JP3519946B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for eliminating delay errors in fuel injection and ignition timing control. . 2. Description of the Related Art In an internal combustion engine, a microcomputer (electronic control unit) is generally used to inject fuel according to an operating state (engine speed, engine load, etc.) detected at a timing synchronized with a crank angle. The amount is calculated to determine the injection start time (or end time), measured and output at an angle (or time) from a reference signal, and the injector (fuel injection valve) is driven to inject. As an example thereof, there is a technique described in Japanese Patent Application Laid-Open No. 8-144806. The same applies to the ignition timing. [0004] That is, as shown in FIG. 9, the crank angle (T) is synchronized with the engine rotation by TDC or the like.
A signal (shown as DC) is detected, and a reference signal (shown as CRK) obtained by subdividing the TDC interval into a crank angle of 30 degrees or the like is detected. The electronic control unit calculates the fuel injection amount (and the injection timing) and the ignition timing in synchronization with the TDC signal, and sets and outputs the time (or angle) from the closest reference signal A. In this case, since the injector has an operation delay, the amount is added to the valve opening time as an invalid time. However, in addition to the operation delay of the injector, a signal processing delay time, which is indicated by a "dead zone" in the figure, necessarily exists. Assuming that the dead zone is from time t1 to t3 and the target value (time) is t2, the actual output value (time) is t3. Therefore, the offset time (or angle) is set in consideration of the dead zone, and the offset counter is started from the reference signal A. However, if the TDC interval becomes smaller as the engine speed rises, the TDC interval becomes shorter. If the offset counter is started from the reference signal A, an error (delay) may occur. In the case of FIG. 9, the dead zone cannot be avoided due to the delay from time t1 to t2, and the target fuel injection and ignition timing may not be achieved. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned disadvantages and to reliably avoid a dead zone and execute fuel injection and ignition at a target timing irrespective of fluctuations in engine speed. An object of the present invention is to provide an injection control device. In order to achieve the above object, according to the present invention, a reference for outputting a reference signal at every predetermined crank angle obtained by subdividing a TDC interval of each cylinder of an internal combustion engine. Signal output means, at least an engine speed and an engine load of the internal combustion engine are detected, a calculation means for calculating a fuel injection amount and an ignition timing based on the detected value, and based on the calculated fuel injection amount and the ignition timing, A fuel injection control device for an internal combustion engine, comprising: an execution unit that outputs at an operation timing including a delay time equivalent value with respect to the reference signal to execute fuel injection and ignition timing, wherein the execution unit includes at least the detected engine speed. The machine
Rotation speed comparing means for comparing with a predetermined value set based on a related rotation speed and the delay time equivalent value, the delay time equivalent value
Is compared with the limit value indicating the dead zone.
The detection by the comparing means and the rotational speed comparing means
Is determined to be higher than the predetermined value.
In both cases, the delay time equivalent value comparing means
When it is determined that the interval equivalent value is equal to or less than the limit value, TD
A configuration is provided in which there is provided selection means for selecting, as the reference signal, a value immediately preceding the most recent value among the reference signals output at predetermined crank angles obtained by subdividing the C interval. Thus, regardless of the fluctuation of the engine speed, the dead zone can be reliably avoided and the fuel injection and ignition can be executed at the target timing. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram generally showing a fuel injection control device for an internal combustion engine according to the present invention. In FIG. 1, reference numeral 10 denotes an OHC in-line four-cylinder internal combustion engine (hereinafter referred to as "engine").
The intake air introduced from the air cleaner 14 disposed at the tip of the intake pipe 12 passes through the surge tank 16, and through an intake (intake) manifold 20 while its flow rate is adjusted by a throttle valve 18, and is provided with two intake valves (FIG. (Not shown), and flows into first to fourth cylinders (cylinders; only one cylinder is shown) 22. A piston 24 is movably provided in each cylinder, a recess is formed at the top thereof, and a combustion chamber 28 is formed between the piston top and the inner wall of the cylinder head 26. An injector (fuel injection valve) 30 is provided near the center of the position facing the combustion chamber 28. The injector 30 is connected to a fuel supply pipe 34, through which a fuel tank (not shown) is connected.
When the fuel supply (gasoline fuel) pressurized by a fuel pump (not shown) is supplied, the fuel is injected into the combustion chamber 28 when the valve is opened. A spark plug 36 is disposed in the combustion chamber 28 of each cylinder. The ignition plug 36 receives ignition energy from an ignition device (not shown) including an ignition coil,
At a predetermined ignition timing, a mixture of injected fuel and intake air is ignited in the order of first, third, fourth, and second cylinders. The ignited mixture burns and explodes, driving the piston 24. As described above, the engine 10 according to this embodiment directly injects gasoline fuel into the cylinder combustion chamber.
It is a direct injection engine. More specifically, when the engine 10 is under a high load, gasoline fuel is injected at an air-fuel ratio of 12.0 to 29: 1 in the intake stroke. The injected fuel is integrated with the intake air and ignited to produce the uniform combustion described above (referred to herein as "premixing"). When the engine 10 is at a low load, the gasoline fuel is supplied with an air-fuel ratio of 30 to 6 during the compression stroke.
Inject at 0: 1. The injected fuel is ignited, producing the stratified combustion described above (referred to herein as "DISC").
DISC stands for super-stratified lean burn. Fuel injection is mainly performed in a suction stroke in premixing and in a compression stroke in DISC. The exhaust gas after combustion is discharged to an exhaust (exhaust) manifold 40 via two exhaust valves (not shown), and travels through an exhaust pipe 42 to a NOx component removing catalyst device 44 and a three-way catalyst device. 46, where it is purified and discharged out of the engine. Downstream of the exhaust manifold 40, an exhaust pipe 42 is connected to the intake pipe 12 via an EGR pipe 50, and recirculates a part of exhaust gas to an intake system. EGR pipe 5
0, the EGR valve 52 near the connection to the intake pipe 12
Is provided to adjust the EGR reflux amount. Further, the mechanical connection between the throttle valve 18 and an accelerator pedal (not shown) arranged on the floor of the driver's seat of the vehicle is eliminated, and the throttle valve 18 is connected to the pulse motor 54 and driven by the output thereof. Then, the intake pipe 12 is opened and closed. As described above, the throttle valve 18 is connected to the DB
It is driven by the W method. The piston 24 is connected to a crankshaft 56, and a crank angle sensor 62 is arranged near the crankshaft 56. Crank angle sensor 62
Is a pulsar 62 attached to a crankshaft 56.
a and a magnetic pickup 62b disposed opposite thereto
Consists of The crank angle sensor 62 is provided at every predetermined crank angle of a specific cylinder, that is, at a crank angle 720
A CYL signal for cylinder discrimination for each degree, a TDC signal for each TDC (top dead center) of each cylinder as shown in FIG. 9, and a crank angle 30 obtained by subdividing the TDC signal interval into six.
A reference signal (CRK signal) is output every time. In this specification and the drawings, a reference signal (CRK signal) interval is called a stage. Returning to FIG. 1, a throttle sensor 64 is connected to the pulse motor 54 and outputs a signal corresponding to the opening TH of the throttle valve 18 through the pulse motor opening. An absolute pressure (MAP) sensor 66 is provided near the position of the throttle valve 18 in the intake pipe 12, and outputs a signal corresponding to the absolute pressure PBA in the intake pipe. In addition, an intake air temperature sensor 68 is provided in the intake pipe 12 upstream of the position where the throttle valve 18 is disposed, and outputs a signal corresponding to the intake air temperature TA. A water temperature sensor 70 is provided near the cylinder 22 and outputs a signal corresponding to the cylinder cooling water temperature TW. An O ₂ sensor (air-fuel ratio sensor) 72 is provided in the exhaust pipe 42 on the upstream side of the catalyst devices 44 and 46.
In addition to outputting a signal proportional to the oxygen concentration in the exhaust gas, an exhaust temperature sensor 74 is provided downstream of the catalyst devices 44 and 46, and outputs a signal proportional to the exhaust gas temperature TEX. These sensor outputs are sent to an electronic control unit (hereinafter referred to as “ECU”) 80. ECU80
Is provided with a microcomputer including a CPU, a ROM, a RAM, and the like, and calculates (determines) a fuel injection amount, an injection timing, and an ignition timing based on sensor input values as described later.
I do. The ECU 80 includes a counter (not shown).
The CRK signal output from the crank angle sensor 62 is counted to detect the engine speed NE. Next, the operation of the fuel injection control device for an internal combustion engine according to the present invention will be described. FIGS. 2 and 3 are flow charts showing the operation.
4 and 5 are time charts for explaining the operation. The object of the present invention is to execute the fuel injection and the ignition timing at the target timing while avoiding the dead zone. Therefore, the following description focuses on this point. This will be described with reference to the flowchart of FIG. The illustrated program is shown in the upper part of FIG time chart is performed in synchronization with the TDC signal as described above. In the following, in S10, the above-mentioned sensor output value is read, and the operating state is detected. Then, the program proceeds to S12, in which the fuel injection amount and the injection timing (specifically, the injection start timing. More specifically, the offset time TWTOFFi.
F and the injection start stage FISTGi. F, etc.). In this specification and drawings, i indicates a cylinder number (1 to 4). That is, in S12, a preset characteristic (map; not shown) is searched using the detected engine speed NE and the intake pipe absolute pressure PBA to obtain the basic fuel injection amount. water temperature TW detected value is corrected in such as oxygen concentration KO ₂ calculates a fuel injection amount. Further, the injection time (defined by the valve opening time of the injector 30) is calculated based on the calculated fuel injection amount, and the offset time TWTOFFi. F and the injection start stage FISTGi. F and the like are calculated. Then, the program proceeds to S14, in which an ignition timing is calculated based on the detected operating condition. That is, a preset characteristic (map, not shown) is searched for using the detected engine speed NE and the intake pipe absolute pressure PBA, a basic ignition timing is obtained, and the obtained value is detected and the detected water temperature TW and the like. To calculate the ignition timing. More specifically, the energization start angle (energization offset angle) IGAONi, the energization timer start stage IG
ONSTGi, ignition angle (offset angle) IGAOF
Fi, and the ignition timer activation stage IGOFF. ST
Gi or the like is calculated. Next, the routine proceeds to S16, where the calculated injection (start) timing is finally determined. That is, the output timing of the fuel injection is finally determined while avoiding the dead zone. In this embodiment, the fuel injection timing and the ignition timing are set by the elapsed time from the reference signal (CRK signal; angle). FIG. 3 is a subroutine flowchart showing the operation. First, in S100, the detected engine speed NE is larger than a predetermined value NEIJMOD, and the calculated offset time TWTOFFi. It is determined whether or not F is equal to or less than a limit value TWTOFFLMT (the above-described dead zone equivalent value). When the result in S100 is affirmative, the program proceeds to S102, in which the injection start stage FISTGi. F is FISTG
i. F−1, that is, the immediately preceding reference signal (CRK signal). Specifically, the reference signal B is used instead of the reference signal A in the time chart of FIG. At the same time, the calculated offset time TWTOFFi. The value CRME is added to F, and the added value is set in the offset counter and started. Here, the value CRME means the crank cycle, that is, the time between stages (between reference signals) (the reciprocal of the engine speed). The added value is limited to 2 × CRME. In other words, the retrospective of the reference signal has a maximum of 2
Up to immediately before. FIG. 4 shows the characteristics of the predetermined value NEIJMOD.
FIG. 5 shows the characteristic of the limit value TWTOFFLMT. As shown in FIG. 4, a predetermined value NEIJMOD
Is set at a point where the time conversion value of the required angle accuracy and the delay time intersect (coincide). The delay time is constant with respect to the engine speed, but the required accuracy (time conversion value) decreases as the engine speed increases, as shown in the figure. Therefore, a value that matches the two values is set as a predetermined value. As shown in FIG. 5, when this control is not performed, fuel injection starts (injector 3) due to the dead zone.
0 drive pulse ON) is not at time t4 but at time t4.
5 and a situation may occur in time. Therefore, the engine speed NE is set to the predetermined value NE.
Greater than IJMOD, offset time TWTOFF
i. When it is determined that F is equal to or less than the limit value TWTOFFLMT, the offset counter is started from the immediately preceding reference signal. That is, as shown in FIG.
The offset time is started not from the reference signal A but from the immediately preceding reference signal B. As a result, as shown in the figure, the target value (time) and the actual output value (time) can be made to coincide with time t2, and fuel injection can be performed at a desired time regardless of an increase in the engine speed. Can be realized. In the flowchart of FIG.
If the result is 0, the process proceeds to S104, and the offset counter is started from the reference signal A according to the calculated value. Returning to the description of the flow chart of FIG. 2, the program proceeds to S18, where the ignition timing is finally determined. FIG. 6 is a subroutine flowchart showing the processing. In the following, in S200, the value CRME is set to the second predetermined value ME. The ignition angle (offset angle) IG smaller than IGOMID and calculated
AOFFi is the limit value IGA. FACT (the above-mentioned dead zone equivalent value) or less, or the aforementioned value CRME is the third value.
Predetermined value ME. It is determined whether or not it is smaller than IGOHI. In S200, CRME is set to the second predetermined value ME.
IGOMID and IGAOFFi is equal to the limit value IGA. It is judged to be less than FACT or C
RME has a third predetermined value ME. Proceeds to S202 when it is determined that IGOHI smaller, ignition timer start scan tape <br/> di IGOFF. Set STGi to IGOFF. STGi-1,
That is, the reference signal (CRK signal) immediately before is used, and
The increase is corrected by adding 30 degrees to the ignition angle IGAOFFi. FIG. 7 shows a second predetermined value ME. The characteristics of IGOMID are shown in FIG. 4 shows the characteristics of FACT. These are NEIJOMOD shown in FIG. 4 and FIG.
Is the same value as TWTOFFLMT shown in FIG. Since the value CRME is the reciprocal of the engine speed, the delay time is shown to be proportional to the engine speed. Further, the third predetermined value ME. IGOHI is also ME. This is a value similar to IGOMID. Thus, when the engine speed is high, the ignition timer can be similarly started from the immediately preceding reference signal, and regardless of the increase in the engine speed, the dead zone can be reliably avoided to achieve the desired time. Ignition can be realized. In the flowchart of FIG.
If the result is 0, the process proceeds to S204, and the ignition timer is started from the reference signal A according to the calculated value. When the time is calculated in S200 of FIG. 6, IGAOFFi is equal to the limit value IGA. FA
CT, the time conversion value TIGi is replaced with the time conversion limit value TIG. You may make it determine whether it is below FACT. In that case, IGA
What is necessary is just to add CRME using TIGi instead of OFFi. In this embodiment, an internal combustion engine (engine 1
0) at each predetermined crank angle, a reference signal (CRK signal,
Reference signal output means (crank angle sensor 62, ECU 80, S10) for outputting reference signals A, B) for detecting at least the engine speed (engine speed NE) and engine load (intake pipe absolute pressure PBA) of the internal combustion engine. and, calculating means for calculating a fuel injection amount and ignition timing on the basis of the detected value (ECU 80, S12, S14), and based on said calculated fuel injection amount and the ignition timing, the time equivalent value TW T delay with respect to the reference signal OFFi. F, IGAOF
In an internal combustion engine fuel injection control device including an execution unit (ECU 80) that outputs fuel at an operation timing including Fi to execute fuel injection and ignition timing, the execution unit includes at least the detected engine speed (engine speed). N
E, crank cycle CRME) to a predetermined value (NEIJOMO
D, ME. Comparison means (ECU for comparison with IGOMID)
80, S100, S200), and the reference signal A output at every predetermined crank angle on the basis of a comparison result of the comparing means, selecting means for selecting as the reference signal either a B (ECU 80, S102, S202). Thus, the ECU 80 can execute the fuel injection and the ignition at the target timing while reliably avoiding the dead zone regardless of the fluctuation of the engine speed. Further, the predetermined value is set based on the engine speed and the delay time equivalent value. Thus, regardless of the fluctuation of the engine speed, the dead zone can be more reliably avoided and the fuel injection and ignition can be executed at the target timing. In the embodiment, the direct injection engine is taken as an example of the internal combustion engine. However, the present invention is not limited to this, and is applicable to other ordinary internal combustion engines. According to the first aspect of the present invention, it is possible to execute the fuel injection and the ignition at the target timing while reliably avoiding the dead zone regardless of the fluctuation of the engine speed. [0065]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an overall fuel injection control device for an internal combustion engine according to the present invention. FIG. 2 is a flowchart showing the operation of the control device of FIG. 1; FIG. 3 is a subroutine flowchart showing an injection (start) timing determination operation in the flowchart of FIG. 2; FIG. 4 is a predetermined value NEI used in the flowchart of FIG. 3;
It is an explanatory graph which shows the characteristic of JOMOD. FIG. 5 is a limit value T used in the flow chart of FIG.
It is an explanatory graph which shows the characteristic of WTOFFLMT. FIG. 6 is a subroutine flowchart showing an ignition timing determination operation in the flowchart of FIG. 2; FIG. 7 shows a predetermined value ME. Used in the flow chart of FIG.
It is an explanatory graph which shows the characteristic of IGOMID. FIG. 8 is a limit value I used in the flow chart of FIG.
GA. It is an explanatory graph which shows the characteristic of FACT. FIG. 9 is a time chart showing the operation of the fuel injection control device for an internal combustion engine according to the present invention in comparison with the conventional art. DESCRIPTION OF SYMBOLS 10 Internal combustion engine (engine) 12 Intake pipe 22 Cylinder (cylinder) 28 Combustion chamber 30 Injector (fuel injection valve) 36 Spark plug 62 Crank angle sensor 66 Absolute pressure (MAP) sensor 80 Electronic control unit (ECU) 14 piston

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02P 5/15 F02P 5/15 C (72) Inventor Hidetoshi Sakurai 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda R & D Co., Ltd. In-house (56) References JP-A-8-326572 (JP, A) JP-A-62-232263 (JP, A) JP-A-60-1666734 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/14 330 F02D 41/02 325 F02D 43/00 301 F02D 45/00 322 F02P 5/15

Claims (1)

(57) [Claims] Claims a. Reference signal output means for outputting a reference signal for each predetermined crank angle obtained by subdividing the TDC interval of each cylinder of the internal combustion engine; b. Calculating means for detecting at least an engine speed and an engine load of the internal combustion engine, and calculating a fuel injection amount and an ignition timing based on the detected values; and c. A fuel injection control device for an internal combustion engine, comprising: an execution unit that outputs at an operation timing including a delay time equivalent value with respect to the reference signal based on the calculated fuel injection amount and ignition timing to execute fuel injection and ignition timing. , Said execution means: d. At least the detected engine speed is used as the engine speed.
A number of revolutions comparing means for comparing the number with a predetermined value set based on the delay time equivalent value ; e . The delay time equivalent value is defined as a limit value indicating a dead zone.
Delay time equivalent value comparing means for comparing , and f . The engine speed detected by the rotation speed comparing means.
When the number of turns is determined to be higher than the predetermined value,
The delay time equivalent value is set earlier by the delay time equivalent value comparison means.
Selecting means for selecting, as the reference signal, a value one immediately before the most recent value among the reference signals output at every predetermined crank angle obtained by subdividing the TDC interval, A fuel injection control device for an internal combustion engine, comprising: