JPH08296477A - Control method for fuel injection device - Google Patents

Abstract

PURPOSE: To improve starting ability at the time of low temperature and reduce white smoke discharge quantity generated immediately after starting. CONSTITUTION: In this control method for fuel injection (unit injector 10) which controls fuel injection timing and injection quantity for each cylinder according to water temperature by a sensor 53 while a diesel engine is starting, a cylinder to be ignited first is detected by a cylinder discriminating sensor 51 at the time of starting, and a command for changing the injection timing and injection quantity for the cylinders to be ignited in order according to engine speed and water temperature is controlled by a control unit 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a fuel injection device, and in particular, it is possible to change 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 control of a fuel injection device that controls the startability at low temperatures and the amount of white smoke emitted immediately after startup.

[0002]

2. Description of the Related Art A conventional electronically controlled unit injector fuel injection control device 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 the unit injector 10 sucks up fuel from a fuel tank (not shown) by a feed pump 11, passes through a fuel feed circuit 12, and pressure-feeds it to the unit injector 10 arranged in each cylinder. To be done. The fuel that has entered the unit injector 10 is the camshaft 3
The fuel is pressurized at 0 and injected into the combustion chamber in 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 the fuel injection timing are determined by opening and closing the solenoid valve 10a. The fuel injection amount and the fuel injection timing are controlled by opening the crankshaft rotation speed sensor 50, the cylinder discrimination sensor 51, the engine water temperature sensor 53, and the access pedal 43. Each signal is processed and controlled by the control unit 40. For example, control of an engine with four cycles, in-line six cylinders, and ignition sequence 1, 5, 3, 6, 2, 4 will be described with reference to FIG. FIG. 8 is a diagram illustrating a relationship between pulse waveforms generated from the crank shaft and the cam shaft. Since it is 4 cycles, one crankshaft rotation (360
Degree), the camshaft has a relationship of rotating 1/2 rotation (180 degrees). When the first cylinder of the crankshaft is at top dead center (compression), the sixth cylinder is at top dead center (exhaust). is there. The cylinder is discriminated by the camshaft, and the ignition order is followed. That is, when the first cylinder of the crankshaft is at top dead center (compression), the camshaft is
Since it is matched with the pulse waveform of the cylinder, it is possible to identify the cylinder. The crankshaft has one revolution (36
36 pulse waveforms (0 per degree) (1 per pulse waveform)
0 degree) is generated at equal intervals. The crankshaft pulse waveform detects not only the engine speed but also the angular position of the crankshaft. The camshaft is provided with 6 pulse waveforms at one rotation (360 degrees) at equal intervals, and a pulse waveform of a reference signal is attached so that the cylinder number can be determined. The fuel injection timing is determined by the rotational speed and angular position of the crankshaft, the pulse waveform signal for determining the cylinder of the camshaft,
The injection amount is controlled. As for the fuel injection timing, the injection timing of each cylinder is determined by the angular position of the crankshaft and the signal for determining the cylinder of the camshaft. The injection amount is controlled by the signals of the opening degree of the accelerator pedal 43 and the rotation speed of the crankshaft.
This is determined by the energization time of the solenoid valve 10a of the unit injector 10 from a power supply device (not shown) inside the unit 40. The fuel injection timing and injection amount of the conventional electronically controlled unit injector are not changed for each cylinder, and the same control is performed.

[0003]

As measures for increasing the engine output and reducing exhaust gas NOx, combustion gas pressure,
As an effective means for lowering the combustion temperature, the compression ratio is often lowered or the injection timing is delayed. However, it is often accompanied by problems such as deterioration of startability and discharge of starting white smoke. Especially when starting at low temperature, after starting with a starter, it often follows the first ignited cylinder, does not ignite correctly according to the ignition order, there are unignited cylinders, ignited cylinders are irregular, so this Since it repeats, it takes time to blow up the complete explosion of all cylinders. If many cylinders have not been ignited after the initial explosion, the starting operation will be repeated. White smoke is emitted at the time of starting and immediately after starting, and because the fuel in the fuel chamber is in a low temperature state, incomplete combustion occurs, acetaldehyde and formaldehyde are generated, and a strong irritating odor is generated. Further, the fuel in the non-ignited cylinder is mixed with the exhaust gas in the state of oil drops and is discharged, which causes the generation of white smoke. Ideally, there should be no white smoke,
Even then, the challenge is to shorten the time to disappear.

The present invention relates to a control method for a fuel injection device of the above conventional problems, and particularly, by changing the fuel injection timing and injection amount for each cylinder of an electronically controlled unit injector used in a diesel engine, An object of the present invention is to improve startability at low temperatures and improve a method for controlling fuel injection that reduces the amount of white smoke emitted immediately after starting.

[0005]

In order to achieve the above object, a first method of controlling a fuel injection device for an engine according to the present invention.
According to the invention, in the fuel injection control method of controlling the fuel injection timing and the injection amount of each cylinder according to the water temperature at the time of starting the diesel engine, at the time of starting, the cylinder for the first ignition is detected, and the engine The command to change the injection timing and the injection amount to the cylinders that are sequentially ignited is controlled according to the rotation speed and the water temperature.

In the second invention of the control method of the fuel injection device,
At low temperature, in order to reduce the amount of white smoke emitted immediately after starting, fuel is sequentially supplied to each cylinder, the injection timing of each cylinder,
In a method of controlling a fuel injection device of a diesel engine for controlling an injection amount, a predetermined two groups are set depending on a cylinder ignition order.
Of the cylinders that are not ignited and the fuel supply to the group of cylinders that are not ignited is stopped.

[0007]

According to the above control method, at the time of starting, the injection timing and the injection amount are initialized according to the water temperature, the cylinder ignited first is detected after the engine rotation speed is input, and the injection of the subsequent cylinder is performed. The timing and injection amount are controlled for each cylinder according to the water temperature and engine speed, so the ignition sequence is reliable and accurate, following the cylinder that ignited first, and the time until the complete explosion of all cylinders rises is short. Become. Further, at a low temperature, to reduce the amount of white smoke emitted immediately after starting, in the fuel injection control method of the diesel engine, which sequentially supplies fuel to each cylinder, and controls the injection timing and injection amount of each cylinder, A predetermined two groups are formed according to the ignition sequence of the cylinders, the unignited cylinders are discriminated, and the fuel supply to the groups of the cylinders that are not ignited is stopped. Since the supply of fuel to the group of cylinders that do not ignite is stopped by this, unburned fuel disappears, and the fuel injection amount per cylinder of the groups of other ignited cylinders is: Since it is almost doubled, the combustion temperature also rises. As a result, the amount of unburned fuel is reduced, the amount of white smoke emitted can be reduced, and the rise in the water temperature is accelerated, so that the combustion is stabilized and the time until the white smoke disappears can be shortened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control method of an engine fuel injection system according to the present invention will be described below with reference to the drawings. In addition,
The structure of the fuel injection amount device of the engine is the same as that of the conventional example shown in FIG. As one embodiment, a control method of the in-line 6-cylinder engine and a control method immediately after the engine start will be described with reference to the flowchart of FIG.

In order to facilitate understanding of the present invention, first, engine starting, complete explosion, and self-sustaining operation will be described with reference to FIG. First of all, the process from the start to the complete explosion is explained. After the start S1 is started by the starter, the rotation speed is increased by the engine cranking and the initial explosion S2 is reached. Ignition order 1, 5 of in-line 6 cylinder
Ignite at 3, 6, 2, and 4. At that time, the engine rotation speed fluctuates, but it decreases with the passage of time, and the complete explosion is blown up to S3. The target rotation speed is set as low idle from the beginning. Further, in the figure, N1: startable rotation speed, N2: target rotation speed for start, N3: target rotation speed lower limit value for self-sustaining operation, N4: target rotation speed upper limit value for self-sustaining operation are used as control judgment values from the beginning. Set and set from the test results for each target engine.

Next, the operation of starting the engine of the present invention will be described with reference to FIG.
This 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 supplied from the engine water temperature sensor 53 to the control unit 40.
To enter. In step 3, depending on the water temperature, the injection timing,
Initialize the injection amount. Note that the relationship between the water temperature, the injection timing, and the injection amount is, for example, as shown in FIG. 3, in which the vertical axis indicates the injection timing and the horizontal axis indicates the water temperature. Advance the injection timing. Similarly, the vertical axis is the injection amount, the horizontal axis is the water temperature, and the relationship between the water temperature and the injection amount is that the injection amount is increased if the water temperature becomes lower as indicated by the solid line. It is set for each test result and stored in a storage device (not shown) of the control unit 40.

Next, at step 4, the engine speed (N
E) is input from the crankshaft rotation speed sensor 50. In step 5, the cylinder that is ignited first is recognized based on the fluctuation of the engine rotation speed (angular speed). For example, as shown in FIG. 5, the vertical axis represents the rotation speed fluctuation (angular speed) and the horizontal axis represents the elapsed time. , 3, 6, 2, 4, the rotation speed fluctuations Na of the engine cranking due to the compression occur in the second cylinder and the fourth cylinder. 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, the camshaft 30
The signals of changes in the rotational speed fluctuations (from Na to Nb) of the cylinder discrimination sensor 51 and the crankshaft rotational speed sensor-50 are sent to the control unit 40, and it is recognized that the first cylinder is ignited for the first time. 5th cylinder and 6th
When the cylinder continues to ignite, the solid line B is shown, but when not ignited, the dotted line C is shown.

In step 6, the injection timing and injection amount of the subsequent cylinders are controlled based on each water temperature TW and engine speed NE. The relationship between the injection timing and the water temperature and the injection amount and the water temperature is as shown in FIG. 3, and the relationship between the injection timing and the injection amount and the rotation speed is, for example, as shown in FIG. The relationship between the injection timing and the rotation speed is that the injection timing is advanced as the rotation speed increases as indicated by the dotted line. Similarly, the vertical axis is the injection amount and the horizontal axis is the rotation speed.
The relationship between the injection amount and the rotation speed is that the control value is to increase the injection amount as the rotation speed increases as indicated by the solid line.
From the beginning, it is set from the test results for each target engine and stored in a storage device (not shown) of the control unit 40. Control according to this memory. In step 7,
It is determined whether or not the engine rotation speed NE is higher than the startable rotation speed N1. This determination is made in step 8 below when the startable rotation speed N1 exceeds 300 rpm, for example.
If it is less than 300 rpm, the process returns to step 6. The startable rotation speed N1 is set as a control judgment value from the test result for each target engine from the beginning, and is controlled.
It is stored in a storage device (not shown) of the unit 40.

In step 8, all cylinder engine rotation speed N
E, controlled by the injection timing and injection amount by the water temperature TW.
All cylinders are controlled by the above-mentioned FIGS. 3 and 4. In step 9, it is determined whether or not the engine rotation speed NE is higher than the starting target rotation speed N2. This determination is based on, for example, that the engine rotation speed is 67 and the start rotation speed N2 is 67.
When it exceeds 5 rpm, proceed to the next step 10, 675
When it is less than or equal to rpm, the process returns to step 8. The target rotation speed N2 for starting is set as a control judgment value from the test result for each target engine from the beginning, and is set from the control unit 4.
0 is stored in a storage device (not shown). The above is the control method from the start to the complete explosion.

Next, the operation of reducing the amount of white smoke emitted by the method for controlling 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 measured water temperature TW is higher than the set water temperature TW1. In this determination, for example, when the set temperature TW1 exceeds 10 ° C, the process proceeds to the next step 11B, and when it is 10 ° C or less, the process proceeds to the next step 11A. The set temperature TW1 of 10 ° C. is set as a judgment value for control against white smoke from the test result for each target engine from the beginning, and is stored in a storage device (not shown) of the control unit 40.

In step 11A, is the cylinder cut-off operation being performed?
I'm judging whether or not. The reduced-cylinder operation means, for example, a 6-cylinder engine operating with three cylinders ignited and the remaining three cylinders not ignited. If the reduced cylinder operation is in progress, step 16
If the reduced-cylinder operation is not performed, the process proceeds to step 12A. In step 12A, it is determined whether or not there is a cylinder that has not ignited due to a change in the engine speed NE. Similar to step 5 at the time of starting, the determination is made based on the magnitude of fluctuations in the rotation speed of the cylinder discrimination sensor 51 of the camshaft 30 and the crankshaft rotation speed sensor-50. That is, if there is a cylinder that is not ignited, the fluctuation of the rotation speed is small, and a cylinder that is ignited has a large fluctuation of the rotation speed. If there is a cylinder that is not ignited, the process proceeds to step 13A, and if there is no cylinder that is not ignited, that is, if all cylinders are ignited, the process proceeds to step 19.

At step 13A, the cylinder number is confirmed by the detection signal of the cylinder discrimination sensor 51 for confirming the unfired cylinder number. In step 14B, the injection of the front three cylinders or the rear three cylinders including the unfired cylinders is stopped. For example, when the first cylinder is the non-fired cylinders, the injection of the first cylinder, the second cylinder, and the third cylinder is stopped. Has stopped the injection. In step 19, if there is no cylinder that has not been ignited as compared with step 12A, that is, if all cylinders are ignited, the injection on the preset side of the front three cylinders or the rear three cylinders is stopped, and the next step 16
Go to.

In step 16, it is determined whether the measured engine speed NE is the same as or lower than the lower limit value N3 of the target rotational speed for self-sustaining operation. When it is less than the lower limit value, the process proceeds to step 15, and when it is less than the lower limit value, the process proceeds to step 17. Step 15 issues an instruction to increase the injection command value, increase the injection amount, and increase the rotation speed, and then execute step 1 again.
Proceed to 6. In step 17, the measured engine speed N
It is determined whether E is equal to or less than the upper limit value N4 of the target rotational speed for self-sustaining operation. If it is less than or equal to the upper limit, proceed to Step 10 again, and if it exceeds the upper limit, go to Step 18
Go to. In step 18, a command for lowering the injection command value, for decreasing the injection amount, and for lowering the rotation 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. Step 1 if the reduced cylinder operation is in progress
2B, and when the reduced cylinder operation is not in progress, the process proceeds to step 13B. In step 12B, the injection of the cylinder that has stopped the injection is started. In step 13B, normal control is performed and all cylinders are injected to perform normal control. Finished in step 20.

[0019]

As described above, according to the present invention,
At start-up, the injection timing and injection amount are initialized according to the water temperature,
After inputting the engine speed, the cylinder that ignited first is detected, and the injection timing and injection amount of the subsequent cylinders are controlled by the water temperature and engine speed for each cylinder.
Following the first ignition of the cylinder, the ignition sequence will be reliable and accurate, the time until the complete explosion of all cylinders will be blown up, and the starting operation will not be repeated, so the startability can be improved. Further, at a low temperature, to reduce the amount of white smoke emitted immediately after starting, in the fuel injection control method of the diesel engine, which sequentially supplies fuel to each cylinder, and controls the injection timing and injection amount of each cylinder, A predetermined two groups are formed according to the ignition sequence of the cylinders, the unignited cylinders are discriminated, and the fuel supply to the groups of the 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 that there is no unburned fuel and the groups of other ignited cylinders have a fuel injection amount per cylinder of approximately 2 As the combustion temperature becomes higher, the amount of unburned fuel decreases, the amount of white smoke emission can be reduced, and the excellent effect of shortening the time until white smoke disappears can be obtained. To be

[Brief description of drawings]

FIG. 1 is a flowchart showing the starting of a method for controlling a fuel injection device according to the present invention.

FIG. 2 is a diagram illustrating complete explosion and self-sustaining operation from engine startup.

FIG. 3 is a diagram illustrating a relationship among a water temperature, an injection amount, and an injection timing.

FIG. 4 is a diagram illustrating a relationship between a rotation speed, an injection amount, and an injection timing.

FIG. 5 is a diagram illustrating a relationship between time and rotation speed fluctuation.

FIG. 6 is a flowchart showing how to reduce the amount of white smoke emitted by the method of controlling the fuel injection device according to the present invention.

FIG. 7 shows an overall system diagram of an electronically controlled unit injector fuel injection device for an engine.

FIG. 8 is a diagram illustrating a relationship between pulse waveforms generated from a crank shaft 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 camshaft 40 control unit 43 accelerator pedal 50 crankshaft rotation speed sensor 51 cylinder discrimination sensor 53 engine water temperature sensor

Claims (2)

[Claims] 1. A fuel injection control method for controlling a fuel injection timing and an injection amount for each cylinder according to a water temperature at the time of starting a diesel engine, and at the time of starting, detecting a cylinder that is ignited for the first time. A method for controlling a fuel injection device, comprising: controlling a command for changing an injection timing and an injection amount to cylinders that are sequentially ignited in accordance with an engine rotation speed and a water temperature. 2. A fuel injection for a diesel engine in which fuel is sequentially supplied to each cylinder to control the injection timing and injection amount of each cylinder in order to reduce the amount of white smoke emitted immediately after starting at low temperature. In the control method of the apparatus, a predetermined two group is formed according to the cylinder ignition sequence, and the unignited cylinder is determined,
A method for controlling a fuel injection device, characterized in that the supply of fuel to a group of cylinders that does not ignite is stopped.