JP4963491B2 - Fuel injection control device for vehicle engine - Google Patents

Description

  The present invention relates to a fuel injection control apparatus for a vehicle engine that controls the fuel injection timing.

Conventionally, in such a fuel injection control device for an engine for a vehicle, the fuel injection timing is determined based on the engine speed and the engine load such as the intake air amount and the accelerator pedal depression amount (for example, Patent Documents). 1).
JP 2008-121539 A

  By the way, as environmental regulations become more stringent in recent years, demands for lower fuel consumption and lower exhaust gas at low vehicle speeds of vehicle engines (for example, at vehicle speeds of less than 100 km / h) have become stricter year by year. In addition to this, there is also a demand for lower combustion noise at low vehicle speeds of vehicle engines. As described above, when the vehicle engine has a low vehicle speed, it is necessary to satisfy the demands for low fuel consumption, low exhaust gas, and low combustion noise, but the vehicle engine has a high vehicle speed (for example, 100 km / h). When the vehicle speed exceeds the maximum level, vehicle interior noise such as road noise and wind noise increases as the vehicle travels. Therefore, there is a tendency that the demand for low combustion noise tends to be compromised, and fuel efficiency is reduced by users. The present situation is the first requirement for the Japanese.

  In that case, in the above-mentioned conventional one, the fuel injection timing is determined based on the engine speed and the engine load, but the combustion noise is included in the element that determines the fuel injection timing at the low vehicle speed. However, since the demand for low combustion noise tends to be compromised at high vehicle speeds, the fuel injection timing must be optimized to meet the demand for low fuel consumption without worrying about combustion noise at high vehicle speeds. There was room for change to plan.

  The present invention has been made in view of such points, and an object of the present invention is to provide a vehicle engine capable of optimizing the fuel injection timing in order to satisfy the demand for low fuel consumption at high vehicle speeds. A fuel injection control device is provided.

In order to achieve the above object, the present invention is premised on a fuel injection control device for a vehicle engine that controls the fuel injection timing. Then, a correction value for a different fuel injection timing is held for each gear position at a high vehicle speed at which the combustion noise of the vehicle engine does not matter, and the fuel injection timing at a high vehicle speed of the vehicle engine is stored in the gear stage. Based on the correction value of the corresponding fuel injection timing, it is corrected to the advance side. For example, the fuel injection timing of the vehicular engine is set to the advance side when traveling at a shift stage having a larger reduction ratio among a plurality of shift stages having different reduction ratios or when traveling at a vehicle speed of 100 km / h or higher. It is corrected to.

  Due to this specific matter, the fuel injection timing of the vehicle engine is corrected to the advance side at high vehicle speeds where the requirement for low combustion noise is compromised, so the combustion efficiency of the fuel is increased by increasing the fuel combustion speed at high vehicle speeds. The demand for lower fuel consumption at higher vehicle speeds will be met. As a result, it is possible to optimize the fuel injection timing that satisfies the demand for low fuel consumption at high vehicle speeds.

In addition, the fuel injection timing at high vehicle speed is corrected to the advance side based on a previously stored correction value of fuel injection timing that differs for each gear position at high vehicle speed. If the vehicle speed is calculated from the number, the fuel injection timing is corrected to the advance side based on the correction value of the fuel injection timing for each gear position according to the high vehicle speed. It is possible to reduce the calculation load capacity when correcting the timing to the advance side.

  The fuel injection timing at a high vehicle speed of the vehicle engine is a correction value of the fuel injection timing according to the shift speed with respect to a reference value of the fuel injection timing according to the shift speed at any vehicle speed range of the vehicle engine. Is corrected to the advance side by taking into account the fuel injection timing at high vehicle speeds, the fuel injection timing reference that is held in advance and that corresponds to the gear position in any vehicle speed range of the vehicle engine The fuel injection timing is corrected to the advance side by adding the correction value of the fuel injection timing in accordance with the gear position to the value, and the calculation for correcting the fuel injection timing to the advance side It becomes possible to further reduce the load capacity.

  Further, when the correction by the correction value of the fuel injection timing for each shift stage at the time of the high speed of the vehicle engine is performed by time synchronization at the high speed of the vehicle engine, the shift at the high vehicle speed is performed. Compared with the case where the correction by the correction value of the fuel injection timing for each stage is performed by synchronizing with the angle of the crankshaft, the calculation load per unit time can be reduced.

  In short, by correcting the fuel injection timing of the vehicular engine to the advance side at high vehicle speeds where the need for low combustion noise is compromised, the combustion efficiency is improved by increasing the fuel combustion speed at high vehicle speeds. Therefore, it is possible to optimize the fuel injection timing that satisfies the demand for low fuel consumption at high vehicle speeds.

  Hereinafter, an embodiment in which a fuel injection control device for a diesel engine according to the present invention is applied to a pressure accumulation type diesel engine (common rail type diesel engine) mounted on a vehicle will be described with reference to FIGS.

  In FIG. 1, the diesel engine 1 in this embodiment and its periphery structure are shown.

  The diesel engine 1 has a plurality of cylinders 11. The diesel engine 1 is provided with an injector 12 corresponding to the combustion chamber of each cylinder 11, and fuel is injected from the injector 12 into the combustion chamber of each cylinder 11. The injector 12 includes an electromagnetic valve 13 for injection control, and fuel injection by the injector 12 is controlled based on the opening / closing operation of the electromagnetic valve 13. Then, the crankshaft is rotated by burning the fuel injected from the injector 12.

  The crankshaft is connected to an automatic transmission 5 having six shift stages having different reduction ratios. The rotation of the crankshaft is shifted by the automatic transmission 5, and the rotation after the shift is transmitted to the drive wheels.

  Each injector 12 is connected to a common rail 14. The common rail 14 is connected to a discharge port 17a of a supply pump 17 via a supply pipe 16 provided with a check valve 15.

  The suction port 17 b of the supply pump 17 is connected to the fuel tank 21 via the filter 18. Further, the return port 17 c of the supply pump 17 and the return port 13 a of the electromagnetic valve 13 are both connected to the fuel tank 21 via a return pipe 22.

  The supply pump 17 includes a plunger that reciprocates in synchronization with the rotation of the crankshaft of the diesel engine 1. The supply pump 17 pressurizes the fuel in the supply pump 17 by the plunger, and discharges the pressurized fuel to the discharge port 17a. To the common rail 14. The fuel pumping amount of the supply pump 17 is adjusted based on the opening / closing operation of the pressure control valve 23 provided in the vicinity of the discharge port 17a.

  The diesel engine 1 is provided with various sensors for detecting the operation state. For example, an accelerator sensor 31 is provided in the vicinity of the accelerator pedal 24 for detecting the amount of depression of the accelerator pedal 24 (accelerator operation amount ACCP). In this case, the engine load is obtained by the accelerator operation amount ACCP detected by the accelerator sensor 31.

  The common rail 14 is provided with a fuel pressure sensor 32 for detecting the fuel pressure PC inside the common rail 14. A vehicle speed sensor 33 for detecting the vehicle speed SPD is provided on the automatic transmission 5 or the wheel of the vehicle. Further, the crank angle sensor 34 provided in the vicinity of the crank shaft detects the rotation angle of the crank shaft, that is, the crank angle, and the engine speed NE is calculated based on this detection signal. Further, a cam angle sensor 35 is provided in the vicinity of the camshaft that rotates in synchronization with the rotation of the crankshaft. Cylinder discrimination is performed based on the detection signal of the cam angle sensor 35.

  The output signals of these sensors 31 to 35 are input to an electronic control device 41 as a fuel injection control device of the diesel engine 1. The electronic control device 41 is configured to include a CPU (Central Processing Unit), a memory, an input / output circuit, a drive circuit, and the like, and various kinds of operations are performed based on engine operating states detected by the sensors 31 to 35. Execute engine control.

  For example, the electronic control device 41 performs automatic shift control of the automatic transmission 5. In this automatic shift control, a shift command value SHI is calculated based on the engine speed NE, the vehicle speed SPD, and the like. The shift command value SHI is a value corresponding to the gear position in the automatic transmission 5. For example, when the gear shift command value SHI is set to “1st speed”, the gear position in the automatic transmission 5 is set to “1st speed”. The transmission mechanism in the automatic transmission 5 is controlled so that Then, by changing the gear position in the automatic transmission 5 to the gear position indicated by the shift command value SHI, the rotation of the crankshaft is decelerated or increased at a reduction ratio according to the running state of the vehicle. The In this case, the vehicle speed SPD is also calculated by the engine speed NE and the gear position (shift command value SHI).

  Then, fuel injection control is performed by the electronic control unit 41. In this fuel injection control, basically, the fuel injection amount (hereinafter referred to as the total fuel injection amount Qfin) and the fuel injection timing (hereinafter referred to as the fuel injection timing T_eabs) are based on the accelerator operation amount ACCP and the engine speed NE. The valve opening timing and valve opening time of the electromagnetic valve 13 are controlled so that the total fuel injection amount Qfin is injected from the injector 12 at an appropriate fuel injection timing T_eabs. In this case, as shown in FIG. 2, the electronic control unit 41 has a map in which the reference value T_abse of the fuel injection timing T_eabs corresponding to the shift speeds in all vehicle speed ranges is recorded in the memory.

  In the diesel engine 1, pilot injection is performed. This pilot injection is a small amount of fuel injection performed prior to main injection, which is fuel injection for obtaining engine output, and the fuel injected in this pilot injection is the amount of fuel injected in the subsequent main injection. It has the effect of reducing the burning rate. That is, there is an effect of suppressing rapid combustion of fuel injected by main injection. Moreover, since the combustion temperature of the fuel injected by main injection also falls by the same effect, production | generation of NOx (nitrogen oxide) is also suppressed by this.

  By the way, with the recent increase in environmental regulations, demands for lower fuel consumption and lower exhaust gas at low vehicle speeds (for example, vehicle speeds below 100 km / h) of vehicle engines have become stricter year by year. In addition, there is also a demand for low combustion noise at low vehicle engine speeds. From this point of view, it is necessary to satisfy the requirements of low fuel consumption, low exhaust gas, and low combustion noise at low vehicle engine speeds, but road noise and wind at high vehicle engine speeds. Vehicle interior noise that occurs as the vehicle travels, such as noise, increases, and this vehicle interior noise becomes a masking noise that masks the combustion noise of fuel. Therefore, there is a tendency for the demand for low combustion noise to be compromised. . For this reason, at the time of high vehicle speed, the current situation is that a reduction in fuel consumption is the first requirement for the user.

  In this case, in the present embodiment, the reference value T_abse of the fuel injection timing T_eabs is determined based on the engine speed NE and the accelerator operation amount ACCP (engine load). However, in determining this reference value T_abse, It includes factors such as combustion noise at vehicle speed. However, since the demand for low combustion noise tends to be compromised at high vehicle speeds, the fuel injection timing T_eabse is optimized in order to satisfy the demand for low fuel consumption without worrying about combustion noise at high vehicle speeds. There was room for change.

  From this point, in this embodiment, as shown in FIG. 3, the electronic control unit 41 has a high gear speed (specifically, a large reduction gear ratio among six gear speeds having different reduction gear ratios). A map in which the correction value T_asft of the fuel injection timing T_eabs that is different for each of the shift speeds of the fourth speed or more on the side) is shown (in FIG. 3, only a map in which the correction value T_asft of the fuel injection timing T_eaft in the fourth speed is shown) is shown. The reference value T_abse of the fuel injection timing T_eabs at the high vehicle speed is corrected to the advance side based on the correction value T_asft of the map corresponding to the gear position at the high vehicle speed. The correction value T_asft corresponding to the gear position is added to the reference value T_abse of the fuel injection timing T_eabs at, that is, the correction is made from the reference value T_abse. T_asft subtracts, and corrects the fuel injection timing T_eabse to the advance side. At this time, the correction by the correction value T_asft of the fuel injection timing T_eabs for each gear position at the time of high vehicle speed is performed by synchronizing the time every predetermined time (for example, every 16 ms) at the time of high vehicle speed.

  On the other hand, when pilot injection is performed, the combustion of fuel injected in the main injection becomes slow, so that the increase in in-cylinder pressure etc. also slows down, and the combustion efficiency decreases accordingly. Therefore, when pilot injection is performed, combustion noise can be suppressed, but fuel consumption (unit output / fuel consumption rate per unit time) is deteriorated. Therefore, in the present embodiment, even if the pilot injection is limited at high vehicle speed, the combustion noise is difficult to hear.At high vehicle speed, in addition to correcting the fuel injection timing T_eabs to the advance side, the pilot injection is limited, The fuel consumption deterioration caused by pilot injection is also suppressed.

  Here, the flow of control for optimizing the fuel injection timing T_eabse at the time of high vehicle speed by the electronic control device 41 will be described along the flowchart of FIG.

  First, in step ST1 of the flowchart of FIG. 4, the operating state of the diesel engine 1 is recognized based on the current gear position of the automatic transmission 5, the engine speed NE, and the accelerator operation amount ACCP.

  Next, in step ST2, a reference value T_abse for the fuel injection timing T_eabse is determined based on the engine speed NE and the accelerator operation amount ACCP.

  Thereafter, in step ST3, it is determined whether or not the current gear position of the automatic transmission 5 is the fourth speed or higher. If the determination in step ST3 is YES when the vehicle speed is greater than or equal to the fourth speed, it corresponds from the map in which the correction value T_asft of the fuel injection timing T_eaft that differs for each gear position at the time of the high vehicle speed is written in step ST4. After selecting a shift speed map (for example, a 4-speed map) from the memory and reading a correction value T_asft that matches the current operating state, that is, the engine speed NE and the accelerator operation amount ACCP, in the corresponding shift speed map. The process proceeds to step ST5.

  On the other hand, when the determination in step ST3 is NO at the time of a low vehicle speed equal to or lower than the third speed, fuel injection is performed at the fuel injection timing T_eabs according to the reference value T_abse.

  In step ST5, the reference value T_abse of the fuel injection timing T_eabse at high vehicle speed is corrected. Specifically, the fuel injection timing T_eabs is corrected to the advance side by adding a correction value T_asft corresponding to the gear position to the reference value T_abse of the fuel injection timing T_eabs at the high vehicle speed (T_abse−T_asft). At this time, the pilot injection amount is limited.

  As described above, the fuel injection timing T_eabs of the diesel engine 1 at the time of high vehicle speed at which the requirement for low combustion noise is compromised is corrected in advance for the fuel injection timing T_eabs that is previously stored in the memory and is different for each gear position at the time of high vehicle speed. Since it is corrected to the advance side based on the value T_asft, the combustion efficiency of the fuel is increased by increasing the fuel combustion speed at the high vehicle speed, and the demand for low fuel consumption at the high vehicle speed is satisfied. As a result, it is possible to optimize the fuel injection timing T_eabse that satisfies the demand for low fuel consumption at high vehicle speeds.

  In addition, at high vehicle speeds, pilot injection is restricted in addition to correction of the fuel injection timing T_eabs to the advance side, and fuel consumption deterioration due to pilot injection is also suppressed, so a reduction in fuel consumption at high vehicle speeds is a high level. Can be achieved.

  In addition, when it is calculated that the vehicle speed is high from the current gear position and the engine speed NE, the fuel injection timing T_eabs is calculated based on the correction value T_asft of the fuel injection timing T_eaft for each gear position corresponding to the high vehicle speed. In addition to being corrected to the advance side, the fuel injection timing T_ebse at the high vehicle speed is preliminarily stored in the memory to the reference value T_abse of the fuel injection timing T_abse corresponding to the gear position in all vehicle speed ranges of the vehicle engine. On the other hand, by adding the correction value T_asft of the fuel injection timing T_eabs according to the shift speed at the high vehicle speed, the fuel injection timing T_eabs is corrected to the advance side, and the fuel injection timing T_eabs is set to the advance side. The calculation load capacity for correction can be greatly reduced.

  Further, the correction by the correction value T_asft of the fuel injection timing T_eabs for each gear position at the time of high vehicle speed is performed by synchronizing the time every predetermined time (for example, every 16 ms) at the time of high vehicle speed. The calculation load per unit time can be reduced as compared with the case where the correction by the correction value T_asft of the fuel injection timing T_eabs for each gear is performed by synchronizing with the angle of the crankshaft.

  In addition, this invention is not limited to the said embodiment, The other various modifications are included. For example, in the above-described embodiment, the pilot injection is limited together with the correction of the reference value T_abse of the fuel injection timing T_eabs to the advance side based on the correction value T_asft at a high vehicle speed. The injection timing reference value may only be corrected to the advance side based on the correction value. In addition, when an exhaust gas recirculation device that recirculates a part of the exhaust gas discharged to the exhaust passage as recirculation gas (EGR gas) to the intake passage through the exhaust gas recirculation passage is provided at high vehicle speed. Combined with the correction of the reference value for the injection timing to the advance side based on the correction value, the amount of recirculation of the recirculated gas to the intake passage is reduced, thereby reducing fuel consumption at high vehicle speeds. Good.

  In the above embodiment, the correction value T_asft of the fuel injection timing T_eabs that is different for each gear position at the high vehicle speed is obtained from the engine speed NE and the accelerator operation amount ACCP. However, the correction value T_asft varies depending on the output value from the vehicle speed sensor. A different fuel injection timing correction value may be obtained for each gear position at the vehicle speed.

  In the above-described embodiment, the case where the six-speed automatic transmission 5 having six gear speeds with different reduction ratios is applied has been described. However, the number of gear speeds possessed by the automatic transmission is limited to this. Instead, for example, it may be an eight-speed automatic transmission having eight different gear positions. In this case, when the vehicle speed is high, the vehicle is traveling at a shift speed of 5 speeds or higher on the side where the reduction ratio is larger among the eight shift speeds. The high vehicle speed may be defined as the case of traveling at a vehicle speed of 100 km / h or higher regardless of the shift speed.

  Furthermore, although the said embodiment described the case where it applied to the diesel engine 1, it cannot be overemphasized that it can apply also to a gasoline engine.

It is the schematic which shows schematic structure of the diesel engine using the fuel-injection control apparatus which concerns on embodiment of this invention. It is a conceptual diagram which shows the map which described the reference value of the fuel injection timing according to the gear stage in all the vehicle speed ranges. It is a conceptual diagram which shows the map which described the correction value of the fuel injection timing which changes for every gear stage at the time of high vehicle speed. It is a flowchart figure which shows the flow of control which optimizes the fuel injection timing at the time of the high vehicle speed by an electronic controller.

Explanation of symbols

1 Diesel engine (vehicle engine)
41 Electronic control device (fuel injection control device)
T_eabse Fuel injection timing T_abse Reference value T_asft Correction value

Claims (4)

In a fuel injection control device for a vehicle engine configured to control fuel injection timing,
It has a different fuel injection timing correction value for each gear position at high vehicle speeds, where combustion noise of the vehicle engine is not a problem ,
A fuel injection control device for a vehicle engine, wherein the fuel injection timing of the vehicle engine at a high vehicle speed is corrected to an advance side based on a correction value of the fuel injection timing according to the shift speed . The fuel injection control device for a vehicle engine according to claim 1,
We have a reference value for the fuel injection timing according to the gear position in any vehicle speed range of the vehicle engine,
The fuel injection timing at a high vehicle speed of the vehicle engine is corrected to the advance side by adding the correction value of the fuel injection timing according to the shift stage to the reference value of the fuel injection timing according to the shift stage. A fuel injection control device for a vehicle engine. The fuel injection control device for a vehicle engine according to claim 1 or 2,
The vehicle engine fuel is characterized in that the correction by the correction value of the fuel injection timing for each shift stage at the time of high vehicle speed of the vehicle engine is performed by time synchronization at the time of high vehicle speed of the vehicle engine. Injection control device. The fuel injection amount control device for a vehicle engine according to any one of claims 1 to 3,
When the vehicle engine is running at a high vehicle speed, it means that the vehicle engine is traveling at a gear having a larger speed reduction ratio among a plurality of gears having different speed reduction ratios, or is traveling at a vehicle speed of 100 km / h or higher. A fuel injection amount control device for a vehicle engine, characterized in that:

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