JP2008095554A - Fuel injection control device and fuel injection control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of accurately learning a non-injection current carrying time without worsening a driving feeling. <P>SOLUTION: The fuel injection control device learning the non-injection current carrying time until fuel is actually injected after instructing fuel injection to an injector, has an injection instructing means for instructing fuel injection to the injector (step S33), an engine state determining means for determining whether a change has occurred to the engine operating state after the lapse of a reference time after instructing the fuel injection (step S36), a reference time updating means for updating the reference time by adding a predetermined time to the reference time when no change has occurred to the engine operating state (step S32), and a non-injection current carrying time learning means for learning the time obtained by subtracting the predetermined time from the reference time at that time, as the non-injection current carrying time (step S38). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus and method for controlling fuel injection of an engine.

  The engine injects fuel from the injector. The injector controls fuel injection / stop by moving a needle valve provided inside. Therefore, even if an injection command signal is sent to the injector, a slight time lag (non-injection energization time) occurs until the needle valve moves and actually injects fuel. Therefore, it is important to accurately detect such non-injection energization time and control the injector in consideration of the non-injection energization time.

Therefore, in the conventional fuel injection control device, the energization time until the output value of the sensor for detecting that the fuel has been injected by increasing / decreasing the energization time when the fuel injection is cut is stored as the minimum energization time. (See Patent Document 1).
JP 2001-90580 A

  However, the above-described conventional fuel injection control device can learn only at the time of fuel cut, that is, at the time of deceleration. When fuel is actually injected, torque is generated, so that the feeling of deceleration is impaired and the driving feeling is deteriorated.

  The present invention has been made paying attention to such conventional problems, and an object of the present invention is to provide a fuel injection control device that can accurately learn the non-injection energization time without deteriorating the driving feeling. Yes.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention is a fuel injection control device that learns a non-injection energization time from when a fuel injection is commanded to an injector (12) to when the fuel is actually injected, with respect to the injector (12). Injection command means for commanding fuel injection (steps S24 and S33), and engine state determination means for determining whether or not a change has occurred in the engine operating state after a lapse of a reference time after commanding fuel injection (steps S27 and S36) When there is no change in the engine operating state, reference time updating means (step S32) for updating the reference time by adding a predetermined time to the reference time, and when there is a change in the engine operating state And non-injection energization time learning means (steps S29 and S38) for learning, as a non-injection energization time, a time obtained by subtracting the predetermined time from the reference time at that time. To.

  According to the present invention, if there is no change in the engine operating state after the lapse of the reference time after commanding the fuel injection, the reference time is updated by adding a predetermined time to the reference time, and the engine operation is performed after the lapse of the reference time. When a change occurs in the state, the time obtained by subtracting the predetermined time from the reference time at that time is learned as the no-injection energization time, so the no-injection energization time can be learned accurately. Further, if such learning is performed by pilot injection during steady driving during driving, the driving feeling of the driver is not deteriorated.

  Hereinafter, the best mode for carrying out the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a system diagram showing an embodiment of a fuel injection control device according to the present invention.

  The fuel injection control device 1 is a device that injects fuel, which has been increased in pressure by the high-pressure pump 14 and temporarily accumulated in the common rail 13, from the injector 12 to the diesel engine 10. The pressure of the common rail 13 is detected by a pressure sensor 13a.

  Part of the exhaust gas discharged from the diesel engine 10 and flowing through the exhaust passage 23 returns to the intake passage 21 via an exhaust gas recirculation device (hereinafter referred to as “EGR device”) 30. The EGR device 30 includes an EGR cooler 32 and an EGR valve 33 in the EGR passage 31. The EGR cooler 32 cools the exhaust gas recirculated from the exhaust passage 23. The EGR valve 33 is opened and closed to adjust the EGR amount. The EGR valve 33 is duty-controlled by the controller 70. Downstream of the exhaust passage 23, a diesel oxidation catalyst (DOC) that reduces particulate matter (PM) by oxidation with a catalyst such as palladium or platinum, or a porous thin wall flows in a lattice pattern. A diesel particulate filter (Diesel Particulate Filter; DPF) or the like that captures PM contained in the exhaust gas is provided, which is a honeycomb structure having a defined path.

  The operating state of the engine 10 is detected by various sensors. The crank angle sensor 61 detects the rotational speed of the diesel engine 10 (the rotational speed of the crankshaft 11). Knock sensor 62 detects vibration of the engine cylinder. The air-fuel ratio sensor 63 is attached to the exhaust passage and detects the exhaust air-fuel ratio.

  The controller 70 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

  The controller 70 receives signals from the crank angle sensor 61, the knock sensor 62, and the air-fuel ratio sensor 63, and determines the operating state of the engine based on these signals. The controller 70 controls the injector 12 and the high pressure pump 14 based on the input signal to adjust the fuel injection amount and the injection timing. The controller 70 adjusts the opening degree of the throttle valve 22 based on the input signal. The controller 70 performs duty control on the EGR valve 33. The controller 70 controls these to adjust the excess air ratio (air-fuel ratio) (λ control) to adjust the unburned components (hydrocarbon HC) contained in the exhaust gas, and increase the exhaust gas temperature flowing out from the DOC 40 And DPF regeneration is executed.

  The injector 12 controls fuel injection / stop by moving a needle valve provided inside. There is a slight time lag between when the controller 70 sends an injection command signal to the injector 12 and when the needle valve moves to actually inject fuel. The time during which the fuel is not injected despite the energization is called the non-injection energization time.

  Next, the specific operation of the fuel injection control apparatus according to the present invention will be described with a focus on the operation of the controller 70. FIG. 2 is a main flowchart for explaining the operation of the fuel injection control device. When the learning operation condition (during steady operation (running) and the injection pressure is within a predetermined range) is established, the controller 70 is repeatedly executed every minute time to learn the non-injection energization time. Further, the controller 70 learns the non-injection energization time for each injection pressure.

  In step S1, the controller 70 determines whether or not the non-injection state flag is 1. This non-injection state flag is a flag for determining that fuel is not being injected even though an injection command signal is sent from the controller 70 to the injector 12, and its initial value is zero. If the non-injection state flag is 1, the process proceeds to step S3, and if not, the process proceeds to step S2.

  In step S2, the controller 70 performs a non-injection state determination process. Specific contents will be described later.

  In step S3, the controller 70 performs a non-injection process. Specific contents will be described later.

  FIG. 3 is a flowchart of a non-injection state determination processing routine.

  In step S21, the controller 70 determines whether or not the pilot injection flag is 1. The pilot injection flag is a flag that becomes 1 during the pilot injection command. If the pilot injection flag is 1, the process proceeds to step S25; otherwise, the process proceeds to step S22.

  In step S22, the controller 70 determines whether or not a learned value of the non-injection energization time Tn is stored. If this time is the first processing, the learning value is not stored, but if the previous processing is performed, the learning value is stored. If not stored, the process proceeds to step S23, and if stored, the process proceeds to step S24.

  In step S23, the controller 70 sets the energization time T0 as the non-injection energization time Tn. The energization time T0 is obtained based on the characteristic map shown in FIG. This map is set in advance through experiments.

  In step S24, the controller 70 commands pilot injection and sets a pilot injection flag to 1.

  In step S25, the controller 70 determines whether or not the time Tn has elapsed since the pilot injection was commanded. If it has not elapsed, the process once exits, and if it has elapsed, the process proceeds to step S26.

  In step S26, the controller 70 resets the pilot injection flag and sets it to zero.

  In step S27, the controller 70 determines whether or not there is a change in the engine operating state. Specifically, the determination is made based on whether or not the engine rotation speed detected by the crank angle sensor 61 has increased and whether or not the engine vibration detected by the knock sensor 62 has decreased. If such a change is detected, the process proceeds to step S28, and if not detected, the process proceeds to step S30.

  In step S28, the controller 70 updates the non-injection energization time Tn by subtracting the fixed time T1 from the non-injection energization time Tn. The fixed time T1 is a preset coincidence value.

  In step S29, the controller 70 stores the updated non-injection energization time Tn as a learning value.

  In step S30, the controller 70 sets 1 to the non-injection state flag.

  FIG. 4 is a flowchart of the non-injection processing routine.

  In step S31, the controller 70 determines whether or not the pilot injection flag is 1. If the pilot injection flag is 1, the process proceeds to step S34; otherwise, the process proceeds to step S32.

  In step S32, the controller 70 adds the fixed time T1 to the non-injection energization time Tn to update the non-injection energization time Tn.

  In step S33, the controller 70 commands pilot injection and sets a pilot injection flag to 1.

  In step S34, the controller 70 determines whether or not the time Tn has elapsed since the pilot injection was commanded. If it has not elapsed, the process once exits, and if it has elapsed, the process proceeds to step S35.

  In step S35, the controller 70 resets the pilot injection flag and sets it to zero.

  In step S36, the controller 70 detects the fluctuation of the exhaust air-fuel ratio based on the signal from the air-fuel ratio sensor 63. If the fluctuation range is larger than the predetermined value A, the process proceeds to step S37, and if not, the process is temporarily exited.

  In step S37, the controller 70 updates the non-injection energization time Tn by subtracting a fixed time T1 from the non-injection energization time Tn.

  In step S38, the controller 70 stores the updated non-injection energization time Tn as a learning value.

  In step S39, the controller 70 resets the non-injection state flag to 1 and sets it to 0.

  With the above processing, the controller operates as follows.

  The non-injection state flag is initially 0 (No in Step S1), the pilot injection flag is also initially 0 (No in Step S21), and the learning value of the non-injection energization time Tn is not stored (No in Step S22). The energization time T0 set in the map is set as the non-injection energization time Tn (step S23), and pilot injection is commanded (step S24).

  In the next cycle, since the pilot injection flag is set to 1 (Yes in Step S21), Steps S1 → S21 → S25 are repeated until the time Tn elapses from the pilot injection command, and when it has elapsed (Yes in Step S25), The pilot injection flag is reset (step S26), and it is determined whether or not the engine operating state has changed (step S27). If there is a change, the non-injection energization time Tn updated in step S28 is stored as a learning value (step S29), and if there is no change, it is determined that the fuel is not injected during the time Tn, and no injection state is determined. A flag is set (step S30).

  When the non-injection state flag is set, the non-injection process is performed in the next cycle (step S1 → S3).

  Since the pilot injection flag is 0 in the initial process, the non-injection energization time Tn is updated (step S32), and pilot injection is commanded (step S33).

  In the next cycle, since the pilot injection flag is set to 1 (Yes in Step S31), Steps S1 → S31 → S34 are repeated until the time Tn has elapsed from the pilot injection command, and when it has elapsed (Yes in Step S34), The pilot injection flag is reset (step S35), and it is determined whether or not the exhaust air / fuel ratio has changed (step S36).

  If there is no change in the exhaust air-fuel ratio, the process is temporarily exited, the non-injection energization time Tn is updated in the next cycle (step S32), pilot injection is commanded (step S33), and the time Tn has elapsed from the pilot injection command (step S32). In S34, Yes), a change in the exhaust air-fuel ratio is determined (step S36).

  The above process is repeated until the exhaust air-fuel ratio changes to update the non-injection energization time Tn. When the exhaust air-fuel ratio changes (Yes in step S36), the non-injection energization time Tn updated in step S37 is stored as a learned value. (Step S38).

  According to this embodiment, it is detected whether fuel is actually injected by a change in the engine when the injector 12 is energized for a short time as pilot injection during steady operation during traveling, and the energization time is changed, Learn no-injection energization time. As described above, since the non-injection energization time can be learned except when the fuel is cut, the learning opportunities increase. Moreover, the non-injection energization time is learned for each injection pressure. By learning the non-injection energization time in this way, fuel can be injected accurately, and variations in vibration and sound can be suppressed.

  Further, since the pilot injection is performed during the steady operation during traveling, the engine torque can be prevented from changing suddenly and the driving feeling of the driver is not deteriorated.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  In the above description, the diesel engine is exemplified as the engine, but a spark ignition engine (gasoline engine) may be used.

1 is a system diagram showing an embodiment of a fuel injection control device according to the present invention. It is a main flowchart explaining operation | movement of a fuel-injection control apparatus. Conte It is a flowchart of a non-injection state determination processing routine. It is a flowchart of the process routine at the time of non-injection. It is a map which sets the initial value of the non-injection energization time from the common rail pressure and the injection amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diesel engine 12 Injector 61 Crank angle sensor 62 Knock sensor 63 Air-fuel ratio sensor 70 Controller Step S24, S33 Injection command means Step S27, S36 Engine state determination means Step S32 Reference time update means Step S29, S38 Non-injection energization time learning means

Claims (7)

A fuel injection control device that learns a non-injection energization time from when a fuel injection is commanded to an injector until fuel is actually injected,
Injection command means for commanding fuel injection to the injector;
Engine state determination means for determining whether or not a change has occurred in the engine operating state after a lapse of a reference time after commanding fuel injection;
Reference time updating means for adding a predetermined time to the reference time and updating the reference time when no change has occurred in the engine operating state;
A non-injection energization time learning means for learning, as a non-injection energization time, a time obtained by subtracting the predetermined time from the reference time at the time when a change occurs in the engine operating state;
A fuel injection control device comprising: The fuel injection is a pilot injection that is injected prior to the main injection.
The fuel injection control device according to claim 1. The fuel injection is performed during steady operation during traveling.
The fuel injection control device according to claim 1. The engine state determining means determines that a change has occurred in the engine operating state when the engine speed increases.
The fuel injection control device according to any one of claims 1 to 3, wherein the fuel injection control device is a fuel injection control device. The engine state determining means determines that a change has occurred in the engine operating state when engine vibration is reduced,
The fuel injection control device according to any one of claims 1 to 3, wherein the fuel injection control device is a fuel injection control device. The engine state determining means determines that a change has occurred in the engine operating state when the exhaust air-fuel ratio fluctuates;
The fuel injection control device according to any one of claims 1 to 3, wherein the fuel injection control device is a fuel injection control device. A fuel injection control method for learning a non-injection energization time from when a fuel injection is commanded to an injector until fuel is actually injected,
An injection commanding step for commanding fuel injection to the injector;
An engine state determination step for determining whether or not a change has occurred in the engine operation state after a lapse of a reference time after commanding fuel injection;
A reference time update step of adding a predetermined time to the reference time and updating the reference time when no change has occurred in the engine operating state;
A non-injection energization time learning step of learning, as a non-injection energization time, a time obtained by subtracting the predetermined time from the reference time at the time when a change occurs in the engine operating state;
A fuel injection control method comprising: