JP3931952B2 - Accumulated fuel injection control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure-accumulation fuel injection control device that injects high-pressure fuel stored in a pressure accumulation chamber from a fuel injection nozzle in response to opening and closing of a fuel injection control valve, and more specifically, a fuel that is a control factor that affects the fuel injection amount The present invention relates to a technique for setting an injection timing, a fuel pressure in a pressure accumulation chamber, and the like.
[0002]
[Related background]
In this type of accumulator fuel injection control device, the fuel is pressurized by a supply pump and stored in the accumulator chamber, and the high-pressure fuel in the accumulator chamber is injected from the fuel injection nozzle according to the opening and closing of the fuel injection control valve. Has been. 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 accumulating chamber). Therefore, the control considering the rail pressure is performed. Specifically, the injection timing and rail pressure are set from the target fuel injection amount and the engine speed, and the opening and closing timing of the fuel injection control valve is controlled based on the injection timing after setting, and based on the rail pressure after setting. The supply pump discharge pressure is controlled.
[0003]
[Problems to be solved by the invention]
In the conventional accumulator 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, an engine torque corresponding to the accelerator opening can be obtained. There was no case. That is, even if the energization time correlated 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 set timing of the energization time at this time. Changes in the timing and rail pressure affect the actual fuel injection amount and change the engine torque. This phenomenon cannot be dealt with by prior matching, and as a result, there is a problem that the engine torque increases or decreases in the direction opposite to the change direction of the accelerator opening, which gives the driver a sense of incongruity. It was.
[0004]
An object of the present invention is to provide an accumulator fuel injection control device that always realizes an engine torque according to a driver's accelerator operation and can smoothly operate the engine without a sense of incongruity.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a pressure accumulating chamber that stores high-pressure fuel, a fuel injection nozzle that is connected to the pressure accumulating chamber via a fuel passage, and injects fuel into the combustion chamber of the engine, A fuel injection control valve arranged to inject the fuel stored in the chamber from the fuel injection nozzle, and controls the injection amount and timing of the fuel from the fuel injection nozzle; An operating state detecting means for detecting the rotational speed, a fuel injection timing setting means for setting the fuel injection timing based on information from the operating state detecting means, and a change in the set injection timing accompanying the transition of the operating state of the engine Fuel pressure setting for setting the fuel pressure in the pressure accumulating chamber based on information from the injection timing torque change amount calculating means for calculating the engine torque change amount and the operating state detecting means. Means, a fuel pressure torque change amount calculating means for calculating an engine torque change amount according to a change in the set fuel pressure associated with the transition of the engine operating state, and an engine torque from an accelerator opening change amount in the operating state detecting means. Required torque change amount calculating means for calculating the change amount of the engine, and the sum of the value calculated by the injection timing torque change amount calculating means and the value calculated by the fuel pressure torque change amount calculating means is the required torque change amount calculating 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 value calculated by
[0006]
Therefore, the fuel injection from the fuel injection nozzle is started with the opening of the fuel injection control valve, and the fuel injection is ended with the closing of the fuel injection control valve. Here, when the engine operating state is in the middle of changing, the injection timing and fuel pressure based on the target fuel injection amount deviate from the actually required values, and as a result, the engine torque is changed.
[0007]
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 these set injection timing and set fuel pressure change as the engine operating state shifts. Then, the change amount of the engine torque corresponding thereto is calculated by the injection timing torque change amount calculating means and the fuel pressure torque change amount calculating means, respectively.
[0008]
Then, the control means controls the fuel injection timing or the pressure accumulation chamber so that the sum of the engine torque changes becomes the engine torque change calculated from the accelerator opening change by the required torque change calculation means. The fuel pressure is adjusted and controlled. That is, the sum of the engine torque changes means the engine torque change that is expected to occur due to the fuel injection timing and the fuel pressure change in the pressure accumulating chamber. The calculated value means the amount of change in engine torque requested by the driver. Therefore, engine torque corresponding to the driver's accelerator operation is always realized as a result of the adjustment control by the control means.
[0009]
According to a second aspect of the present invention, a first pressure accumulation chamber for storing high-pressure fuel, a fuel injection nozzle that is connected to the first pressure accumulation chamber via a fuel passage and injects fuel into the combustion chamber of the engine, A switching valve that controls discharge of high-pressure fuel in the pressure accumulating chamber 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. 2 A pressure accumulating chamber, a fuel injection control valve arranged to inject fuel in the fuel passage from the fuel injection nozzle and controlling the injection amount and timing of fuel from the fuel injection nozzle, and at least the accelerator open as the engine operating state Operating state detecting means for detecting the engine speed and the engine speed, fuel injection timing setting means for setting the fuel injection timing based on information from the operating state detecting means, and setting injection accompanying the transition of the engine operating state An injection timing torque change amount calculating means for calculating an engine torque change amount according to a change in a period, a fuel pressure setting means for setting a fuel pressure in the first pressure accumulating chamber based on information from the operating state detecting means, First fuel pressure torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set fuel pressure in the first pressure accumulation chamber accompanying the shift of the operating state, and a second pressure accumulation based on information from the operating state detecting means First injection waveform setting means for setting the fuel pressure in the room, and second fuel pressure torque for calculating the amount of change in the engine torque in accordance with the change in the set fuel pressure in the second pressure accumulator chamber as the engine operating state shifts 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 at the time of setting operation of the switching valve accompanying the transition of the operating state of the engine Switching valve operating timing torque change amount calculating means for calculating the torque change amount of the engine according to the change of the engine, and required torque change amount calculating means for calculating the engine torque change amount from the accelerator opening change amount in the operating state detecting means A value calculated by the injection timing torque change amount calculating means, a value calculated by the first fuel pressure torque change amount calculating means, a value calculated by the second fuel pressure torque change amount calculating means, and the switching valve operating timing And control means for adjusting and controlling the operation timing of the switching valve so that the sum of the values calculated by the torque change amount calculating means becomes the value calculated by the required torque change amount calculating means.
[0010]
Therefore, when the switching valve is closed, the fuel injection control valve is opened, and the low pressure fuel from the second pressure accumulating chamber is injected from the fuel injection nozzle. The high pressure fuel from the first pressure accumulating chamber is injected from the fuel injection nozzle, and then the fuel injection control valve is closed to complete the fuel injection. As a result, low-pressure fuel injection is performed prior to high-pressure fuel injection, the amount of fuel injected before ignition is reduced, and combustion in the initial stage of the fuel injection period is accompanied by a decrease in the amount of premixed combustion. Becomes relatively slow, and a reduction in the amount of NOx in the exhaust gas and a reduction in noise during operation are achieved.
[0011]
Here, when the operating state of the engine is in the middle of change, the injection timing, the fuel pressure in the first pressure accumulation chamber and the second pressure accumulation chamber, and the operation timing of the switching valve deviate from the actually required values. As a result, the engine torque is reduced. Will change. 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 set by the second injection waveform setting means, and when the set injection timing, the set fuel pressure, and the set operation timing change with the transition of the engine operating state, the engine torque corresponding thereto is changed. The amount of change is calculated by the injection timing torque change amount calculating means, the first fuel pressure torque change amount calculating means, the second fuel pressure torque change amount calculating means, and the switching valve operating timing torque change amount calculating means.
[0012]
Then, the operation timing of the switching valve is adjusted 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. Be controlled. That is, the sum of the engine torque changes is predicted to be generated due to changes in the fuel injection timing, the fuel pressure in the first pressure accumulation chamber and the second pressure accumulation chamber, and the operation timing of the switching valve. On the other hand, the calculated value of the required torque change amount calculation means means the change amount of the engine torque requested by the driver. Therefore, engine torque corresponding to the driver's accelerator operation is always realized as a result of the adjustment control by the control means.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the pressure accumulation type fuel injection control device according to the first aspect of the invention is embodied will be described.
FIG. 1 is an overall configuration diagram showing an accumulator fuel injection control device of the present 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 the fuel in the fuel tank 3 and pressurize it. The supply pump 2 is composed of, for example, a positive displacement plunger pump, and the effective section of the pressure feed stroke is changed according to the opening / closing timing of a solenoid valve (not shown), thereby adjusting the fuel discharge pressure.
[0014]
The fuel pressurized by the supply pump 2 is stored in a pressure accumulation chamber (common rail) 4 common to each cylinder, and the pressure accumulation chamber 4 communicates with a fuel passage 5. The fuel passage 5 branches 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 to an on / off valve 9 (fuel injection control valve) for controlling injection timing, which is composed of, for example, a two-way solenoid valve, and the on / off valve 9 is connected to the fuel tank 3 through a return passage 10. .
[0015]
The fuel injection nozzle 6 includes a needle valve 12 that opens and closes the nozzle hole 11 and a hydraulic piston 13 that is movably disposed in the control chamber 7. The needle valve 12 is moved to the nozzle hole 11 by a spring (not shown). Is biased to the side. Reference numerals 14 and 15 denote 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 on-off valve 9 is closed, the resultant force of the urging force of the spring and the fuel pressure in the control chamber 7 is Acting on the needle valve 12 via the hydraulic piston 13, the needle valve 12 closes the nozzle hole 11 against the fuel pressure in the fuel chamber 8. On the other hand, when the on-off valve 9 is opened, the fuel in the control chamber 7 is drained to the fuel tank 3 through the orifice 15 and the return passage 10. Therefore, the fuel pressure in the control chamber 7 decreases, and the needle valve 12 moves toward the hydraulic piston 13 against the urging force of the spring by the fuel pressure in the fuel chamber 8 to open the nozzle hole 11, and the fuel The fuel in the chamber 8 is injected from the nozzle hole 11.
[0016]
On the other hand, an ECU (electronic control unit) 21 for controlling the accumulator fuel injection control device of the present embodiment is a storage device (ROM, RAM) provided for storage of an input / output device (not shown), a control program, a control map, and the like. , BURAM, etc.), a central processing unit (CPU), a timer counter, and the like. On the input side of the ECU 21, a pressure sensor 22 that detects a rail pressure P that is a pressure in the pressure accumulating chamber 4, an engine rotation speed sensor 23 (operation state detection means) that detects an engine rotation speed Ne, an accelerator opening (accelerator pedal). Various sensors such as an accelerator opening sensor 24 (operating state detecting means) for detecting Acc are connected, and various devices such as a supply pump 2 and an on-off valve 9 are connected on the output side. .
[0017]
The ECU 21 controls the driving of the on-off valve 9 based on the fuel injection start timing and the injection end timing determined from the energization time T and the injection timing I of the on-off valve 9 set as will be described later. The fuel injection is executed with the injection pattern. That is, until the fuel injection start timing comes, the ECU 21 keeps the on-off valve 9 closed, and closes the nozzle hole 11 by applying the fuel pressure in the control chamber 7 to the needle valve 12. Yes. At the fuel injection start timing, the on-off valve 9 is opened to lower the fuel pressure in the control chamber 7, the nozzle hole 11 is opened by the needle valve 12, and fuel injection is started. Thereafter, when the fuel injection end timing is reached, the on-off valve 9 is closed to increase the fuel pressure in the control chamber 7 again, the nozzle hole 11 is closed by the needle valve 12, and the fuel injection is ended.
[0018]
Here, when the engine tail operation state is in the middle of changing, the injection timing I and the rail pressure P of the pressure accumulating chamber 4 deviate from the actually required values, and as a result, the engine torque is changed.
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 takes in the accelerator opening Acc and the engine speed Ne in step S2, and in step S4, based on the accelerator opening Acc and the engine speed Ne, from the map (not shown) The fuel injection amount Q is set. In the subsequent 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 rail pressure P and temperature, while in step S8, the target fuel injection amount Q and Based on the engine speed Ne, the injection timing I is set from a map (not shown) (fuel injection timing setting means). Thereafter, a correction process for the injection timing I, which will be described later, is executed in step S10. 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 driven and controlled.
[0019]
In parallel with this, the ECU 21 sets a target rail pressure tgtP from a map (not shown) based on the target fuel injection amount Q and the engine speed Ne in step S14 (fuel pressure setting means), and in step S16, sets the target rail pressure tgtP. Based on the detected rail pressure P, 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.
[0020]
FIG. 3 is a flowchart showing details of the injection timing correction process. When the process of step S10 is started, the ECU 21 proceeds to step S22 in FIG. 3 and takes in the accelerator opening Acc and the engine speed Ne. In step S24, based on the accelerator opening Acc and the engine speed Ne, A required torque change amount ΔT is set from the map (requested torque change amount calculating means). The required torque change amount ΔT is set as the change amount of the engine torque corresponding to the change amount of the accelerator opening Acc between the previous process and the current process, and means the torque change amount requested by the driver.
[0021]
Next, in step S26, based on the change in the rail pressure P between the previous process and the current process, a torque change amount ΔTp that is expected to be generated due to this rail pressure change is calculated from the map (fuel pressure torque change). Quantity setting means). Similarly, based on the change in the injection timing I between the previous process and the current process in step S28, a torque change amount ΔTt that is predicted to be generated due to this injection timing change is calculated from the map (injection timing torque). Change amount setting means).
[0022]
In step S30, the torque change amounts ΔTp and ΔTt are added to calculate a predicted torque change amount ΔT ′. In subsequent step S32, it is determined whether the predicted torque change amount ΔT ′ is equal to the required torque change amount ΔT. When the determination is NO (No), 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. 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. If 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.
[0023]
Thereafter, returning to step S28, the torque change amount ΔTt is calculated using the value reset as the injection timing I of the current process, and then step S30 and step S32 are executed. By repeating the processes of steps S28 to S34 described above, the predicted torque change amount ΔT ′ coincides with the required torque change amount ΔT. In step S32, the determination is YES (positive), and the routine is ended (control means).
[0024]
As described above, in the accumulator fuel injection control device of the present embodiment, the required torque change amount ΔT requested by the driver is calculated based on the change amount of the accelerator opening Acc, while the change in the rail pressure P and the injection timing I is calculated. By calculating a predicted torque change amount ΔT ′ that is predicted to be generated due to the above, and when the predicted torque change amount ΔT ′ is excessive or insufficient with respect to the required torque change amount ΔT, by resetting the injection timing I, The predicted torque change amount ΔT ′ is matched with 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 operated smoothly without a sense of incongruity.
[0025]
[Second Embodiment]
Next, a second embodiment in which the pressure accumulation type fuel injection control device of the invention of claim 2 is embodied will be described. The difference of this embodiment with respect to the first embodiment is that the fuel supply from two pressure accumulating chambers having different rail pressures is used to realize the injection pattern shown in FIG. 5 in which the fuel injection rate at the initial stage of injection is suppressed. is there. Therefore, the description of the common components is omitted, and the differences are focused on.
[0026]
FIG. 4 is an overall configuration diagram showing the accumulator fuel injection control device of this embodiment. In the middle of the fuel passage 5, for example, a switching valve 31 for switching the fuel injection rate made up of a two-way electromagnetic valve is provided for each cylinder, and a check valve 32 is provided immediately downstream of the switching valve 31. A branch passage 33 is branched into the fuel passage 5 immediately downstream of the check valve 32, and the branch passage 33 is connected to the fuel tank 3. A check valve 34 and an orifice 35 are connected in parallel to the branch passage 33, 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.
[0027]
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 accumulating chamber 36 through the orifice 35 and the branch passage 33.
In contrast to the above-described low pressure accumulator chamber 36 (second accumulator chamber), in this embodiment, the accumulator chamber 4 on the fuel passage 5 side is a high pressure accumulator chamber (first accumulator chamber), and the high pressure accumulator chamber is on the input side of the ECU 21. In addition to the pressure sensor 22 that detects the high-pressure rail pressure PHP in 4, a pressure sensor 38 that detects the low-pressure rail pressure PLP in the low-pressure accumulation chamber 36 is connected.
[0028]
The ECU 21 injects fuel with the injection pattern shown in FIG. 5, and controls the on-off valve 9, the switching valve 31, and the pressure control valve 37 in the following order in order to realize this injection pattern.
Until the fuel injection start time arrives, the ECU 21 holds both the on-off valve 9 and the switching valve 31 in the closed state. Therefore, low pressure fuel is supplied from the low pressure accumulating chamber 36 to the fuel passage 5 on the downstream side of the switching valve 31, and this low pressure fuel is supplied to the control chamber 7 and the fuel chamber 8 of the fuel injection nozzle 6. In this state, since the on-off valve 9 is closed, the needle valve 12 closes the nozzle hole 11 by receiving the fuel pressure in the control chamber 11.
[0029]
At the fuel injection start timing, the ECU 21 opens only the on-off 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 nozzle hole 11 is opened by the needle valve 12, low pressure fuel is injected, and initial injection with a relatively small fuel injection rate is started. When the fuel pressure switching timing t described later is reached after the initial injection is started, the switching valve 31 is opened while the on-off valve 9 is kept 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 is switched to a relatively large fuel injection rate.
[0030]
Thereafter, when the fuel injection end timing is reached, the ECU 21 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 fuel injection ends. In parallel with this, the ECU 21 drives the pressure control valve 37, and gradually returns the fuel pressure in the low pressure pressure accumulation chamber 36 from the fuel passage 5 through the orifice 35 to the fuel tank 3 while returning the fuel to the fuel tank 3. The target low-pressure rail pressure tgtPLP described later is held. The switching valve 31 is closed simultaneously with the closing of the on-off valve 9 or after a predetermined time.
[0031]
When the engine operating state is changing, the injection timing I, the high and low pressure rail pressures PHP and PLP, and the fuel pressure switching timing t deviate from the actually required values, and as a result, the engine torque is changed. Become.
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 to realize the above-described injection pattern in FIG. More specifically, the ECU 21 controls the opening / closing valve 9 in step S12 based on the energization time T and the injection timing I, and controls the supply pump 2 in step S16 based on the target high-pressure rail pressure tgtPHP, while in step S102. Performs waveform control factor setting processing. The waveform control factor in this case means the above-described target low-pressure rail pressure tgtPLP and fuel pressure switching timing t. In step S102, these values are set based on the target fuel injection amount Q and the engine speed Ne, respectively. (First injection waveform setting means, second injection waveform setting means).
[0032]
Thereafter, in step S104, a waveform control factor correction process, which will be described later, is executed, and in step S106, fuel injection control is executed based on the corrected waveform control factor. That is, when the fuel pressure switching time t is reached as described above, the switching valve 31 is switched to switch the fuel injection from the low pressure to the high pressure, while the pressure control valve 37 is driven when the fuel injection end timing is reached. In preparation for the next initial injection, the rail pressure PLP in the low pressure accumulator 36 is adjusted to the target low pressure rail pressure tgtPLP.
[0033]
FIG. 7 is a flowchart showing details of the waveform control factor correction processing. When the process of step S104 is started, the ECU 21 proceeds to step S122 in FIG. 7, and in the same manner as steps S22 to S28 in FIG. 3 described in the first embodiment, in step S122, the accelerator opening Acc and the engine speed are increased. In step S124, the required torque change amount ΔT by the driver is set (requested torque change amount calculating means), and in step S126, the torque change amount ΔTp resulting from the change in the high-pressure rail pressure PHP is calculated from the map (step S124). First fuel pressure torque change amount setting means), a torque change amount ΔTt resulting from a change in injection timing I is calculated from the map in step S128 (injection timing torque change amount setting means).
[0034]
In the subsequent step S130, it is expected to occur due to changes in these waveform control factors based on changes in the waveform control factors (fuel pressure switching timing t and low-pressure rail pressure PLP) between the previous process and the current process. Torque change amount ΔTr is calculated from the map (switching valve operating timing torque change amount setting means, second fuel pressure torque change amount setting means). In step S132, the torque change amounts ΔTp, ΔTt, and ΔTr are added to calculate a predicted torque change amount ΔT ′. In subsequent step S134, it is determined whether the predicted torque change amount ΔT ′ is equal to the required torque change amount ΔT. . When the determination is NO (No), the process proceeds to step S136 to reset the fuel pressure switching timing t. The resetting process in this case is performed according to the map characteristics shown in step S130 in the figure. 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 processes in steps S130 to S136, the predicted torque change amount ΔT ′ coincides with the required torque change amount ΔT (control unit).
[0035]
The reason why the predicted torque change 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 to reduce NOx and reduce noise obtained by the initial injection. This is because the low pressure rail pressure PLP has a higher contribution to the effect and is more important.
As described above, in the accumulator fuel injection control device according to the present embodiment, the low pressure initial injection is performed prior to the high pressure main injection based on the injection pattern of FIG. As the amount of premixed combustion decreases, the combustion at the initial stage of the fuel injection period becomes relatively slow. As a result, the amount of NOx in the exhaust gas can be reduced and noise during operation can be reduced.
[0036]
In order to realize such an injection pattern, for example, in addition to the injection timing I and the rail pressure P (high pressure rail pressure PHP) applied to the rectangular wave injection pattern of the first embodiment, the fuel pressure switching related to waveform control is performed. It becomes necessary to control the time t and the low-pressure rail pressure PLP. As a result, with the conventional method in which each control factor is set independently, the engine torque correlated with the accelerator opening Acc becomes more difficult to obtain than in the first embodiment.
[0037]
On the other hand, in the present embodiment, the required torque change amount ΔT requested by the driver is calculated based on the change amount of the accelerator opening Acc, while the high and low pressure rail pressures PHP and PLP, the injection timing I, and the fuel pressure switching. A predicted torque change amount ΔT ′ generated due to a change in time t is calculated, and when the predicted torque change amount ΔT ′ is excessive or insufficient with respect to the required torque change amount ΔT, the fuel pressure switching time t is reset. As a result, the predicted torque change amount ΔT ′ is matched with the required torque change amount ΔT. Therefore, the engine torque according to the driver's accelerator operation is always realized, so that the engine can be smoothly operated without a sense of incongruity.
[0038]
This is the end of the description of the embodiment, but 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 setting procedure of the fuel injection amount Q shown in FIGS.
Further, in the first embodiment, the rail pressure P remains the set value, the injection timing I is reset and the predicted torque change amount ΔT ′ is adjusted, but conversely, the injection timing I remains the set value. The rail pressure P may be reset.
[0039]
【The invention's effect】
As described above in detail, according to the pressure accumulation type fuel injection control device of the first aspect of the invention, the engine torque change amount requested by the driver is calculated based on the change amount of the accelerator opening, while the fuel injection amount is calculated. The amount of torque change according to the timing and the change in the fuel pressure in the pressure accumulator chamber is calculated, and the injection timing or the fuel pressure in the pressure accumulator chamber is adjusted so that they match, so the engine always responds to the driver's accelerator operation Torque can be realized, and the engine can be operated smoothly without a sense of incongruity.
[0040]
Further, according to the pressure accumulation type fuel injection control device of the second aspect of the invention, since the low pressure fuel injection is performed prior to the high pressure fuel injection, the combustion in the initial stage of the fuel injection period is slowed down, and the exhaust gas NOx reduction and noise reduction during operation can be achieved, and the engine torque change amount required by the driver is calculated based on the accelerator opening change amount, while the fuel injection timing, the first accumulator chamber and the first (2) The amount of torque change corresponding to the change in the fuel pressure in the pressure accumulator chamber and the changeover valve operation timing is calculated, and the operation timing of the changeover valve is adjusted so that they match. The engine torque can be realized and the engine can be operated smoothly without any sense of incongruity.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an accumulator fuel injection control apparatus according to a first embodiment.
FIG. 2 is a flowchart showing a procedure for setting each control factor by an ECU during fuel injection control.
FIG. 3 is a flowchart showing details of injection timing correction processing.
FIG. 4 is an overall configuration diagram showing an accumulator 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 setting procedure of each control factor by the ECU at the time of fuel injection control.
FIG. 7 is a flowchart showing details of a waveform control factor correction process.
[Explanation of symbols]
4 High pressure accumulator (first accumulator)
5 Fuel passage
6 Fuel injection nozzle
9 On-off valve (fuel injection control valve)
23 Rotational speed sensor (Operating state detection means)
24 Accelerator opening sensor (operating state detection means)
31 selector 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)

Claims (2)

A pressure storage chamber for storing high-pressure fuel;
A fuel injection nozzle that is connected to the pressure accumulating chamber via a fuel passage and injects fuel into the combustion chamber of the engine;
A fuel injection control valve arranged to inject fuel stored in the pressure accumulating chamber from the fuel injection nozzle, and controls an injection amount and timing of fuel 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 of the engine;
Fuel injection timing setting means for setting the fuel injection timing based on information from the operating state detection means;
Injection timing torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set injection timing accompanying the transition of the operating state of the engine;
Fuel pressure setting means for setting a fuel pressure in the pressure accumulating chamber based on information from the operating state detecting means;
Fuel pressure torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set fuel pressure accompanying the transition of the operating state of the engine;
A required torque change amount calculating means for calculating a change amount of the engine torque from a change amount of the accelerator opening in the operating state detecting means;
The sum of the value calculated by the injection timing torque change amount calculating means and the value calculated by the fuel pressure torque change amount calculating means is the value calculated by the required torque change amount calculating means. An accumulator fuel injection control device comprising: a control means for adjusting and controlling a fuel injection timing or a fuel pressure in the accumulator chamber. A first pressure accumulation chamber for storing high-pressure fuel;
A fuel injection nozzle connected to the first accumulator through a fuel passage and injecting fuel into the combustion chamber of the engine;
A switching valve for controlling discharge of the high-pressure fuel in the first pressure accumulating chamber to the downstream side of the fuel passage;
A second pressure accumulation chamber connected to the fuel passage downstream from the switching valve via a branch passage, and storing fuel lower than the high pressure fuel in the first pressure accumulation chamber;
A fuel injection control valve arranged to inject fuel in the fuel passage from the fuel injection nozzle, and controlling an injection amount and timing of fuel 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 of the engine;
Fuel injection timing setting means for setting the fuel injection timing based on information from the operating state detection means;
Injection timing torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set injection timing accompanying the transition of the operating state of the engine;
Fuel pressure setting means for setting the fuel pressure in the first accumulator chamber based on information from the operating state detection means;
First fuel pressure torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set fuel pressure in the first pressure accumulating chamber accompanying the transition of the operating state of the engine;
First injection waveform setting means for setting a fuel pressure in the second pressure accumulating chamber based on information from the operating state detection means;
Second fuel pressure torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set fuel pressure in the second pressure accumulating chamber accompanying the transition of the operating state of the engine;
Second injection waveform setting means for setting the operation timing of the switching valve based on information from the operating state detection means;
A switching valve operation timing torque change amount calculating means for calculating a torque change amount of the engine in accordance with a change in the set operation timing of the switching valve in accordance with the transition of the operating state of the engine;
A required torque change amount calculating means for calculating a change amount of the engine torque from a change amount of the accelerator opening in the operating state detecting means;
The value calculated by the injection timing torque change amount calculating means, the value calculated by the first fuel pressure torque change amount calculating means, the value calculated by the second fuel pressure torque change amount calculating means, and the switching valve Control means for adjusting and controlling the operation timing of the switching valve so that the sum of the values calculated by the operation timing torque change amount calculation means becomes the value calculated by the required torque change amount calculation means. An accumulator fuel injection control device.

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