JP2003003896A - Accumulated pressure type fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulated pressure type fuel injection control device capable of realizing an engine torque corresponding to a driver's accelerator operation to smoothly operate an engine without having an uncomfortable feeling. SOLUTION: Based on the changing amount of an accelerator opening Acc, the torque change amount ΔT required by the driver is calculated (step S124). Then, a predicted torque change amount ΔT' is calculated by adding, to the above mount ΔT, the amount caused by the change of a high pressure side common rail pressure PHP, injection timing I, fuel pressure switch timing (t) and low pressure side common rail pressure PLP (step S126 to 132). In the case where the predicted torque change amount ΔT' exceeds or is deficient comparing with the required amount ΔT, the fuel pressure switch timing (t) is reset (step S136), and thereby the former matches the latter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulation type fuel injection control device for injecting high pressure fuel stored in a pressure accumulation chamber from a fuel injection nozzle according to opening / closing of a fuel injection control valve. The present invention relates to a technique for setting a fuel injection timing, a fuel pressure in a pressure accumulating chamber, and the like, which are control factors that influence.

[0002]

2. Related Background Art In this type of pressure accumulation type fuel injection control device, fuel is pressurized by a supply pump and stored in a pressure accumulation chamber, and high pressure fuel in the pressure accumulation chamber is opened and closed according to the opening and closing of a fuel injection control valve. It is configured to eject from. The energization time of the fuel injection control valve is set to a value that can achieve the target fuel injection amount set from the accelerator opening and the engine speed, but the actual fuel injection amount is the rail pressure (fuel pressure in the pressure accumulator). Therefore, control is performed in consideration of the rail pressure. Specifically, the injection timing and rail pressure are set from the target fuel injection amount and the engine rotation speed, the opening / closing timing of the fuel injection control valve is controlled based on the set injection timing, and the rail pressure is set based on the set rail pressure. Control the discharge pressure of the supply pump.

[0003]

In the conventional pressure-accumulation type fuel injection control device, since the injection timing and the rail pressure are independently set with respect to the energization time of the fuel injection control valve as described above, the accelerator opening is performed. There was a case where the engine torque according to the degree could not be obtained. That is, even if the energization time that correlates with the accelerator opening is set via the target fuel injection amount, the injection timing and rail pressure are set at a timing different from the setting timing of the energization time at this time, so these injections are performed. Changes in timing and rail pressure affect the actual amount of fuel injection, resulting in changes in engine torque. This phenomenon cannot be dealt with by prior matching, and as a result, there is a problem that, for example, a problem such as an increase or decrease in engine torque in a direction opposite to the direction in which the accelerator opening changes occurs, and the driver feels uncomfortable. It was

An object of the present invention is to provide a pressure-accumulation type fuel injection control device which always realizes an engine torque according to a driver's accelerator operation and can smoothly operate the engine without feeling a sense of discomfort.

[0005]

In order to achieve the above object, in the invention of claim 1, the pressure chamber for storing high-pressure fuel and the fuel chamber are connected to the pressure chamber via a fuel passage to transfer the fuel to the combustion chamber of the engine. A fuel injection nozzle for injecting fuel into the fuel storage chamber, a fuel injection control valve for controlling the injection amount and injection timing of the fuel from the fuel injection nozzle, the fuel injection control valve being arranged to inject the fuel stored in the pressure accumulating chamber from the fuel injection nozzle. An operating state detecting means for detecting at least the accelerator opening and the engine speed as the operating state, a fuel injection timing setting means for setting a fuel injection timing based on information from the operating state detecting means, and a transition of the operating state of the engine. Based on the information from the injection timing torque change amount calculating means for calculating the torque change amount of the engine according to the change in the set injection timing, and the information from the operating state detecting means, A fuel pressure setting means for setting the fuel pressure, a fuel pressure torque change amount calculating means for calculating the torque change amount of the engine according to a change in the set fuel pressure accompanying a transition of the operating state of the engine, and an accelerator in the operating state detecting means. A required torque change amount calculation means for calculating the change amount of the engine torque from the change amount of the opening degree, the sum of the value calculated by the injection timing torque change amount calculation means and the value calculated by the fuel pressure torque change amount calculation means. , The control means for adjusting and controlling the fuel injection timing or the fuel pressure in the pressure accumulating chamber so that the value becomes the value calculated by the required torque change amount calculating means.

Therefore, the fuel injection from the fuel injection nozzle is started when the fuel injection control valve is opened, and the fuel injection is ended when the fuel injection control valve is closed. Here, when the operating state of the engine is in the process of changing, the injection timing and the fuel pressure based on the target fuel injection amount deviate from the values actually required, and as a result, the engine torque fluctuates.

Here, the fuel injection timing is set by the fuel injection timing setting means, the fuel pressure in the pressure accumulating chamber is set by the fuel pressure setting means, and the set injection timing and the set fuel pressure are used to shift the operating state of the engine. When there is a change, the change amount of the engine torque corresponding to the change is calculated by the injection timing torque change amount calculating means and the fuel pressure torque change amount calculating means.

Then, the fuel injection timing or the fuel injection timing is controlled by the control means so that the sum of these engine torque changes becomes the engine torque change calculated from the accelerator opening change by the required torque change calculation means. The fuel pressure in the accumulator is regulated and controlled. That is, the sum of the amounts of change in the engine torque means the amounts of change in the engine torque that are predicted to occur due to changes in the fuel injection timing and the fuel pressure in the pressure accumulator, while the sum of the amounts of change in the required torque change amount calculation means The calculated value means the amount of change in engine torque required by the driver. Therefore, as a result of the adjustment control by the control means, the engine torque according to the accelerator operation of the driver is always realized.

Further, according to the invention of claim 2, a first pressure accumulating chamber for storing high-pressure fuel, and a fuel injection nozzle for injecting fuel into the combustion chamber of the engine, connected to the first pressure accumulating chamber via a fuel passage. , A switching valve for controlling the discharge of the high-pressure fuel in the first pressure accumulation chamber to the downstream side of the fuel passage, and a fuel passage downstream of the switching valve connected via a branch passage so that fuel lower than the high-pressure fuel in the first pressure accumulation chamber is discharged. A second pressure accumulating chamber that stores the fuel, a fuel injection control valve that is arranged to inject fuel in the fuel passage from the fuel injection nozzle, and controls the injection amount and injection timing of the fuel from the fuel injection nozzle, and the operating state of the engine. At least the operating state detecting means for detecting the accelerator opening and the engine speed, the fuel injection timing setting means for setting the fuel injection timing based on the information from the operating state detecting means, and the transition of the operating state of the engine. An injection timing torque change amount calculating means for calculating the torque change amount of the engine according to the change of the set injection timing, and a fuel pressure setting means for setting the fuel pressure in the first pressure accumulating chamber based on the information from the operating state detecting means. , Based on information from a first fuel pressure torque change amount calculating means for calculating an amount of torque change of the engine according to a change in the set fuel pressure in the first pressure accumulating chamber due to a change in the operating state of the engine, and information from the operating state detecting means. First injection waveform setting means for setting the fuel pressure in the second pressure accumulating chamber, and second for calculating the torque change amount of the engine according to the change in the set fuel pressure in the second pressure accumulating chamber due to the transition of the operating state of the engine. Fuel pressure torque change amount calculating means, second injection waveform setting means for setting the operation timing of the switching valve based on information from the operating state detecting means, and switching valve accompanying transition of the operating state of the engine Changeover valve operation timing torque change amount calculating means for calculating the torque change amount of the engine according to the change of the set operation timing, and required torque change for calculating the engine torque change amount from the change amount of the accelerator opening in the operating state detecting means. Amount calculation means, a value calculated by the injection timing torque change amount calculation means, a value calculated by the first fuel pressure torque change amount calculation means, a value calculated by the second fuel pressure torque change amount calculation means, and switching The sum of the values calculated by the valve operation timing torque change amount calculation means is
The control means adjusts and controls the operation timing of the switching valve so that the value is calculated by the required torque change amount calculation means.

Therefore, when the fuel injection control valve is opened with the switching valve closed, the low-pressure fuel from the second pressure accumulating chamber is injected from the fuel injection nozzle, and when the operation timing of the switching valve comes, the switching is performed. The valve is opened, the high-pressure fuel from the first pressure accumulator is injected from the fuel injection nozzle, and then the fuel injection control valve is closed to end the fuel injection. As a result, low-pressure fuel injection is performed prior to high-pressure fuel injection, and the amount of fuel injected before ignition is reduced.Combustion in the initial stage of the fuel injection period is accompanied by a decrease in premixed combustion amount. Becomes relatively slow, and the NOx amount in the exhaust gas and the noise during operation can be reduced.

Here, when the operating state of the engine is in the process of changing, the injection timing, the fuel pressure in the first pressure accumulating chamber and the second pressure accumulating chamber, and the operation timing of the switching valve deviate from the actually required values, and as a result, The engine torque will be changed. Here, the fuel injection timing is set by the fuel injection timing setting means, the fuel pressure in the first pressure accumulation chamber is set by the fuel pressure setting means, and the fuel pressure in the second pressure accumulation chamber is set by the first injection waveform setting means. , The operation timing of the switching valve is the second
When the set injection timing, the set fuel pressure, and the set operating timing are changed by the transition of the operating state of the engine, the change amount of the engine torque corresponding to the change is calculated. Means, first fuel pressure torque change amount calculation means, second fuel pressure torque change amount calculation means, switching valve operation timing torque change amount calculation means.

Then, the control means actuates the switching valve so that the sum of these engine torque variations becomes the engine torque variation calculated from the accelerator opening variation by the required torque variation calculation means. Timing is adjusted and controlled. That is, the sum of the changes in the engine torque is the amount of change in the engine torque that is predicted to occur due to changes in the fuel injection timing, the fuel pressures in the first pressure accumulating chamber and the second pressure accumulating chamber, and the operating timing of the switching valve. On the other hand, the calculated value of the required torque change amount calculating means means the change amount of the engine torque requested by the driver. Therefore, as a result of the adjustment control by the control means, the engine torque according to the accelerator operation of the driver is always realized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] Claim 1
1st Embodiment which materialized the pressure accumulation type fuel injection control apparatus of the invention of this invention is demonstrated. FIG. 1 is an overall configuration diagram showing a pressure-accumulation type fuel injection control device of this embodiment, and the fuel injection control device 1 is provided in a diesel engine (not shown). The supply pump 2 of the fuel injection control device 1 is driven by the engine to pump up and pressurize the fuel in the fuel tank 3. The supply pump 2 is, for example, a positive displacement plunger pump, and the effective section of the pressure feeding stroke is changed according to the opening / closing timing of a solenoid valve (not shown), whereby the fuel discharge pressure is adjusted.

The fuel pressurized by the supply pump 2 is stored in a pressure accumulating chamber (common rail) 4 common to each cylinder, and the pressure accumulating chamber 4 communicates with a fuel passage 5. Fuel passage 5
Is branched into each cylinder of the engine and is connected to a control chamber 7 and a fuel chamber 8 in a fuel injection nozzle 6 provided in each cylinder. The control chamber 7 is connected with an on-off valve 9 (fuel injection control valve) for injection timing control, which is composed of, for example, a two-way solenoid valve, and the on-off valve 9 is connected to the fuel tank 3 via a return passage 10. .

The fuel injection nozzle 6 has a nozzle hole 1
1 has a needle valve 12 for opening and closing, and a hydraulic piston 13 movably arranged in the control chamber 7.
Is biased toward the nozzle hole 11 by a spring (not shown). In addition, 14 and 15 are orifices. Therefore, when the fuel from the fuel passage 5 is supplied to the control chamber 7 and the fuel chamber 8 of the fuel injection nozzle 6 and the opening / closing valve 9 is closed, the resultant force of the spring biasing force and the fuel pressure in the control chamber 7 is It acts on the needle valve 12 via the hydraulic piston 13, and the needle valve 12 closes the nozzle hole 11 against the fuel pressure in the fuel chamber 8. On the other hand, when the opening / closing valve 9 is opened, the fuel in the control chamber 7 is drained to the fuel tank 3 via the orifice 15 and the return passage 10. Therefore, the fuel pressure in the control chamber 7 decreases, and the fuel pressure in the fuel chamber 8 causes the needle valve 12 to move toward the hydraulic piston 13 side against the biasing force of the spring to open the nozzle hole 11, The fuel in the chamber 8 is injected from the nozzle hole 11.

On the other hand, an ECU (electronic control unit) 21 for controlling the pressure-accumulation type fuel injection control device of this embodiment.
Is a storage device (ROM, RAM, BU) for storing input / output devices (not shown), control programs, control maps, and the like.
RAM, etc.), a central processing unit (CPU), a timer counter, etc. On the input side of the ECU 21, a pressure sensor 2 for detecting a rail pressure P which is a pressure in the pressure accumulating chamber 4.
2. Various sensors such as an engine rotation speed sensor 23 (operating state detecting means) for detecting the engine rotation speed Ne and an accelerator opening sensor 24 (operating state detecting means) for detecting accelerator opening (accelerator pedal depression amount) Acc Various devices such as the supply pump 2 and the opening / closing valve 9 are connected to the output side.

The ECU 21 drives and controls the on-off valve 9 based on the fuel injection start timing and the injection end timing which are determined from the energization time T of the on-off valve 9 and the injection timing I which are set as will be described later. Fuel injection is executed in the rectangular wave injection pattern of. That is, until the fuel injection start timing arrives, the ECU 21 keeps the on-off valve 9 closed and causes the fuel pressure in the control chamber 7 to act on the needle valve 12 to close the nozzle hole 11. There is. At the fuel injection start timing, the on-off valve 9 is opened to reduce the fuel pressure in the control chamber 7,
The nozzle hole 11 is opened by the needle valve 12, and fuel injection is started. After that, when the fuel injection end timing is reached, the on-off valve 9 is closed to raise the fuel pressure in the control chamber 7 again, and the nozzle hole 11 is closed by the needle valve 12 to end the fuel injection.

Then, when the engine tail operation state is in the process of changing, the injection timing I and the rail pressure P of the pressure accumulating chamber 4 deviate from the values actually required, and as a result, the engine torque fluctuates. . FIG. 2 is a flowchart showing a procedure for setting each control factor by the ECU 21 during fuel injection control. As shown in this figure, first, the ECU
21. In step S2, the accelerator opening Acc and the engine rotation speed Ne are fetched, and in step S4, a target fuel injection amount Q is set from a map (not shown) based on the accelerator opening Acc and the engine rotation speed Ne. In the following step S6, the energization time T of the on-off valve 9 that can achieve the target fuel injection amount Q is set in consideration of various conditions such as the rail pressure P and the temperature. On the other hand, in step S8, the target fuel injection amount Q is set.
Based on the engine rotational speed Ne and the injection timing I is set from a map (not shown) (fuel injection timing setting means).
Then, in step S10, a correction process of the injection timing I described later is executed, and based on the fuel injection start timing and the injection end timing obtained from the corrected injection timing I and the energization time T, as described above in step S12. The on-off valve 9 is drive-controlled.

In parallel with this, the ECU 21 executes the step S
In step 14, the target rail pressure tgtP is set from a map (not shown) based on the target fuel injection amount Q and the engine speed Ne (fuel pressure setting means), and in step S16, based on the rail pressure P detected by the pressure sensor 22. The fuel discharge pressure of the supply pump 2 is adjusted to control the fuel pressure in the pressure accumulating chamber 4 to the target rail pressure tgtP.

FIG. 3 is a flow chart showing the details of the injection timing correction process. When the process of step S10 is started, the ECU 21 proceeds to step S22 of FIG. 3 and takes in the accelerator opening Acc and the engine rotation speed Ne,
In step S24, the required torque change amount ΔT is set from the map based on the accelerator opening Acc and the engine rotation speed Ne (requested torque change amount calculation means). The required torque change amount ΔT is the accelerator opening A between the previous processing and the current processing.
It is set as the amount of change in engine torque corresponding to the amount of change in cc, and means the amount of torque change required by the driver.

Next, at step S26, based on the change in the rail pressure P between the previous processing and the current processing, the torque change amount Δ expected to occur due to this rail pressure change Δ.
Tp is calculated from the map (fuel pressure torque change amount setting means). Similarly, in step S28, based on the change in the injection timing I between the previous process and the present process, the torque change amount ΔTt predicted to occur due to this injection timing change is calculated from the map (injection timing torque Change amount setting means).

In step S30, the torque change amount ΔT
p, ΔTt are added to calculate the predicted torque change amount ΔT ′,
In the following step S32, it is determined whether the predicted torque change amount ΔT ′ is equal to the required torque change amount ΔT. Judgment is NO
In the case of (negative), the process proceeds to step S34 and the injection timing I is reset. The resetting process in this case is performed according to the map characteristics shown in step S28 in the figure, and when the predicted torque change amount ΔT 'is lower than the required torque change amount ΔT, the injection timing I advances by a predetermined value. When the predicted torque change amount ΔT ′ is higher than the required torque change amount ΔT, the injection timing I is reset to the retard side by a predetermined value.

After that, returning to the step S28, the torque change amount ΔTt is calculated using the value reset as the injection timing I of this process, and then the steps S30 and S32 are executed. By repeating the above steps S28 to S34, the predicted torque change amount ΔT ′ matches the required torque change amount ΔT, and YES in step S32.
The determination is affirmative and the routine ends (control means).

As described above, in the pressure-accumulation type fuel injection control device of this embodiment, the required torque change amount ΔT required by the driver is calculated based on the change amount of the accelerator opening Acc.
A predicted torque change amount ΔT ′ predicted to occur due to changes in the rail pressure P and the injection timing I is calculated, and when the predicted torque change amount ΔT ′ is excessive or insufficient with respect to the required torque change amount ΔT, injection is performed. By resetting the timing I, the predicted torque change amount ΔT ′ matches the required torque change amount ΔT. Therefore, the engine torque according to the driver's accelerator operation is always realized, and the engine can be smoothly driven without a feeling of discomfort.

[Second Embodiment] Next, a second embodiment of the pressure-accumulation type fuel injection control apparatus according to the present invention will be described. The difference of this embodiment from the first embodiment is that
By using fuel supply from two pressure accumulating chambers having different rail pressures, the injection pattern shown in FIG. 5 in which the fuel injection rate at the initial stage of injection is suppressed is realized. Therefore, the description of the common components is omitted, and the differences are mainly described.

FIG. 4 is an overall configuration diagram showing the pressure accumulation type fuel injection control device of the present embodiment. A switching valve 3 for switching the fuel injection rate, which is, for example, a two-way solenoid valve, is provided in the middle of the fuel passage 5.
1 is provided for each cylinder, and a check valve 32 is provided immediately downstream of the switching valve 31. Directly downstream of the check valve 32, a branch passage 33 branches into the fuel passage 5, and the branch passage 33 is connected to the fuel tank 3. Branch passage 3
A check valve 34 and an orifice 35 are connected in parallel to the valve 3, and a low pressure accumulating chamber 36 and a pressure control valve 37 are provided on the fuel tank 3 side of these members 34 and 35.

Therefore, when the fuel pressure in the fuel passage 5 is higher than the pressure in the branch passage 33, the fuel in the fuel passage 5 gradually flows into the low pressure accumulator chamber 36 via the orifice 35 and the branch passage 33. The low pressure accumulator 36 (second
In the present embodiment, the pressure accumulating chamber 4 on the fuel passage 5 side is a high pressure accumulating chamber (first accumulating chamber), and the high pressure rail pressure PHP in the high pressure accumulating chamber 4 is detected on the input side of the ECU 21. In addition to the pressure sensor 22 that operates, a pressure sensor 38 that detects the low-pressure rail pressure PLP in the low-pressure accumulator 36 is connected.

The ECU 21 injects fuel in the injection pattern shown in FIG. 5, and in order to realize this injection pattern, the on-off valve 9, the switching valve 31, and the pressure control valve 37 are drive-controlled in the following order. The ECU 21 holds both the open / close valve 9 and the switching valve 31 in the closed state until the fuel injection start timing arrives. Therefore, the low pressure fuel is supplied from the low pressure accumulation chamber 36 to the fuel passage 5 on the downstream side of the switching valve 31, and the low pressure fuel is supplied to the control chamber 7 and the fuel chamber 8 of the fuel injection nozzle 6.
Is being supplied to. In this state, since the opening / closing valve 9 is closed, the needle valve 12 receives the fuel pressure in the control chamber 11.
Closes the nozzle hole 11.

At the fuel injection start timing, the ECU 21 opens only the open / close valve 9. Since the low pressure fuel in the control chamber 7 is drained through the orifice 15 and the return passage 10, the fuel pressure in the control chamber 7 decreases. As a result, the needle valve 1
2, the nozzle hole 11 is opened, low-pressure fuel is injected, and the initial injection with a relatively small fuel injection rate is started.
When the fuel pressure switching timing t, which will be described later, is reached after the initial injection is started, the switching valve 31 is held with the opening / closing valve 9 held in the open state.
Open. Therefore, the high-pressure fuel is supplied into the fuel chamber 8 and is injected from the nozzle hole 11, and the main injection having a relatively high fuel injection rate is switched.

After that, when the fuel injection end timing is reached, the EC
U21 closes the on-off valve 9. The fuel pressure in the control chamber 7 rises again, the nozzle hole 11 is closed by the needle valve 12, and the fuel injection ends. In parallel with this, the ECU 2
Reference numeral 1 drives the pressure control valve 37 to gradually return the fuel flowing from the fuel passage 5 to the low pressure accumulation chamber 36 through the orifice 35 to the fuel tank 3 while changing the fuel pressure in the low pressure accumulation chamber 36 to a target low pressure rail described later. Hold at pressure tgt PLP. The switching valve 31 is closed at the same time as the closing of the on-off valve 9 or after a predetermined time.

When the engine operating condition is in the process of changing, the injection timing I, the high pressure and low pressure rail pressures PHP, PL
P, the fuel pressure switching timing t deviates from the actually required value,
As a result, the engine torque is changed. FIG. 6 is a flowchart showing a procedure for setting each control factor by the ECU 21 during fuel injection control. In the present embodiment, the correction process for the injection timing I in step S10 is omitted, and the processes after step S102 are added in order to realize the injection pattern of FIG. 5 described above. More specifically, the ECU 21 drives and controls the on-off valve 9 in step S12 based on the energization time T and the injection timing I,
The supply pump 2 is driven and controlled in step S16 based on the target high rail pressure tgtPHP, while in step S10.
In step 2, setting processing of the waveform control factor is performed. The waveform control factor in this case means the above-described target low-pressure rail pressure tgtPLP and fuel pressure switching timing t, and in step S102, these values are set based on the target fuel injection amount Q and the engine rotation speed Ne, respectively. (First injection waveform setting means, second injection waveform setting means).

After that, in step S104, the correction processing of the waveform control factor, which will be described later, is executed, and the subsequent step S106.
Then, the fuel injection control is executed based on the corrected waveform control factor. That is, as described above, the switching valve 31 is switched when the fuel pressure switching time t is reached to switch the fuel injection from low pressure to high pressure, while the pressure control valve 37 is driven when the fuel injection end timing is reached. The rail pressure PLP of the low pressure accumulator 36 is adjusted to the target low pressure rail pressure tgtPLP in preparation for the next initial injection.

FIG. 7 is a flow chart showing details of the waveform control factor correction processing. When the process of step S104 is started, the ECU 21 proceeds to step S122 of FIG. 7 and starts from step S22 of FIG. 3 described in the first embodiment.
Similar to step 28, the accelerator opening Acc and the engine speed Ne are fetched in step S122, and step S124
The required torque change amount ΔT is set by the driver (requested torque change amount calculation means), and the torque change amount ΔTp due to the change in the high-pressure rail pressure PHP is calculated from the map in step S126 (first fuel pressure torque change amount). (Setting means), in step S128, the torque change amount ΔTt due to the change of the injection timing I is calculated from the map (injection timing torque change amount setting means).

In the following step S130, it is caused by the change of these waveform control factors based on the change of the waveform control factors (fuel pressure switching timing t and low pressure rail pressure PLP) between the previous process and the present process. An expected torque change amount ΔTr is calculated from a map (switching valve operation timing torque change amount setting means, second fuel pressure torque change amount setting means). In step S132, the torque change amounts ΔTp, ΔTt, Δ
The predicted torque change amount ΔT ′ is calculated by adding Tr, and it is determined in the following step S134 whether the predicted torque change amount ΔT ′ is equal to the required torque change amount ΔT. Judgment is NO
In the case of (negative), the flow shifts to step S136 to reset the fuel pressure switching timing t. The resetting process in this case is performed according to the map characteristic shown in step S130 in the figure, and when the predicted torque change amount ΔT ′ is lower than the required torque change amount ΔT, the fuel pressure switching timing t is a predetermined value. When the predicted torque change amount ΔT ′ is higher than the required torque change amount ΔT, the fuel pressure switching timing t is reset to the retard side by a predetermined value. By repeating the above steps S130 to 136, the predicted torque change amount ΔT ′ matches the required torque change amount ΔT (control means).

Incidentally, the reason why the predicted torque change amount ΔT 'is adjusted by resetting the fuel pressure switching timing t while keeping the low-pressure rail pressure PLP at the set value in this way is that the NOx reduction obtained by the initial injection is reduced. This is because the low-pressure rail pressure PLP has a higher contribution to the noise reduction effect and is more important. As described above, in the pressure accumulation type fuel injection control device of the present embodiment,
Since the low-pressure initial injection is performed prior to the high-pressure main injection based on the injection pattern of FIG. 5, the amount of fuel injected before ignition is reduced, and the fuel injection period is reduced as the premixed combustion amount decreases. Combustion in the early stages is relatively slow. As a result, the amount of NOx in the exhaust gas can be reduced and the noise during operation can be reduced.

In order to realize such an injection pattern, for example, the injection timing I and the rail pressure P (high pressure rail pressure P) applied to the rectangular wave injection pattern of the first embodiment are used.
In addition to HP), it becomes necessary to control the fuel pressure switching time t relating to waveform control and the low pressure rail pressure PLP. as a result,
In the conventional method that only sets each control factor independently,
The engine torque that correlates with the accelerator opening Acc is more difficult to obtain than in the first embodiment.

On the other hand, in this embodiment, the required torque change amount ΔT required by the driver is calculated based on the change amount of the accelerator opening Acc, while the high and low rail pressures PH are set.
The predicted torque change amount ΔT ′ generated due to changes in P, PLP, the injection timing I, and the fuel pressure switching timing t is calculated, and the predicted torque change amount ΔT ′ is excessive or insufficient with respect to the required torque change amount ΔT. In this case, the predicted pressure change amount ΔT ′ is made equal to the required torque change amount ΔT by resetting the fuel pressure switching time t. Therefore, the engine torque according to the driver's accelerator operation is always realized, and the engine can be smoothly driven without a feeling of discomfort.

Although the embodiment has been described above, the aspect of the present invention is not limited to this embodiment. Therefore, for example, the circuit configuration shown in FIGS. 1 and 4 of the first and second embodiments, or the fuel injection amount Q shown in FIGS.
You may change the setting procedure, such as. In the first embodiment, the rail pressure P is kept at the set value and the injection timing I is reset to adjust the predicted torque change amount ΔT '. However, conversely, the injection timing I is kept at the set value. The rail pressure P may be reset.

[0039]

As described in detail above, according to the pressure-accumulation fuel injection control apparatus of the invention of claim 1, the engine torque change amount required by the driver is calculated based on the change amount of the accelerator opening. On the other hand, the torque change amount according to the change of the fuel injection timing and the fuel pressure in the pressure accumulating chamber is calculated, and the injection timing or the fuel pressure in the pressure accumulating chamber is adjusted so as to match the two. The engine torque can be realized according to the operation, so that the engine can be operated smoothly without any discomfort.

Further, according to the pressure-accumulation type fuel injection control device of the present invention, since the low-pressure fuel injection is performed prior to the high-pressure fuel injection, the combustion is slowed in the initial stage of the fuel injection period. As a result, NOx in exhaust gas and noise during operation can be reduced, and the engine torque change amount required by the driver is calculated based on the accelerator opening change amount, while the fuel injection timing and the first pressure accumulation are calculated. Since the amount of torque change corresponding to the change in fuel pressure in the chamber and the second accumulator and the change in the operation timing of the switching valve is calculated and the operation timing of the switching valve is adjusted so as to match the two, the driver's accelerator is always operated. The engine torque can be realized according to the operation, so that the engine can be operated smoothly without any discomfort.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a pressure accumulation type fuel injection control device of a first embodiment.

FIG. 2 is a flowchart showing a procedure for setting each control factor by the ECU during fuel injection control.

FIG. 3 is a flowchart showing details of an injection timing correction process.

FIG. 4 is an overall configuration diagram showing a pressure accumulation type fuel injection control device of a second embodiment.

FIG. 5 is a time chart showing an injection pattern by the pressure accumulation type fuel injection control device of the second embodiment.

FIG. 6 is a flowchart showing a procedure for setting each control factor by the ECU during fuel injection control.

FIG. 7 is a flowchart showing details of waveform control factor correction processing.

[Explanation of symbols]

4 High-pressure accumulator (first accumulator) 5 Fuel passage 6 Fuel injection nozzle 9 Open / close valve (fuel injection control valve) 23 Rotational speed sensor (operating state detecting means) 24 Accelerator opening sensor (operating state detecting means) 31 Switching valve 33 branch passage 36 low pressure accumulator (second accumulator) 21 ECU (fuel injection timing setting means, fuel pressure setting means, first injection waveform setting means, second injection waveform setting means, injection timing torque change amount setting means , Fuel pressure torque change amount setting means, first fuel pressure torque change amount setting means, second fuel pressure torque change amount setting means, switching valve operation timing torque change amount setting means, required torque change amount setting means, control means)

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 37/00 311 F02M 37/00 311J 47/00 47/00 P 47/02 47/02 (72) Inventor Kei Tanabe 5-3-33 Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Minehiro Murata F-term, 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (reference) 3G066 AA07 AB02 AC09 BA00 BA19 CB16 CE22 DA06 DC01 DC04 DC08 DC18 3G301 HA02 HA04 HA06 JA03 KA06 KA23 LB11 LB13 MA11 MA18 MA28 NA06 NA08 NB02 NB03 NC04 ND02 NE01 NE06 NE11 NE12 PB08A PB08Z PE01Z PF03Z

Claims (2)

[Claims] 1. A pressure accumulation chamber for storing high-pressure fuel, a fuel injection nozzle connected to the pressure accumulation chamber via a fuel passage for injecting fuel into a combustion chamber of an engine, and a fuel accumulated in the pressure accumulation chamber. A fuel injection control valve that is arranged to inject fuel from the fuel injection nozzle and that controls the injection amount and injection timing of fuel from the fuel injection nozzle; and at least an accelerator opening degree and an engine rotation speed as operating conditions of the engine. According to a change in the set injection timing accompanying the transition of the operating state of the engine, the operating state detecting means for detecting, the fuel injection timing setting means for setting the fuel injection timing based on the information from the operating state detecting means. An injection timing torque change amount calculating means for calculating the torque change amount of the engine, and a fuel pressure in the pressure accumulating chamber based on information from the operating state detecting means are set. And a fuel pressure torque change amount calculating means for calculating a torque change amount of the engine according to a change in the set fuel pressure accompanying a transition of the operating state of the engine, Required torque change amount calculation means for calculating the change amount of the engine torque from the change amount of the accelerator opening, the value calculated by the injection timing torque change amount calculation means, and the value calculated by the fuel pressure torque change amount calculation means And a control means for adjusting and controlling the fuel injection timing or the fuel pressure in the pressure accumulating chamber so that the sum of the above is equal to the value calculated by the required torque change amount calculating means. Injection control device. 2. A first pressure accumulation chamber for storing high-pressure fuel, a fuel injection nozzle which is connected to the first pressure accumulation chamber via a fuel passage and injects fuel into a combustion chamber of an engine, and the first pressure accumulation chamber. And a switching valve for controlling the discharge of the high-pressure fuel to the downstream side of the fuel passage, and a fuel passage that is connected to the fuel passage downstream of the switching valve via a branch passage, and stores fuel lower than the high-pressure fuel in the first pressure accumulating chamber. A second pressure accumulating chamber, a fuel injection control valve that is arranged to inject the fuel in the fuel passage from the fuel injection nozzle, and controls the injection amount and injection timing of the fuel from the fuel injection nozzle; An operating state detecting means for detecting at least an accelerator opening and an engine speed as an operating state; a fuel injection timing setting means for setting a fuel injection timing based on information from the operating state detecting means; An injection timing torque change amount calculating means for calculating the torque change amount of the engine according to the change of the set injection timing accompanying the transition of the operating state of the engine, and the first pressure accumulation chamber based on information from the operating state detecting means. Fuel pressure setting means for setting the fuel pressure of the engine, and a first fuel pressure torque change for calculating the torque change amount of the engine according to the change of the set fuel pressure in the first pressure accumulator chamber due to the transition of the operating state of the engine. An amount calculation means, a first injection waveform setting means for setting a fuel pressure in the second pressure accumulation chamber based on information from the operation state detection means, and a second injection pressure accumulation chamber in the second pressure accumulation chamber due to a transition of the operating state of the engine. Second fuel pressure torque change amount calculation means for calculating a torque change amount of the engine according to a change in set fuel pressure, and the switching valve of the switching valve based on information from the operating state detection means. A second injection waveform setting means for setting a dynamic timing, and a switching valve operating timing torque change for calculating a torque change amount of the engine according to a change in a set operating timing of the switching valve accompanying a transition of an operating state of the engine. An amount calculation means, a required torque change amount calculation means for calculating a change amount of the engine torque from a change amount of the accelerator opening in the operating state detection means, a value calculated by the injection timing torque change amount calculation means, 1 The sum of the value calculated by the fuel pressure torque change amount calculation means, the value calculated by the second fuel pressure torque change amount calculation means, and the value calculated by the switching valve operation timing torque change amount calculation means, And a control means for adjusting and controlling the operation timing of the switching valve so that the value is calculated by the required torque change amount calculating means. Injection control device.