JP2005069237A - Control method of fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of fuel injection to reduce the exhaust quantity of white smoke generated immediately after the starting by adjusting a fuel injection period and an injection quantity by each cylinder of an electronic control-type unit injector used in a diesel engine. <P>SOLUTION: In this control method of fuel injection device of the diesel engine, the fuel is successively supplied to each of cylinders, and the injection period and the injection quantity are controlled by each cylinder to reduce the exhaust quantity of white smoke generated at low temperature and immediately after the starting. Specific two groups are formed on the basis of the order of ignition of cylinders, the unignited cylinder is discriminated, and the supply of the fuel to the group of the unignized cylinders is stopped. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for controlling a fuel injection device, and more particularly to a fuel injection device capable of changing the fuel injection timing and injection amount for each cylinder of an electronically controlled unit injector used in a diesel engine. The present invention relates to the control of a fuel injection device that controls the amount of white smoke generated in the engine.

  An electronically controlled unit injector fuel injection control device conventionally used in a diesel engine will be described. FIG. 7 shows an overall system diagram of an electronically controlled unit injector fuel injection device for an engine. In FIG. 1, a fuel supply circuit to a unit injector 10 sucks fuel from a fuel tank (not shown) by a feed pump 11, passes through a fuel feed circuit 12, and is pumped to a unit injector 10 disposed in each cylinder. Is done. The fuel entering the unit injector 10 is pressurized by the camshaft 30 and injected into the combustion chamber by an amount necessary for the engine, and the remaining fuel passes through the fuel return circuit 13 and returns to a fuel tank (not shown).

  A solenoid valve 10a is attached to the unit injector 10 of each cylinder. The fuel injection amount and fuel injection timing are determined by opening and closing the solenoid valve 10a. The fuel injection amount and fuel injection timing are controlled by the crankshaft rotation speed sensor 50, the cylinder discrimination sensor 51, the engine water temperature sensor 53, and the opening degree of the accelerator pedal 43. These signals are processed and controlled by the control unit 40. For example, the control of the engine of four cycles, in-line six cylinders, and firing order 1, 5, 3, 6, 2, 4 will be described with reference to FIG.

  FIG. 8 is a diagram for explaining the relationship between pulse waveforms generated from the crankshaft and the camshaft. Since there are four cycles, the camshaft is ½ rotation (180 degrees) with respect to one rotation of the crankshaft (360 degrees). When the first cylinder of the crankshaft is at top dead center (compression), The six cylinders are at top dead center (exhaust). The cylinder is discriminated by the camshaft and follows the firing order. That is, when the first cylinder of the crankshaft is at top dead center (compression), the camshaft is matched with the pulse waveform of the first cylinder so that the cylinder can be discriminated. Note that 36 pulse waveforms (10 degrees per pulse waveform) are generated at equal intervals during one rotation (360 degrees) on the crankshaft. The crankshaft pulse waveform detects the angular position of the crankshaft simultaneously with the detection of the engine speed.

  The camshaft is provided with a reference signal pulse waveform so that six pulse waveforms can be determined at equal intervals in one rotation (360 degrees) and the number of cylinders can be determined.

  The fuel injection timing and the injection amount are controlled by a signal of a pulse waveform for discriminating the rotational speed and angular position of the crankshaft and the cylinder of the camshaft. The fuel injection timing is determined by the angular position of the crankshaft and the signal for discriminating the cylinder of the camshaft. The injection amount is determined by the energization time from the power supply device (not shown) inside the control unit 40 to the solenoid valve 10a of the unit injector 10 according to the opening degree of the accelerator pedal 43 and the rotation speed of the crankshaft.

  The fuel injection timing and the injection amount of the conventional electronically controlled unit injector are controlled by the same control without changing in each cylinder. Further, for example, Patent Document 1 discloses a method for controlling the fuel injection device that changes the fuel injection to the sequentially ignited cylinders.

Japanese Patent Laid-Open No. 3-185239

  As measures for increasing engine output and reducing exhaust gas NOx, as an effective means for lowering the combustion gas pressure and combustion temperature, the compression ratio is often lowered or the injection timing is delayed. However, it often involves a problem of startability deterioration and discharge of starting white smoke.

  Especially when starting at low temperatures, after starting with a starter, the cylinder that ignited first is often not ignited exactly in the order of ignition, and there are some unignited cylinders and some ignited cylinders. Since it repeats, it takes time to blow up all cylinders. When there are many unignited cylinders after the first explosion, the starting operation is repeated.

  White smoke is discharged at the start and immediately after the start, and combustion occurs in a low temperature state of the combustion chamber, resulting in incomplete combustion, acetaldehyde and formaldehyde, and a strong irritating odor. Further, since the fuel in the unignited cylinder is discharged in the form of oil droplets mixed with the exhaust gas, white smoke is generated. Ideally, there should be no white smoke, but the challenge is to reduce the time to disappear.

  The present invention relates to a conventional method for controlling a fuel injection device, and particularly, immediately after starting by changing the fuel injection timing and the injection amount for each cylinder of an electronically controlled unit injector used in a diesel engine. The purpose is to improve the control method of fuel injection to reduce the amount of white smoke generated.

  In order to achieve the above object, in the invention of the control method of the fuel injection device, in order to reduce the amount of white smoke generated immediately after start-up at low temperatures, fuel is sequentially supplied to each cylinder, and the injection timing of each cylinder is In the control method of the fuel injection device of the diesel engine for controlling the injection amount, the predetermined two groups are formed according to the cylinder ignition order, the unignited cylinders are discriminated, and the fuel is supplied to the groups of cylinders that are not ignited. The supply will be stopped.

  According to the above control method, the amount of white smoke generated immediately after starting at low temperatures is reduced by supplying fuel to each cylinder sequentially and controlling the injection timing and injection amount of each cylinder. In the fuel injection control method, the predetermined two groups are formed according to the cylinder firing order, the unignited cylinders are discriminated, and the supply of fuel to the groups of cylinders that are not ignited is stopped. As a result, the supply of fuel to the group of cylinders that do not ignite is stopped, so there is no unburned fuel, and the group of other ignited cylinders has a fuel injection amount per cylinder, Since it is approximately doubled, the combustion temperature is also increased. As a result, the amount of unburned fuel is reduced, the amount of white smoke discharged can be reduced, and the temperature of the water is increased rapidly, so that combustion is stabilized and the time until the white smoke disappears can be further shortened.

  Hereinafter, a control method for a fuel injection device for an engine according to the present invention will be described with reference to the drawings. The configuration of the engine fuel injection amount device is the same as that of FIG. As an example, the inline 6-cylinder engine is started and the control method immediately after the start is described with reference to the flowchart of FIG.

  In order to facilitate understanding of the present invention, first, the complete explosion and the self-sustaining operation from the start of the engine will be described with reference to FIG. First, the process from the start to the completion of the complete explosion will be explained. After the start S1 is started with the starter, the rotation speed is increased with the engine crankin and the initial explosion S2 is followed. The in-line 6 cylinders are ignited in the firing order 1, 5, 3, 6, 2, 4. At that time, there is a fluctuation in the engine rotation speed, but it decreases with the passage of time and reaches the completion of the complete explosion until S3. The target rotation speed is set from the beginning as low idle. In the figure, N1: startable rotation speed, N2: target rotation speed for start, N3: target rotation speed lower limit value for autonomous operation, and N4: target rotation speed upper limit value for autonomous operation are used as control judgment values from the beginning. Set from the test results for each target engine.

  Next, the starting operation of the engine of the present invention will be described with reference to the flowchart of FIG. In step 1, the start SW is input. In step 2, the water temperature (TW) is input from the engine water temperature sensor 53 to the control unit 40. In step 3, the injection timing and the injection amount are initially set according to the water temperature. The relationship between the water temperature, the injection timing, and the injection amount is, for example, as shown in FIG. 3, the vertical axis is the injection timing, the horizontal axis is the water temperature, and the relationship between the water temperature and the injection timing is as follows: Advance the injection timing. Similarly, the injection amount is plotted on the vertical axis, and the water temperature is plotted on the horizontal axis. The relationship between the water temperature and the injection amount is that the target engine from the beginning with the injection amount increasing as the control judgment value if the water temperature decreases as shown by the solid line. The test result is set for each time and stored in a storage device (not shown) of the control unit 40.

  Next, at step 4, the engine rotational speed (NE) is input from the crankshaft rotational speed sensor 50. In step 5, the cylinder that first ignited is recognized by the fluctuation of the engine speed (angular speed). For example, as shown in FIG. 5, the vertical axis represents the rotational speed fluctuation (angular speed) and the horizontal axis represents the elapsed time. , 3, 6, 2 and 4, the second cylinder and the fourth cylinder have a rotation speed fluctuation Na of engine cranking due to compression. When the first cylinder is ignited for the first time at the elapsed time S1, the rotational speed fluctuation due to combustion increases to Nb. At this time, signals of changes in rotational speed fluctuations (from Na to Nb) of the cylinder discrimination sensor 51 and the crankshaft rotational speed sensor 50 of the camshaft 30 are sent to the control unit 40, and the first cylinder is ignited for the first time. Be recognized. After that, when the fifth and sixth cylinders continue to be ignited, the result is as shown by a solid line B, but when not ignited, the result is as shown by a dotted line C.

  In step 6, the subsequent cylinder injection timing and injection amount are controlled from each water temperature TW and engine speed NE. The relationship between the injection timing, the water temperature, the injection amount, and the water temperature is performed as shown in FIG. 3, and the relationship between the injection timing, the injection amount, and the rotation speed is, for example, as shown in FIG. As for the relationship between the injection timing and the rotation speed, the injection timing is advanced if the rotation speed is increased as shown by the dotted line. Similarly, the injection amount is plotted on the vertical axis and the rotational speed is plotted on the horizontal axis, and the relationship between the injection amount and the rotational speed is initially set as a control judgment value to increase the injection amount if the rotational speed increases as shown by the solid line. Further, it is set from the test result for each target engine and stored in a storage device (not shown) of the control unit 40. Control is performed according to this memory.

  In step 7, it is determined whether or not the engine rotational speed NE is higher than the startable rotational speed N1. This determination proceeds to the next step 8 when the startable rotation speed N1 exceeds 300 rpm, for example, and returns to step 6 again when it is 300 rpm or less. The startable rotation speed N1 is set as a control judgment value from the test result for each target engine from the beginning, and stored in a storage device (not shown) of the control unit 40.

  In step 8, control is performed based on the injection timing and the injection amount based on the all-cylinder engine rotational speed NE and the water temperature TW. All cylinders are controlled by the above-described FIG. 3 and FIG. Step 9 determines whether or not the engine rotational speed NE is higher than the starting target rotational speed N2. For example, this determination proceeds to the next step 10 when the engine rotation speed N2 exceeds 675 rpm, and returns to step 8 when the engine rotation speed N2 is less than 675 rpm. The starting target rotational speed N2 is initially set as a control judgment value from the test result for each target engine and stored in a storage device (not shown) of the control unit 40. The above is the control method from the start to the complete explosion.

  Next, the operation of reducing the amount of white smoke emission in the control method for the fuel injection device of the present invention will be described with reference to the flowchart of FIG. In step 10, it is determined whether or not the actually measured water temperature TW is higher than the set water temperature TW1. For example, when the set temperature TW1 exceeds 10 ° C., the process proceeds to the next step 11B. When the set temperature TW1 is 10 ° C. or less, the process proceeds to the next step 11A. A set temperature TW1 of 10 ° C. is initially set as a judgment value for white smoke countermeasure control from the test results for each target engine and stored in a storage device (not shown) of the control unit 40.

  In step 11A, it is determined whether or not a reduced cylinder operation is being performed. The reduced-cylinder operation refers to, for example, a 6-cylinder engine that is ignited by 3 cylinders and the remaining 3 cylinders are operated without being ignited. If the reduced-cylinder operation is being performed, the process proceeds to step 16; otherwise, the process proceeds to step 12A. In step 12A, it is determined whether or not there is a cylinder that is not ignited due to fluctuations in the engine speed NE. As in the above-described step 5 at the time of starting, the determination is made based on the magnitude of fluctuations in the rotational speeds of the cylinder discrimination sensor 51 of the camshaft 30 and the crankshaft rotational speed sensor-50. That is, if there is a cylinder that is not ignited, the fluctuation of the rotational speed is small, and the cylinder that is ignited has a large fluctuation of the rotational speed. If there is a cylinder that has not been ignited, the process proceeds to step 13A, and if there is no cylinder that has not been ignited, that is, if all cylinders have been ignited, the process proceeds to step 19.

  In step 13A, an unignited cylinder number is confirmed, and a cylinder detection sensor 51 detects and confirms which cylinder. Step 14B stops the injection of the front three cylinders or the rear three cylinders including the unignited cylinder. For example, when the first cylinder is the unignited cylinder, the injection of the first cylinder, the second cylinder, and the third cylinder is stopped. Stopped the injection. In step 19, if there is no cylinder that has not ignited from step 12A, that is, if all cylinders are ignited, the injection of the pre-set three cylinders or the rear three cylinders is stopped, and the process proceeds to the next step 16.

  In step 16, it is determined whether or not the actually measured engine rotational speed NE is the same as the target rotational speed lower limit value N3 for autonomous operation or less than the lower limit value. When the value is below the lower limit value, the process proceeds to step 15, and when the value exceeds the lower limit value, the process proceeds to step 17. In step 15, a command for increasing the injection command value, increasing the injection amount, and increasing the rotational speed is issued, and the process proceeds to step 16 again. In step 17, it is determined whether or not the actually measured engine speed NE is the same as the target rotation speed upper limit value N4 for independent operation or less than the upper limit value. When it is below the upper limit value, the process proceeds to step 10 again, and when the upper limit value is exceeded, the process proceeds to step 18. In step 18, a command for lowering the injection command value, decreasing the injection amount, and lowering the rotational speed is issued, and the process proceeds to step 17 again.

  In step 11B, it is determined whether or not the reduced cylinder operation is being performed. If the reduced-cylinder operation is being performed, the process proceeds to step 12B, and if not, the process proceeds to step 13B. Step 12B starts the injection of the cylinder that has stopped the injection. Step 13B performs normal control and normal control by injecting all cylinders. End in step 20.

  As described above, according to the present invention, at the time of start-up, the injection timing and the injection amount are initially set according to the water temperature, and after the engine rotational speed is input, the first ignited cylinder is detected and the subsequent cylinders are detected. Since the injection timing and injection amount are controlled by the water temperature and engine speed for each cylinder, the ignition sequence is ensured and accurate following the cylinder that ignited first, and the time until the complete explosion of all cylinders is shortened. In addition, since the starting operation is not repeated, the startability can be improved. Further, the reduction of the amount of white smoke generated immediately after starting at low temperatures is achieved by supplying fuel to each cylinder sequentially, and controlling the injection timing and injection amount of each cylinder. The predetermined two groups are formed according to the cylinder firing order, the unignited cylinders are discriminated, and the supply of fuel to the groups of cylinders that are not ignited is stopped. As a result, the supply of fuel to the groups of cylinders that do not ignite is stopped, so that there is no unburned fuel, and the groups of other ignited cylinders have a fuel injection amount per cylinder of about 2. As a result, the combustion temperature is also increased, resulting in less unburned fuel, the reduction of white smoke emission, and the excellent effect of shortening the time until the white smoke disappears. It is done.

FIG. 2 is a flowchart of starting the fuel injection device control method according to the present invention. It is a figure explaining complete explosion and independent operation from starting of an engine. It is a figure explaining the relationship between water temperature, injection amount, and injection timing. It is a figure explaining the relationship between a rotational speed, injection amount, and injection timing. It is a figure explaining the relationship between time and a rotational speed fluctuation | variation. FIG. 2 is a flowchart for reducing white smoke emission in the control method of the fuel injection device according to the present invention. An overall system diagram of an electronically controlled unit injector fuel injection system for an engine is shown. It is a figure explaining the relationship of the pulse waveform which generate | occur | produces from a crankshaft and a cam shaft.

Explanation of symbols

10 Unit injector, 10a
Solenoid valve, 11 feed pump, 12 fuel feed circuit, 13 fuel return circuit, 20 crankshaft, 30
Cam shaft, 40 control unit, 43 accelerator pedal, 50 crankshaft rotation speed sensor, 51 cylinder discrimination sensor, 53 engine water temperature sensor.

Claims (1)

In a control method for a fuel injection device of a diesel engine, fuel is supplied sequentially to each cylinder in order to reduce the amount of white smoke emitted immediately after starting at low temperatures, and the injection timing and injection amount of each cylinder are controlled. A control method for a fuel injection device, wherein two predetermined groups are formed according to a cylinder ignition order, an unignited cylinder is discriminated, and supply of fuel to a group of cylinders that are not ignited is stopped.

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