JP7127256B2 - fuel injection controller - Google Patents

Description

The present disclosure relates to fuel injection control devices.

For example, Patent Document 1 discloses a fuel injection control device that includes a circuit that generates an energization detection signal whose signal level is inverted between a period in which a current is flowing through an injector and a period in which a current is not flowing through the injector. An injection control system is described. Then, in the fuel injection control device described in Patent Document 1, it is determined whether or not the fuel injection by the injector is normal based on the energization detection signal output from the circuit.

JP 2013-36344 A

In the fuel injection control device described in Patent Document 1, when the signal level of the energization detection signal is fixed to high or low, the execution state of fuel injection by the injector cannot be known, and the engine output is lower than normal. Since there is a risk of the fuel injection becoming excessively large, there was no choice but to forcibly stop the fuel injection. For this reason, there is a possibility that an unnecessary injection stop procedure, that is, the fuel injection is stopped even when the engine output is not excessively large.

Therefore, the present disclosure provides a technology for suppressing unnecessary injection stop processing in a fuel injection control device when the level of an energization detection signal indicating whether or not an injector is energized is fixed. .

The fuel injection control device of the present disclosure includes a drive instruction section (31, 48, S130) and a monitoring section (31, 49, S110, S120, S140 to S240).
The drive instruction unit causes the drive units (32, 33) to drive the plurality of injectors (11 to 13) in a predetermined order for a fuel injection time required to make the output torque of the engine equal to the required torque, which is the target torque. and output a plurality of driving instructions corresponding to each of the plurality of injectors .

An energization detection signal output from the detection unit (56) is input to the monitoring unit. The detection unit outputs the energization detection signal by detecting the presence or absence of current flowing through the plurality of injectors as a result of the drive unit driving the plurality of injectors according to the plurality of drive instructions. The energization detection signal output by the detection unit is at an active level during a period when a current is flowing through any of the plurality of injectors, and is at a non-active level during a period when no current is flowing through any of the plurality of injectors. is a signal.

The monitoring unit includes a sticking determination unit (S170), a first processing unit (S180), and a second processing unit (S110, S120, S140 to S160, S190 to S240).
The fixation determination unit determines whether or not the level of the energization detection signal changes within a predetermined time period from when the output of the drive instruction by the drive instruction unit is started and when the output of the drive instruction is finished. It is determined whether or not the level of the detection signal has stuck to either the active level or the non-active level .

The first processing unit sets the level of the energization detection signal to the active level when the fixation determination unit determines that the level of the energization detection signal is not stuck to either the active level or the non-active level. The actual torque, which is the torque output by the engine, is estimated based on the active duration, which is the duration of time at the level . Specifically, the first processing unit estimates the actual torque such that the longer the active duration, the larger the estimated value of the actual torque. Then, when determining that the estimated actual torque is greater than the required torque by a predetermined value or more, the first processing unit causes the driving unit to stop driving the plurality of injectors.

The second processing unit stores fuel supplied to the plurality of injectors when the fixation determination unit determines that the level of the energization detection signal is fixed to either the active level or the non-active level. The actual torque is estimated based on the reservoir pressure, which is the pressure of the fuel in the reservoir (26), and the number of revolutions of the engine .
Specifically, for each of the plurality of injectors, the second processing unit detects, as the pre-injection pressure, the reservoir pressure at a timing before the drive instruction is output by the drive instruction unit, and a function (S120, S140) of detecting, as a post-injection pressure, the reservoir pressure at a timing at which a predetermined time after the end of the output of the drive instruction is assumed to end the fuel injection of the injector; The number of rotations before the drive instruction unit starts outputting the drive instruction corresponding to a specific injector, which is any one of the injectors, is detected as a first number of rotations, and the first number of rotations is detected. After detecting the number of injectors, the number of rotations after output of all the drive instructions corresponding to the plurality of injectors is terminated by the drive instruction section is detected as a second number of rotations (S110, S160). and when the fixation determination unit determines that the level of the energization detection signal is fixed to either the active level or the non-active level, the injection detected for each of the plurality of injectors The amount of decrease for each of the plurality of injectors based on the amount of decrease in the post-injection pressure with respect to the front pressure and the amount of increase in rotation speed, which is the amount of increase in the second rotation speed with respect to the first rotation speed. The actual torque is estimated so that the estimated value of the actual torque increases as the number of revolutions increases and as the rotational speed increase amount increases.
Then, the second processing unit causes the drive unit to stop driving the plurality of injectors when determining that the estimated actual torque is greater than the required torque by the predetermined value or more .
Further, the second processing unit calculates the amount of decrease based on the total amount of decrease in the post-injection pressure relative to the pre-injection pressure detected for each of the plurality of injectors and the amount of increase in the rotational speed. The actual torque may be estimated such that the larger the total value or the larger the rotational speed increase, the larger the estimated value of the actual torque.

According to such a configuration, even if the level of the energization detection signal input from the detection section to the monitoring section is fixed, the second processing section can control the estimated actual torque to be higher than the required torque by a predetermined value or more. If it is not determined to be large, driving of the plurality of injectors is not stopped. Therefore, when the level of the energization detection signal is fixed, it is possible to prevent unnecessary injection stop measures from being performed.

It should be noted that the symbols in parentheses described in this column and the scope of claims indicate the correspondence with specific means described in the embodiment described later as one aspect, and the technical scope of the present disclosure is It is not limited.

1 is a block diagram showing the configuration of an engine control system according to an embodiment; FIG. 4 is a flowchart showing torque monitoring processing performed by a microcomputer; It is a time chart explaining an example of an operation of an embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. Constitution]
An electronic control unit (ECU) 1 of the embodiment shown in FIG. 1 is a device that controls an engine mounted on a vehicle. In this embodiment, the engine to be controlled is a three-cylinder diesel engine. ECU is an abbreviation of "Electronic Control Unit".

The ECU 1 is connected to three injectors 11, 12 and 13 provided for each of the three cylinders of the engine. In this example, the injector 11 is provided in the first cylinder, the injector 12 is provided in the second cylinder, and the injector 13 is provided in the third cylinder.

Each of the injectors 11 to 13 is opened by being energized by the ECU 1 and injects fuel into the cylinder corresponding to the injector. Energizing the injectors 11-13 specifically means energizing the electromagnetic coils provided in the injectors 11-13. Also, energizing the injectors 11-13 corresponds to driving the injectors 11-13.

Furthermore, a crank angle sensor 21, a cam angle sensor 22, a common rail pressure sensor 23, and an accelerator sensor 24 are connected to the ECU 1.
The common rail pressure sensor 23 outputs a voltage signal corresponding to the pressure of fuel (hereinafter referred to as rail pressure) in a common rail 26 as a storage portion in which the fuel to be supplied to the injectors 11 to 13 is stored. Rail pressure corresponds to reservoir pressure. Fuel is pumped to the common rail 26 from a fuel tank of the vehicle by a high-pressure pump. The high-pressure pump is controlled so that the rail pressure becomes the target pressure. Fuel is then supplied from the common rail 26 to the injectors 11-13. As the injectors 11 to 13 inject fuel, the rail pressure temporarily decreases, but the high-pressure pump pumps fuel to the common rail 26 and the rail pressure returns to the target pressure. On the other hand, the accelerator sensor 24 outputs a voltage signal corresponding to the amount of operation of the accelerator pedal by the driver of the vehicle (hereinafter referred to as accelerator opening).

The ECU 1 includes a microcomputer (hereinafter referred to as microcomputer) 31 , an ASIC 32 , a drive circuit 33 and an input circuit 34 . ASIC is an abbreviation for "Application Specific Integrated Circuit", that is, an application specific integrated circuit.

A signal output from the crank angle sensor 21 (hereinafter referred to as a crank angle signal) and a signal output from the cam angle sensor 22 (hereinafter referred to as a cam angle signal) are waveform-shaped into rectangular waves by an input circuit 34, and then processed by a microcomputer. 31.

A signal output from the common rail pressure sensor 23 (hereinafter referred to as a rail pressure signal) and a signal output from the accelerator sensor 24 (hereinafter referred to as an accelerator opening signal) are input to the microcomputer 31 via, for example, a low-pass filter circuit (not shown). be done. The rail pressure signal and the accelerator opening signal are A/D converted by an A/D converter 41 provided in the microcomputer 31 . The microcomputer 31 detects the rail pressure and the accelerator opening from the A/D conversion result by the A/D converter 41 .

Drive request signals SD1 to SD3, which are signals requesting driving of the injectors 11 to 13, are output from the microcomputer 31 to the ASIC 32. FIG. The drive request signal SD1 corresponds to the injector 11 of the first cylinder, the drive request signal SD2 corresponds to the injector 12 of the second cylinder, and the drive request signal SD3 corresponds to the injector 13 of the third cylinder. The drive request signals SD1 to SD3 are signals that are set to an active level during the period for driving the corresponding injector, and are set to an inactive level during the other periods. The active levels of the drive request signals SD1 to SD3 are high level in this embodiment, but may be low level.

A common path 50 common to the three injectors 11 to 13 and individual paths 51, 52, and 53 for each of the injectors 11 to 13 are connected to the drive circuit 33 as current paths for energizing the injectors 11 to 13. It is The common path 50 is an energization path upstream of the injectors 11-13, and the individual paths 51-53 are energization paths downstream of the injectors 11-13.

The drive circuit 33 includes a first high-side switch for applying a boosted voltage higher than the power supply voltage to the common path 50, a second high-side switch for applying the power supply voltage to the common path 50, and an individual path. and three downstream switches for connecting each of 51-53 to the ground line.

When any one of the drive request signals SD1 to SD3 becomes high level, the ASIC 32 outputs a signal for turning on the first high-side switch to the drive circuit 33, and turns on one of the three downstream switches. Outputs a signal to turn on the downstream switch corresponding to the target injector. Therefore, a large current (hereinafter referred to as peak current) in the initial stage of driving flows through the injector to be driven due to the application of the boosted voltage. Here, the injector to be driven is the injector corresponding to the high-level drive request signal among the injectors 11 to 13 .

When the ASIC 32 determines that the current flowing through the injector to be driven has reached a predetermined value, the ASIC 32 stops outputting the signal for turning on the first high-side switch. After that, the ASIC 32 controls the drive circuit 33 so that a constant current smaller than the peak current flows through the injector to be driven until the drive request signal, which has become a high level, becomes a low level. 2 Outputs a signal to turn on/off the high-side switch.

When the high level drive request signal becomes low level, the ASIC 32 stops outputting the signal for turning on/off the second high side switch and also stops outputting the signal for turning on the downstream side switch.

The drive circuit 33 is provided with a current detection resistor 55 that generates a voltage proportional to the current flowing through any one of the injectors 11-13. Based on the voltage generated by the current detection resistor 55, the ASIC 32 detects the value of the current flowing through any one of the injectors 11-13.

Further, the ASIC 32 is provided with an energization detection section 56 . The energization detection unit 56 detects the presence or absence of current flowing through the injectors 11 to 13 based on the voltage generated by the current detection resistor 55, and outputs to the microcomputer 31 an energization detection signal SI indicating the detection result. The energization detection signal SI is at an active level during a period when a current is flowing through any of the injectors 11-13, and is at a non-active level during a period when no current is flowing through any of the injectors 11-13. The active level of the energization detection signal SI is low level in this embodiment, but may be high level.

The ASIC 32 and the driving circuit 33 correspond to a driving section that drives the injectors 11 to 13 according to driving instructions. The energization detector 56 corresponds to a detector. The energization detector 56 may be provided outside the ASIC 32 .

The microcomputer 31 includes, in addition to the A/D converter 41, a CPU 42 and a semiconductor memory (hereinafter referred to as memory) 43 such as RAM, ROM, and flash memory. Various processes by the microcomputer 31 are realized by the CPU 42 executing a program stored in a non-transitional substantive recording medium. In this example, the memory 43 corresponds to a non-transitional substantive recording medium storing programs. Also, by executing this program, a method corresponding to the program is executed. The number of microcomputers provided in the ECU 1 may be one or plural.

The microcomputer 31 includes a rotation speed calculation unit 45, a rail pressure calculation unit 46, an accelerator opening calculation unit 47, a demand torque calculation unit 48, and a monitoring unit as functions realized by the CPU 42 executing a program. a portion 49; The method of realizing the functions of these units 45 to 49 is not limited to software, and some or all of the functions may be realized using one or more pieces of hardware. For example, when the above functions are realized by an electronic circuit that is hardware, the electronic circuit may be realized by a digital circuit including many logic circuits, an analog circuit, or a combination thereof.

Based on the crank angle signal and the cam angle signal whose waveforms have been shaped by the input circuit 34, the rotation speed calculation unit 45 calculates the rotation speed of the engine (hereinafter referred to as engine rotation speed) and determines the crank position. Calculation of the engine speed by the rotation speed calculation unit 45 corresponds to detection of the engine speed.

The rail pressure calculator 46 calculates the rail pressure from the A/D conversion result of the rail pressure signal by the A/D converter 41 . Calculation of the rail pressure by the rail pressure calculator 46 corresponds to detection of the rail pressure.

The accelerator opening calculator 47 calculates the accelerator opening from the A/D conversion result of the accelerator opening signal by the A/D converter 41 . Calculation of the accelerator opening by the accelerator opening calculator 47 corresponds to detection of the accelerator opening.

The engine speed calculated by the speed calculation unit 45, the rail pressure calculated by the rail pressure calculation unit 46, and the accelerator opening calculated by the accelerator opening calculation unit 47 are used by the required torque calculation unit 48. be done. Also, the engine speed calculated by the speed calculation unit 45 and the rail pressure calculated by the rail pressure calculation unit 46 are used by the monitoring unit 49 .

The requested torque calculation unit 48 calculates a requested torque, which is a target torque to be output from the engine, based on the engine speed and the accelerator opening. Further, the required torque calculation unit 48 calculates the fuel injection amount for making the output torque of the engine equal to the required torque for each cylinder, in other words, for each injector 11 to 13. The injection time is converted based on the rail pressure. In other words, the required torque calculator 48 calculates the injection time of fuel from each of the injectors 11 to 13 required to achieve the required torque. Calculating the injection time corresponds to determining the injection time.

Then, the required torque calculator 48 outputs drive request signals SD1 to SD3 to the ASIC 32 based on the calculated injection times of the injectors 11 to 13. FIG. The required torque calculator 48 sets the drive request signal SD1 to a high level for the injection time calculated for the injector 11, and sets the drive request signal SD2 to a high level for the injection time calculated for the injector 12. The same applies to the drive request signal SD3.

For this reason, drive instructions for driving the injectors 11 to 13 for the injection times calculated for the injectors 11 to 13 are output from the microcomputer 31 to the ASIC 32 as high-level drive request signals SD1 to SD3. The high-level drive request signals SD1-SD3 are hereinafter also referred to as drive instructions for the injectors 11-13. The injection times of the injectors 11 to 13 are not calculated individually, but may be calculated as the same value in one cycle of the engine, for example.

The monitoring unit 49 receives the energization detection signal SI output by the energization detection unit 56 of the ASIC 32, the engine rotation speed calculated by the rotation speed calculation unit 45, and the rail pressure calculated by the rail pressure calculation unit 46. is entered. Then, the monitoring unit 49 performs at least the following first monitoring process.

<<First monitoring process>>
The monitoring unit 49 detects the time when the energization detection signal SI becomes low level (hereinafter referred to as low time), and estimates the actual torque of the engine based on the detected low time. Since the low time of the energization detection signal SI represents the time when the fuel is injected from the injectors 11 to 13, the actual torque can be estimated by substituting the low time into, for example, a calculation formula or a data map. The longer the low time of the energization detection signal SI, the larger the estimated value of the actual torque. Furthermore, the monitoring unit 49 determines whether or not the estimated actual torque is greater than the required torque by a predetermined value or more. When the monitoring unit 49 determines that the estimated actual torque is greater than the required torque by a predetermined value or more, the monitoring unit 49 determines that an unintended torque increase has occurred, and outputs a drive stop command to the ASIC 32. to forcibly stop the driving of the injectors 11 to 13.

When the drive stop command is input, the ASIC 32 turns off all the switches provided in the drive circuit 33 regardless of the drive request signals SD1 to SD3. Also, the actual torque is the torque that the engine actually outputs. Further, unintended torque increase means that the output torque of the engine becomes larger than the torque assumed for control.

By the way, if the level of the energization detection signal SI is stuck at the high level or the low level, the actual torque cannot be estimated in the first monitoring process.
Therefore, if the monitoring unit 49 only performs the first monitoring process, when the level of the energization detection signal SI is fixed, it cannot be determined whether or not an unintended torque increase has occurred. The only way to prevent the increase is to stop driving the injectors 11-13. However, the driving of the injectors 11 to 13 is stopped even though an unintended torque increase does not actually occur, that is, the fuel injection to the engine is stopped. there is a possibility.

Therefore, in this embodiment, when the monitoring unit 49 determines that the level of the energization detection signal SI is not fixed, the first monitoring process is performed. When it is determined that it is stuck, the following second monitoring process is performed.

<<Second monitoring process>>
The monitoring unit 49 estimates the actual torque based on the engine speed and the rail pressure, and determines whether or not the estimated actual torque is greater than the required torque by a predetermined value or more. When the monitoring unit 49 determines that the estimated actual torque is greater than the required torque by a predetermined value or more, the monitoring unit 49 determines that an unintended torque increase has occurred, and outputs a drive stop command to the ASIC 32 .

[2. process]
A torque monitoring process performed by the microcomputer 31 to function at least as the monitoring unit 49 will be described with reference to FIG. It should be noted that the order of fuel injection in each cylinder will be described as "first cylinder→third cylinder→second cylinder". In the torque monitoring process of FIG. 2, any one of the injectors 11 to 13 is regarded as the reference injector for torque estimation, and the injector 11 is assumed to be the reference injector.

In the torque monitoring process of FIG. 2, after the drive request signal SD2 corresponding to the injector 12, one ahead of the injector 11 in the execution order of fuel injection, is set to low level, the drive request signal SD1 corresponding to the injector 11 is set to high level. It is started at a predetermined timing until the level is reached. Specifically, the torque monitoring process is started at a timing that is a predetermined time before the timing at which the drive request signal SD1 is made high level. This predetermined time is the time required for the processes of S110 and S120, which will be described later, and is very short. Therefore, it can be said that the torque monitoring process is started at the timing immediately before the drive request signal SD1 is changed to the high level.

As shown in FIG. 2, when the torque monitoring process is started, the microcomputer 31 detects the current engine speed in S110. Specifically, the microcomputer 31 performs processing as the rotation speed calculation unit 45 and acquires the calculation result of the engine rotation speed by the processing. The engine speed acquired in S110 is the engine speed immediately before the instruction to drive the injector 11 is output from the microcomputer 31 to the ASIC 32, that is, immediately before the drive request signal SD1 is set to high level. Further, the engine speed detected in S110 corresponds to the engine speed at the start timing of the monitoring target period in one cycle of the engine. The term "monitoring period" as used herein is a period for determining whether or not the output torque of the engine has increased, and is also a period for estimating the actual torque. Below, the engine speed detected in S110 is referred to as the first speed.

The microcomputer 31 detects the current rail pressure in next S120. Specifically, the microcomputer 31 performs processing as the rail pressure calculation unit 46 and acquires the calculation result of the rail pressure by the processing.

In the next S130, the microcomputer 31 outputs a drive instruction for the injector to be driven next among the injectors 11-13. In S130, which is executed first after the torque monitoring process is started, an instruction to drive the injector 11 is output. In S130, which is executed for the second time after the torque monitoring process is started, an instruction to drive the injector 13 is output. A drive instruction is output. Note that the processing of S130 is processing corresponding to a part of the required torque calculation unit 48 .

When the microcomputer 31 finishes outputting the drive instruction in S130, that is, when any one of the drive request signals SD1 to SD3 that has been high level is set to low level, in the next S140, after waiting for a predetermined time Ta, the microcomputer 31 Detects rail pressure. The predetermined time Ta is set to an assumed value of the delay time from the termination of the output of the drive instruction to the termination of the fuel injection of the injector. Therefore, in S140, the rail pressure is detected at the timing when it is assumed that the fuel injection of the injector has ended.

In the next step S150, the microcomputer 31 determines whether or not the output of drive instructions for all the injectors 11 to 13 has ended. In this example, it is determined whether or not the output of the drive instruction for the injector 12 has ended.

If the microcomputer 31 makes a "NO" determination in S150, that is, if there is an injector among the injectors 11 to 13 that has not yet output a drive instruction, the microcomputer 31 returns to S120. Therefore, in S120, the rail pressure immediately before the drive instruction for each injector 11-13 is output, that is, the rail pressure immediately before each injector 11-13 starts fuel injection is detected. Further, in S140, the rail pressure is detected at the timing when it is assumed that the fuel injection of each injector 11-13 is completed. Hereinafter, for each injector 11 to 13, the rail pressure detected at S120 is referred to as pre-injection pressure, and the rail pressure detected at S140 is referred to as post-injection pressure. If the injector 11 actually injects fuel, the post-injection pressure of the injector 11 will be smaller than the pre-injection pressure. This is the same for the other injectors 12 and 13 as well.

Further, if the microcomputer 31 determines "YES" in S150, that is, if the drive instruction output for all the injectors 11 to 13 is finished, the process proceeds to S160.
In S160, the microcomputer 31 waits until a predetermined time Tb has passed since the output of the instruction to drive the injector 12 was completed, and when the predetermined time Tb has passed, the engine speed is detected again. The predetermined time Tb is longer than the aforementioned predetermined time Ta, but is sufficiently longer than the time from the end of the output of the instruction to drive the injector 12 to the start of the output of the instruction to drive the injector 11 to be driven next. short to The engine speed detected in S160 corresponds to the engine speed at the end timing of the monitoring target period. Below, the engine speed detected in S160 is referred to as the second speed.

In next S170, the microcomputer 31 determines whether or not the level of the energization detection signal SI is fixed. For example, the microcomputer 31 changes the level of any one of the drive request signals SD1 to SD3 in S130. is determined to be stuck.

When the microcomputer 31 determines in S170 that the level of the energization detection signal SI is not fixed, the process proceeds to S180.
In S180, the microcomputer 31 performs the above-described first monitoring process, and then terminates the torque monitoring process. Incidentally, in the first monitoring process performed in S180, the actual torque is estimated based on the low time of the energization detection signal SI detected in synchronization with the output of the driving instruction of each injector 11-13. The process of detecting the low time is performed in parallel with the processes of S120 to S140, for example.

On the other hand, when the microcomputer 31 determines in S170 that the level of the energization detection signal SI is fixed, the microcomputer 31 performs the second monitoring process by performing the processes from S190 onward.
In S190, the microcomputer 31 determines whether or not the post-injection pressure detected in S140 is lower than the pre-injection pressure detected in S120 for all of the injectors 11-13. Specifically, the microcomputer 31 calculates a value obtained by subtracting the post-injection pressure from the pre-injection pressure as the rail pressure decrease amount, and determines whether or not the rail pressure decrease amount is equal to or greater than a predetermined value. If the amount of decrease is equal to or greater than the predetermined value, it is determined that the post-injection pressure has decreased relative to the pre-injection pressure. This determination is performed for each injector 11-13.

If the microcomputer 31 determines in S190 that the post-injection pressure is lower than the pre-injection pressure for all the injectors 11-13, it means that the fuel has been injected from all the injectors 11-13. Make a decision and proceed to S200.

In S200, the microcomputer 31 determines whether or not the second rotational speed detected in S160 is greater than the first rotational speed detected in S110.
Specifically, the microcomputer 31 calculates a value obtained by subtracting the second rotation speed from the first rotation speed as the rotation speed increase amount, and determines whether or not the rotation speed increase amount is equal to or greater than a predetermined value. If the rotation speed increase amount is equal to or greater than a predetermined value, it is determined that the second rotation speed is increasing with respect to the first rotation speed.

Then, when the microcomputer 31 determines in S200 that the second rotation speed has increased with respect to the first rotation speed, it determines that the output torque of the engine has increased, and proceeds to S210. . In this case, it is determined that the fuel has been injected from all of the injectors 11 to 13 by the determination in S190, and since an increase in the engine speed is confirmed in S200, fuel is not injected from the injectors 11 to 13. It is determined that the output torque of the engine has increased.

In S210, the microcomputer 31 estimates the actual torque of the engine based on the engine speed and the rail pressure.
Specifically, the microcomputer 31 substitutes the rail pressure decrease amount for each injector 11 to 13 calculated in S190 and the rotational speed increase amount calculated in S200 into, for example, a calculation formula or a data map. Calculate an estimate of torque. The calculation formula and data map for estimating the actual torque are set so that the estimated actual torque increases as the amount of decrease in rail pressure and the amount of increase in rotation speed for each injector 11 to 13 increases. It is This is because there is a correlation between the rail pressure reduction amount for each injector 11-13 and the fuel injection amount from each injector 11-13, and the rotation speed increase amount increases as the actual torque increases.

Incidentally, the rail pressure reduction amount for each injector 11 to 13 may be summed up and used for estimating the actual torque. Also, in S210, the current engine speed may be further used to estimate the actual torque. In this case, the second engine speed detected in S160 may be used as the current engine speed.

In next S220, the microcomputer 31 determines whether or not the actual torque estimated in S210 is greater than the required torque by a predetermined value or more. , it is determined that an unintended increase in torque has occurred, and the process proceeds to S230.

Then, in S230, the microcomputer 31 forcibly stops the driving of the injectors 11 to 13 by outputting a drive stop command to the ASIC 32, and then terminates the torque monitoring process. In other words, determining in S220 that the actual torque is greater than the required torque by a predetermined value or more corresponds to determining to stop driving the injectors 11-13.

Further, when the microcomputer 31 determines in S190 that the post-injection pressure has not decreased with respect to the pre-injection pressure for at least one of the injectors 11 to 13, the process proceeds to S240. Also, when the microcomputer 31 determines in S200 that the second rotation speed has not increased with respect to the first rotation speed, the process proceeds to S240. Also, when the microcomputer 31 determines in S220 that the actual torque is not greater than the required torque by a predetermined value or more, the process proceeds to S240.

In S240, the microcomputer 31 determines that an unintended torque increase has not occurred. Then, the microcomputer 31 terminates the torque monitoring process without stopping the driving of the injectors 11-13.

[3. Action example]
An operation example of the ECU 1 will be described with reference to FIG. In FIG. 3, "#1 current waveform" on the fourth level is the waveform of the current flowing through the injector 11, and "#3 current waveform" on the fifth level is the waveform of the current flowing through the injector 13. The “#2 current waveform” on the tier is the waveform of the current flowing through the injector 12 .

Since the order of fuel injection in each cylinder is "1st cylinder→3rd cylinder→2nd cylinder", the drive request signals SD1 to SD3 are made high in the order of "SD1→SD3→SD2".
When the drive request signal SD1 becomes high level at time t1, the drive circuit 33 causes the injector 11 to pass a peak current to open the injector 11 as shown at time t2. That is, the injector 11 starts injecting fuel. The time from time t1 to time t2 represents a hard delay.

At time t2, the current flow through the injector 11 is detected by the energization detector 56 of the ASIC 32, and as a result, the energization detection signal SI becomes low level.
After that, when the drive request signal SD1 becomes low level at time t3, the energization to the injector 11 is stopped and the injector 11 is closed at time t4, which is slightly later than this time. That is, the fuel injection of the injector 11 ends. At time t4, the energization detection signal SI returns to high level. The time between time t3 and time t4 also represents a hard delay.

On the other hand, since the injector 11 is opened at time t2, the rail pressure drops, but the high-pressure pump described above attempts to return the rail pressure to the target pressure. Therefore, the rail pressure decreases by a predetermined amount due to the valve opening of the injector 11, then gradually increases toward the target pressure, and returns to the target pressure after the injector 11 closes. Therefore, when the injector 11 opens and injects fuel, the rail pressure at time t4 corresponding to the post-injection pressure decreases with respect to the rail pressure at time t1 corresponding to the pre-injection pressure. The amount of decrease increases as the fuel injection amount increases. Further, if fuel injection leading to an increase in torque is performed, the engine speed will increase.

In each of injector 13 and injector 12, a state similar to the state shown from time t1 to time t4 appears.
Then, when the fuel injection of the injector 12 ends at time t5, the microcomputer 31 makes the determination of S170 in FIG. In this case, it is determined that the energization detection signal SI is not fixed, and the first monitoring process based on the energization detection signal SI is performed at S180 in FIG.

On the other hand, as shown at time t7, it is assumed that the energization detection signal SI is stuck at the low level while the drive request signal SD1 is at the high level.
At time t6 immediately before switching the drive request signal SD1 from low level to high level, the microcomputer 31 detects the engine speed (that is, the first speed) in S110 in FIG. , the rail pressure corresponding to the pre-injection pressure for the injector 11 is detected. Immediately after this, the microcomputer 31 makes the drive request signal SD1 high level.

Then, at time t8 after the predetermined time Ta has elapsed after switching the drive request signal SD1 from high level to low level, the microcomputer 31 determines the post-injection pressure of the injector 11 through S140 in FIG. Detects rail pressure.

Next, the microcomputer 31 detects the rail pressure corresponding to the pre-injection pressure of the injector 13 through S120 in FIG. 2 at time t9 immediately before the drive request signal SD3 is switched from low level to high level. Immediately after this, the microcomputer 31 makes the drive request signal SD3 high level.

Then, the microcomputer 31 switches the drive request signal SD3 from the high level to the low level, and at the time t10 after the above-described predetermined time Ta has elapsed, the microcomputer 31 performs S140 in FIG. Detects rail pressure.

Next, the microcomputer 31 detects the rail pressure corresponding to the pre-injection pressure of the injector 12 through S120 in FIG. 2 at time t11 immediately before the drive request signal SD2 is switched from low level to high level. Immediately after this, the microcomputer 31 makes the drive request signal SD2 high level.

Then, at time t12 after the predetermined time Ta has elapsed after switching the drive request signal SD2 from high level to low level, the microcomputer 31 determines the post-injection pressure of the injector 13 through S140 in FIG. Detects rail pressure.

After that, at S150 in FIG. 2, the microcomputer 31 determines that the output of drive instructions for all the injectors 11 to 13 has ended.
Then, at time t13 after the above-described predetermined time Tb has elapsed after switching the drive request signal SD2 from high level to low level, the microcomputer 31 performs S160 in FIG. number) again. The reason why the engine speed is detected when the predetermined time Tb has passed after the drive request signal SD2 is switched to the low level is to accurately detect the engine speed generated by driving the injector 12 .

After that, the microcomputer 31 determines in S170 in FIG. 2 that the level of the energization detection signal SI is stuck, and performs the processing from S190 in FIG.
If fuel is injected from each of the injectors 11 to 13 during the period from time t6 to time t13 (that is, the monitoring target period) and the engine speed increases, the microcomputer 31 performs S190 in FIG. "YES" is determined in both S200 and S200. In this case, the microcomputer 31 estimates the actual torque at S210 in FIG. 2 without using the energization detection signal SI. When the microcomputer 31 determines in S220 in FIG. 2 that the actual torque is greater than the required torque by a predetermined value or more, the microcomputer 31 stops the fuel injection, but the actual torque is not greater than the required torque by a predetermined value or more. If so, the fuel injection is continued.

[4. effect]
According to the embodiment detailed above, the following effects are obtained.
(1) When the microcomputer 31 determines that the level of the energization detection signal SI is stuck, it estimates the actual torque based on the rail pressure and the engine speed. Then, when the microcomputer 31 determines that the actual torque is greater than the required torque by a predetermined value or more, it stops driving the injectors 11 to 13 . On the other hand, even if the microcomputer 31 determines that the level of the energization detection signal SI is fixed, if it determines that the estimated actual torque is not greater than the required torque by a predetermined value or more, the injectors 11 to 13 Do not stop driving. Therefore, when the level of the energization detection signal SI is fixed, it is possible to prevent unnecessary injection stop measures from being performed.

(2) When the microcomputer 31 determines that the level of the energization detection signal SI is stuck, at S190 and S200 in FIG. has increased. Then, when it is determined that the output torque of the engine has increased, the actual torque is estimated at S210 in FIG.

Therefore, when there is a possibility that an unintended increase in torque has occurred, the actual torque can be estimated, and the processing load can be suppressed.
(3) In S200 in FIG. 2, the microcomputer 31 determines whether or not the second rotation speed is increasing with respect to the first rotation speed. The first rotation speed is the engine rotation speed before the output of the drive instruction corresponding to the injector 11 corresponding to the reference injector among the injectors 11 to 13 is started. The second rotation speed is the engine rotation speed after the output of all the drive instructions corresponding to the injectors 11 to 13 has ended since the first rotation speed was detected. Then, the microcomputer 31 determines that the output torque of the engine has increased on the condition that it is determined that the second rotation speed has increased with respect to the first rotation speed.

Therefore, it is possible to improve the accuracy of determining whether or not the output torque of the engine has increased. This is because the second rotation speed does not become greater than the first rotation speed unless the output torque of the engine increases.

(4) For each of the injectors 11 to 13, the microcomputer 31 detects the rail pressure at the timing immediately before outputting the drive instruction as the pre-injection pressure. Further, the microcomputer 31 detects, as the post-injection pressure, the rail pressure at the timing when a predetermined time Ta, which is assumed to end the fuel injection of the injector after the end of outputting the drive command, has passed for each of the injectors 11 to 13. do. Then, in S190 in FIG. 2, the microcomputer 31 determines whether or not the post-injection pressure has decreased with respect to the pre-injection pressure for all of the injectors 11-13. The microcomputer 31 determines that the output torque of the engine has increased on the condition that the post-injection pressure for all of the injectors 11 to 13 has decreased relative to the pre-injection pressure.

Therefore, it is possible to improve the accuracy of determining whether or not the output torque of the engine has increased. The fact that the post-injection pressure is lower than the pre-injection pressure for all the injectors 11-13 is because it is presumed that the fuel is injected from all the injectors 11-13.

(5) At S210 in FIG. 2, the microcomputer 31 estimates the actual torque based on the amount of increase in the second rotational speed from the first rotational speed (that is, the amount of increase in the rotational speed). Therefore, the actual torque is estimated based on the amount of increase in the engine speed during one period in which all the injectors 11 to 13 inject fuel. Therefore, it is possible to improve the estimation accuracy of the actual torque.

(6) In S210 in FIG. 2, the microcomputer 31 estimates the actual torque based on the amount of decrease in the post-injection pressure relative to the pre-injection pressure (that is, the amount of rail pressure decrease) detected for each of the injectors 11 to 13. . Therefore, the actual torque is estimated based on information correlated with the fuel injection amount from each injector 11-13. Therefore, it is possible to improve the estimation accuracy of the actual torque.

In the above-described embodiment, the microcomputer 31 functioning as the required torque calculating section 48 corresponds to the driving instruction section, and the microcomputer 31 functioning as the monitoring section 49 corresponds to the monitoring section. Among the plurality of steps in FIG. 2, S110, S120, S140 to S240 correspond to the processing of the monitoring unit. Further, S170 corresponds to the processing of the fixation determination section, S180 corresponds to the processing of the first processing section, and S110, S120, S140 to S160, S190 to S240 correspond to the processing of the second processing section. Equivalent to processing.

[5. Other embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be made.

For example, in S200 in FIG. 2, it may be determined whether or not the amount of increase in engine rotation during a period of a plurality of engine cycles is equal to or greater than a predetermined value. Similarly, at S210 in FIG. 2, the actual torque may be estimated based on the amount of increase in engine speed over a period of multiple cycles of the engine. Also, the number of injectors is not limited to three, and may be one, two, or four or more. Also, a driving unit including the ASIC 32 and the driving circuit 33 may be provided separately from the ECU 1 .

Also, a plurality of functions possessed by one component in the above embodiment may be realized by a plurality of components, or a function possessed by one component may be realized by a plurality of components. Also, a plurality of functions possessed by a plurality of components may be realized by a single component, or a function realized by a plurality of components may be realized by a single component. Also, part of the configuration of the above embodiment may be omitted. It should be noted that all aspects included in the technical idea specified by the wording described in the claims are embodiments of the present disclosure.

In addition to the above-described ECU 1, a system having the ECU 1 as a component, a program for causing a computer to function as the ECU 1, a non-transitional actual recording medium such as a semiconductor memory in which the program is recorded, a fuel injection control method, etc. , the disclosure may be implemented in various forms.

DESCRIPTION OF SYMBOLS 1... ECU, 11-13... Injector, 26... Common rail, 31... Microcomputer, 32... ASIC, 33... Drive circuit, 48... Required torque calculation part, 49... Monitoring part, 56... Electricity detection part

Claims (4)

A plurality of drives for driving the plurality of injectors (11 to 13) in a predetermined order by the drive units (32, 33) for the fuel injection time required to make the output torque of the engine equal to the required torque, which is the target torque. a driving instruction unit (31, 48, S130) configured to output a plurality of driving instructions corresponding to each of the plurality of injectors ;
The drive unit drives the plurality of injectors according to the plurality of drive instructions, thereby detecting the presence or absence of current flowing through the plurality of injectors, thereby detecting the energization detection from a detection unit (56) that outputs a energization detection signal. A monitoring unit (31, 49, S110, S120, S140 to S240) to which a signal is input,
The energization detection signal output by the detection unit is at an active level during a period when current is flowing through any of the plurality of injectors, and is at an inactive level during a period when current is not flowing through any of the plurality of injectors. is a signal that
The monitoring unit
The level of the energization detection signal is determined by determining whether or not the level of the energization detection signal changes before a predetermined time elapses from each of the start and end of the output of the drive instruction by the drive instruction unit. is stuck to either the active level or the inactive level; and
When the fixation determination unit determines that the level of the energization detection signal is not fixed to either the active level or the non-active level, the level of the energization detection signal continues at the active level. Based on the active continuation time , which is time, the actual torque, which is the torque output by the engine, is estimated, and when it is determined that the estimated actual torque is greater than the required torque by a predetermined value or more, the drive unit and estimating the actual torque such that the longer the active duration time, the larger the estimated value of the actual torque. A first processing unit (S180) configured as
When the fixation determination unit determines that the level of the energization detection signal is fixed to either the active level or the non-active level, the fuel to be supplied to the plurality of injectors is stored in the storage unit. The actual torque is estimated based on the reservoir pressure, which is the fuel pressure, and the rotational speed of the engine, and when it is determined that the estimated actual torque is greater than the required torque by the predetermined value or more, a second processing unit (S110, S120, S140 to S160, S190 to S240) configured to stop driving of the plurality of injectors by the driving unit ;
The second processing unit is
For each of the plurality of injectors, the reservoir pressure at a timing before the drive command is output by the drive command unit is detected as a pre-injection pressure, and the injector is operated after output of the drive command is terminated. a function (S120, S140) of detecting the reservoir pressure at the timing after a predetermined time has elapsed when it is assumed that the fuel injection is finished, as the post-injection pressure;
The number of rotations before the drive instruction unit starts outputting the drive instruction corresponding to a specific injector, which is any one of the plurality of injectors, is detected as a first number of rotations; After detecting one number of rotations, the number of rotations after output of all the drive instructions corresponding to the plurality of injectors is terminated by the drive instruction unit is detected as a second number of rotations (S110 , S160) and
When the fixation determination unit determines that the level of the energization detection signal is fixed at either the active level or the non-active level, the pre-injection pressure detected for each of the plurality of injectors is Based on the decrease amount of the post-injection pressure and the rotation speed increase amount, which is the increase amount of the second rotation speed with respect to the first rotation speed, the greater the decrease amount for each of the plurality of injectors, the more Also, the actual torque is estimated so that the estimated value of the actual torque increases as the rotation speed increase amount increases (S210).
Fuel injection control device. A plurality of drives for driving the plurality of injectors (11 to 13) in a predetermined order by the drive units (32, 33) for the fuel injection time required to make the output torque of the engine equal to the required torque, which is the target torque. a driving instruction unit (31, 48, S130) configured to output a plurality of driving instructions corresponding to each of the plurality of injectors ;
The drive unit drives the plurality of injectors according to the plurality of drive instructions, thereby detecting the presence or absence of current flowing through the plurality of injectors, thereby detecting the energization detection from a detection unit (56) that outputs a energization detection signal. A monitoring unit (31, 49, S110, S120, S140 to S240) to which a signal is input,
The energization detection signal output by the detection unit is at an active level during a period when current is flowing through any of the plurality of injectors, and is at an inactive level during a period when current is not flowing through any of the plurality of injectors. is a signal that
The monitoring unit
The level of the energization detection signal is determined by determining whether or not the level of the energization detection signal changes before a predetermined time elapses from each of the start and end of the output of the drive instruction by the drive instruction unit. is stuck to either the active level or the inactive level; and
When the fixation determination unit determines that the level of the energization detection signal is not fixed to either the active level or the non-active level, the level of the energization detection signal continues at the active level. Based on the active continuation time , which is time, the actual torque, which is the torque output by the engine, is estimated, and when it is determined that the estimated actual torque is greater than the required torque by a predetermined value or more, the drive unit and estimating the actual torque such that the longer the active duration time, the larger the estimated value of the actual torque. A first processing unit (S180) configured as
When the fixation determination unit determines that the level of the energization detection signal is fixed to either the active level or the non-active level, the fuel to be supplied to the plurality of injectors is stored in the storage unit. The actual torque is estimated based on the reservoir pressure, which is the fuel pressure, and the rotational speed of the engine, and when it is determined that the estimated actual torque is greater than the required torque by the predetermined value or more, a second processing unit (S110, S120, S140 to S160, S190 to S240) configured to stop driving of the plurality of injectors by the driving unit ;
The second processing unit is
For each of the plurality of injectors, the reservoir pressure at a timing before the drive command is output by the drive command unit is detected as a pre-injection pressure, and the injector is operated after output of the drive command is terminated. a function (S120, S140) of detecting the reservoir pressure at the timing after a predetermined time has elapsed when it is assumed that the fuel injection is finished, as the post-injection pressure;
The number of rotations before the drive instruction unit starts outputting the drive instruction corresponding to a specific injector, which is any one of the plurality of injectors, is detected as a first number of rotations; After detecting one number of rotations, the number of rotations after output of all the drive instructions corresponding to the plurality of injectors is terminated by the drive instruction unit is detected as a second number of rotations (S110 , S160) and
When the fixation determination unit determines that the level of the energization detection signal is fixed at either the active level or the non-active level, the pre-injection pressure detected for each of the plurality of injectors is Based on the total amount of decrease in the post-injection pressure and the amount of increase in rotation speed, which is the amount of increase in the second rotation speed with respect to the first rotation speed, the larger the total amount of decrease, the more , the actual torque is estimated (S210) so that the estimated value of the actual torque increases as the rotational speed increase amount increases;
Fuel injection control device. The second processing unit is
When the fixation determination unit determines that the level of the energization detection signal is fixed at either the active level or the non-active level , all of the plurality of injectors have the injection pressure with respect to the pre-injection pressure. Determining whether or not the output torque of the engine has increased by determining whether or not the after pressure has decreased and the second rotation speed has increased with respect to the first rotation speed. Then (S190, S200), for all of the plurality of injectors, the post-injection pressure is reduced relative to the pre-injection pressure, and the second rotational speed is increased relative to the first rotational speed. When it is determined that the output torque of the engine has increased, the actual torque is estimated (S210).
The fuel injection control device according to claim 1 or 2 . The drive instruction unit
determining the injection duration based on the required torque, and outputting the plurality of drive instructions based on the determined injection duration;
The fuel injection control device according to any one of claims 1 to 3 .

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