actuators described above. Also, the temperature, pressure, etc. of each part may be calculated by estimation calculation without mounting the 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 detection means described above, and controls various actuators including the actuators described above. The storage device 53 is, for example, a flash-ROM or the like, and stores programs, data, and the like for executing control of the diesel engine, self-diagnosis, and the like.

The control device 50 (CPU 51) has a detecting injection timing-related quantity calculating section 51A, a detecting injection amount calculating section 51B, a detecting injection executing section 51C, and a cetane number detecting section 51D. will be described later.

● [Heat release rate by detection injection Kinj for detecting cetane number (Figs. 2 and 3)]
FIG. 2 shows that the fuel with the same cetane number is injected in the same manner under different operating conditions/environmental conditions: operating condition/environmental condition (a); operating condition/environmental condition (b); This shows an example in which the same injection amount is injected at the timing, and an example in which the injection timing and the injection amount are not corrected according to the operating state and environmental state. h(a) indicates the heat release rate for the operating state/environmental state (a), h(b) indicates the heat release rate for the operating state/environmental state (b), and h(c) indicates the operating The heat release rate for the state/environmental state (c) is shown. Even if the fuel with the same cetane number is injected at the same injection timing and in the same injection amount, the shape of the heat release rate differs depending on the operating conditions and environmental conditions.

The environmental condition of the diesel engine refers to the condition of the ambient atmosphere that does not change depending on the operating condition of the diesel engine. In the example of the diesel engine system shown in FIG. 1, atmospheric pressure (detected by the atmospheric pressure detection means 23), outside air temperature (detected by the intake air temperature detection means 28A), etc. correspond to environmental conditions. In addition, the operating state of the diesel engine refers to the operating state of the diesel engine that has changed according to the user's operation or the control from the control device, excluding the environmental conditions described above. In the example of the diesel engine system shown in FIG. 1, the amount of depression of the accelerator pedal (detected by the accelerator pedal depression amount detection means 25) corresponds to the operating state as the operation from the user. As controls (controls of various actuators) from the control device, control of injectors 43A to 43D, throttle device 48, EGR valve 14, nozzle driving means 31, etc. corresponds to the operating state.

In addition, the operating states that have changed accordingly include the intake flow rate (detected by the intake flow rate detection means 21), the pressure of the intake air in the intake pipe (the compressor upstream pressure detection means 24A, the compressor downstream pressure detection means 24B, the intake manifold pressure detection means means 24C), rotation speed (detected by crank angle detection means 22A), coolant temperature (detected by coolant temperature detection means 28C), exhaust pressure in the exhaust pipe (turbine upstream pressure detection means 26A, turbine downstream pressure detection means 26B and differential pressure detection means 26C), the temperature of the exhaust gas in the exhaust pipe (detected by the exhaust temperature detection means 28D and 28E), and the temperature, pressure, flow rate, etc. Corresponds to state. Hereinafter, the operating conditions and environmental conditions of the diesel engine described above are referred to as the operating conditions and environmental conditions of the diesel engine. The state may be collectively described as the operating state of the diesel engine.

Since the conditions shown in FIG. 2 are not suitable for detecting the cetane number, the operating conditions and environmental Injection timing and injection amount are corrected according to the state. Note that in the example of FIG. 3, in the case of (target) ignition timing = P [°CA] and fuel with a reference cetane number (for example, cetane number = 54), the operating state is adjusted so that (target) torque equivalent = TQ.・This shows an example in which the injection timing and injection amount are corrected according to the environmental conditions.

● [Calculation of injection timing and injection amount according to operating conditions and environmental conditions of diesel engine]
As for the injection timing, the ignition delay time corresponding to the operating state and environmental state of the diesel engine is obtained in the following manner. Combustion can be started from the (target) ignition timing by injecting the fuel with the injection (start) timing at the timing before the ignition delay time from the position of (target) ignition timing = P [°CA]. . Therefore, the following ignition delay time is a time including correction according to the operating state and environmental state of the diesel engine. It is known that the following (Equation 1) holds when the ignition delay time is T _DLY .
T _DLY =1/{A[Fuel] ^B [ _O2 ] ^Cexp (-D/ _Tcyl )} (Formula 1)
A, B, C, D: Constant [Fuel]: Fuel partial pressure [ _O2 ]: Oxygen partial pressure T _cyl : In-cylinder temperature at target main ignition timing P _cyl : In-cylinder pressure at target main ignition timing

Also, the following equations (2) to (4) are established from the equation of state of the gas.
T _cyl =P _cyl V _cyl /(R·g _cb ·M _air ) (Formula 2)
g _cb =g _cyl +ρ _f ·qfinr·α _cb (Formula 3)
_αcb =ΣdQ/( _ρf ·qfinr· _Ef ) (Formula 4)
V _cyl : In-cylinder volume at target main ignition timing M _air : Average molecular weight of air g _cb : Combustion gas g _cyl : Air volume at target main ignition timing
qfinr: injection amount α _cb : combustion ratio ρ _f : fuel density E _f : lower heating value of fuel

Also, P _cyl can be obtained as follows.
dQ = dU + PdV
=(c _v /R)·d(PV)+PdV
= [k/(k-1)] PdV + [1/(k-1)] VdP (Equation 5)
P=( _Pcylo + _Pcyl )/2, V=( _Vcylo + _Vcyl )/2,
dP = P _cyl - P _cylo , dV = V _cyl - V _cylo discretized as P _cyl =[2(k-1)dQ-{(k-1)V _cyl -(k+1)V _cylo }P _cylo ]
/[(k+1)V _cyl -(k-1)V _cylo (equation 6)
k: specific heat ratio c _p : specific heat at constant pressure c _v : specific heat at constant volume R: gas constant dQ: calorific value V: in-cylinder volume P: in-cylinder pressure U: heat quantity

Moreover, the following formula holds.
_dTw = (Qc- _Qout )/mc
= { _hg ( _Tg -Tw)-h(Tw-thw)}/mc
= {Qc_s( _Tg -Tw)/( _Tg -Tw_s)-Qc_s(Tw-thw)/(Tw_s-thw)}/mc
= Qc_s (Tw_s-Tw) [1/( _Tg -Tw_s)+1/(Tw_s-thw)]/mc (Formula 7)
_Twi+1 =Tw+ _Qcs (Tw_s-Tw) [1/( _Tg -Tw_s)+1/(Tw_s-thw)]/mc (Formula 8)
_s: Steady state Qc: In-cylinder ---> Wall heat radiation Q _out : Wall --> Cooling water heat radiation Tw: Wall temperature T _g : Combustion gas temperature
thw: Water temperature (cooling water temperature)
h _g : Thermal conductivity (combustion chamber side)
h: Thermal conductivity (cooling water side)
m: wall mass c: specific heat

From the above, the following formula holds.
[O ₂ ]=P _cyl ( _na ·m _o2 )/(n _f +n)
= P _cyl (n _a /n _f ) _st・m _o2 /[(n _f /n _a )・(n _a /n _f ) _st +(n _a /n _f ) _st ]
= P _cyl [n(1+0.25α _HC )]/[φ+n(1+0.25α _HC )/m _o2 ] (Formula 9)
n _a : Carbon content in fresh air n _f : Carbon content in fuel ( _na /n _f ) _st : Excess air ratio per injection α _HC : H/C in fuel
φ: Equivalence ratio n: Carbon content in fuel composition m _o2 : O ₂ concentration ratio

By obtaining the ignition delay time T _DLY based on the operating state and environmental state of the diesel engine 10, even if the operating state and environmental state fluctuate, the (target) ignition timing (corresponding to a predetermined crank angle position set in advance) The fuel injection timing can be appropriately controlled so that the ignition occurs at It should be noted that the ignition delay time T _DLY is, as described above, the cylinder inflow gas amount, the EGR amount, the exhaust manifold internal pressure, the exhaust manifold internal temperature, the cooling water temperature (coolant temperature), the supercharging pressure, the intercooler outlet gas temperature, It is obtained from the EGR outlet gas temperature, etc.

The cylinder inflow gas amount is detected based on the detection signal from the intake air flow rate detecting means 21 (see FIG. 1). The EGR amount is calculated from the EGR rate calculated by the control device 50, the control amount of the EGR valve 14 (see FIG. 1), and the like. The internal pressure of the exhaust manifold is detected based on a detection signal from the pressure detection means when the exhaust manifold has a pressure detection means, and when the pressure detection means is not provided, the exhaust temperature, the intake air flow rate, and the like are detected. It can be estimated from the opening degree of the variable nozzle, the number of revolutions, and the like. The internal temperature of the exhaust manifold is detected based on a detection signal from the temperature detection means when the exhaust manifold has a temperature detection means, and when the temperature detection means is not provided, the internal temperature of the oxidation catalyst is detected on the upstream side of the oxidation catalyst. It can be estimated from the exhaust temperature or the like. The cooling water temperature (coolant temperature) is detected based on the detection signal from the coolant temperature detection means 28C (see FIG. 1). The supercharging pressure is detected based on a detection signal from the intake manifold pressure detection means 24C (see FIG. 1). The intercooler outlet gas temperature is detected based on a detection signal from the intake air temperature detection means 28B (see FIG. 1). The EGR outlet gas temperature is detected based on a detection signal from the temperature detection means when the outlet of the EGR pipe 13 has a temperature detection means, and is detected from the exhaust manifold when the temperature detection means is not provided. It can be estimated based on the internal temperature, the coolant temperature of the EGR cooler, the amount of EGR, and the like.

As described above, for example, when the reference cetane number Ss = 54, the (target) ignition timing = P [° CA] = 7 [° CA], and the target reference torque equivalent in that case = TQ, the operating state and Even if the environmental conditions change, the injection timing and the injection amount are adjusted so that the ignition timing = 7 [° CA] (crank angle position of ignition = 7 [° CA]) and the generated torque equivalent = TQ. The corrected detection injection Kinj can be executed from the control device 50 .

As with the injection timing, the injection amount depends on the cylinder inflow gas amount, EGR amount, exhaust manifold internal pressure, exhaust manifold internal temperature, cooling water temperature (coolant temperature), supercharging pressure, intercooler outlet gas temperature, EGR outlet gas Based on the operating and environmental conditions of the diesel engine such as temperature, the injection quantity including correction can be calculated by a known method. Since a known calculation method is used for the calculation, the detailed description of the method of calculating the injection amount including the correction will be omitted. As a result, even if the operating state/environmental state fluctuates, (target) torque equivalent = TQ when (target) ignition timing = P [°CA] and fuel with a reference cetane number (for example, cetane number = 54) Thus, the injection amount can be appropriately corrected.

● [Heat release rate according to cetane number when injection timing and injection amount are corrected (Fig. 4) and torque equivalent amount (Fig. 5)]
FIG. 4 shows the above injection timing so that, for example, the reference cetane number Ss=54, the (target) ignition timing=P [° CA]=7 [° CA], and the (target) torque equivalent in that case=TQ. and injection amount correction, the detection injection Kinj is executed with fuel having a different cetane number. h(d1) is the heat release rate at a high cetane number (e.g. cetane number = 60), h(d2) is the heat release rate at a medium cetane number (e.g. cetane number = 54), h(d3) shows an example of heat release rate for low cetane number (eg cetane number=46). It is possible to stably obtain the ignition timing = P [° CA] = 7 [° CA] even if the operating conditions and environmental conditions of the diesel engine fluctuate and even if the cetane number is different. A heat release rate corresponding to the value can be obtained. As can be seen from FIG. 4, the higher the cetane number, the larger the peak of the heat release rate, and the closer the peak position is to the top dead center (crank angle=0 [° CA]). Therefore, the larger the cetane number, the larger the torque equivalent.

FIG. 5 shows an example in which the detection injection Kinj for detecting the cetane number is executed when the diesel engine stops fuel injection and gradually decreases the rotational speed while coasting (corresponding to the detectable period). showing. For example, this detectable period is during coasting before the driver releases the accelerator pedal and depresses the brake pedal before a red light or the like while traveling in an urban area.

In FIG. 5, N(d1) indicates the rotational speed increased by the torque generated by the detection injection of the cetane number (high) fuel, and N(d2) indicates the detection of the cetane number (middle) fuel. The rotational speed increased by the torque generated by the injection is shown, and N(d3) shows the rotational speed increased by the torque generated by the detection injection of the cetane number (low) fuel. Based on ΔN, which is the difference between the number of revolutions immediately before execution of the injection Kinj for detection (previous number of revolutions) and the number of revolutions immediately after the execution of injection Kinj for detection (immediate number of revolutions), and the number of revolutions immediately before. , the torque equivalent TQ corresponding to the cetane number can be obtained.

● [Example of cetane number and torque equivalent characteristics (Fig. 6)]
FIG. 6 shows the torque equivalent at ignition timing = P [° CA] (for example, ignition timing = 7 [° CA]) when using fuel with a reference cetane number = Ss (for example, fuel with a cetane number = 54). =TQs(P), showing an example of the cetane number/torque equivalent amount characteristics when the injection timing and the injection amount are corrected. In the cetane number/torque equivalent amount characteristic, the horizontal axis is the cetane number, and the vertical axis is the torque equivalent amount (a physical quantity equivalent to torque such as torque and rotation speed fluctuation amount). The torque equivalent amount is, for example, a rotational speed fluctuation amount converted into a rotational speed fluctuation amount in the case of a reference rotational speed (for example, 1500 [rpm]). The cetane number/torque equivalent characteristics are set based on the results of various experiments and simulations using actual vehicles.

In addition, the characteristics indicated by the solid line in the example of FIG. It shows the value/torque equivalent amount characteristics. In the example of FIG. 6, the characteristics indicated by the dashed line are ignition timing = P - ΔP [°CA] and torque equivalent = TQs (P - ΔP) when using fuel with a standard cetane number = Ss. The cetane number/torque equivalent amount characteristic (P-ΔP) set as above is shown. The characteristic indicated by the dotted line in the example of FIG. 6 is the cetane value set so that ignition timing = P + ΔP [° CA] and torque equivalent = TQs (P + ΔP) when using fuel with a standard cetane number = Ss. It shows the value/torque equivalent amount characteristic (P+ΔP). In this manner, various cetane number/torque equivalent amount characteristics can be created in advance according to target ignition timing and torque equivalent amount.

Focusing on the cetane number/torque equivalent amount characteristic (P) (ignition timing = P) indicated by the solid line, the cetane number torque equivalent amount characteristic (P) shows that the torque equivalent amount changes with respect to the cetane number difference. It has a small indistinguishable cetane number range (a region in which the cetane number is lower than the lower discriminable cetane number SL(P) and a region in which the cetane number is higher than the upper discriminable cetane number SH(P)). In addition, the cetane number torque equivalent characteristic (P) is a discriminable cetane number range (distinguishable lower limit cetane number SL (P) or higher) in which the change in torque equivalent amount is greater for different cetane numbers than in the undistinguishable cetane number range. and a region below the discriminable upper limit cetane number SH(P)). If the cetane number is within the discriminable cetane number range, the cetane number can be detected with higher accuracy based on the torque equivalent. On the other hand, in the case of the cetane number in the indistinguishable cetane number range, the cetane number detected based on the torque equivalent has a large error compared to the cetane number in the discriminable cetane number range.

● [Processing of the fuel property detection device (control device 50) of the first embodiment (Figs. 7 to 12)]
Next, a first embodiment of the processing of the fuel property detection device (control device 50) for detecting the cetane number will be described with reference to FIGS. 7 to 12. FIG. In the first embodiment, the cetane number within the cetane number detection range from the detection lower limit cetane number SKL to the detection upper limit cetane number SKH is detected using the cetane number/torque equivalent characteristic (P) shown in FIG. The cetane number/torque equivalent characteristic (P) shown in FIG. °CA]), and the cetane number/torque equivalent amount characteristic is set so that the torque equivalent amount=TQs(P). In the first embodiment, the discriminable cetane number range (P) of the cetane number/torque equivalent characteristic (P) (the range from the discriminable lower limit cetane number SL (P) to the discriminable upper limit cetane number SH (P) ) includes the cetane number detection range (the range from the lower detection limit cetane number SKL to the upper detection limit cetane number SKH). For example, when the detected torque equivalent is TQ, it can be detected that the cetane number to be detected is S based on the cetane number/torque equivalent amount characteristic (P) shown in FIG.

● [Processing procedure of overall processing (FIG. 8) in the processing procedure (FIGS. 8 to 11) of the first embodiment]
Next, the processing procedure of the first embodiment of the cetane number detection processing by the control device 50 will be described with reference to the flow charts shown in FIGS. 8 to 11. FIG. The control device 50 (CPU 51) starts the process shown in FIG. 8, for example, at each predetermined crank angle (for example, at every 15 degrees CA, see FIG. 12), and advances the process to step S110. For example, the crank angle detection means 22A (see FIG. 1) outputs a detection signal each time the crankshaft rotates 15 degrees CA, and the cylinder detection means 22B detects immediately before the No. 1 cylinder reaches the compression top dead center position. Output a signal. The processing shown in FIG. 8 is activated each time a detection signal is input from the crank angle detection means 22A. Further, the detection injection for detecting the cetane number may be performed for any cylinder, but in the present embodiment, an example in which the detection injection is performed for the first cylinder will be described. Further, in the present embodiment, an example in which the ignition timing=P [°CA] is 7 [°CA] will be described.

In step S110, the control device 50 updates the value of the crank angle counter (00 to 47 (see FIG. 12)), acquires the time when the crank angle signal was input this time, and the value of the crank angle counter (00 47), and the process proceeds to step S115.

For example, in step S110, the control device 50 initializes the value of the crank angle counter to (00) (see FIG. 12) when the cylinder detection signal from the cylinder detection means 22B (see FIG. 1) is detected. When the cylinder detection signal from the cylinder detection means 22B is not detected, the value of the crank angle counter is incremented by one (see FIG. 12). As a result, the value of the crank angle counter is updated to any value (00 to 47) every 15 degrees CA. For example, the period in which the value of the crank angle counter is (00) indicates that the crank angle is between 0 [° CA] and 15 [° CA] of the compression top dead center of the first cylinder, and the value of the crank angle counter is (24) indicates that the crank angle is between 360 [° CA] and 375 [° CA] of the intake top dead center of the first cylinder.

In step S115, the control device 50 determines whether or not the execution conditions for the injection for detection are satisfied. advances the process to step S190. For example, the detection injection execution condition is that fuel injection is currently stopped, the rotation speed is gradually decreasing while coasting, and the rotation speed range is from the detection lower limit rotation speed to the detection upper limit rotation speed. It is within the range, the accelerator pedal depression amount is 0, the engine brake is not in operation, and the like. It should be noted that the condition for executing the injection for detection is essential for "a state in which fuel injection is currently stopped and the number of revolutions is gradually decreasing while coasting", but other conditions are added. I don't mind.

In step S120, the control device 50 determines whether or not the current crank angle counter value is (47), and if the crank angle counter value is (47) (Yes), the process proceeds to step S125. If the value of the crank angle counter is not (47) (No), the process proceeds to step S135.

When proceeding to step S125, control device 50 executes process SA100 and advances the process to step S130. Note that the process SA100 includes a process of calculating the ignition delay time and the injection amount of the detection injection, and a process of obtaining the injection start time and the injection end time for the injector of the first cylinder in which the detection injection is to be executed. This is a process for setting a timer, and the details of process SA100 will be described later.

In step S130, the control device 50 sets the detection injection execution flag to ON, sets the actuator maintenance request flag to ON (see FIG. 12), and advances the process to step S135.

The detection injection execution flag indicates that the detection injection has been scheduled (process SA100 has been executed), is used for determination in step S135 described later, and is set to OFF in step S160. . Further, the actuator maintenance request flag is set to the intake/exhaust system actuator (throttle device, EGR valve) during the period from execution of detection injection scheduling until detection injection is executed and rotation speed fluctuation (torque equivalent amount) is acquired. , nozzle driving means for variable nozzles, etc.) is set to OFF in step S160. In the control process for an actuator (not shown), if the actuator maintenance request flag is ON, the control device 50 stops changing the operating state of the actuator and maintains the current operating state (engine braking such as regeneration). actions related to are prohibited).

When the process proceeds to step S135, the control device 50 determines whether or not the injection execution flag for detection is ON. If it is ON (Yes), the process proceeds to step S140. ) terminates the process shown in FIG.

When the process proceeds to step S140, the control device 50 determines whether or not the current crank angle counter value is (00), and if the current crank angle counter value is (00) (Yes). If the current value of the crank angle counter is not (00) (No), the process proceeds to step S150.

When the process proceeds to step S145, the control device 50 executes the process SA200 and ends the process shown in FIG. The processing of processing SA200 is a processing of measuring the number of revolutions immediately before execution of the detection injection (Ne [immediately before], see FIG. 12), and the details of processing SA200 will be described later.

When the process proceeds to step S150, the control device 50 determines whether or not the current crank angle counter value is (03), and if the current crank angle counter value is (03) (Yes). advances the process to step S155, and if the current value of the crank angle counter is not (03) (No), the process shown in FIG. 8 ends.

When the process proceeds to step S155, the control device 50 executes the process SA300 and advances the process to step S160. The process SA300 is a process of measuring the number of revolutions (Ne [immediately after], see FIG. 12) immediately after execution of the detection injection and detecting the cetane number, and the details of the process SA300 will be described later.

In step S160, control device 50 sets the detection injection execution flag to OFF, sets the actuator maintenance request flag to OFF (see FIG. 12), and ends the processing shown in FIG.

When the process proceeds to step S190, the control device 50 sets the detection injection execution flag to OFF, sets the actuator maintenance request flag to OFF, and ends the process shown in FIG.

● [Processing procedure of processing SA100 (Fig. 9)]
Next, details of the processing SA100 of step S125 in the flowchart shown in FIG. 8 will be described using the flowchart shown in FIG. Processing SA100 calculates the ignition delay time T _DLY of the detection injection Kinj according to the operating state/environmental state of the diesel engine, and calculates the injection amount (injection time Tinj) of the detection injection Kinj according to the operating state/environmental state. , timer setting of injection start time and injection end time. When executing process SA100 in step S125 shown in FIG. 8, control device 50 advances the process to step SA110 shown in FIG.

At step SA110, control device 50 calculates ignition delay time T _DLY corresponding to the operating state and environmental state of the diesel engine, and advances the process to step SA120. The method for calculating the ignition delay time T _DLY is the same as described above, so the explanation is omitted. Further, the ignition delay time T _DLY corresponds to an injection timing-related quantity related to the injection timing of the detection injection Kinj.

The control device 50 (CPU 51) executing the process of step SA110 determines any cetane number within the cetane number range from the detection lower limit cetane number to the detection upper limit cetane number regardless of the operating state and environmental state of the diesel engine. Also, the injection timing of the detection injection is adjusted so that the crank angle position at which the injected fuel ignites becomes a predetermined crank angle position (in this case, (target) ignition timing = 7 [°CA]). It corresponds to the detection injection timing related quantity calculator 51A (see FIG. 1) that calculates the related injection timing related quantity.

At step SA120, the control device 50 selects fuel with a reference cetane number Ss (for example, reference cetane number = 54), ignition timing = P (in this case, 7 [° CA]), and current operational and environmental conditions of the diesel engine. Based on this, the fuel amount Q for generating the reference torque equivalent amount TQs is calculated. A method for calculating the fuel amount Q is calculated by a known method as described above, so the explanation is omitted. Then, control device 50 converts the obtained fuel amount Q into injection time Tinj, and advances the process to step SA130. The injection time Tinj corresponds to the injection amount of the detection injection Kinj.

The control device 50 (CPU 51) executing the process of step SA120, in the case of fuel with a preset reference cetane number Ss within the cetane number detection range, is for detection regardless of the operating state and environmental state of the diesel engine. A torque equivalent amount corresponding to torque generated by combustion following ignition at a predetermined crank angle position (in this case, (target) ignition timing = 7 [° CA]) by injection is a preset reference torque equivalent amount. As shown in FIG. 7, it corresponds to the detection injection amount calculator 51B (see FIG. 1) that calculates the injection amount of the detection injection.

At step SA130, control device 50 predicts T(15) (see FIG. 12), which is the next 15 [°CA] time, based on the state of the decrease in the rotational speed. Further, based on T(15), the control device 50 predicts T(7) (see FIG. 12), which is the time corresponding to 7 [°CA] where the ignition timing is P [°CA], and performs step The process proceeds to SA140.

At step SA140, as shown in FIG. 12, the control device 50 performs detection injection for ignition at ignition timing = P [° CA] after a crank angle signal with a crank angle counter value of (00) is input. The injection start time of Kinj is obtained by the time when the crank angle signal whose crank angle counter value is (47) + T (15) + T (7) - _TDLY , and the calculated injection start time is calculated by the injection start timer. , and the process proceeds to step SA150.

At step SA150, as shown in FIG. 12, the control device 50 obtains the injection end time of the detection injection Kinj by (injection start time)+injection time Tinj, and sets the obtained injection end time to the injection end timer. After setting, the process shown in FIG. 9 is terminated, and the process proceeds to step S130 shown in FIG.

The control device 50 (CPU 51) executing the processes of steps SA130 to SA150, in the case of the detectable period (when the conditions for executing the injection for detection are satisfied (step S115)), for a predetermined cylinder, the injection amount for detection The injection timing calculated by the calculation unit 51B (see FIG. 1) is calculated based on the injection timing-related quantity (ignition delay time T _DLY ) calculated by the injection timing-related quantity calculation unit 51A for detection (see FIG. 1). , which corresponds to the injection-for-detection execution unit 51C (see FIG. 1) that executes the injection for detection Kinj injected at .

In the present embodiment, the injection start time and the injection end time of the detection injection Kinj are set at the timing when the crank angle counter value is (47) shown in FIG. ), the injection start time and the injection end time of the detection injection Kinj may be set.

● [Procedure of processing SA200 (FIG. 10)]
Next, details of the processing SA200 of step S145 in the flowchart shown in FIG. 8 will be described using the flowchart shown in FIG. Process SA200 is a process of measuring Ne [previous] (see FIG. 12), which is the number of revolutions immediately before the detection injection Kinj. When executing process SA200 in step S145 shown in FIG. 8, control device 50 advances the process to step SA210 shown in FIG.

At step SA210, the control device 50 outputs the time when the (current) crank angle counter value (00) of the crank angle signal and the (previous) crank angle counter value (47) of the crank angle signal are input. is input and the difference (time of 15 [° CA]), Ne [previous] (see FIG. 12), which is the number of revolutions immediately before the detection injection Kinj, is calculated (measured) and shown in FIG. 10 is completed, the process returns, the process proceeds immediately after step S145 shown in FIG. 8, and the process shown in FIG. 8 ends.

● [Procedure of processing SA300 (Fig. 11)]
Next, details of the processing SA300 of step S155 in the flowchart shown in FIG. 8 will be described using the flowchart shown in FIG. The process SA300 is a process of measuring Ne [immediately] (see FIG. 12), which is the number of revolutions immediately after the injection Kinj for detection, and a process of detecting the cetane number. When executing process SA300 in step S155 shown in FIG. 8, control device 50 advances the process to step SA310 shown in FIG.

At step SA310, control device 50 receives the time when a crank angle signal with a (current) crank angle counter value of (03) and the (previous) crank angle signal with a (previous) crank angle counter value of (02) are input. is input and the difference (time of 15 [° CA]), Ne [immediately after] (see FIG. 12), which is the rotation speed immediately after the combustion generated by the detection injection Kinj, is calculated (measured ) and advance the process to step SA320.

At step SA320, the control device 50 determines the difference ΔN (Fig. 12). Then, the controller 50 calculates the torque equivalent TQ based on the obtained ΔN and Ne [preceding], which is the rotational speed immediately before the detection injection Kinj, and proceeds to step SA330.

At step SA330, the controller 50 calculates (detects) the cetane number S corresponding to the torque equivalent TQ based on the torque equivalent TQ and the cetane number/torque equivalent characteristic (P) shown in FIG. 11 to end the process shown in FIG. 11, and the process proceeds to step S160 shown in FIG.

The cetane number/torque equivalent amount characteristic (P) in which the torque equivalent amount corresponding to the cetane number by the detection injection Kinj is set, and in the case of the detection injection of the fuel with the reference cetane number Ss, the reference torque equivalent amount TQs The cetane number/torque equivalent characteristic (P) (see FIG. 7) is stored in the storage device 53 so that (P) is obtained.

The control device 50 (CPU 51) executing the process of step SA330 stores the actual torque equivalent amount corresponding to the torque actually generated by the detection injection Kinj, and the cetane number/torque equivalent amount stored in the storage device. It corresponds to the cetane number detector 51D (see FIG. 1) that detects the cetane number based on the characteristic (P).

The detected cetane number is used for correcting injection timing and injection amount of normal fuel injection of a diesel engine.

● [Processing of the fuel property detection device (control device 50) of the second embodiment (FIGS. 13 to 19)]
As shown in FIG. 7 of the first embodiment, the cetane number/torque equivalent characteristic (P) is a "determinable cetane number range (P)" in which the cetane number can be accurately determined according to the torque equivalent. and an "inappropriate cetane number range (P)" that is not suitable for determining the cetane number according to the torque equivalent. In the first embodiment, the "identifiable cetane number range (P )” can cover the required cetane number detection range (detection lower limit cetane number SKL to detection upper limit cetane number SKH). However, if the required cetane number detection range is even wider, it may not be possible to cover it with the "determinable cetane number range" of one cetane number/torque equivalent amount characteristic.

Therefore, in the second embodiment, as shown in FIG. 13, when the required cetane number detection range (detection lower limit cetane number SKL to detection upper limit cetane number SKH) is very wide, a plurality of cetane numbers with different ignition timings are used.・Prepare torque equivalent characteristics. Each cetane number/torque equivalent characteristic is selected so that the required cetane number detection range can be covered by superimposing each "distinguishable cetane number range".

In the example of FIG. 13, for the required cetane number detection range, the cetane number/torque equivalent characteristic (P[1]) of ignition timing=P[1][° CA], ignition timing=P[2] [°CA] cetane number/torque equivalent characteristics (P[2]), ignition timing = P[3] [°CA] cetane number/torque equivalent characteristics (P[3]), ignition timing = P[ 4] shows an example in which the cetane number/torque equivalent characteristic (P[4]) of [°CA] is prepared. In the description of the second embodiment, P[1][°CA]=7[°CA], P[2][°CA]=9[°CA], P[3][°CA]=11 [°CA], P[4][°CA]=13 [°CA] will be described as an example, but the ignition timing is not limited to these. As shown in FIG. 13, "distinguishable cetane number range (P[1])", "distinguishable cetane number range (P[2])", "distinguishable cetane number range (P[3])", " If the discriminable cetane number range (P[4])" is superimposed, the required cetane number detection range can be covered.

In the example of FIG. 13, four cetane number/torque equivalent characteristics are prepared for the required cetane number detection range (that is, four ignition timings are prepared), but the number is limited to four. Any integer greater than or equal to 2 may suffice. That is, the example of FIG. 13 shows an example in which “n” corresponding to the number of (target) ignition timings is set to 4 (example of n=4) ((target) ignition timing=7 [°CA], 9 [° CA], 11 [° CA], and 13 [° CA] are shown as an example). Further, the detection injection for detecting the cetane number may be executed for any cylinder, but the detection injection is executed for the No. 1 cylinder as in the first embodiment.

Further, the detection injection Kinj[1] corresponding to the ignition timing=P[1] corresponds to the first detection injection, and the detection injection Kinj[n] corresponding to the ignition timing=P[n] corresponds to the nth detection injection. Equivalent to injection. Further, when "n" is an integer equal to or greater than 2, the crank angle positions at which the fuel injected by the detection injection Kinj[1] to the detection injection Kinj[n] ignite are set to the first crank angle position to the first crank angle position. n crank angle positions are set in advance. In this case, first crank angle position = 7 [° CA], second crank angle position = 9 [° CA], third crank angle position = 11 [° CA], fourth crank angle position = 13 [° CA]. is set to

● [Processing procedure of the overall process (FIG. 14) in the processing procedure (FIGS. 14 to 18) of the second embodiment]
A processing procedure of the second embodiment of the cetane number detection processing by the control device 50 will be described below with reference to flowcharts shown in FIGS. 14 to 18. FIG. A detection signal is output each time the crankshaft rotates 15 degrees CA, and a detection signal is output from the cylinder detection means 22B immediately before the No. 1 cylinder reaches the compression top dead center position. The point that the value is counted from (00 to 47) is the same as in the first embodiment. In the flow chart shown in FIG. 14, steps indicated by thick solid lines indicate processing different from that of the flow chart of the first embodiment shown in FIG. The control device 50 (CPU 51) starts the process shown in FIG. 14, for example, at each predetermined crank angle (for example, at every 15[° CA]), and advances the process to step S210.

In step S210, the control device 50 updates the value of the crank angle counter (00 to 47 (see FIG. 12)), acquires the time when the crank angle signal was input this time, and the value of the crank angle counter (00 47), and the process proceeds to step S212. Since the processing of step S210 is the same as the processing of step S110 shown in FIG. 8, details thereof will be omitted.

In step S212, the control device 50 determines whether the (previous) starting flag=ON and the (current) starting flag=OFF, that is, whether the state at the time of starting has changed to the state after starting. If there is a transition from starting to after starting (Yes), the process proceeds to step S213; otherwise (No), the process proceeds to step S215.

When the process proceeds to step S213, the control device 50 sets the post-startup initial detection flag to ON, initializes the repetition counter i to 1, and proceeds to step S215. It should be noted that the post-start initial detection flag is set to detect injection Kinj[1]-Kinj[4] for ignition timing = P[1]-P[4] when the value of the cetane number is not yet known. This is a flag for running through (see FIG. 19). Since the value of the cetane number can be detected by executing the injections Kinj[1] to Kinj[4] for detection, after that, the cetane number and Injection for detection of ignition timing corresponding to the torque equivalent characteristic is performed. In the example of FIG. 19, when the initial detection flag after starting is ON, detection injections Kinj[1] to Kinj[4] are executed to detect the cetane number (for example, the cetane number is a value in the range of 50 to 60). ), the detection injection Kinj[2] and the detection injection Kinj[3] are performed.

When the process proceeds to step S215, the control device 50 determines whether or not the condition for executing the injection for detection is satisfied. If not (No), the process proceeds to step S290. Since the processing of step S215 is the same as the processing of step S115 shown in FIG. 8, details thereof will be omitted.

When the process proceeds to step S220, the control device 50 determines whether or not the current crank angle counter value is (47), and if the crank angle counter value is (47) (Yes), The process proceeds to step S225, and when the value of the crank angle counter is not (47) (No), the process proceeds to step S235.

When the process proceeds to step S225, the control device 50 executes process SB100 and proceeds to step S230. The process of process SB100 includes a process of calculating the ignition delay time and the injection amount of the detection injection Kinj[i], and a process of calculating the injection start time for the injector of the first cylinder to execute the detection injection Kinj[i]. This is a process of obtaining the time and the injection end time and setting them in the timer, and the details of the process SB100 will be described later.

In step S230, control device 50 sets the injection execution flag for detection to ON, sets the actuator maintenance request flag to ON, and advances the process to step S235. Since the processing of step S230 is the same as the processing of step S130 shown in FIG. 8, details thereof will be omitted.

When the process proceeds to step S235, the control device 50 determines whether or not the injection execution flag for detection is ON. If it is ON (Yes), the process proceeds to step S240. ) terminates the process shown in FIG.

When the process proceeds to step S240, the control device 50 determines whether or not the current crank angle counter value is (00), and if the current crank angle counter value is (00) (Yes). If the current value of the crank angle counter is not (00) (No), the process proceeds to step S250.

When the process proceeds to step S245, the control device 50 executes the process SB200 and ends the process shown in FIG. The process of process SB200 is a process of measuring the number of revolutions (Ne[i] [immediately before]) immediately before execution of the detection injection Kinj[i], and the details of process SB200 will be described later.

When the process proceeds to step S250, the control device 50 determines whether or not the current crank angle counter value is (03), and if the current crank angle counter value is (03) (Yes). advances the process to step S255, and if the current value of the crank angle counter is not (03) (No), the process shown in FIG. 14 is terminated.

If the process proceeds to step S255, the control device 50 executes process SB300 and proceeds to step S260. Note that the process of process SB300 is a process of measuring the rotation speed (Ne[i] [immediately after]) immediately after execution of the detection injection Kinj[i] and detecting the (provisional) cetane number S[i]. , the details of the process SB300 will be described later.

In step S260, control device 50 sets the injection execution flag for detection to OFF, sets the actuator maintenance request flag to OFF, and advances the process to step S265.

In step S265, control device 50 executes process SB400 and ends the process shown in FIG. The process of process SB400 is a process of obtaining the (final) cetane number S from each (provisional) cetane number S[i] detected by the detection injection Kinj[i], and the details of process SB400 will be described later.

When the process proceeds to step S290, the control device 50 sets the detection injection execution flag to OFF, sets the actuator maintenance request flag to OFF, and ends the process shown in FIG.

● [Processing procedure of processing SB100 (Fig. 15)]
Next, details of the process SB100 of step S225 in the flowchart shown in FIG. 14 will be described using the flowchart shown in FIG. Processing SB100 calculates the ignition delay time T _DLY [i] of the detection injection Kinj[i] according to the operating state/environmental state of the diesel engine, This is a process of calculating the injection amount (injection time Tinj[i]) and setting timers for the injection start time and the injection end time.

Note that when the repetition counter i=1, the ignition timing = P[1][°CA] (in this case, 7[°CA]) using the ignition delay time T _DLY [1] and the injection time Tinj[1]. ) is executed, and the (provisional) cetane number S[1 ]. Similarly, when the repetition counter i = 2, the ignition timing = P [2] [°CA] (in _this case, 9 [°CA ]) is executed, and the (provisional) cetane number S[ 2].

When executing process SB100 in step S225 shown in FIG. 14, control device 50 advances the process to step SB110 shown in FIG.

At step SB110, control device 50 calculates ignition delay time T _DLY [i] according to the operating state and environmental state of the diesel engine, and proceeds to step SB120. The method of calculating the ignition delay time T _DLY [i] is the same as described above, so the explanation is omitted. Further, the ignition delay time T _DLY [i] corresponds to an injection timing-related quantity related to the injection timing of the detection injection Kinj[i].

The control device 50 (CPU 51) executing the process of SB110 detects any cetane number within the cetane number detection range from the detection lower limit cetane number to the detection upper limit cetane number regardless of the operating state and environmental state of the diesel engine. Also, the crank angle position at which the fuel injected by the detection injection is ignited is each of the preset first crank angle position to the nth crank angle position. Injection timing related quantities (in this case, ignition delay time T _DLY [ i]), and corresponds to the detection injection timing-related quantity calculation unit 51A (see FIG. 1).

At step SB120, the control device 50 selects fuel with a reference cetane number Ss (for example, reference cetane number = 54), ignition timing = P[i] (when i = 1, P[1] = 7 [°CA]), A fuel amount Q[i] for generating a reference torque equivalent amount TQs(P[i]) is calculated based on the current operating state and environmental state of the diesel engine. Then, control device 50 converts the obtained fuel amount Q[i] into injection time Tinj[i], and advances the process to step SB130. The injection time Tinj[i] corresponds to the injection amount of the detection injection Kinj[i].

The control device 50 (CPU 51) executing the process of step SB120, in the case of fuel with a preset reference cetane number Ss within the cetane number detection range, sets the first At the first crank angle position (P[1]) to the nth crank angle position (P[n]) by the detection injection (Kinj[1]) to the nth detection injection (Kinj[n]), respectively A first reference torque equivalent amount (TQs[1]) to an n-th reference torque equivalent amount ( Detection injection amount calculation for calculating the injection amounts of the first detection injection (Kinj[1]) to the n-th detection injection (Kinj[n]) so as to satisfy each of TQs[n]) It corresponds to the part 51B.

At step SB130, control device 50 predicts T(15), which is the time of the next 15 [° CA], based on the decrease in the rotational speed. Further, based on T(15), the control device 50 determines T (P[i]) is predicted, and the process proceeds to step SB140.

At step SB140, control device 50 performs detection injection Kinj[i] for ignition at ignition timing=P[i][° CA] after a crank angle signal with a crank angle counter value of (00) is input. The injection start time is determined by the time when the crank angle signal with the value of the crank angle counter (47) is input + T (15) + T (P [i]) - T _DLY [i], and the determined injection start time is set in the injection start timer, and the process proceeds to step SB150.

At step SB150, the control device 50 obtains the injection end time of the detection injection Kinj[i] by (injection start time)+the injection duration Tinj[i], and sets the obtained injection end time to the injection end timer. 15 to end the process shown in FIG. 15, and the process proceeds to step S230 shown in FIG.

The control device 50 (CPU 51) executing the processing of steps SB130 to SB150, during the detectable period (when the condition for executing the injection for detection is satisfied (step S215)), determines the injection amount for detection for a predetermined cylinder. Each injection amount calculated by the calculation unit 51B (see FIG. 1) is used as an injection timing-related quantity (ignition delay time T _DLY [i ]), which executes the first injection for detection (Kinj[1]) to the n-th injection for detection (Kinj[n]) injected at respective injection timings based on 1).

In the present embodiment, the injection start time and the injection end time of the detection injection Kinj[i] are set at the timing when the crank angle counter value is (47), but the crank angle counter value is (00). The injection start time and the injection end time of the detection injection Kinj[i] may be set at the timing of .

● [Processing procedure of processing SB200 (Fig. 16)]
Next, details of the process SB200 of step S245 in the flowchart shown in FIG. 14 will be described using the flowchart shown in FIG. Process SB200 is a process for measuring Ne[i] [previous], which is the number of revolutions immediately before the detection injection Kinj[i]. When executing process SB200 in step S245 shown in FIG. 14, control device 50 advances the process to step SB210 shown in FIG.

At step SB210, the controller 50 outputs the time when the (current) crank angle counter value (00) of the crank angle signal and the (previous) crank angle counter value (47) of the crank angle signal are input. is input and the difference (time of 15[° CA]), Ne[i] [immediately before] is calculated (measured), which is the number of revolutions immediately before the detection injection Kinj[i]. After completing the processing shown in FIG. 16, the process returns, the processing proceeds immediately after step S245 shown in FIG. 14, and the processing shown in FIG. 14 ends.

● [Procedure of processing SB300 (FIG. 17)]
Next, details of the process SB300 of step S255 in the flowchart shown in FIG. 14 will be described using the flowchart shown in FIG. Process SB300 is a process of measuring Ne[i] [immediately], which is the number of revolutions immediately after injection Kinj[i] for detection, and a process of detecting a (temporary) cetane number S[i]. When executing process SB300 in step S255 shown in FIG. 14, control device 50 advances the process to step SB310 shown in FIG.

At step SB310, the control device 50 receives the time when the (current) crank angle signal with the value (03) of the crank angle counter and the (previous) crank angle signal with the value (02) of the crank angle counter. is input and the difference (time of 15 [° CA]), Ne [i] [immediately], which is the number of rotations immediately after the combustion caused by the detection injection Kinj [i], is calculated ( measurement) and advance the process to step SB320.

At step SA320, control device 50 determines Ne[i] [immediately], which is the number of rotations immediately after injection Kinj[i] for detection, and Ne[i], which is the number of rotations immediately before injection Kinj[i] for detection. ΔN[i], which is the difference between [immediate] and [immediate], is obtained. Then, the controller 50 calculates the torque equivalent TQ (P[i]) based on the obtained ΔN[i] and Ne[i] [immediately before], which is the rotational speed immediately before the detection injection Kinj[i]. is calculated, and the process proceeds to step SB330.

At step SB330, control device 50 determines torque equivalent TQ(P The (provisional) cetane number S[i] corresponding to [i]) is calculated (detected), the process shown in FIG. 17 is terminated, the process returns, and the process proceeds to step S260 shown in FIG.

First cetane number/torque equivalent amount characteristics (P[ 1]) to the nth cetane number/torque equivalent characteristic (P[n]), which are the first detection injection (Kinj[1]) of the fuel having the reference cetane number Ss to the nth detection injection ( Kinj[n]), the first cetane number/torque set to be each of the first reference torque equivalent amount (TQs[1]) to the n-th torque equivalent amount (TQs[n]) Each of the equivalent characteristic (P[1]) to the n-th cetane number/torque equivalent characteristic (P[n]) (see FIG. 13) is stored in the storage device 53 .

The control device 50 (CPU 51) executing the process of step SB330 determines the torque actually generated in each of the first injection for detection (Kinj[1]) to the n-th injection for detection (Kinj[n]). Corresponding 1st actual torque equivalent to nth actual torque equivalent, and 1st cetane number/torque equivalent amount characteristics (P[1]) to nth cetane number/torque equivalent amount characteristics (P[n]), respectively , and corresponds to the cetane number detection unit 51D (see FIG. 1) that detects the (provisional) cetane number S[i] based on .

● [Processing procedure of processing SB400 (Fig. 18)]
Next, details of the process SB400 of step S265 in the flowchart shown in FIG. 14 will be described using the flowchart shown in FIG. Process SB400 is a process for detecting the (final) cetane number S based on the (provisional) cetane number S[i]. When executing process SB400 in step S265 shown in FIG. 14, control device 50 advances the process to step SB410 shown in FIG.

At step SB410, the controller 50 determines whether or not the post-startup initial detection flag is ON. If it is ON (Yes), the process proceeds to step SB415. Proceed with processing.

If the process proceeds to Step SB415, the value of the repetition counter i is incremented by +1, and the process proceeds to Step SB420 (preparing for the next detection injection Kinj[i]).

At step SB420, the control device 50 determines whether or not the incremented repetition counter i is greater than the value set to "n", and if greater than n (Yes), the process proceeds to step SB425. If the number is equal to or less than n (No), the process shown in FIG. 18 is terminated and returned to the bottom of step S265 shown in FIG. 14, and the process shown in FIG. 14 is terminated. The value of "n" is the number of cetane number/torque equivalent quantity characteristics shown in FIG. 13 (that is, the number of prepared ignition timings), and in the example of FIG. 13, "n=4". In the example of FIG. 13, four of ignition timing = P[1] to P[4] (ignition timing = 7 [°CA], 9 [°CA], 11 [°CA], 13 [°CA]) are Since it is prepared, it is "n=4".

As shown in FIG. 19, in the cetane number initial detection period in which the post-startup initial detection flag is ON, the control device 50 performs detection corresponding to all prepared ignition timings = P[1] to P[n]. Injections Kinj[1] to [n] (in this case, n=4) are executed in order, and the (provisional) cetane number S[i] corresponding to each injection Kinj[i] for detection is detected.

When the process proceeds to step SB425, the detection injection Kinj[1] to Kinj[n] are executed once during the cetane number initial detection period in which the initial detection flag after starting is ON, and the (provisional) cetane number S [1] to S[n] have already been detected. Therefore, the control device 50 detects (calculates) the (final) cetane number S based on the (provisional) cetane numbers S[1] to S[n].

In the present embodiment, during the cetane number initial detection period (in this case, the initial start detection flag = ON period), which is a predetermined period after the start of the diesel engine (determined in step S212), a series of detection Although an example in which injections Kinj[1] to Kinj[n] are executed only once has been described, in order to detect the cetane number with higher accuracy, a series of detection injections Kinj[1] to Kinj[n] may be performed twice or more. In other words, a set of detection injections Kinj[1] to Kinj[n] is executed at least once during the cetane number initial detection period in which the post-startup initial detection flag is ON. Further, in the description of the present embodiment, in step S212, when the starting flag transitions from ON to OFF (when the transition occurs from starting to after starting), the post-starting initial detection flag is set to ON. Instead of this, when it is detected that fuel has been replenished based on a detection signal from a fuel amount level sensor (not shown) or the like (when it is detected that the fuel has been replenished), the initial detection flag after starting is set. It may be set to ON.

For example, the control device 50 sets the average of the cetane number S[1] to the cetane number S[n] as the (final) cetane number S. For example, in the case of FIG. 13, when the cetane number is less than 50, the ignition timing=P[4] detection injection Kinj[4] and the cetane number/torque equivalent amount characteristic (P[4]) The (provisional) cetane number S[4] detected using this method has a large error. It is known that the error in the (provisional) cetane number S[1] detected using the method is very small. Therefore, when the (provisional) cetane number S[1]<50, the (provisional) cetane number S[4] is discarded, and the average of the (provisional) cetane number S[1] to the (provisional) cetane number [3] may be used as the (final) cetane number S. Similarly, in the example of FIG. 13, when the cetane number>60, the ignition timing=P[1] detection injection Kinj[1] and the cetane number/torque equivalent characteristic (P[1]) The (provisional) cetane number S[1] detected using It is known that the error in the (provisional) cetane number S[4] detected using is very small. Therefore, when the (provisional) cetane number S[4]>60, the (provisional) cetane number S[1] is discarded, and the average of the (provisional) cetane number S[2] to the (provisional) cetane number [4] may be used as the (final) cetane number S.

Further, in step SB425, the control device 50 selects the prepared cetane number/torque equivalent characteristics (P[1]) to cetane number torque equivalent characteristics (P[n]) according to the (final) cetane number S. ), the selected lower characteristic number is set to "a", the selected upper characteristic number is set to "b", and the process proceeds to step SB430.

For example, in the example shown in FIG. 13, when the control device 50 detects that the (final) cetane number S=55, the cetane number/torque equivalent characteristic (P[1]) in FIG. Select the cetane number/torque equivalent characteristic suitable for detecting the cetane number = 55 from the quantitative characteristics (P[4]) select). In this case, the cetane number/torque equivalent amount characteristic (P[2]) (characteristic number=2) and the cetane number/torque equivalent amount characteristic (P[3]) (characteristic number=3) are selected. Then, from among the selected characteristic numbers, the lower characteristic number "2" is substituted for "a", and the upper characteristic number "3" is substituted for "b".

At step SB430, control device 50 substitutes the value of "a" for repetition counter i, and advances the process to step SB435. When "2" is substituted for "a" in the above example, "2" is substituted for the repetition counter i.

At step SB435, the control device 50 sets the post-startup initial detection flag to OFF, ends the processing shown in FIG. 18, returns to step S265 shown in FIG. 14, and ends the processing shown in FIG. do.

When the process proceeds to step SB465, the control device 50 counts up the value of the repetition counter i by +1 and proceeds to step SB470 (preparing for the next detection injection Kinj[i]).

The processing of steps SB465 to SB480 is the processing of the detectable period after the cetane number initial detection period (in this case, the period during which the initial detection flag is ON after starting), and after the cetane number initial detection period (initial detection after starting) This is a process for executing the detection injections Kinj[a] to Kinj[b] selected based on the cetane number detected after the transition from ON to OFF of the flag.

At step SB470, the control device 50 determines whether or not the counted-up repetition counter i is greater than the value set in "b". If it is equal to or less than b (No), the process shown in FIG. 18 is terminated and returned to the bottom of step S265 shown in FIG. 14, and the process shown in FIG. 14 is terminated. The value of "b" is set at step SB425 or step SB475.

As shown in FIG. 19, when the post-startup initial detection flag is OFF, detection injections Kinj[1] to Kinj[1] to P[n] corresponding to all prepared ignition timings =P[1] to P[n], respectively. Detecting injections corresponding to selected ignition timings (ignition timings corresponding to selected cetane number/torque equivalent characteristics) are executed in order from [n] (in this case, n=4) (see FIG. 19). In the example, the detection injection Kinj[2] and the detection injection Kinj[3] are executed in order). Then, the control device 50 detects the (provisional) cetane number S[i] corresponding to each detection injection Kinj[i].

When the process proceeds to step SB475, since the initial post-startup detection flag is OFF, the detection injections Kinj[a] to Kinj[b] are executed once, and the (provisional) cetane value S[a] ~S[b] have been detected. Therefore, the control device 50 detects (calculates) the (final) cetane number S based on the (provisional) cetane numbers S[a] to S[b]. For example, the control device 50 sets the average of the cetane number S[a] to the cetane number S[b] as the (final) cetane number S.

The method for calculating the (final) cetane number S is not limited to the above averaging. For example, where M is an integer of 2 or more, the current (final) cetane number S = [(M-1) * (previous (final) cetane number S) + (current cetane number S [a] ~ S [b ]]/M, and the (final) cetane number S can be calculated using various methods.

Further, in step SB475, the control device 50 selects the prepared cetane number/torque equivalent characteristics (P[1]) to cetane number torque equivalent characteristics (P[n]) according to the (final) cetane number S. ), the selected lower characteristic number is set to "a", the selected upper characteristic number is set to "b", and the process proceeds to step SB480. Since the selection and setting of "a" and "b" are the same as in step SB425, the description thereof is omitted.

At step SB480, the control device 50 substitutes the value of "a" for the repetition counter i (when "2" is substituted for "a" in the above example, "2" is substituted for the repetition counter i), and After completing the processing shown in FIG. 18, the process returns to step S265 shown in FIG. 14, and the processing shown in FIG. 14 ends.

The control device 50 (CPU 51) executing the processes of steps SB425 and SB475 determines whether the first detection injection (Kinj[1]) to the n-th detection injection (Kinj[n]) have actually occurred. 1st actual torque equivalent amount to n-th actual torque equivalent amount equivalent to torque, and 1st cetane number/torque equivalent amount characteristic (P[1]) to n-th cetane number/torque equivalent amount characteristic (P[n]) and the (final) cetane number S from the (provisional) cetane number S[i] based on each of and the cetane number detection unit 51D (see FIG. 1).

The detected (final) cetane number S is used for correcting the injection timing and injection amount of normal fuel injection of the diesel engine.

● [Effects of the application]
In the present application, a detection injection is executed in a predetermined cylinder during a detectable period in which the diesel engine stops fuel injection and gradually decreases the rotation speed while coasting, and the torque generated by the detection injection is calculated. The cetane number of the fuel is detected based on the corresponding torque equivalents. Therefore, compared to detecting the amount of change in the generated torque by changing the injection amount of the secondary injection during normal operation to two levels as in Patent Document 1, the torque fluctuation amount due to the difference in the cetane number is higher. Accurate detection becomes possible, and the cetane number can be detected with higher accuracy.

In addition, the ignition delay time (T _DLY ) according to the operating and environmental conditions of the diesel engine is obtained, and the injection timing of the detection injection is finely adjusted (corrected) to achieve stable ignition timing. Similarly, by adjusting (correcting) the injection amount of the detection injection according to the operating and environmental conditions of the diesel engine, it is possible to stably generate torque according to the cetane number, resulting in higher accuracy. Cetane number can be detected.

In addition, when the required cetane number detection range is wide and the required cetane number detection range cannot be covered by the discriminable cetane number range of one cetane number/torque equivalent characteristic, as shown in the second embodiment. In addition, by preparing a plurality of cetane number/torque equivalent amount characteristics, the cetane number within the required cetane number detection range can be detected appropriately. In addition, instead of executing a plurality of injections for detecting the (target) ignition timing each time, once the (final) cetane number is detected, the (target) ignition timing that can appropriately detect the cetane number is determined. Unnecessary detection injections can be omitted by focusing on the execution of detection injections.

The fuel property detection device (control device 50) of the present invention is not limited to the configuration, processing procedure, etc. described in the present embodiment, and various changes, additions, and deletions are possible without changing the gist of the present invention. be.

In the description of the present embodiment, an example in which the detection signal from the crank angle detection means is output every 15 [° CA] rotation of the crankshaft has been described, but the detection signal is limited to every 15 [° CA]. isn't it. Moreover, although the example in which the cylinder discriminating means outputs the compression top dead center position signal of the first cylinder has been described, the present invention is not limited to this. There are various types of crank angle signals and cylinder discrimination signals.

In the second embodiment, as shown in FIG. 13, four cetane number/torque equivalent characteristics (P[i]) (i=1 to n, FIG. 13 In the above example, n=4) was prepared, but the value of n is not limited to 4, and may be an integer of 2 or more.

Further, in the second embodiment, after the (final) cetane number S is detected by sequentially executing a set of prepared detection injections from injection for detection Kinj[1] to injection for detection Kinj[n], Although the example in which only the selected injection for detection is performed has been described, even after the (final) cetane number is detected, the injection for detection Kinj[1] to the injection for detection Kinj[n] are executed in order. may

In the description of the present embodiment, examples of (target) ignition timing = 7 [° CA], 9 [° CA], 11 [° CA], and 13 [° CA] were described, but the (target) ignition timing is It is not limited to these, and can be set to various values. Also, an example in which the reference cetane number is 54 has been described, but the present invention is not limited to this.

Also, the numerical values used in the description of the present embodiment are examples, and the present invention is not limited to these numerical values.

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 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 temperature detection means 30 Turbocharger 31 Nozzle drive means 32 Nozzle opening detection means 33 Variable nozzle 35 Compressor 35A Compressor impeller 36 Turbine 36A Turbine impeller 41 Common rail 43A-43D Injector 45A to 45D cylinder 48 throttle device 48S throttle opening detection means 50 control device (fuel property detection device)
51 CPUs
51A Injection timing-related quantity calculation unit for detection 51B Injection amount calculation unit for detection 51C Injection execution unit for detection 51D Cetane number detection unit 53 Storage device 61 Oxidation catalyst 62 Particulate collection filter Kinj, Kinj[1] to Kinj[4] Detection Injection SH Identifiable upper limit cetane number SL Identifiable lower limit cetane number SKH Detectable upper limit cetane number _SKL Detectable lower limit cetane number
Tinj Injection time (injection amount for detection injection)

Claims (3)

During a detectable period in which the diesel engine stops fuel injection and gradually reduces the rotation speed while coasting, a detection injection is executed for a predetermined cylinder, and corresponds to the torque generated by the detection injection. A fuel property detection device that detects the cetane number of the fuel used in the diesel engine based on the torque equivalent,
A first crank angle position to an n-th crank angle position are set in advance as crank angle positions at which the injected fuel ignites when n is an integer of 2 or more,
When fuel having a preset reference cetane number is used, the fuel injected by the first detection injection to the n-th detection injection is injected at each of the first crank angle position to the n-th crank angle position. In order to ignite, an in-cylinder temperature estimated based on an operating state including an intake air amount of the diesel engine and an in-cylinder state including an in-cylinder oxygen concentration-related quantity are estimated, and based on the estimated in-cylinder state, a detection injection timing related quantity calculation unit that calculates each injection timing related quantity related to each of the injection timings of the first detection injection to the nth detection injection;
The fuel having the reference cetane number is injected based on the injection timing-related quantity in each of the first detection injection to the n-th detection injection, and is injected at each of the first crank angle position to the n-th crank angle position. In the case of ignition, each of the torque equivalent amounts corresponding to the torque generated by each combustion following each ignition becomes the preset first reference torque equivalent amount to n-th reference torque equivalent amount. a detection injection amount calculator that calculates the respective injection amounts of the first detection injection to the n-th detection injection,
The torque equivalent amount is set according to the cetane number, and a first cetane number/torque equivalent amount characteristic to an nth cetane number set for each of the first detection injection to the nth detection injection. Each of the torque equivalent characteristics, wherein each of the first reference torque equivalent to the n-th reference torque equivalent is calculated when the fuel having the reference cetane number is used. a storage device in which each of the first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic is stored;
In the case of the detectable period, each of the injection timings calculated by the injection timing-related quantity calculation unit for detection is calculated for each of the injection amounts calculated by the injection amount calculation unit for detection for the predetermined cylinder. an injection-for-detection execution unit that executes each of the first to n-th detection injections to be injected at respective injection timings based on related quantities;
A first actual torque equivalent amount to an nth actual torque equivalent amount corresponding to the torque actually generated in each of the first detection injection to the nth detection injection, and the first cetane number/torque equivalent amount characteristic ~ a cetane number detection unit that detects the cetane number based on each of the n-th cetane number and torque equivalent characteristics;
has
Each of the first cetane number/torque equivalent amount characteristic to the nth cetane number/torque equivalent amount characteristic corresponding to each of the first detection injection to the nth detection injection is determined according to the difference in cetane number. An indistinguishable cetane number range in which the torque equivalent amount hardly changes, and a distinguishable cetane number range in which the torque equivalent amount changes according to the difference in the cetane number with respect to the indistinguishable cetane number range. has
Each of the first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic is a part of the cetane number detection range from the detection lower limit cetane number to the detection upper limit cetane number required to be detected. It has a discriminable cetane number range,
The first cetane number/torque equivalent amount characteristic to the n-th cetane number/torque equivalent amount characteristic are discriminable from the first cetane number/torque equivalent amount characteristic to the nth cetane number/torque equivalent amount characteristic. When the cetane number range is superimposed, it is set to cover the entire range from the lower detection limit cetane number to the upper detection limit cetane number.
Fuel property detector. The fuel property detection device according to claim 1 ,
In the cetane number initial detection period, which is a predetermined period after the diesel engine is refueled or after the diesel engine is started, the first detection injection to the n-th detection by the detection injection execution unit performing injection at least once to detect the cetane number at the cetane number detection unit;
In the detectable period after the cetane number initial detection period,
When m is an integer of 2 or more and n or less, the first cetane number/torque equivalent amount characteristic to the nth cetane number/torque equivalent amount are calculated based on the cetane number detected after the cetane number initial detection period. Among the characteristics, the m-th cetane number/torque equivalent amount characteristic is selected so that the cetane number detected after the cetane number initial detection period is close to the center of the discriminable cetane number range. selecting an m-th detection injection corresponding to the m-th cetane number/torque equivalent characteristic from among the n detection injections, and executing the selected m-th detection injection by the detection injection execution unit;
Fuel property detector. The fuel property detection device according to claim 1 or 2,
After each of the first detection injection to the n-th detection injection is injected, the cetane number is detected by the cetane number detection unit corresponding to each of the first detection injection to the n-th detection injection. During each period until the operation, the operating state of the actuator provided in the intake and exhaust system of the diesel engine is maintained without being changed.
Fuel property detector.

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